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DICTIONARY 

OF 

CHEMISTRY, 

ON  THE 

BASIS  OF  MR.  NICHOLSON'S; 

IN  WHICH 

THE  PRINCIPLES  OF  THE  SCIENCE  ARE  INVESTIGATED  ANEW, 

AND  ITS  APPLICATIONS  TO  THE  PHENOMENA  OF  NATURE,  MEDICINE, 

MINERALOGY,  AGRICULTURE,  AND  MANUFACTURES, 

DETAILED. 


BY  ANDREW  URE,  M.  D. 

I'HOIESSOR  OF  THE  ANDERSONIAN  INSTITUTION,  MEMBER  OF  THE  GEOLOGICAL  SOCIETY, 

&c.  &c. 


WITH  AN 

3}ntr0twctorp 

CONTAINING 

INSTRUCTIONS  FOR  CONVERTING  THE  ALPHABETICAL  ARRANGEMENT 
INTO  A  SYSTEMATIC  ORDER  OF  STUDY. 


FIRST  AMERICAN  EDITION,- 

WITH  SOME  ADDITIONS,  NOTES,  AND  CORRECTIONS, 
BY  ROBERT  HARE,  M.  D. 

PROFESSOR  OF  CHEMISTRY  IN  THE  UNIVERSITY  OF  PENNSYLVANIA. 
ASSISTED   BY 

FRANKLIN  BACHE,  M.  D. 

MEMBER  OF  THE  AMERICAN  PHILOSOPHICAL   SOCIETY,  AND   OF  THE  ACADEMY  OF  NATURAL 
SCIENCES  OF  PHILADELPHIA. 


IN  TWO  VOLUMES, 

VOL.  I. 

PHILADELPHIA: 

PUBLISHED  BY  ROBERT  DESILVER,  No.  110,  WALNUT  STREET 


Eastern  District  of  Pennsylvania,  to  wit: 

BE  IT  REMEMBERED,  That  on  the  thirteenth  day  of  October,  in  the  forty-sixth 
year  of  the  independence  of  the  United  States  of  America,  A.  D.  1821,  Robert  Desil- 
ver,  of  the  said  district,  hath  deposited  in  this  office  the  title  of  a  book,  the  right 
thereof  he  claims  as  proprietor,  in  the  words  following,  to  wit : 

"  A  Dictionary  of  Chemistry  on  the  basis  of  Mr.  Nicholson's ;  in  which  the  prin- 
"  ciples  of  the  Science  are  investigated  anew,  and  its  applications  to  the  phenomena 
**  of  Nature,  Medicine,  Mineralogy,  Agriculture,  and  Manufactures,  detailed.  By  An- 

-  "  drew  Ure,  M.  D.  Professor  of  the  Andersonian  Institution,  Member  of  the  Geologi- 
"  cal  Society,  <xc  &c  with  an  Introductory  Dissertation ;  containing  instructions  for 
"  converting  the  Alphabetical  Arrangement  into  a  systematic  order  of  study.  First 
"  American  edition ;  with  some  additions,  notes,  and  corrections,  by  Robert  Hare,  M. 
"  D.  Professor  of  Chemistry  in  the  University  of  Pennsylvania :  Assisted  by  Franklin 
"  Bache,  M.  D  Member  of  the  American  Philosophical  Society,  and  of  the  Academy 

.  «« of  Natural  Sciences  of  Philadelphia.   In  two  Volumes." 

In  conformity  to  the  act  of  the  Congress  of  the  United  States,  entitled  "  An  Act  for 
the  Encouragement  of  Learning,  by  securing  the  copies  of  Maps,  Charts,  and  Books,  to 
the  authors  and  proprietors  of  such  copies,  during  the  times  therein  mentioned." — And 
also  to  the  act,  entitled,  "  An  act  supplementary  to  an  act,  entitled,  '  An  act  for  the  En- 
couragement of  Learning,  by  securing  the  copies  of  Maps,  Charts,  and  Books,  to  the  au- 
thors and  proprietors  of  such  copies  during  the  times  therein  mentioned,'  and  extending 
the  benefits  thereof  to  the  arts  of  designing,  engraving1,  and  etching  historical  and  other 
prints."  D.  CALDWELL, 

Clerk  of  the  Eastern  District  of  Pennsylvania. 


Paper,  manufactured  by       ; 
Joshua  and  Thomas  Gilpin.  j 


•y.i 

TO 

THE  RIGHT  HONOURABLE 

THE    EARL    OF    GLASGOW, 

BARON  ROSS  OF  HAWIIEAD, 
&c.  &c.  &c. 

LORD-LIEUTENANT  OF  AYRSHIRE. 

MY  LORD, 

WHEN  I  inscribe  this  volume  to  your  Lordship,  it  is  neither 
to  offer  the  incense  of  adulation,,  which  your  virtues  do  not  need,  and 
your  understanding  would  disdain;  nor  to  solicit  the  patronage  of  exalted 
rank  to  a  work,  which  in  this  age  and  nation  must  seek  support  in  scientific 
value  alone.  The  present  dedication  is  merely  an  act  of  gratitude,  as  pure 
on  my  part,  as  your  Lordship's  condescension  and  kindness  to  me,  have 
been  generous  and  unvarying.  At  my  outset  in  life,  your  Lordship's  dis- 
tinguished favour  cherished  those  studious  pursuits,  which  Jiave  since 
formed  my  chief  pleasure  and  business;  and  to  your  Lordship's  hospitali- 
ty I  owe  the  elegant  retirement,  in  which  many  of  the  following  pages 
were  written.  Happy  would  it  have  been  for  their  readers,  could  I  hare 
transfused  into  them  a  portion  of  that  gracq  of  diction,  and  elevation  of 
sentiment,  which  I  have  so  often  been  permitted  to  admire  in  your  Lord-- 
ship's family. 

I  have  the  honour  to  be, 

MY  LORD, 

Your  Lordship's  most  obedient 
And  very  faithful  Servant, 

ANDREW  URE, 
Glasgow,  JVou.  7, 1820. 


M360409 


INTRODUCTION. 


AN  this  Introduction  I  shall  first  present  a  GENERAL  VIEW  of  the  objects 
of  chemistry,  along  with  a  scheme  for  converting  the  alphabetical  arrange- 
ment adopted  in  this  volume,  into  a  systematic  order  of  study.  I  shall  then 
describe  the  manner  in  which  this  Dictionary  seems  to  have  been  original- 
ly compiled,  and  the  circumstances  under  which  its  present  regeneration 
has  been  attempted.  This  exposition  will  naturally  lead  to  an  account  of 
the  principles  on  which  the  investigations  of  chemical  theory  and  facts 
have  been  conducted,which  distinguish  this  Work  from  a  mere  compilation. 
Some  notice  is  then  given  of  a  treatise  on  practical  chemistry,  publicly  an- 
nounced by  me  upwards  of  three  years  ago,  and  of  the  peculiar  circum- 
stances of  my  situation  as  a  teacher,  which  prompted  me  to  undertake  it, 
though  its  execution  has  been  delayed  by  various  obstructions. 


THE  forms  of  matter  are  numberless,  and  subject  to  incessant  change. 
Amid  all  this  variety  which  perplexes  the  common  mind,  the  eye  of  science 
discerns  a  few  unchangeable  primary  bod'es,  by  whose  reciprocal  actions 
and  combinations,  this  marvellous  diversity  and  rotation  of  existence,  are 
produced  and  maintained.  These  bodies,  having  resisted  every  attempt  to 
resolve  them  into  simpler  forms  of  matter,  are  called  undecomfiounded,  and 
must  be  regarded  in  the  present  state  of  our  knowledge  as  experimental 
elements.  It  is  possible  that  the  elements  of  nature  are  very  dissimilar;  it 
is  probable  that  they  are  altogether  unknown;  and  that  they  are  so  recon- 
dite, as  for  ever  to  elude  the  sagacity  of  human  research. 

The  primary  substances  which  can  be  subjected  to  measurement  and 
•weight,  are  fifty-three  in  number.  To  these,  some  chemists  add  the  im- 
ponderable elements, — light,  heat,  electricity,  and  magnetism.  But  their 
separate  identity  is  not  clearly  ascertained. 

Of  the  fifty-three  ponderable  principles,  certainly  three,  possibly  four, 
require  a  distinct  collocation  from  the  marked  peculiarity  of  their  powers 
and  properties.  These  are  named  Chlorine,  Oxygen,  Iodine  (and  Fluo- 
rine?) These  bodies  display  a  pre-eminent  activity  of  combination,  an 
intense  affinity  for  most  of  the  other  forty -nine  bodies,  which  they  corrode, 
penetrate,  and  dissolve;  or,  by  uniting  with  them,  so  impair  their  cohesive 
force,  that  they  become  friable,  brittle,  or  soluble  in  water,  however  dense, 
refractory,  and  insoluble  they  previously  were.  Such  changes,  for  exam- 
ple, are  effected  on  platinum,  gold,  silver,  and  iron,  by  the  agency  of 
chlorine,  oxygen,  or  iodine.  But  the  characteristic  feature  of  these  archeal 
elements  is  this,  that  when  a  compound  consisting  of  one  of  them,  and 
one  of  the  other  forty -nine  more  passive  elements,  is  exposed  to  voltaic 
electrize  Ion,  the  former  is  uniformly  evolved  at  the  positive  or  vitreo- 
electric  pole,  while  the  latter  appears  at  the  negative  or  rcsino-electric 
pole. 


Vi  INTRODUCTION. 

The  singular  strength  of  their  attractions  for  the  other  simple  forms  of 
matter,  is  also  manifested  by  the  production  of  heat  and  light,  or  the  phe- 
nomenon of  combustion,  at  the  instant  of  their  mutual  combination.  But 
this  phenomenon  is  not  characteristic;  for  it  is  neither  peculiar  nor  neces- 
sary to  their  action,  and,  therefore,  cannot  be  made  the  basis  of  a  logical 
arrangement.  Combustion  is  vividly  displayed  in  cases  where  none  of 
these  primary  dissolvents  is  concerned.  Thus  some  metals  combine  with 
others  with  such  vehemence  as  to  elicit  light  and  heat;  and  many  of  them, 
by  their  union  with  sulphur,  even  in  vacua,  exhibit  intense  combustion. 
Potassium  burns  distinctly  in  cyanogen  (carburetted  azote),  and  splendid- 
ly in  sulphuretted  hydrogen,  for  other  examples  to  the  same  purpose, 
see  COMBUSTIBLE  and  COMBUSTION. 

And  again,  thephenomenon  of  flame  doesnot  necessarily  accompany  any 
of  the  actions  of  oxygen,  chlorine,  and  iodine.  Its  production  may  be  re- 
gulated at  the  pleasure  of  the  chemist,  and  occurs  merely  when  the  mutual 
combination  is  rapidly  effected.  Thus  chlorine  or  oxygen  will  unite  with 
hydrogen,  either  silently  and  darkly,  or  with  fiery  explosion,  as  the  opera- 
tor shall  direct. 

Since,  therefore,  the  quality  of  exciting  or  sustaining  combustion  is  not 
peculiar  to  these  vitreo-electric  elements;  since  it  is  not  indispensable  to 
their  action  on  other  substances,  but  adventitious  and  occasional,  we  per- 
ceive the  inaccuracy  of  that  classification  which  sets  these  three  or  four 
bodies  apart  under  the  denomination  ofsufi/iorters  of  combustion;  as  if,  for- 
sooth, combustion  could  not  be  supported  without  them,  and  as  if  the  sup- 
port of  combustion  was  their  indefeisible  attribute,  the  essential  concomi- 
tant of  their  action.  On  the  contrary,  every  change  which  they  can  pro- 
duce, by  their  union  with  other  elementary  matter,  may  be  effected  without 
the  phenomenon  of  combustion.  See  section  5th  of  article  COMBUSTION. 

The  other  forty -nine  elementary  bodies  have,  with  the  exception  of 
azote  (the  solitary  incombustible),  been  grouped  under  the  generic  name 
of  combustibles.  But  in  reality  combustion  is  independent  of  the  agency  of 
all  these  bodies,  and  therefore  combustion  may  be  produced  wit/tout  any  com- 
bustible. Can  this  absurdity  form  a  basis  of  chemical  classification?  The 
decomposition  of  euchlorine,  as  well  as  of  the  chloride  and  iodide  of  azote, 
is  accompanied  with  a  tremendous  energy  of  heat  and  light;  yet  no  com- 
bustible is  present.  The  same  examples  are  fatal  to  the  theoretical  part  of 
Black's  celebrated  doctrine  of  latent  heat.  His  facts  are,  however,  invalu- 
able, and  not  to  be  controverted,  though  the  hypothetical  thread  used  to 
connect  them  be  finally  severed. 

To  the  term  combustible  is  naturally  attached  the  idea  of  the  body  se 
named  affording  the  heat  and  light.  Of  this  position,  it  has  been  often 
remarked,  that  we  have  no  evidence  whatever.  We  know,  on  the  other 
hand,  that  oxygen,  the  incombustible,  could  yield,  from  its  latent  stores,  in 
Black's  language,  both  the  light  and  heat  displayed  in  combustion;  for  mere 
mechanical  condensation  of  that  gas,  in  a  syringe,  causes  their  disengage- 
ment. A  similar  condensation  of  the  combustible  hydrogen,  occasions,  I 
believe,  the  evolution  of  no  light.  From  all  these  facts,  it  is  plain,  that 
the  above  distinction  is  unphilosophical,  and  must  be  abandoned.  In  truth, 
every  insulated  or  simple  body  has  such  an  appetency  to  combine,  or  is 
solicited  with  such  attractive  energy  by  other  forms  of  matter,  whether  the 
actuating  forces  be  electo-attractive,  or  electrical,  that  the  motion  of  the 
particles  constituting  the  change,  if  sufficiently  rapid,  may  always  produce 
the  phenomenon  of  combustion. 

Of  the  forty -nine  resino-polar  elements,  forty -three  are  metallic,  and  six 
non-metallic. 

The  latter  group  may  be  arranged  into  three  pairs:— 


INTRODUCTION.  y}i 

1st.  The  gaseous  bodies,  HYDROGEN  and  AZOTE; 

2d.  The  fixed  and  infusible  solids,  CARBON  and  BORON; 

3d.  The  fusible  and  volatile  solids,  SULPHUR  and  PHOSPHORUS. 

The  forty -three  metallic  bodies  are  distinguishable  by  their  habitudes 
with  oxygen,  into  two  great  divisions,  the  BASIFIABLE  and  ACIDIFIABLE 
metals.  The  former  are  thirty-six  in  number,  the  latter  seven. 

Of  the  thirty-six  metals,  which  yield  by  their  union  with  oxygen  salifi- 
able  bases,  three  are  convertible  into  alkalies,  ten  into  earths,*  and  twenty- 
three  into  ordinary  metallic  oxides.  Some  of  the  latter,  however,  by  a 
maximum  dose  of  oxygen,  seem  to  graduate  into  the  acidifiable  group,  or 
at  least  cease  to  form  salifiable  bases. 

We  shall  now  delineate  a  general  chart  of  Chemistry,  enumerating  its 
various  leading  objects  in  a  somewhat  tabular  form,  and  pointing  out  their 
most  important  relations,  so  that  the  readers  of  this  Dictionary  may  have 
it  in  their  power  to  study  its  contents  in  a  systematic  order, 

CHEMISTRY 

Is  the  science  which  treats  of  the  specific  differences  in  the  nature  of 
bodies,  and  the  permanent  changes  of  constitution,  to  which  their  mutual 
actions  give  rise.f 

This  diversity  in  the  nature  of  bodies  is  derived  either  from  the  AGGRE- 
GATION or  COMPOSITION  of  their  integrant  particles.  The  state  of  aggre- 
gation seems  to  depend  on  the  relation  between  the  cohesive  attraction  of 
these  integrant  particles,  and  the  antagonizing  force  of  heat.  Hence,  the 
three  general  forms  of  solid^  liquid^  and  gaseous^  under  one  or  other  of 
which  every  species  of  material  being  may  be  classed. 

For  instruction  on  these  general  forms  of  matter,  the  student  ought  to 
read,  1st,  The  early  part  of  the  article  ATTRACTION;  2d,  CRYSTALLIZA- 
TION; 3d,  That  part  of  CALORIC  entitled,  "  Of  the  change  of  state  pro- 
duced in  bodies  by  caloric,  independent  of  change  of  composition."  He 
may  then  peruse  the  introductory  part  of  the  article  GAS  and  BALANCE, 
and  LABORATORY.  He  will  now  be  sufficiently  prepared  for  the  study  of 
the  rest  of  the  article  CALORIC,  as  well  as  that  of  its  correlative  subjects, 
TEMPERATURE,  THERMOMETER,  EVAPORATION,  CONGELATION,  CRYO- 
METER,  DEW,  and  CLIMATE.  The  order  now  prescribed  will  be  found 
convenient.  In  the  article  CALORIC,  there  are  a  few  discussions,  which 
the  beginner  may  perhaps  find  somewhat  difficult.  These  he  may  pass 
over  at  the  first  reading,  and  resume  their  consideration  in  the  sequel. 
After  CALORIC  he  may  peruse  LIGHT,  and  the  first  three  sections  of  ELEC- 
TRICITY. 

The  article  COMBUSTION,  will  be  most  advantageously  examined,  after  he 
has  become  acquainted  with  some  of  the  diversities  of  COMPOSITION;  viz. 
with  the  three  vitreo-polar  dissolvents,  oxygen,  chlorine,  and  iodine;  and 
the  six  non-metallic  resino-polar  elements,  hydrogen,  azote,  carbon, 
boron,  sulphur,  and  phosphorus.  Let  him  begin  with  oxygen,  and  then, 
peruse,  for  the  sake  of  connexion,  hydrogen^  and  water.  Should  he  wish 
to  know  how  the  specific  gravity  of  gaseous  matter  is  ascertained,  he  may 
consult  the  fourth  section  of  the  article  GAS. 

The  next  subject  to  which  he  should  direct  his  attention  is  CHLORINE; 
on  which  he  will  meet  with  ample  details  in  the  present  Work.  This 
article  will  bear  a  second  perusal.  It  describes  a  series  of  the  most  splen- 

*  I  here  regard  silica  noting  as  a  base  to  fluoric  acid,  in  the  fluosilicic  compound;  but  the 
subject  ia  mysterious.  See  ACID  (FLUORIC). 

f  I  do  not  know  whether  this  definition  be  ray  own,  or  borrowed.  I  find  it  in  the  syllabus  of 
ray  Belfast  Lectures,  printed  many  years  ago.  Another  definition  has  been  given  in  the 
Dictionary,  article  CUEMISTIIY. 


INTRODUCTION. 

did  efforts  ever  made  by  the  sagacity  of  man,  to  unfold  the  mysteries  of 
nature.  In  connexion  with  it  be  may  read  the  articles  CHLOROUS  and  CHLO- 
BIC  OXIDES,  or  the  protoxide  and  deutoxide  of  Chlorine.  Let  him 
next  study  the  copious  article  Iodine,  from  beginning  to  end. 

Carbon,  boron,  sulphur,  phosphorus,  and  azote,  must  now  come  under 
review.  Related  closely  with  the  first,  he  will  study  the  carbonous  oxide, 
carburetttd  and  subcarburettcd  hydrogen.  What  is  known  of  the  element 
boron,  will  be  speedily  learned;  and  he  may  then  enter  on  the  examination 
of  sulphur,  sulphuretted  hydrogen,  and  carburet  of  sulphur.  Phosphorus  and 
phosphuretttd  hydrogen,  with  nitrogen  or  azote,  and  its  oxides  and  chlorides, 
will  form  the  conclusion  of  the  first  division  of  chemical  study,  which  re- 
lates to  the  elements  of  most  general  interest  and  activity.  The  general 
articles  Combustible,  Combustion,  and  Safe-lamp  may  now  be  read  with  ad- 
vantage; as  well  as  the  remainder  of  the  article  attraction,  which  treats  of 
affinity. 

Since  in  the  present  work  the  alkaline  and  earthy  salts  are  annexed  to 
their  respective  acids,  it  will  be  proper,  before  commencing  the  study  of 
the  latter,  to  become  acquainted  with  the  alkaline  and  earthy  bases. 

The  order  of  reading  may  therefore  be  the  following :  first,  The  gene- 
ral article  alkali,  then  potash  and  potassium,  soda  and  sodium,  lithia,  and 
ammonia.  Next,  the  general  article  earth;  afterwards  calcium  and  lime, 
barium  and  baryies,  strontia,  magnesia,  alumina,  silica,  glucina,  zirconia, 
yttria,  and  thorina. 

Let  him  now  peruse  the  general  articles  acid  and  salt ;  and  then  the  non- 
metallic  oxygen  acids,  with  their  subjoined  salts,  in  the  following  order:— 
sulphuric,  sulphurous,  hyposulfihurou8,an&hyposulphuric;  phosphoric,  phos- 
phorous and  hypophosphorou*;  carbonic  and  chioro-carbonous;  boracic;  and 
lastly,  the  nitric  and  nitrous.  The  others  may  be  studied  conveniently 
with  the  hydrogen  group.  The  order  of  perusing  them  may  be,  the  mu- 
riatic (hydrochloric  of  M.  Gay-Lussac),  chloric  and  perchloric  ;  the  hydri- 
odic,  iodic  and  chloriodic;  the  Jluoric,Jluoboric,  and  Jiuosilicic;  the  prussic 
(hydrocyanic  of  M.  Gay-Lussac),  ferroprussic,  chloroprussic,  and  sulphuro- 
firws&ic  The  hydrosulphurous  and  hydrotellurous,  are  discussed  in  this  Dic- 
tionary, under  the  names  of  sulphuretted  hydrogen,  and  telluretted  hydrogen. 
These  compound  bodies  possess  acid  powers,  as  well  perhaps  as  arsenuret- 
ted  hydrogen.  It  would  be  advisable  to  peruse  the  article  prussine  (cy- 
anogen) either  before  or  immediately  after  prussic  acid. 

As  to  the  vegetable  and  animal  acids,  they  may  be  read  either  in 
their  alphabetical  order  or  in  any  other  which  the  student  or  his  teacher 
shall  think  fit.  Thirty-eight  of  them  are  enumerated  in  the  sequel  of  the 
article  ACID;  of  which  two  or  three  are  of  doubtful  identity. 

The  metallic  acids  fall  naturally  under  metallic  chemistry;  on  the  study 
of  which  I  have  nothing  to  add  to  the  remarks  contained  in  the  general 
article  METAL.  Along  with  each  metal  in  its  alphabetical  place,  its  na- 
tive state,  or  ores,  may  be  studied.  See  ORES. 

The  chemistry  of  organized  matter  may  be  methodically  studied  by 
perusing,  first  of  all,  the  article  vegetable  kingdom,  with  the  various  pro- 
ducts of  vegetation  there  enumerated;  and  then  the  article  animal  king- 
dom, with  the  subordinate  animal  products  and  adipocere. 

The  article  analysis  may  be  now  consulted;  then  mineral  WATERS; 
equivalents  (chemical);  and  analysis  of  ores. 

The  mineralogical  department  should  be  commenced  with  the  gene- 
ral articles  mineralogy,  and  crystallography;  after  which  the  different  spe- 
cies and  varieties  may  be  examined  under  their  respective  titles.  The 
enumeration  of  the  genera  of  M.  Mohs,  given  in  the  first  article,  will 


INTRODUCTION.  <^ 

the  student  to  a  considerable  extent  in  their  methodical  considera- 
tion. Belonging  to  mineralogy,  are  the  subjects,  blow-fiifie,  geology  with 
its  subordinate  rocks,  ores,  and  meteorolite. 

The  medical  student  may  read  with  advantage,  the  articles,  acid  (arseni- 
ous,)  antimony,  bile,  blood,  calculus  (urinary),  the  sequel  of  cofifier,  digestion^ 
gall-stones,  galvanism,  intestinal  concretion^  lead,  mercury,  fioisons,  resfiira* 
lion,  urine,  bV. 

The  agriculturist  will  find  details  not  unworthy  of  his  attention,  under 
the  articles,  absorbent,  analysis  of  soils,  carbonate,  lime,  manure,  and  soils. 

Among  the  discussions  interesting  to  manufacturers  are,  acetic,  and  other 
acids,  alcohol,  alum,  ammonia,  beer,  bleaching,  bread*  caloric,  coal,  and  coal- 
gas,  distillation,  dyeing,  ether,  fat, fermentation,  glass,  ink,  iron,  ores,fiotash, 
/lottery,  salt,  soafi,  soda,  steel,  sugar,  tanning,  &c* 

The  general  reader  will  find,  it  is  hoped,  instruction  blended  with  enter- 
tainment, in  the  articles,  aerostation,  air,  climate,  combustion,  congelation, 
dewi  electricity,  equivalents,  galvanism,  geology,  light,  meteorolitey  rain,  and 
several  other  articles  formerly  noticed. 

It  may  be  proper  now  to  say  something  concerning  the  execution  of  the 
present  Work.  In  the  month  of  June,  a  gentleman  from  London,  who  had 
become  possessed  of  the  copy-right  of  Nicholson's  Dictionary,  waited  on 
me  in  Glasgow,  requesting  that  I  would  superintend  the  revision  of  a  new 
edition,  which  he  purposed  immediately  to  send  to  the  press.  I  stated  to 
him*  that,  however  valuable  Nicholson's  compilation  might  have  been  at  its 
appearance  in  1808,  the  science  of  chemistry  had  undergone  such  altera- 
tions since,  as  would  require  a  Dictionary  to  be  written  in  a  great  measure 
anew.  To  this  he  replied,  that  the  above  work  had  enjoyed  great  popu- 
larity; that  he  was  certain  a  new  edition  of  it  would  be  well  received;  that 
he  did  not  expect  me  to  compose  original  articles  or  dissertations,  but 
merely  to  add,  from  recent  publications,  such  notices  of  new  discoveries 
and  improvements  as  might  seem  proper,  and  to  retrench  what  appeared 
obsolete  or  useless;  taking  care  to  comprise  the  whole  in  such  a  caropass 
as  would  render  the  price  moderate,  and  thus  place  the  book  within  the 
reach  of  manufacturers,  medical  students,  and  general  readers.  The  terms 
offered  appearing  reasonable  relative  to  the  work  required,  I  entered  into 
an  engagement  to  revise  the  new  edition  in  time  for  the  winter  classes. 

Having  assembled  complete  series  of  all  the  British  scientific  journals, 
with  several  of  the  foreign,  and  the  various  chemical  compilations  from 
Newman  and  Macquer,  to  the  present  day,  1  commenced  the  stipulated 
revision.  I  had  advanced  a  very  little  way,  however,  when  I  became 
alarmed  at  the  dilemna  in  which  I  found  myself  placed.  A  large  propor- 
tion of  the  articles  which  I  had  reckoned  on  reprinting,  as  having  under  * 
gone  little  change  since  1808,  were  found  to  have  been  quite  obsolete  at 
that  period.  They  had  been  evidently  copied,  with  scarcely  any  alteration, 
through  Nicholson's  quarto  Dictionary, from  Macquer  and  Newman,  back 
I  believe  to  the  era  of  Stahl,  Becher,  and  Agricola.  Under  the  article 
acid  (acetic},  36  pages  of  Crell's  Annals  had  been  copied  verbatim  et  seriatim 
on  the  concentration  of  vinegar  by  charcoal,  Sec.  A  larger  space  was  al- 
lotted to  the  separation  of  silver,  under  the  articles  silver,  parting,  and  as- 
say, than  was  dedicated  to  all  the  gases  and  earths.  The  article  CALORIC 
was  meagre  and  vapid,  while  desul/ihuration  or  roasting  of  pyrites,  Brazil 
wood,  and  safflower,  occupied  a  far  greater  extent.  Putrefaction  consist- 
ed of  extracts  from  Becher's  subterranean  world,  and  other  details  belong- 
ing to  a  former  age  of  chemistry. 

The  contents  of  the  8vo  Dictionary  were  made  up  from  four  sources. 

lst>  From  his  quarto  Dictionary  of  1795.  The  long  article  Ores,  for 

h 


x  INTRODUCTION, 

example,  was  taken  chiefly  from  Cramer,  while  the  labours  of  Klaproth 
and  Vauquelin  were  seldom  noticed.  Large  excerpts  were  also  given  from 
obsolete  Dispensatories,  concerning  substances  of  no  chemical  importance, 
and  destitute  of  all  medicinal  power. 

2d,  From  the  contemporary  systems  of  Brongniart,  Henry,  Murray, 
Thomson,  Sec.  about  another  fourth  was  copied  in  continuous  articles. 
This  formed  the  best  part  of  the  whole. 

3d,  Large  excerpts  were  given  from  his  own  Journal,  quite  dispropor- 
tionate to  the  rest  of  the  work,  and  to  the  exclusion  of  numerous  interest- 
ing topics.  Indeed  a  journalist,  who  compiles  a  system,  has  great  tempta- 
tions to  fall  into  this  practice* 

4th,  The  fourth  portion  was  composed  by  himself.  This  seems  to  have 
constituted  about  one-twentieth  of  the  Dictionary,  and  related  chiefly  to 
physics,  in  which  he  was  experimentally  versant.  These  articles  were 
very  respectable,  and  have  been  in  some  measure  retained;  see  detrac- 
tion, Balance,  Hydrometer,  and  Laboratory.  What  follows  the  first 
asterisk  in  Attraction,  has  been  now  added.  Mr.  Nicholson  was  indeed  a 
man  of  candour,  intelligence,  and  ingenuity.  His  original  papers  on 
electricity,  and  mechanical  science,  do  him  much  honour;  and  the  ab- 
stracts of  experimental  chemical  memoirs,  which  he  occasionally  drew  up 
for  his  Journal,  were  ably  executed.  Had  he  bestowed  corresponding 
pains  on  his  8vo  Dictionary,  my  present  task  would  have  been  greatly 
lighter. 

After  making  such  a  survey,  the  feelings  under  which  I  began  to  labour 
were  similar  to  those  of  an  architect,  who  having  undertaken  to  repair  a 
building  within  a  certain  period,  by  replacing  a  few  unsightly  or  moulder- 
ing stones,  finds  himself,  on  his  first  operations,  overwhelmed  in  its  rubbish. 
Reverence  to  public  opinion,  and  anxiety  to  fulfil  my  engagement,  how- 
ever irksome,  have  induced  me  to  make  every  possible  exertion  to  restore 
the  edifice,  and  renew  the  decayed  parts  with  solid  materials.  If  it  has 
not  all  the  symmetry,  or  compactness,  of  an  original  design,  leisurely  exe- 
cuted, still  I  trust  it  will  prove  not  altogether  unworthy  the  attention  ot 
the  chemical  world.  I  have  investigated  the  foundation  of  almost  every 
fact  or  statement  which  it  contains,  and  believe  they  merit  general  confi- 
dence. Many  inaccurate  positions  and  deductions,  in  our  most  elaborate 
modern  system,  I  have  taken  the  liberty  of  pointing  out;  aware  that  the 
influence  of  Dr.  Thomson's  name  and  manner  is  capable  of  giving  consi- 
derable currency  to  his  opinions,  however  erroneous  they  may  be.  His  in- 
dustry deserves  the  highest  praise  ;  and  his  chemical  experience  would 
entitle  his  decisions  to  deference,  were  they  less  precipitate,  and  less  dog- 
matical. Many  of  my  embarrassments  in  compiling  the  present  volume, 
have  arisen  from  his  contradictory  judgments,  pronounced  in  the  Annals 
of  Philosophy;  see  ACIDS  PHOSPHORIC,  PRUSSIC',  Sec.  If  under  the  in- 
fluence of  the  feelings  thus  excited,  a  hasty  expression  has  escaped  me  in 
the  ardour  of  composition,  I  hope  it  will  not  be  imputed  to  personal  ani- 
mosity. I  have  always  lived  on  amicable  terms  with  this  distinguished 
chemist,  and  trust  to  continue  so  to  do.  Perhaps  in  commenting  on  his 
opinions,  I  may  have  unconsciously  caught  the  plain  manner  of  his  criti- 
cisms. My  sole  object,  however,  was  the  establishment  of  truth.  The 
refutation  of  error  was  undertaken,  only  when  its  existence  seemed  in- 
compatible with  that  object.  On  our  other  valuable  systematic  works,  I 
have  made  no  critique,  because  Dr.  Thomson's  is  the  most  comprehen- 
sive, professedly  taken  from  original  memoirs,  and  of  highest  authority. 

I  Have  long  meditated  to  publish  a  methodical  treatise  on  chemistry,  in 

which  both  its  study  and  practice  would  be  greatly   simplified,    and  its 

.  applications  to  the  phenomena  of  nature,  medicine,  and  the  arts,  faithfully 


INTRODUCTION.  XJ 

detailed.  In  my  memoir  on  sulphuric  acid,  inserted  in  the  Journal  of 
Science  and  the  Arts,  for  October  1817,  is  the  following  passage:  "  I  was 
led  to  examine  the  subject  very  minutely,  in  preparing  for  publication  a 
general  system  of  chemical  instructions,  to  enable  apothecaries,  manufac- 
turing chemists,  and  dealers,  to  practise  analysis  with  accuracy  and  des- 
patch, as  far  as  their  respective  arts  and  callings  require.  I  hope  that 
this  work  will  soon  appear.  Meanwhile,  the  following  details  will  afford  a 
specimen  of  the  experimental  researches  executed  with  this  view."  The 
three  years  and  a  half  which  have  elapsed  since  the  above  paper  was  com- 
posed, would  have  enabled  me  to  fulfil  the  promise,  but  for  various  un- 
foreseen interruptions  to  my  labours. 

If  the  public,  after  this  larger  specimen  of  my  chemical  studies,  shall  deem 
me  qualified  for  the  task,  I  may  promise  its  completion  within  a  year  from 
this  date.  The  work  will  be  comprised  in  four  octavo  volumes,  and  will  con- 
tain the  results  of  numerous  investigations  into  the  various  objects  of  prac- 
tical chemistry,  joined  to  a  systematic  view  of  its  principles.  By  several 
simple  instruments,  tables,  and  rules  of  calculation,  chemical  analysis,  the 
highest  and  most  intricate  part  of  the  science,  may,  I  apprehend,  be,  in 
many  cases,  brought  within  the  reach  of  the  busy  manufacturer;  while,  by 
the  same  means,  such  accuracy  and  despatch  may  be  insured,  as  to  render 
the  analysis  of  saline  mixtures,  complex  minerals,  and  mineral  waters,  the 
work  of  an  hour  or  two;  the  proportions  of  the  constituents  being  deter- 
mined to  one  part  in  the  thousand. 

In  prosecution  of  this  plan  of  simplifying  analysis,  I  contrived,  about 
five  years  ago,  an  alkalimeter  and  acidimeter.  Being  then  connected  by 
a  biennial  engagement  with  the  Belfast  Academical  Institution,  I  was  oc- 
casionally called  upon  to  examine  the  barillas  and  potashes  so  extensively 
employed  in  the  linen  manufacture,  the  staple  trade  of  Ireland.  I  \vas 
sorry  to  observe,  that  while  these  materials  of  bleaching  differed  exces- 
sively in  their  qualities,  no  means  was  possessed  by  those  who  imported  or 
who  used  them,  of  ascertaining  their  value;  and  that  a  generous  people, 
with  whom  every  stranger  becomes  a  friend,  frequently  paid  an  exorbitant 
price  for  adulterated  articles.  The  method  which  I  devised  for  analyzing 
alkaline  and  acid  matter,  was  laid  before  the  Honourable  Linen  Board  in 
Dublin,  and  by  them  referred  to  a  competent  chemical  tribunal.  The 
most  decisive  testimonies  of  its  accuracy  and  importance  were  given  by 
that  tribunal ;  and  it 'was  finally  submitted,  by  desire  of  the  Board,  to  a 
public  meeting  of  bleachers  assembled  at  Belfast.  Unexceptionable  docu- 
ments of  its  practicability  and  value  were  thence  returned  to  Dublin, 
accompanied  by  an  official  request,  that  measures  might  immediately  be 
taken  to  introduce  the  method  into  general  use.  Descroizilles  had  seve- 
ral years  before  described,  in  the  Annales  de  Chimie,  an  alkalimeter,  but  so 
clumsy,  operose,  and  indirect,  as  to  be  not  at  all  adapted  to  the  purposes 
of  the  linen  manufacture.  My  instrument,  indeed,  was  founded,  as  well 
as  his,  on  the  old  principle  of  neutralizing  alkali  with  acid;  but  in  every 
other  respect  it  was  different. 

After  spending  about  two  months  on  this  project,  and  no  answer  being 
returned  either  to  the  public  request  of  the  bleachers,  or  to  my  own  me- 
morial, I  set  off  on  an  intended  tour  to  France,  and  have  never  since  re- 
sumed the  negotiation.*  The  terms  on  which  I  had  offered  the  instru- 
ment, were  merely  honorary;  for  the  sum  proposed,  would  not  have  re- 
paid the  expense  of  my  journey  and  attendance.  However  important  there- 

*  The  Right  Hon.  John  Foster,  who  took  the  chief  direction  of  the  Board,  showed  me 
every  possible  attention;  but  from  the  absence  of  many  ofits  members  in  England,  a  quorum 
•?onld  not  be  assembled  at  the  time. 


X\i  INTRODUCTION. 

fore  the  adoption  of  that  instrument  was  to  Ireland,  it  was  of  no  pecuniary 
importance  whatever  to  me.  Of  the  two  hundred  and  ten  thousand  pounds 
expended  that  year  (1815-1816)  on  imported  alkalies,  a  very  large  pro- 
portion might  have  been  saved  by  the  application  of  my  alkalimeter;  and 
what  is  perhaps  of  more  consequence,  the  alkaline  leys  used  in  bleaching, 
would,  by  its  means,  havebeen  rendered  of  a  regulated  strength,  suited  to 
the  stage  of  the  process,  and  fabric  of  the  cloth.  What  would  we  say  of 
a  company,  who  imported  spirituous  liquors  to  an  enormous  amount,  and 
paid  for  them  all  as  proof,  though  they  were  diluted  with  fifty  per  cent,  of 
water?  Now,  though  this  neglect  of  the  hydrometer  would  have  a  happy 
moral  influence  on  the  consumer,  it  would  be  vastly  absurd  in  the  dealer. 
No  such  apology  can  be  offered  for  neglecting  the  alkalimeter. 

The  following  is  an  extract  from  the  Belfast  News-Letter  of  July  9, 
1816:— 

"  I  now  submit  the  following  document  to  public  inspection,  and  hum- 
bly ask,  whether  any  such  experiment  has  been  ever  made  publicly  be- 
fore; or  whether  there  is  described  in  any  publication  prior  to  my  late 
exhibition  in  Dublin,  and  in  the  Linen  Hall  of  Belfast,  an  instrument  by 
which  it  can  be  performed? 

"  This  day,  one  of  the  porters  of  the  Linen  Hall,  Belfast,  was  called 
into  the  Library -room,  at  the  request  of  Dr.  Ure,  who,  being  quite  un- 
known to  Dr.  Ure,  and  never  having  seen  any  experiments  made  with 
acids  and  alkalies,  he  took  the  instrument  at  our  desire,  which,  being 
filled  with  coloured  acid,  by  pouring  it  slowly  on  adulterated  alkali,  which 
we  had  previously  prepared,  he  ascertained  exactly  the  per  centage  of 
genuine  alkali  in  the  mixture. — Belfast  2,5th  June,  1816. 

(Signed)  JOHN  S.  FERGUSON,   Chairman. 

JAMES    M'DONNEL,   M.  D. 
JOHN  M.  STOUPE, 
S.  THOMSON,  M.  D. 

"  The  above  experiment  did  not  occupy  the  porter  above  five  minutes. 
1  believe  it  is  a  new  document,  though,  after  the  egg  has  been  placed  on 
end,  others  will  set  to  work  to  do  the  same. 

"  Though  the  instrument  was  entirely  the  result  of  my  own  experiments 
and  calculations,  I  never  claimed  a  greater  share  in  its  invention,  than  I 
hope  its  peculiarity  merits.  The  following  excerpt  from  a  letter  addressed 
to  the  Right  Hon.  John  Foster,  prior  to  any  public  discussion  on  its  me- 
rits, will  satisfy  the  public  on  this  head. 

«  Dublin,  June  12,  1816. 

"  SIR, — In  the  letter  which  I  had  yesterday  the  honour  of  addressing 
you,  I  omitted  some  scientific  details,  which  I  now  beg  leave  to  submit  to 
your  consideration.  That  the  quantity  of  alkali,  present  in  any  portion  of 
potash  or  barilla,  is  directly  proportional  to  the  quantity  of  acid  requisite 
to  produce  saturation,  is  a  fact  which  has  been  known  for  upwards  of  a 
century  to  every  chemist,  and  forms  a  fundamental  law  of  his  science.  In 
establishing  my  instrument  on  this  law,  the  principle  of  it  may  be  said  not 
to  be  new."  Sec. 

"  The  practica-.  application  of  the  established  laws  of  nature,  or  of  the 
general  deductions  of  science,  to  the  uses  of  life,  is,  perhaps,  the  most 
beneficial  and  meritorious  employment  of  the  philosophic  mind.  The 
novelty  \vhich  I  lay  claim  to  in  my  contrivance,  is  this,  that  it  enables  a 
person  versant  neither  in  chemical  researches  nor  in  arithmetical  computa- 
tion^ to  determine  by  inspection  of  a  scale,  as  simple  as  that  of  a  thermo- 
meter, the  purity  or  value  to  one  part  in  the  hundred,  of  the  alkalies,  oil  of 
vitriol,  and  oxyrnuriate  of  lime,  so  extensively,  and  often  so  injudiciously 
employed  by  the  linen-bleaqher." 


INTRODUCTION. 

In  my  journey  through  England  to  France,  I  submitted  my  Essay  on 
Alkalimetry,  See.  to  Dr.  Henry,  in  the  confidence  of  friendship,  and  under 
the  injunction  of  secrecy.  From  the  unreserved  communication  of  ideas, 
however,  which  subsists  between  this  chemist  and  his  townsman  Mr.  Dai- 
ton,  he  soon  gave  him  a  perusal  of  the  Essay.  In  the  then  existing  edi- 
tion of  Dr.  Henry's  Elements,  Descroizilles*  plan  for  testing  alkalies  was 
alone  given;  in  the  edition  published  since,  he  has  inserted  four  supple- 
mentary pages  entitled, 

"  Im}ira-ved  Alkalimeter  and  Acidimeter" 

This  instrument  is  essentially  mine,  very  slightly  disguised.  He  concludes 
by  saying,  "  No  chemical  operation  can  be  more  simple,  or  more  easily- 
managed,  than  the  measurement  of  the  strength  of  alkalies  by  acid  liquors, 
and  of  acids  by  alkaline  ones,  in  the  way  which  has  bten  dfscribtd  "  This 
is  exactly  Columbus's  egg,  or  Roger  Bacon's  gunpowder;  et  sic  fades 
tonitrit)  si  SCIAS  ARTIFICIUM.  By  comparing  his  new  way  taken  from 
my  Essay,  with  the  methods  which  he  formerly  gave,  the  world  will  see 
whence  the  simplification  originated.  I  offered  to  give  him  an  abridged 
account  of  my  plan,  for  insertion  in  his  Elements,  after  my  negotiation 
about  the  alkalimeter  was  finished.  Without  consulting  me  on  the  sub- 
ject, he  publishes  to  the  whole  world,  what  he  conceives  to  be  the  essence 
of  my  improvement.* 

Two  motives  have  hitherto  withheld  me  from  laying  the  instrument 
before  the  public.  First,  a  desire  to  render  it  as  complete  as  possible; 
and  secondly,  an  expectation,  that  the  Honourable  Board,  who  superin- 
tend the  linen  manufactures  of  Ireland  with  extensive  powers,  might  wish 
that  an  instrument  originally  presented  to  them,  and  which  is  capable  ol 
giving  light  and  precision  to  all  the  processes  of  bleaching,  should  appear 
under  their  auspices. 

As  it  now  exists,  the  instrument  is  greatly  superior  to  that  described  by 
Dr.  Henry.  For  the  commercial  alkalies  and  acids,  I  use  only  two  test 
liquids  and  one  scale;  and  these  are  such,  that  a  man  unacquainted  with 
science,  may  prepare  the  first,  and  verify  the  second.  The  instrument  is 
at  once  an  alkalimeter,  an  acidimeter,  a  complete  lactometer,  a  nitrometer 
for  estimating  the  value  of  nitre,  an  indigometer  for  ascertaining  the  dyeing 
quality  of  indigo,  and  a  blanchimeter  for  measuring  the  bleaching  power 
of  oxymuriate  (chloride)  of  lime  and  potash.  With  it,  a  busy  manufac- 
turer or  illiterate  workman  may  solve  all  these  useful  problems  in  a  few 
minutes  ;  and  many  others,  such  as  the  composition  of  alloys  of  silver, 
of  copper,  tin,  lead,  Sec.  the  purity  of  white  lead,  and  other  pigments.  It 
is,  moreover,  a  convenient  hydrometer,  comprehending  in  its  range,  light 
and  heavy  liquids,  from  ether  to  oil  of  vitriol;  and  is  particularly  adapted 
to  take  the  specific  gravity  of  soils. 

It  may  be  said,  that  the  solution  of  the  above  problems  may  be  accom- 
plished by  any  skilful  chemist.  But  surely,  in  a  manufacturing  nation, 
the  person  who  brings  the  science  of  Klaproth,  Sir  H.  Davy,  Dr.  Wollas- 
ton,  and  M.  Gay-Lussac,  into  the  workshop  of  the  manufacturer,  is  not  a 
useless  member  of  the  community. 

The  result  of  numerous  researches  made  with  that  view,  has  shown  m< 
the  possibility  of  rendering  analysis  in  general,  a  much  easier,  quicker, 
and  more  certain  operation,  than  it  seems  hitherto  to  have  been,  in  ordi- 

*  It  "A'onld  seem  that  Dr.  Ure  lias  since  been  satisfied  that  Dr.  Henry  intended  him  no  in- 
justice, as  tills  gentleman  has  explained  to  him,  that  in  a  passage  of  his  Elements,  "  page  512, 
vol  ii.  he  intended  to  give  Dr.  Ure  the  credit  of  inventing  an  instrument  on  the  principle  of 
directly,  and  without  calculation,  indicating;  the  per  centage  of  alkali  in  nny  specimen,  and  that 
he  pretended  to  nothing  mor^  than  a  modification  of  Dr.  Ure's  method  "  See  Letter  ef  Dr. 
Ure,  in  the  Journal  of  Science,  No.  22,  p.  401,  -Tnly,  1820. — American  Editor. 


INTRODUCTION. 

nary  hands.  To  these  practical  applications  of  science,  my  attention  has 
been  particularly  directed,  in  conducting  that  department  of  Anderson's 
Institution,  destined  to  diffuse  among  the  manufacturers  and  mechanics 
of  Glasgow  and  its  neighbourhood,  a  knowledge  of  the  scientific  principles 
of  their  respective  arts.  In  a  public  address,  delivered  to  the  members  of 
this  class,  on  a  gratifying  occasion  in  April  1816,  I  remarked,  "  That 
Europe  affords  no  similar  example  of  a  class,  composed  of  several  hun- 
dred artisans,  mechanicians,  and  engineers,  weekly  assembled,*  with 
exemplary  decorum,  to  study  the  scientific  principles  of  the  useful  arts; 
to  have  the  great  practical  truths  of  philosophy,  first  revealed  by  Newton 
and  Lavoisier,  made  level  to  tlfeir  various  capacities  by  familiar  descrip- 
tions, models,  and  experiments.  The  original  design  of  the  mechanic's 
class  was  limited,  as  you  know,  to  the  exhibition  and  explanation  of  me- 
chanical models.  But  a  subject  deserving  particular  attention,  was  that 
of  the  chemical  arts,  in  which  many  of  you  are  engaged;  a  knowledge  of 
the  scientific  principles  of  which,  as  taught  in  the  Colleges,  circumstances 
permit  few  of  you  to  acquire.  You  have  listened  to  my  chemical  lessons 
with  the  keenest  interest;  and  have  applied  your  studies  to  conspicuous 
advantage.  Need  I  adduce,  among  other  things,  the  unrivalled  beauty  oi 
the  Adrianople  madder  dye,  as  executed  on  the  most  extensive  scale, f  by 
individuals  who  have  been  my  faithful  pupils,  for  nearly  the  whole  course 
of  my  public  career.  By  a  steady  prosecution  of  this  expanded  system  of 
instruction,  your  class  has  progressively  increased  in  number  and  impor- 
tance; so  that,  within  the  last  twelve  years,  I  have  delivered  twenty-one 
courses  of  lectures  to  upwards  of  six  thousand  students  in  this  department 
alone." 

It  is  much  to  be  desired,  that  similar  courses  of  prelections  were  insti- 
tuted in  all  the  large  towns  of  the  British  empire.  The  deportment  of 
the  mechanic's  class,  amounting  occasionally  to  five  hundred  members, 
jmight  serve  as  a  pattern  to  more  dignified  assemblies.  I  have  never  seen 
any  University  class  so  silent  and  attentive.  Though  the  evening  on  which 
the  workmen  meet,  be  that  in  which  they  receive  their  wages,  and  when, 
therefore,  they  might  be  expected  to  indulge  themselves  in  drinking,  yet 
no  instance  of  intemperance  has  ever  occurred  to  annoy  the  audience. 
And  even  during  the  alarms  of  insurrection  with  which  our  city  was  dis- 
turbed last  winter,  the  artisans  continued  with  unaltered  docility  and 
punctuality  to  frequent  the  lectures. 

Of  the  actual  result  of  such  a  system  of  instruction,  a  stranger  is  pro- 
bably the  best  judge.  I  shall  therefore  quote  a  few  sentences  from  the 
Scientific  Tour  through  Great  Britain,  recently  published  by  an  accom- 
plished member  of  the  Institute  of  France,  M.  Ch.  Dupin. 

"  It  is  easier  to  visit  the  establishments  and  manufactures  of  Glasgow, 
than  those  of  any  other  city  in  the  British  empire.  The  liberal  spirit  of 
the  inhabitants,  is,  in  this  respect,  carried  as  far  as  possible,  among  a 
manufacturing  people,  who  must  naturally  dread,  and  seek  to  prevent, 
not  only  the  loss  of  their  preponderance,  but  their  foreign  rivalry. 

"  The  rich  inhabitants  of  Glasgow  have  founded  the  Andersonian  In- 
stitution, where  are  taught,  in  the  evenings  of  winter,  the  elements  of 
mechanics,  physics,  and  chemistry,  as  applied  to  the  arts.  These  courses 
are  especially  designed  for  young  artisans,  who  have  to  pay  only  about 
five  shillings  in  the  season  (course  of  three  months.) 

*  Every  Saturday  evening  at  eight  o'clock. 

;  Particularly  at  the  establishment  of  H.  Monteith,  Esq.  M.  P.  where  the  sciences  of  me- 
chanics and  chemistry  co-operate,  in  a  flesree  of  precision  an  '  elegance,  which  I  believe  << 
?>e  unparalleled  in  the  ->vorld. 


INTRODUCTION.  xv 

*  This  trifling  fee  is  exacted,  in  order  that  the  class  may  include 
only  students  actuated  by  the  love  of  instruction,  and  willing  to  make 
some  small  sacrifice  for  it. 

"  The  Andersonian  Institution  has  produced  astonishing  effects.  It  is 
an  admirable  thing  now,  t6  see  in  many  Glasgow  manufactories,  simple 
workmen,  who  understand,  and  explain  when  necessary,  the  principles  of 
their  operations,  and  the  theoretical  means  of  arriving  at  the  most  perfect 
possible  practical  results." 

The  philanthropist  may  perhaps  wish  to  know,  at  what  expense  of 
patronage  this  useful  department  is  carried  on.  I  shall  satisfy  this  desire, 
by  the  following  statement  from  the  above  mentioned  public  address. 

u  The  original  design  of  the  mechanic's  class  was  limited,  as  you  know, 
to  the  exhibition  and  explanation  of  mechanical  models.  But  the  pro- 
gress of  machinery  in  your  workshops,  has  now  so  far  outrun  the  state  of 
the  models  left  by  the  venerable  Founder  of  the  Institution,  as  to  render 
their  display,  with  a  very  few  exceptions,  useless,  except  as  historical 
documents  of  the  rudeness  of  the  times  in  which  they  were  framed.  1 
have,  accordingly,  for  ten  years,  employed  chiefly  modern  apparatus,  pro- 
cured at  my  own  expense,  and  by  rendering  the  instructions  miscella- 
neous, have  adapted  them  better  to  the  diversity  of  your  pursuits.  Be- 
sides teaching  the  usual  elements  of  mechanics  and  their  general  combi- 
nations, I  have  made  it  my  business  to  explain  the  properties  of  the  at- 
mosphere, on  which  the  action  of  pumps  depends  ;  the  nature  of  hydro 
static  equilibrium,  and  hydraulic  impulse,  as  subservient  to  the  construc- 
tion of  Bramah's  press,  and  water-wheels;  the  beautiful  laws  of  heat  so 
admirably  applied  to  perfect  the  steam-engine,  by  our  illustrious  fellow 
citizen;  nor  have  I  declined,  in  compliance  with  your  wishes,  to  lay  be- 
fore you  from  time  to  time,  such  views  of  the  constitution  of  nature,  in 
electricity,  optics,  and  astronomy,  as  might  awaken  the  powers  of  your 
minds,  and  reward  your  attention  to  the  less  attractive  branches  oi 
science.  But  a  subject,  deserving  particular  attention,  was  that  of  the 
chemical  arts/'  Sec.  (as  above  quoted.) 

The  whole  experimental  means  at  present  employed  in  carrying  on  this 
POLYTECHNIC  SCHOOL,  have  been  derived  from  the  exertions  and  sacri- 
fices of  the  Professor,  and  the  generous  aid  and  contributions  of  his  pupils. 
They  have  supplied  him  with  much  valuable  practical  information  on 
their  respective  arts,  with  many  curious  models,  and  subsidiary  instruments 
of  illustration;  while  he,  in  return,  has  expended  large  sums  of  money, 
in  framing  popular  representations  of  the  scientific  discoveries  and  im- 
provements, in  which  the  present  age  is  so  prolific. 

To  the  mechanic's  class  a  library  is  attached,  consisting  of  the  best 
treatises  on  the  sciences  and  arts,  with  some  valuable  works  on  general 
literature,  such  as  history,  geography,  travels,  Sec.  of  which  they  have  the 
exclusive  management  and  perusal.  -The  foundation  of  it  was  laid  in  the 
year  1807,  by  a  voluntary  subscription,  amounting,  I  think,  to  about 
60/.;  and  several  books  which  I  collected  from  my  friends,  with  about 
100  volumes  from  my  own  library.  Many  members  of  the  class  have 
contributed  from  time  to  time;  and  it  has  recently  acquired  consider- 
able extension,  from  the  receipts  of  lectures  which  I  delivered  for  its 
benefit. 

Besides  the  acknowledged  and  palpable  effect  of  such  a  plan  of  tuition, 
on  the  improvement  of  the  useful  arts,  it  has  another  operation,  more 
silent,  but  neither  less  certain,  nor  less  important,  namely,  its  influence 
in  meliorating  the  moral  condition  of  the  operative  order  of  society. 

A  taste  for  science  elevates  the  character,  and  creates  a  disrelish,  and 
disgust,  at  the  debasement  of  intoxication.  Philosophy  dressed  in  an  at- 


INTRODUCTION. 

tractive  garb,  leads  away  from  the  temptations  of  the  tavern.  Thus,  too,  the 
transition  from  the  drudgery  or  turmoil  of  the  week,  to  the  tranquillity  of 
Sunday,  is  secured  by  the  preceding  evening's  occupation.  The  man  indeed 
whose  Saturday  night  is  spent  in  rioting  or  drunkenness,  will  make  a  bad 
Christian  on  the  Sabbath,  an  indifferent  workntan  on  Monday,  and  an  un- 
happy husband  and  father  through  the  week.  To  promote  this  moral  ope- 
ration of  science,  I  have  always  taken  occasion  to  point  out  the  beneficent 
design  which  the  whole  mechanism  of  nature  displays.  If  the  contemplation 
of  the  miseries  and  crimes  which  stain  the  page  of  history,  have  led  some 
speculators  to  cavil  at  the  government  of  a  benevolent  Creator;  the  con- 
templation of  the  harmonious  Isfcvs,  and  benignant  adjustments  which  the 
science  of  nature  discloses,  must  satisfy  every  candid  student,  of  the  pre- 
sence and  providence  of  a  wise  and  beneficent  Lawgiver.  The  first  and 
most  exalted  function  of  physics,  then,  is  to  dissipate  the  gloomy  and  be- 
wildering mists  of  metaphysics.  A  second  function  of  supreme  importance., 
is  to  point  out  the  mysterious  and  impassable  barriers,  to  which  the  clearest 
paths  of  physical  demonstration  ultimately  lead  the  human  mind;  and  thence 
to  inculcate  docility  to  the  analogous  mysteries  of  Revelation. 

I  hope  that  the  preceding-  statements  and  remarks,  will  remove  every 
possible  objection  to  the  establishment  of  schools  for  teaching  the  elements 
of  science  to  artisans,  and  that  they  will  induce  other  cities  to  follow  the 
example  so  happily  set  by  Glasgow,  of  popularizing  philosophy. 

Having  detailed  the  circumstances  under  which  I  have  struggled  to  re- 
generate this  Dictionary,  I  hope  the  candid  Public  will  mak;e  allowance  for 
occasional  faults  of  expression  and  arrangement.  All  the  articles  to  which 
the  asterisks  are  affixed,  were,  with  trifling  exceptions,  printed  from  my 
manuscript,  written  expressly  for  this  work,  within  the  last  five  months. 
From  the  style  of  its  typography,  and  the  manner  of  stating  proportions  of 
constituents,  each  page  of  this  volume  is  fully  equivalent  to  two  pages  of 
our  octavo  systems  of  chemistry,  and  required  rather  more  than  four  pages 
of  closely  written  manuscript.  There  is  however  a  great  advantage  to  the 
reader  of  a  scientific  work,  (which  must  necessarily  be  compiled  from  many 
quarters),  in  an  author  being  his  own  amanuensis.  Every  fact  and  detail 
will  thus  be  exposed  to  a  much  severer  scrutiny,_than  if  excerpts  were 
made  by  the  scissars,  or  the  pen  of  an  assistant.  Hence  many  of  the  pas- 
sages which  may  seem,  at  first  sight,  to  be  merely  copied  from  other  works, 
will  be  found  to  have  corrections  and  remarks  either  interwoven  with  the 
details, or  enclosed  in  parentheses.  Thus,  for  example,  in  transcribing  Mr. 
Hatchett's  admirable  analyses  of  the  magnetic  iron  ores,  computation  will 
be  found  within  parentheses, deduced  from  Dr.Wollaston's  equivalent  scale, 
Numerous  insertions  and  corrections  are  made  in  the  reprinted  parts  to 
which  no  asterisk  is  affixed.  M.  Vauquelin's  general  mode  of  analyzing 
minerals  is  now  introduced,  Professor  Gahn's  instructions  relative  to  the 
blow-pipe,  a  long  passage  under  slrsenious  Acid,  and  many  other  unnoted 
insertions,  such  as  Chlorofiftyte,  Cholesierine,  Comfitonite. 

The  dissertations  on  Caloric,  Combustion,  f)e?y..  Distillation,  Electricity^ 
Gas,  Light, Thermometer,  &c.  which  form  a  large  proportion  of  the  volume, 
are  beyond  the  letter  and  spirit  of  my  engagement  with  the  publisher. 
I  receive  no  remuneration  for  them,  not  even  at  the  most  moderate  rate  of 
literary  labour.  They  are  therefore  voluntary  contributions  to  the  che- 
mical student,  and  have  been  substituted  for  what  I  deemed  frivolous  and 
uninteresting  details  on  some  unimportant  dye-stuffs,  and  articles  from  old 
dispensatories,  such  as  althea,  chamomile,  &c. 

For  whatever  is  valuable  in  the  mineralogical  department,  the  reader  is 
ultimately  indebted  to  Professor  Jameson.  The  chief  part  of  the  descrip- 
tions of  mineral  species,  is  abridged  from  the  third  edition  of  his  excel- 


INTRODUCTION.  xvil 

lent  System.  In  compiling  the  early  part  of  the  Dictionary,  I  collated 
several  mineralogical  works,  both  British  and  foreign ;  but  I  soon  found 
that  this  had  been  done  to  my  hand  by  Professor  Jameson,  with  much 
greater  ability  than  I  could  pretend  to  rival;  and  that  he  had  enriched 
the  whole  with  many  important  remarks  of  his  own. 

Much  of  the  purely  chemical  part  is  drawn  from  that  treasure  of  facts, 
Sir  H.  Davy's  elements.  When  the  subject  permitted  me,  I  was  happy 
to  repose  on  his  never-failing  precision,  like  the  wave-tossed  mariner  in  a 
secure  haven.  With  regard  to  the  language  used  by  him,  Dr.  Wollaston, 
M.  Gay-Lussac,  and  some  other  original  investigators,  I  have  used  no 
further  freedom  than  was  necessary  to  accommodate  it  to  the  context. 
Their  expressions  can  very  seldom  be  changed  with  impunity.  There  are 
other  chemical  writers  again,  whose  thoughts  acquire  intellectual  spring 
only  by  great  condensation.  If  the  curious  reader  compare  the  article 
DISTILLATION,  in  this  Dictionary,  with  that  in  the  Supplement  to  the 
Encyclopaedia  Britannica,  he  will  understand  my  meaning. 

In  the  discussion  on  the  Atomic  Theory  of  Chemistry,  under  the 
article  EQUIVALENTS,  reference  is  made  to  a  table  of  the  relative  weights 
of  the  atoms,  or  of  the  numbers  representing  tke  prime  equivalents  of 
chemical  bodies.  On  subsequent  consideration,  it  was  perceived,  that 
such  a  list  would  be  merely  a  repetition  of  numbers  already  given  in  their 
alphabetical  places,  and  therefore  most  readily  found;  whilst  it  would 
have  caused  the  omission  of  requisite  tables  of  a  different  kind;  the  space 
allotted  to  the  volume  being  entirely  occupied. 

In  my  paper  on  Sulphuric  Acid,  published  in  the  7th  number  of  the 
Journal  of  Science,  I  assigned  the  numbers  4,  5,  6,  as  respectively  denot- 
ing the  prime  equivalents  of  soda,  sulphuric  acid,  and  potash.  Minute 
researches,  subsequently  made,  on  the  nitrates,  (Journal  of  Science,  No, 
xii.)  led  me  to  regard  3.96,  and  5.96,  as  better  approximations  for  soda 
and  potash.  Throughout  this  Dictionary,  the  numbers  3.95  and  5.95 
have  been  used.  It  is,  however,  very  possible  that  the  number  6,  origi- 
nally assigned  by  Sir  H.  Davy  for  potash,  may  be  correct;  as  also  4  fov 
soda. 

Dr.  Thomson  has  just  published  a  paper  in  his  Annals,  (November 
1820J  "  On  the  true  weight  of  the  atoms  of  barytes,  potash,  soda,"  &c. 
In  his  experiments  to  determine  these  fundamental  quantities,  he  has 
adopted  Richter's  original  plan  of  reciprocal  saturation  of  two  neutro-saline 
compounds.  But  the  Doctor  seems  to  have  forgotten,  that  for  want  of 
an  initial  experiment,  none  of  his  ratios  is  referable  to  the  oxygen  scale, 
or  to  any  atomic  radix.  He  assumes  the  atom  of  barytes  to  be  9.75,  and 
that  of  potash  to  be  6;  that  of  sulphuric  acid  being  5.  He  then  proceeds 
to  show  that  the  atomic  weight  13.25  of  dry  muriate  of  barytes  (chloride 
of  barium),  and  11,  that  of  sulphate  of  potash,  produce  perfect  reciprocal 
decomposition,  when  their  aqueous  solutions  are  mixed.  But  had  he 
called  the  atom  of  barytes  9.7,  with  Sir  H.  Davy  and  Dr.  Wollaston,  (the 
chloride  would  become  13.2),  and  the  atom  of  sulphate  of  potash  10.96, 
as  found  in  my  experiments  on  nitric  acid,  he  would  have  obtained,  by- 
mixing  the  two,  in  these  atomic  proportions,  as  perfect  an  experimental 
result  as  with  his  own  numbers:  For  13.25  :  11 : :  13.2  :  10.96, 

His  atomic  chain  wants,  in  fact,  its  first  link;  it  floats  loosely;  and  ma/ 
therefore  be  accommodated  to  a  variety  of  different  numbers,  provided  the 
arithmetical  proportions  be  observed.  He  ought  to  have  commenced  with 
a  clear  demonstration,  that  the  atom  of  barytes  is  9.75,  and  the  atom  of 
potash  6,  referred  to  oxygen  as  unity. 

The  idea,  however,  suggested  by  Dr.  Prout,  that  the  numbers  repre- 
senting the  weights  of  the  different  atoms,  are  multiples  by  a  whole  nuiji* 


INTRODUCTION. 

ber  of  that  denoting  hydrogen,  is  very  ingenious,  and  most  probably  just. 
And  therefore,  as  well  as  for  experimental  reasons,  which  I  cannot  here 
detail,  I  would  willingly  adopt  9.75  for  barytes,  4  for  soda,  6  for  potash, 
and  4.5  for  chlorine.  The  atomic  numbers  given  in  this  volume,  for  the 
various  simple  and  compound  objects  of  chemistry,  are  directly  deduced 
from  a  mean  of  the  most  exact  experiments;  and  I  believe  them  to  be  more 
worthy  of  confidence,  than  those  deducible  from  theoretic  considerations. 
Thus,  Dr.  Thomson,  from  these,  assigns  3.625  for  the  atom  of  lime;  from 
experiment,  it  is  certainly  not  so  high.  I  have  stated  it  from  my  own,  at 
3.56.  Dr.  Marcet's  analysis  of  the  carbonate  would  make  it  about  3.5. 
In  the  article  EQUIVALENTS  (CHEMICAL),  as  well  as  under  the  individual 
substances,  the  reader  will  find  the  primitive  combining  ratios,  or  atoms 
as  they  are  hypothetically  called,  fully,  and  I  trust  fairly,  investigated 
from  experiment.  This  is  the  sheet-anchor  of  scientific  research,  which 
we  must  never  part  with,  or  we  shall  drift  into  interminable  intricacies. 
We  should  continually  bear  in  mind  this  aphorism  of  the  master  of  che- 
mical Logic:  *'  The  substitution  of  analogy  for  fact  is  the  bane  of  chemi- 
cal philosophy;  the  legitimate  use  of  analogy  is  to  connect  facts  together, 
and  to  guide  to  new  experiments." — Sir  H.  Da-vy,  Journal  of  Science^ 
vol.  i. 

These  analogical  substitutions  appear  to  be  the  predominant  defect  of 
Dr.  Thomson's  otherwise  valuable  compilation. 

The  typographical  economy  of  this  work  precluded  me  from  multiply- 
ing references  at  the  bottom  of  the  page;  a  plan  which  authors  readily 
adopt  to  show  the  extent  of  their  reading.  The  authorities  for  facts  will 
be  generally  found  interwoven  with  the  text.  The  desire  to  condense 
much  practical  information,  in  a  small  compass,  made  me  abridge  many 
historical  details.  The  progressive  steps  of  an  investigation,  however, 
occasionally  required  to  be  traced,  in  order  to  make  the  existing  state  of 
our  knowledge  more  intelligible.  Whenever  this  seemed  necessary,  I 
have  offered  such  a  retrospect,  and  have  endeavoured  to  take  truth  and 
justice  for  my  sole  guides.  As  the  only  recompense  which  the  man  of 
science  usually  receives  or  can  expect,  is  the  credit  of  his  discoveries, 
neither  prejudice  nor  passion  should  be  suffered  to  influence  the  compiler, 
in  awarding  honour  to  whom  honour  is  due. 

One  of  the  most  elegant  investigations  which  the  Science  of  Chemistry 
affords,  is  contained  in  M .  Gay-Lussac's  short  letter  to  M.  Clement,  pub- 
lished in  the  Annales  de  Chimie  et  de  Physique  for  July  1815,  and  reprint- 
ed in  1816,  by  M.  Thenard  in  his  valuable  Traite  de  Chimie,  iv.  p.  238. 
It  is  there  demonstrated  that  sulphuric  ether  is  composed  of 
2  volumes  olefiant  gas, 
1  volume  vapour  of  water, 

condensed  into  one  volume;  or  by  weight  in  M.  Gay-Lussac's  numbers,  of 
0.978   x  2  =  1.956  olefiant  gas,  and 
0.625   x   1  =  0.625  vapour  of  water. 

2.581  sum  =  theoretic  density  of  vapour, 

which  differs  from  2.586,  the  experimental  density  of  ether  vapour  by  only 
L.^__  parts.  This  fine  coincidence  is  fully  developed  by  the  French  che- 
mist. Now  Dr.  Thomson  was  obviously  familiar  with  that  paper,  for  he 
copies  a  good  part  of  it,  (though  without  acknowledgment),  on  the  con- 
stitution of  alcohol,  into  his  articles  Brewing  and  Distillation,  Su/ifilement 
to  Encyclopedia  Britan.,  as  well  as  into  his  System  published  in  October 
1817,  vol.  iv.  p.  385.  See  FERMENTATION  in  this  Dictionary. 

I  was  therefore  equally  surprised  and  amused  at  the  following  claim, 
recently  set  up  by  him  to  M.  Gay-Lussac's  incontestable  discovery. 


INTRODUCTION.  Xix 

"  The  experiments  which  Mr.  Dalton  has  made  on  the  analysis  of  ether, 
show  in  a  very  satisfactory  manner,  that  the  notion  which  I  threw  out  in 
my  System  of  Chemistry,  that  sulphuric  ether  is  a  compound  of  two  atoms 
defiant  gas,  and  one  atom  vapour  of  water  condensed  into  one  volume,  is 
the  true  one."  t;  Hence  2  volumes  olefiant  gas  weigh  1.9416 
1  volume  vapour  of  water  0.6250 

Total  2.5666 

Specific  gravity  of  ether  vapour  2.5860." — dnnals  of  Philosophy,   August 
1820,  p.  81.      Historical  Sketch,  &c.  by  Thomas  Thomson,  M.  D.  &c. 

Now,  though  in  that  Sketch  the  Dr.  seems  to  show,  that  Mr.  Dalton 
was  unacquainted  with  M.  Gay-Lussac's  researches  on  ether,  it  was  a 
rather  rash  presumption  to  extend  that  analogy  of  ignorance  to  all  other 
British  Chemists.  The  first  of  the  Doctor's  periods,  quoted  above,  is  non- 
sense, from  his  u^e  of  the  favourite  word  atom,  instead  of  volume.  The 
statement  in  the  second  is  taken  from  M.  Gay-Lussac,  and  bears  the  ele- 
gant impression  of  its  author. 

Glasgow,  Nov.  7,  1820. 


• 


N.  B.— -The  Articles  with  ttfe  asterisk(*),  are  inserted  by  Dr.  Ure;  the 
others,  with  the  exceptions  noticed  in  the  Introduction,  are  reprinted 
from  NICHOLSON'S  Octavo  Dictionary. 


PREFATORY  REMARKS,  BY  DR.  HARE. 

Being  requested  by  the  publisher  to  make  any  additions  or  corrections 
in  this  American  edition  of  Ure's  Nicholson's  Dictionary,  which  might  to 
me  appear  proper,  I  have  complied  as  far  the  allotted  time  would  per- 
mit. This,  however,  was  so  short,  that  I  have  only  been  enabled  to  write 
on  some  of  the  topics,  concerning  which  my  practical  experience,  and 
peculiar  and  mature  reflections,  have  qualified  me  to  comment  advanta- 
geously. 

The  passages  added  by  me  will  be  distinguished  by  a  cross  (f),  as  those 
by  Dr.  Ure  are  by  an  asterisk. 

After  the  above  was  written,  pursuant  to  my  advice,  the  publisher  en- 
gaged Dr.  Franklin  Bache  to  revise  the  work,  and  read  the  proofs.  I  feel 
it  due  to  Dr.  Bache  to  state,  that  I  am  under  the  impression  that  he  has 
performed  his  office  with  zeal  and  ability;  and  that  I  conceive  the  work 
will  be  much  indebted  to  him  for  its  typographical  correctness.  His  sci- 
entific knowledge  has  enabled  him,  not  only  to  prevent  various  new  er- 
rors, but  to  correct  many  previously  existing  in  the  original  English 
copy. 


DICTIONARY 


OF 


CHEMISTRY 


ABS 

*  A  BS9RBENT-  An  epithet  introduc- 
I\.  ed  into  chemistry  by  the  physicians, 
to  designate  such  earthy  substances,  as 
seemed  to  check  diarrhoea,  by  the  mere 
absorption  of  the  redundant  liquids.  In 
this  sense  it  is  obsolete  and  unfounded. 
Professor  Leslie  has  shown  that  the  facul- 
ty of  withdrawing  moisture  from  the  air,  is 
not  confined  to  substances  which  unite 
with  water  in  every  proportion,  as  the 
strong  acids,  dry  alkalis,  alkaline  earths, 
and  deliquescent  salts ;  but  is  possessed  by 
insoluble  and  apparently  inert  bodies,  in 
various  degrees  offeree.  Hence  the  term 
Absorbent  merits  a  place  in  chemical  no- 
menclature. 

The  substance  whose  absorbent  power 
is  to  be  examined,  after  thorough  desicca- 
tion before  a  fire,  is  to  be  immediately 
transferred  into  a  phial,  furnished  with  a 
well  ground  stopper.  When  it  is  cooled, 
a  portion  of  it  is  transferred  into  a  large 
wide-mouthed  bottle,  where  it  is  to  be 
closely  confined  for  some  time.  A  deli- 
cate hygrometer  being  then  introduced, 
indicates  on  its  scale  the  dryness  produced 
in  the  inclosed  air,  which  should  have 
been  previously  brought  to  the  point  of 
extreme  humidity,  by  suspending  a  moist- 
ened rag  within  the  bottle.  The  following 
table  exhibits  the  results  of  his  experi- 
ments : — 

Alumina  causes  a  dryness  of    84  degrees. 
Carbonate  of  magnesia      ...  75 

Carbonate  of  lime     70 

Silica 40 

Carbonate  of  barytes .32 

Carbonate  of  strontites  ....  23 

Pipe  clay 85 

Greenstone,  or  trap  in  powder  80 


ABS 

Shelly  sea  sand .  70  degrees. 

Clay  indurated  by  torrefaction  35 

Ditto  strongly  ignited 8 

Greenstone  ignited 23 

Quartz  do 19 

Decomposed  greenstone  ...  86 
Greenstone  resolved  into  soil  92 
Garden  mould  95 

The  more  a  soil  is  comminuted  by  labour 
and  vegetation,  the  greater  is  its  absor- 
bent power.  This  ingenious  philosopher 
infers,  that  the  fertility  of  soils  depends 
chiefly  on  their  disposition  to  imbibe  mois- 
ture; and  illustrates  this  idea  by  recent  and 
by  disintegrated  lava.  May  not  the  finely 
divided  state  most  penetrable  by  the  deli- 
cate fibres  of  plants,  derive  its  superior 
power  of  acting  on  atmospherical  vapour 
from  the  augmentation  of  its  surface,  or 
the  multiplication  of  the  points  of  contact  ? 

In  similar  circumstances  100  gr.  of  the 
following  organic  substances  absorb  the 
following  quantities  of  moisture:  Ivory  7  gr. 
boxwood  14,  down  16,  wool  18,  beech  28. 
— Leslie  on  Heat  and  Moisture.* 

AHSOTIPTTO.Y.  By  this  term  chemists  un- 
derstand the  conversion  of  a  gaseous  fluid 
into  a  liquid  or  solid,  on  being  united  with 
some  other  substance.  It  differs  from  con- 
densation in  this  being  the  effect  of  mecha- 
nical pressure,  or  the  abstraction  of  caloric. 
Thus,  if  muriatic  acid  gas  be  introduced 
into  water,  it  is  absorbed,  and  muriatic 
acid  is  formed ;  if  carbonic  acid  gas  and 
ammoniacal  gas  be  brought  into  contact, 
absorption  takes  place,  and  solid  carbo- 
nate of  ammonia  is  produced  by  the  union 
of  their  ponderable  bases. 

There  is  a  case  of  condensation,  which 
has  sometimes  no  doubt  been  mistaken  for 


ACH 


ACl 


absorption,  though  none  has  taken  place. 
When  an  inverted  jar  containing1  a  gas  con- 
fined by  quicksilver  is  removed  into  a 
trough  of  water,  the  quicksilver  runs  out, 
and  is  replaced  by  water.  But  as  the 
specific  gravity  of  water  is  so  much  infe- 
rior to  that  of  quicksilver,  the  column  of 
\vater  in  the  jar  resists  the  atmospheric 
pressure  only  with  one  14th  of  the  power 
of  the  quicksilver,  so  that  the  gas  occu- 
pies less  room  from  being  condensed  by 
the  increased  pressure,  not  from  absorp- 
tion. 

ABSTRACTION.  In  the  process  of* dis- 
tillation, the  volatile  products  whicli  come 
over,  and  are  condensed  in  the  receivers, 
are  sometimes  said  to  be  abstracted  from 
the  more  fixed  part  which  remains  behind. 
This  term  is  chiefly  used  when  an  acid  or 
other  fluid  is  repeatedly  poured  upon  any 
substance  in  a  retort,  and  distilled  off',  with 
<a  view  to  change  the  state  or  composition 
of  either.  See  DISTILLATION. 

*  ACAMTICOXK.     See  PISTACTTE.* 

*  ACEUATER.      The  acer  cornpestre,  or 
common  maple,  yields   a  milky  sweetish 
sap,  containing-  a  salt  with   basis  of  lime, 
possessed,  according  to  Schercr,  of  pecu- 
liar properties.     It  is  white,  semi-transpa- 
rent,  not  altered  by  the  air,  and  soluble  in 
nearly  100  parts  of  cold,  or  50  of  boiling- 
water.* 

*  ACKHTC  ACIP.     See  ACID  (Acciuc).* 

*  ACESCKXT.     Said  of  substances  which 
become  sour  spontaneously,  as  vegetable 
and  animal  juices,  or  infusions.     The  sud- 
denness with  which  this  change  is  effected 
during-  a  thunder  storm,  even  in  corked 
bottles,  has  not   been  accounted  for.     In 
morbid  states  of  the  stomach,  also,  it  pro- 
ceeds with    astonishing    rapidity.      It    is 
counteracted  by  bitters,  antacids,  and  pur- 
gatives.* 

ACETATES.  The  salts  formed  by  the 
combination  of  the  acetic  acid  with  alkalis, 
eai-ths,  and  metallic  oxides.  See  the  dif- 
ferent bases. 

*  AOKTIC  ACIP.     See  Ann  (ACETIC).* 

*  ACETOMETEH.     An  instrument  for  es- 
timating the   strength  of  vinegars.     It  is 
described  under  ACID  (ACETIC).* 

ACETOUS.  Of  or  belonging  to  vinegar. 
See  ACID  (ACETIC.) 

AcHnowATic.  Telescopes  formed  of  a 
combination  of  lenses,  which  in  a  great 
measure  correct  the  optical  aberration, 
arising  from  the  various  colours  of  light, 
are  called  achromatic  telescopes.  Some 
of  these  have  been  made  wonderfully  per- 
fect, and  their  excellence  appears  to  be 
limited  only  by  the  imperfections  of  the 
art  of  glass-making.  The  artifice  of  this 
capital  invention  of  Dollond  consists  in  se- 
lecting, by  trial,  two  such  pieces  of  glass, 
to  form  the  object  lenses,  as  separate  the 
variously  coloured  rays  of  light  to  equal 


angles  of  divergence,  at  different  angles 
of  refraction  of  the  mean  ray  ;  in  which 
case  it  is  evident,  that,  if  they  be  made  to 
refract  towards  contrary  parts,  the  whole 
ray  may  be  caused  to  deviate  from  its 
course  without  being  separated  into  co- 
lours. The  difficulty  of  the  glass-maker 
is  in  a  great  measure  confined  to  the 
problem  of  making  that  kind  of  glass 
which  shall  cause  a  great  divergence  of 
the  coloured  rays  with  respect  to  each 
other,  while  the  mean  refraction  is  small. 
See  GLASS;  also  APLAXATIC. 

*  Ac i us.  The  most  important  class  of 
chemical  compounds.  In  the  generaliza- 
tion of  facts  presented  by  Lavoisier  and 
the  associated  French  chemists,  it  was  the 
leading  doctrine  that  acids  resulted  from 
the  union  of  a  peculiar  combustible  base 
called  the  radical,  with  a  common  princi- 
ple technically  called  oxygen,  or  the  aci- 
difier.  This  general  position  was  founded 
chiefly  on  the  phenomena  exhibited  in  the 
formation  and  decomposition  of  sulphuric, 
carbonic,  phosphoric,  and  nitric  acids; 
and  was  extended  b)  a  plausible  analogyto 
other  acids  whose  radicals  were  unknown. 

"  1  have  already  shown,1'  savs  Lavoisier, 
"  that  phosphorus  is  changed  by  combus- 
tion into  an  extremely  light,  white,  flaky 
matter.  Its  properties  are  likewise  en- 
tirely altered  by  this  transformation  ;  from 
being  insoluble  in  water,  it  becomes  not 
only  soluble,  but  so  greedy  of  moisture  as 
to  attract  the  humidity  of  the  air  with  as- 
tonishing rapidity.  By  this  means,  it  is 
converted  into  a  liquid,  considerably  more 
dense,  and  of  more  specific  gravity  than 
water.  In  the  state  of  phosphorus  before 
combustion,  it  had  scarcely  any  sensible 
taste ;  by  its  union  with  oxygen,  it  acquires 
an  extremely  sharp  and  sour  taste ;  in  a 
word,  from  one  of  the  class  of  combustible 
bodies,  it  is  changed  into  an  incombusti- 
ble substance,  and  becomes  one  of  those 
bodies  called  acids. 

"  This  property  of  a  combustible  sub- 
stance, to  be  converted  into  an  acid  by  the 
addition  of  oxygen,  we  shall  presently  find 
belongs  to  a  great  number  of  bodies. 
Wherefore  strict  logic  requires  that  we 
should  adopt  a  common  term  for  indicating 
all  these  operations  which  produce  ana- 
logous results.  This  is  the  true  way  to 
simplify  the  study  of  science,  as  it  would 
be  quite  impossible  to  bear  all  its  specific 
details  in  the  memory  if  they  were  not 
classically  arranged.  For  this  reason  we 
shall  distinguish  the  conversion  of  phos- 
phorus into  an  acid  by  its  union  with  oxy- 
gen, and  in  general  every  combination  of 
oxygen  with  a  combustible  substance,  by 
the  term  oxygenation ;  from  this  I  shall 
adopt  the  verb  to  oxygenate ;  and  of  con- 
sequence shall  say,  that  in  oxygenating- 
phosphorus,  we  convert  it  into  an  acid* 


ACI 


ACI 


«  Sulphur  also,  in  burning-,  absorbs  ox- 
ygen gas ;  the  resulting1  acid  is  considera- 
bly heavier  than  the  sulphur  burnt;  its 
weight  is  equal  to  the  sum  of  the  weights 
of  the  sulphur  which  has  been  burnt,  and 
of  the  oxygen  absorbed  ;  and,  lastly,  this 
acid  is  weighty,  incombustible  andmiscible 
with  water  in  all  proportions." 

"I  might  multiply  these  experiments, 
and  show,  by  a  numerous  succession  of 
facts,  that  all  acids  are  formed  by  the  com- 
bustion of  certain  substances ;  but  I  am 
prevented  from  doing  so  in  this  place  by 
the  plan  which  I  have  laid  down,  of  pro- 
ceeding only  from  facts  already  ascertained 
to  such  as  are  unknown,  and  of  drawing 
my  examples  only  from  circumstances  al- 
ready explained.  In  the  mean  time,  how- 
ever, the  examples  above  cited  may  suf- 
fice for  giving  a  clear  and  accurate  con- 
ception of  the  manner  in  which  acids  are 
formed.  By  these  it  may  be  clearly  seen 
that  oxygen  is  an  element  common  to  them 
all,  and  which  constitutes  or  produces  their 
acidity ;  and  that  they  differ  from  each 
other  according  to  the  several  natures  of 
the  oxygenated  or  acidified  substances. 
We  must,  therefore,  in  every  acid  care- 
fully distinguish  between  the  acidifiable 
base,  which  M.  de  Morveau  calls  the  radi- 
cal, and  "  the  acidifying  principle  or  oxy- 
gen." Elements,  p.  115.  Although  we 
have  not  yet  been  able  either  to  compose 
or  to  decompound  this  acid  of  sea  salt,  we 
cannot  have  the  smallest  doubt  that  it,  like 
all  other  acids,  is  composed  by  the  union 
of  oxygen  with  an  acidifiable  base.  We 
have,  therefore,  called  this  unknown  sub- 
stance the  muriatic  base,  or  muriatic  radi- 
cal." P.  122.  5th  Edition. 

Berthollet's  sound  discrimination  led  him 
to  maintain  that  Lavoisier  had  given  too 
much  latitude  to  the  idea  of  oxygen  being 
the  universal  acidifying  principle.  "  In 
fact,"  says  he,  "  it  is  carrying  the  limits  of 
analogy  too  far  to  infer,  that  all  acidity, 
even  that  of  the  muriatic,  fluoric,  and 
boracic  acids,  arises  from  oxygen,  be- 
cause it  gives  acidity  to  a  great  number  of 
substances.  Sulphuretted  hydrogen,  which 
really  possesses  the  properties  of  an  acid, 
proves  directly  that  acidity  is  not  in  all  ca- 
ses owing  to  oxygen.  There  is  no  better 
foundation  for  concluding  that  hydrogen 
is  the  principle  of  alkalinity  not  only  in  the 
alkalis,  properly  so  called,  but  also  in  mag- 
nesia lime,  strontian,  and  barytes,  because 
ammonia  appears  to  owe  its  alkalinity  to 
hydrogen. 

"  These  considerations  prove  that  oxy- 
gen may  be  regarded  as  the  most  usual 
principle  of  acidity,  but  that  this  species 
of  affinity  for  the  alkalis  may  belong  to 
substances  which  do  not  contain  oxygen ; 
that  we  must  not,  therefore,  always  infer, 
i't-om  the  acidity  of  a  substance,  that  it  con- 


tains oxygen,  although  this  may  be  an  in- 
ducement to  suspect  its  existence  in  it; 
still  less  should  we  conclude,  because  a 
substance  contains  oxygen,  that  it  must 
have  acid  properties ;  on  the  contrary,  the 
acidity  of  an  oxygenated  substance  s'hows 
that  the  oxygen  has  only  experienced  an 
incomplete  saturation  in  it,  since  its  pro- 
perties rem:  in  predominant." 

Amid  the  just  views  which  pervade  the 
early  part  of  this  quotation  from  Berthol- 
let,  it  is  curious  to  remark  the  solecism  with 
which  it  terminates.  For  after  maintain- 
ing that  acidity  may  exist  independent  of 
oxygen,  and  that  the  presence  of  oxygen 
does  not  necessarily  constitute  acidity,  he 
concludes  by  considering  acidity  as  the 
criterion  of  unsatu rated  oxygen. 

This  unwarrantable  generalization  of 
the  French  chemists  concei-ning  oxygen, 
which  had  succeeded  Stahl's  equally  un- 
warrantable generalization  of  a  coo.mon 
principle  of  combustibility  in  all  combus- 
tible bodies,  was  first  experimentally  com- 
bated by  Sir  H.  Davy,  in  a  series  of  admi- 
rable dissertations  published  in  the  Philo- 
sophical Transactions.  * 

His  first  train  of  experiments  were  insti- 
tuted with  the  view  of  operating  by  voltaic 
electricity  on  muriatic  and  other  acids 
freed  from  water.  Substances  which  are 
now  known  by  the  names  of  chlorides  of 
phosphorus  and  tin,  but  which  he  then 
supposed  to  contain  dry  muriatic  acid,  led 
him  to  imagine  intimately  combined  water 
to  be  the  real  acidifying  principle,  since 
acid  properties  were  immediately  develo- 
ped in  the  above  substances  by  the  addi-* 
tion  of  that  fluid,  though  previously  they 
exhibited  no  acid  powers.  In  July  1810, 
however,  he  advanced  those  celebrated 
views  concerning  acidification,  which,  ia 
the  opinion  of  the  best  judges,  display  an 
unrivalled  power  of  scientific  research.— 
The  conclusions  to  which  these  led  him, 
were  incompatible  with  the  general  hy- 
pothesis of  Lavoisier.  He  demonstrated 
that  oxymuriatic  acid  is,  as  far  as  our  know- 
ledge extends,  a  simple  substance,  which 
may  be  classed  in  the  same  order  of  natu- 
ral bodies  as  oxygen  gas,  being  determined, 
like  oxygen  to  the  positive  surface  in  vol- 
taic combinations,  and  like  oxygen  com- 
bining with  inflammable  substances,  pro- 
ducing heat  and  light.  The  combinations 
of  oxymuriatic  acid  with  inflammable  bo- 
dies were  shown  to  be  analogous  to  ox* 
ides  and  acids  in  their  properties  and  pow 
ers  of  combination,  but  to  differ  from 
them  in  being  for  the  most  part  decompo- 
sable by  water :  And  finally,  that  oxymuri- 
atic acid  has  a  stronger  attraction  for  most 
inflammable  bodies  than  oxygen.  His  pre  - 
ceding  decomposition  of  the  alkalis  and 
earths  having  evinced  the  absurdity  of  that 
nomenclature,  which  gives  to  the  g-enera! 


ACI 


ACSl 


and  essential  constituent  of  alkaline  na- 
ture, the  term  oxygen  or  aci diner ;  his 
new  discovery  of  the  simplicity  of  oxymu- 
riatic  acid,  showed  the  theoretical  system 
of  chemical  language  to  be  equally  vicious 
in  another  respect.  Hence  this  philoso- 
pher most  judiciously  discarded  the  appel- 
lation oxymuriatic  acid,  and  introduced  in 
its  place  the  name  chlorine,  which  merely 
indicates  an  obvious  and  permanent  char- 
acter of  the  substance,  its  greenish  yellow 
colour.  The  more  recent  investigations 
of  chemists  on  fluoric,  hydriodic,  and  hy- 
drocyanic acids  have  brought  po\^rful 
analogies  in  support  of  the  chloridic  theory, 
by  showing  that  hydrogen  alone  can  con- 
vert certain  undecompounded  bases  into 
acids  well  characterized,  without  the  aid 
of  oxygen.  Dr.  Murray  indeed  has  en- 
deavoured to  revive  and  new-model  the 
early  opinion  of  Sir  H.  Davy,  concerning 
the  necessity  of  the  presence  of  water,  or 
its  elements,  to  the  constitution  of  acids. 
He  conceives  that  many  acids  are  ternary 
compounds  of  a  radical  with  oxygen  and 
hydrogen;  but  that  the  two  latter  ingre- 
dients do  not  necessarily  exist  in  them  in 
the  state  of  water.  Oil  of  vitriol,  for  in- 
stance, in  this  view,  instead  of  consisting 
of  81.  5  real  acid,  and  18.  5  water  in  100 
parts  may  be  regarded  as  a  compound  of 
32.6  sulphur  +  65.2  oxygen  •+•  2.2  hydro- 
gen. When  it  is  saturated  with  an  alka- 
line  base,  and  exposed  to  heat,  the  hydro- 
gen unites  to  its  equivalent  quantity  of  ox- 
ygen, to  form  water,  which  evaporates,  and 
the  remaining  oxygen  and  the  sulphur 
combine  with  the  base.  But  when  the  acid 
is  made  to  act  on  a  metal,  the  oxygen  part- 
ly unites  to  it,  and  hydrogen  alone  es- 
capes. 

"  Nitric  acid,  in  its  highest  state  of  con- 
centration, is  not  a  definite  compound  of 
real  acid,  with  about  a  fourth  of  its  weight 
of  water,  but  a  tenary  compound  of  ni- 
trogen, oxypren,  and  hydrogen.  Phospho- 
ric acid  is  a  triple  compound  of  phospho- 
rus, oxygen,  and  hydrogen ;  and  phospho- 
rous acid  is  the  proper  binary  compound  of 
phosphorus  and  oxygen.  The  oxalic,  tar- 
taric,  and  other  vegetable  acids,  are  ad- 
mitted to  be  ternary  compounds  of  carbon, 
oxygen,  and  hydrogen  ;  and  are  therefore 
in  strict  conformity  to  the  doctrine  now 
illustrated. 

"  A  relation  of  the  elements  of  bodies  to 
acidity  is  thus  discovered  different  from 
what  has  hitherto  been  proposed.  When 
a  series  of  compounds  exists,  which  have 
certain  common  characteristic  properties, 
and  when  these  compounds  all  contain  a 
common  element,  we  conclude,  with  jus- 
tice, that  these  properties  are  derived 
more  peculiarly  from  the  action  of  this 
element.  On  this  ground  Lavoisier  infer- 
red, by  an  ample  induction,  that  oxygen  i$ 


a  principle  of  acidity.  Berthollet  brought 
into  view  the  conclusion,  that  it  is  not  ex- 
clusively so,  from  the  examples  of  prussie 
acid  and  sulphuretted  hydrogen.  In  the 
latter,  acidity  appeared  to  be  produced  by 
the  action  of  hydrogen.  The  discovery 
by  Gay-Lussac,  of  the  compound  radical 
cyanogen,  and  its  conversion  into  prussie 
acid  by  the  addition  of  hydrogen,  confirm- 
ed this  conclusion ;  and  the  discovery  of  the 
relations  of  iodine  still  further  established 
it.  And  now,  if  the  preceding  views  are 
just,  the  system  must  be  still  further  modi- 
fied. While  each  of  these  conclusions 
are  just  to  a  certain  extent,  each  of  them 
requires  to  be  limited  in  some  of  the  ca- 
ses to  which  they  are  applied ;  and  while 
acidity  is  sometimes  exclusive!}  connected 
with  oxvgen,  sometimes  with  hydrogen, 
the  principle  must  also  be  admitted,  that 
it  is  more  frequently  the  result  of  their 
combined  operation. 

"  There  appears  even  sufficient  reason 
to  infer,  that,  from  the  united  action  of 
these  elements,  a  higher  degree  of  acidity 
is  acquired  than  from  the  action  of  either 
alone.  Sulphur  affords  a  striking  exam- 
ple of  this.  With  hydrogen  it  forms  a 
wreak  acid.  With  oxygen  it  also  forms  an 
acid,  which,  though  of  superior  energy, 
still  does  not  display  much  power.  With 
hydrogen  and  oxygen  it  seems  to  receive 
the  acidifying  influence  of  both,  and  its 
acidity  is  proportionally  exalted. 

*'  Nitrogen,  with  hydrogen,  forms  a  com- 
pound altogether  destitute  of  acidity,  and 
possessed  even  of  qualities  the  reverse. — 
With  oxygen,  in  two  definitive  propor- 
tions, it  forms  oxides ;  and  it  is  doubtful 
if,  in  any  proportion,  it  can  establish  with 
oxygen  an  insulated  acid.  But  with  oxy- 
gen and  hydrogen  in  union  it  forms  nitric 
acid,  a  compound  more  permanent,  and 
of  energetic  action." 

It  is  needless  to  give  at  more  detail  Dr. 
Murray's  speculations,  which,  supposing 
them  plausible  in  a  theoretical  point  of 
view,  seem  barren  in  practice ;  at  least 
their  practical  tendency  cannot  be  perceiv- 
ed by  the  editor  of  this  work.  It  is  suffi- 
ciently singular,  that,  in  an  attempt  to 
avoid  "the  mysterious  and  violent  transfor- 
mations, which,  on  the  chloridic  theory,  a 
little  moisture  operates  on  common  salt, 
instantly  changing  it  from  chlorine  and  so- 
dium, into  muriatic  acid  and  soda,  Dr. 
Murray  should  have  actually  multiplied, 
with  one  hand,  the  very  difficulties  which 
he  had  laboured,  with  the  other,  to  re- 
move. 

He  thinks  it  doubtful  if  nitrogen  and 
oxygen  can  alone  form  an  insulated  acid. — « 
Hydrogen  he  conceives  essential  to  its  en- 
ergetic action.  What,  we  may  ask  then, 
exists  in  dry  nitre,  which  contains  no  hy- 


ACI 


ACI 


dreg-en  ?f  Is  it  nitric  acid,  or  merely  two 
of  its  elements,  in  want  of  a  little  water  to 
furnish  the  requisite  hydrogen  ?  The  same 
questions  may  be  asked  relative  to  the  sul- 
phate of  potash.  Since  he  conceives  hy- 
drogen necessary  to  communicate  full 
force  to  sulphuric  and  nitric  acids,  the  mo- 
ment they  lose  their  water  they  should 
lose  their  saturating-  power,  and  become 
incapable  (if  retaining  caustic  potash  in  a 
neutral  state.  Out  of  this  dilemma  he 
may  indeed  try  to  escape,  by  saying,  that 
moisture  or  hydrogen  is  equally  essential 
to  alkaline  strength,  and  that  therefore  the 
same  desiccation  or  de-hydrogenation 
which  impairs  the  acid  power,  impairs  also 
that  of  its  alkaline  antagonist.  The  result 
must  evidently  be,  that,  in  a  saline  hydrate 
er  solution,  we  have  the  reciprocal  attrac- 
tions of  a  strong  acid  and  alkali,  while,  in 
a  dry  salt,  the  attractive  forces  are  those  of 
relatively  feeble  bodies.  On  this  hypo- 
thesis, the  difference  ought  to  be  great 
between  dry  and  moistened  sulphate  of 
potash.  Carbonic  acid  he  admits  to  be 
destitute  of  hydrogen  ;  yet  its  saturating 
power  is  very  conspicuous  in  neutralizing 
dry  lime.  Now,  oxalic  acid,  by  the  last 
analysis  of  Berzelius,  contains  no  hydro- 
gen. It  differs  from  the  carbonic  only  in 
the  proportion  of  its  two  constituents. 
And  oxalic  acid  is  appealed  to  by  Dr. 
Murray  as  a  proof  of  the  superior  acidity 
bestowed  by  hydrogen. 

On  what  grounds  he  decides  carbonic  to 
be  a  feebler  acid  than  oxalic,  it  is  difficult 
to  see.  By  Berthollet's  test  of  acidity,  the 
former  is  more  energetic  than  the  latter 
in  the  proportion  of  100  to  about  ;>8  ;  for 
these  numbers  are  inversely  as  the  quan- 
tity of  each  requisite  to  saturate  a  given 
base.  If  he  be  inclined  to  reject  this  rule, 
and  appeal  to  the  decomposition  of  the 
carbonates  by  oxalic  acid,  as  a  criterion  of 
relative  acid  power,  let  us  adduce  his  own 
commentary  on  the  statical  affinities  of 
Berthollet,  where  he  ascribes  such  chan- 
ges not  to  a  superior  attraction  in  the  de- 
composing substance,  but  to  the  elastic 
tendency  of  that  which  is  evolved.  Am- 
monia separates  magnesia  from  its  muri- 
atic solution  at  common  temperatures  ;  at 
the  boiling  heat  of  water,  magnesia  separ- 
ates ammonia.  Carbonate  of  ammonia,  at 
temperatures  under  230°,  precipitates  car- 
bonate of  lime  from  the  muriate  ;  at  high- 
er temperatures  the  inverse  decomposi- 
tion takes  place  with  the  same  ingredients. 
If  the  oxalic  be  a  more  energetic  acid  than 

j-  The  acid  in  dry  nitre  contains  water, 
and  of  course  hydrogen.  Liquid  nitric  acid 
is  obtained  from  dry  nitre  by  strong  sul- 
phuric acid,  and  holds,  according  to  the  ta- 
ble in  this  work,  under  the  head  of  nitric 
acid,  more  than  a  fifth  of  water. 


the  carbonic,  or  rank  higher  in  the  scale 
of  acidity,  then,  on  adding  to  a  given 
weight  of  liquid  muriate  of  lime,  a  mix- 
ture of  oxalate  and  carbonate  of  ammonia, 
each  in  equivalent  quantity  to  the  calca- 
reous salt,  oxalate  of  lime  ought  alone  to 
be  separated.  It  will  be  found,  on  the 
contrary,  by  the  test  of  acetic  acid,  that  as 
much  carbonate  of  lime  will  precipitate  as 
is  sufficient  to  unsettle  these  speculations. 

Finally,  dry  nitre,  and  dry  sulphate  of 
potash,  are  placed,  by  this  supposition,  in 
as  mysterious  a  predicament  as  dry  muri- 
ate of  soda  in  the  chloridic  theory.  De- 
prived of  hydrogen,  their  acid  and  alkali 
are  enfeebled  or  totally  changed.  With  a 
little  water  both  instantly  recruit  their 
powers.  In  a  word,  the  solid  sulphuric 
acid  of  Nordhausen,  and  the  dry  potash  of 
potassium,  are  alone  sufficient  to  subvert 
this  whole  hypothesis  of  hydrogenation. 

We  shall  introduce,  under  the  head  of 
alkali,  some  analogous  speculations  by  Dr. 
Murray  on  the  influence  of  the  elements  of 
water  on  that  class  of  bodies.  Edin.  PhiL 
Trans,  vol.  viii.  part  2d.^ 

After  these  observations  on  the  nature 
of  acidity,  we  shall  now  state  the  general 
properties  of  the  acids. 

1.  The  taste  of  these  bodies  is  for  the 
most   part  sour,  as  their  name  denotes ; 
and  in  the  stronger  species  it  is  acrid  and 
corrosive. 

2.  They  generally  combine  with  water 
in  every  proportion,  with  a  condensation 
of  volume  and  evolution  of  heat. 

3.  W7ith  a  few  exceptions  they  are  vo- 
latilized or  decomposed   at  a  moderate 
heat. 

4.  They  usually  change  the  purple  co- 
lours of  vegetables  to  a  bright  red. 

5.  They  uni'e  in   definite   proportions 

f  I  conceive  Mr.  Murray's  views  on  this 
subject  as  nearer  the  truth  than  those  of 
the  editor.  1  had  adopted  conclusions 
somewhat  similar,  ere  J  met  with  them.  - 

.\s  the  characteristic  attributes  of  acidity 
are  never  observed  in  the  absence  of  mois- 
ture, water  would  seem  to  have  higher 
pretensions  to  be  considered  as  the  acidi- 
fying principle  than  any  other  ponderable 
substance. 

It  may  be  a  question,  whether  acids  in  a 
very  high  state  of  dephlegmation  are  really 
acids  or  act  as  such.  They  do  not  merely 
change  vegetable  blues ;  they  destroy 
them.  They  do  not  produce  a  sour  taste 
upon  the  tongue,  they  cauterize  it,  and  are 
destructive  of,  or  are  destroyed  by,  sub- 
stances,  which,  in  a  weaker  state,  they 
would  combine  with,  so  as  to  yield  them 
up  uninjured  in  obedience  to  higher  affi- 
nities. 

Concentrated  sulphuric  acid  destroys  or- 
ganic products,  by  taking  up  the  elements 


AC1 


ACI 


With  the  alkalis,  earths,  and  metallic  oxides, 
and  form  the  important  class  of  salts.  This 
may  be  reckoned  their  characteristic  and 
indispensable  property.  The  powers  of 
the  different  acids  were  originally  estimat- 
ed by  their  relative  causticity  and  sour- 
ness, afterwards  by  the  scale  of  their  at- 
tractive force  towards  any  particular  base, 
and  next  by  the  quantity  of  the  base  which 
they  could  respectively  neutralize.  But 
Berthollet  proposed  the  converse  of  this 
last  criterion  as  the  measure  of  their  pow- 
ers. "  The  power  with  which  tb^y  can 
exercise  their  acidity,"  he  estimates  "  by 
the  quantity  of  each  of  the  acids  which  is 
required  to  produce  the  same  effect,  viz. 
to  saturate  a  given  quantity  of  the  same 
alkali."  It  is  therefore  the  capacity  for 
saturation  of  each  acid,  which,  in  ascer- 
taining its  acidity,  according  to  him,  gives 
the  comparative  force  of  the  affinity  to 
which  it  is  owing.  Hence  he  infers,  that 
the  affinity  of  the  different  acids  for  an  al- 
kaline base,  is  in  the  inverse  ratio  of  the 
ponderable  quantity  of  each  of  them  which 
is  necessary  to  neutralize  an  equal  quanti- 
ty of  the  same  alkaline  base.  An  acid  is, 
therefore  in  this  view,  the  more  powerful, 
when  an  equal  weight  can  saturate  a  great- 
er quantity  of  an  alkali.  Hence,  all  those 
substances  which  can  saturate  the  alkalis, 
and  cause  their  properties  to  disappear, 
ought  to  be  classed  among  the  acids ;  in 
like  manner,  among  the  alkalis  should  be 
placed  all  those  which,  by  their  union,  can 
saturate  acidity.  And  the  capacity  for 
saturation  being  the  measure  of  this  pro- 
perty, it  should  be  employed  to  form  a 
scale  of  the  comparative  power  of  alkalis 
as  well  as  that  of  acids. 

However  plausible,  a  priori,  the  opinion 

of  water  and  leaving  the  carbon.  Hence  its 
blackening  power.  When  diluted,  it  acts 
in  a  totally  different  way.  Of  course  if  it  be 
an  acid  in  the  last  case,  it  cannot  be  so  in 
the  first.  In  evolving  carbon  by  its  action 
on  alcohol,  it  isprecisely  analogous  to  pot- 
ash, which  darkens  that  fluid,  and  evolves 
a  carbonaceous  resin,  which  may  be  seen 
when  the  alcoholic  solution  of  that  alkali  is 
evaporated,  in  order  to  obtain  the  hydrate. 

It  seems  to  me  that  the  galvanic  fluid  is 
the  acidifying  principle,  and  that  the  acid 
state  is  the  consequence  of  galvanic  ar- 
rangements or  polarities.  It  is  known  that 
moisture  is  indispensable  to  the  efficiency 
of  these. 

On  adding  water  to  concentrated  sulphu- 
ric acid,  the  hydrogen  and  oxygen  seve- 
rally go  to  the  different  poles  of  the  pre- 
vious compound.  Hence  the  hydrogen 
evolved  by  iron  or  zinc  and  diluted  sul- 
phuric acid,  does  not  come  from  a  simul- 
taneous, but  a  previous  decomposition  of 
water. 


of  this  illustrious  philosopher  may  be,  that 
the  smaller  the  quantity  of  an  acid  or  alka- 
li required  to  saturate  a  given  quantity  of 
its  antagonist  principle,  the  higher  should 
it  rank  in  the  scale  of  power  and  affinity, 
it  will  not,  however,  accord  with  chemical 
phenomena.  100  parts  of  nitric  acid  are 
saturated  by  about  36£  of  magnesia,  and 
by  52£  of  lime. 

Hence,  by  Berthollet'srule,  the  powers 
of  these  earths  ought  to  be  as  the  inverse 

1  1 

of  their  quantities,  viz.  —   and    — ;    yet 

36$          52$ 

the  very  opposite  effect  takes  place,  for 
lime  separates  magnesia  from  nitric  acid. 
And,  in  the  present  example,  the  differ- 
ence of  effect  cannot  be  imputed  to  the 
difference  offeree  with  which  the  substan- 
ces tend  to  assume  the  solid  state. 

We  have  therefore  at  present  no  single 
acidifying  principle,  nor  absolute  criterion 
of  the  scale  of  power  among  the  different 
acids:  nor  is  the  want  of  this  of  great  im- 
portance. Experiment  furnishes  us  with 
the  order  of  decomposition  ofoneacido- 
alkaline  compound  by  another  acid,  wheth- 
er alone,  or  aided  by  temperature  ;  and 
this  is  all  which  practical  chemistry  seems 
to  require. 

Before  entering  on  the  particular  acids 
we  shall  here  describe  the  general  process 
by  which  M.  Thenard  has  lately  succeeded 
in  communicating  to  many  of  them  appa- 
rently a  surcharge  of  oxygen,  and  thus  pro- 
ducing a  new  class  of  bodies,  the  oxygen- 
ized acids,  which  he  has  had  the  good  for- 
tune of  forming  and  making  known  to  the 
chemical  world.  The  first  notice  of  these 
new  compounds  appeared  in  the  Jinn,  de 
Chimie  et  Physique,  viii.  306.  for  July  1818, 
since  which  time  several  additional  com- 
munications of  a  very  interesting  nature 
have  been  made  by  the  same  celebrated 
chemist.  He  has  likewise  formed  a  com- 
pound of  water  with  oxygen,  in  which  the 
proportion  of  the  latter  principle  is  dou- 
bled, or  616  times  its  volume  is  added. 
The  methods  of  oxygenizing  the  liquid 
acids  and  water,  agree  in  this,  that  deu- 
toxide  of  barium  is  formed  first  of  all,  from 
which  the  above  liquids,  by  a  subsequent 
process,  derive  their  oxygen.  He  pre- 
scribes the  following  precautions,  without 
which  success  will  be  only  partial. 

1.  Nitrate  of  barytes  should  first  be  ob- 
tained perfectly  pure,  and,  above  all,  free 
from  iron  and  manganese.  The  most  cer- 
tain means  of  procuring  it,  is  to  dissolve  the 
nitrate  in  water,  to  add  to  the  solution  a 
small  excess  of  barytes  water,  to  filter  and 
crystallize.  2.  The  pure  nitrate  is  to  be 
decomposed  by  heat.  This  ought  not  to 
be  done  in  a  common  earthenware  retort, 
because  it  contains  too  much  of  the  oxides 
of  iron  and  manganese,  but  in  a  perfectly 


ACI 


ACI 


white  porcelain  retort.  Four  orfive  pounds 
of  nitrate  of  barytes  may  be  decomposed 
at  once,  and  the  process  will  require  about 
three  hours  The  barytes  thus  procured 
will  contain  a  considerable  quantity  of  si- 
lex  and  alumina ;  but  it  will  have  only 
very  minute  traces  of  manganese  andiron, 
a  circumstance  of  essential  importance. 
3.  The  barytes,  divided  by  a  knife  into 
pieces  as  large  as  the  end  of  the  thumb, 
should  then  be  placed  in  a  luted  tube  of 
glass.  This  tube  should  be  long1  and  large 
enough  to  contain  from  2£  to  3^  libs.  It 
is  to  be  surrounded  with  fire,  and  heated 
to  dull  redness,  and  then  a  current  of  dry 
oxygen  gas  is  to  be  passed  through  it. 
However  rapid  the  current,  the  gas  is  com- 
pletely absorbed;  so  that  when  it  passes 
by  the  small  tube,  which  ought  to  termi- 
nate the  larger  one,  it  may  be  concluded 
that  the  deutoxide  of  barium  is  completed. 
It  is,  however,  right  to  continue  the  cur- 
rent for  seven  or  eight  minutes  more. 
Then  the  tube  being  nearly  cold,  the  deu- 
toxide, which  is  of  a  light  grey  colour,  is 
taken  out,  and  preserved  in  stoppered  bot- 
tles. When  this  is  moistened  it  falls  to 
powder,  without  much  increase  of  temper- 
ature. If  in  this  state  it  be  mixed  with 
seven  or  eight  times  its  weight  of  water, 
and  a  dilute  acid  be  poured  in,  it  dissolves 
gradually  by  agitation,  without  the  evolu- 
tion of  any  gas.  The  solution  is  neutral, 
or  has  no  action  on  turnsole  or  turmeric. 
When  we  add  to  this  solution  the  requi- 
site quantity  of  sulphuric  acid,  a  copious 
precipitate  of  barytes  falls,  and  the  filtered 
liquor  is  merely  water,  holding  in  solution 
the  oxygenized  acid,  or  deutoxide  of  hy- 
drogen, combined  with  the  acid  itself. 

The  class  of  acids  has  been  distributed 
into  three  orders,  according  as  they  are 
derived  from  the  mineral,  the  vegetable, 
or  the  animal  kingdom.  But  a  more  spe- 
cific distribution  is  now  requisite.  They 
have  also  been  arranged  into  those  which 
have  a  single,  and  those  which  have  a  com- 
pound basis  or  radical.  But  this  arrange- 
ment is  not  only  vague,  but  liable  in  other 
respects  to  considerable  objections.  The 
chief  advantage  of  a  classification  is  to 
give  general  views  to  beginners  in  the 
study,  by  grouping  together  such  substan- 
ces as  have  analogous  properties  or  com- 
position. These  objects,  it  is  hoped,  will 
be  tolerably  well  attained  by  the  following 
divisions  and  subdivisions. 

Division  1st.  Acids  from  inorganic  nature, 
or  which  are  procurable  without  having 
recourse  to  animal  or  vegetable  products. 

Division  2d.  Acids  elaborated  by  means 
of  organization. 

The  first  group  is  subdivided  into  three 
families,  1st,  Oxygen  acids;  2d,  Hydrogen 
acids;  3d,  Acids  destitute  of  both  these 
supposed  acidifiers. 


Family  1st.— Oxygen  acids. 

Section  1st,  Non-metallic. 

1.  Boracic.  9.  Hypophosphorous. 

2.  Carbonic.  10.  Phosphorous. 

3.  Chloric.  11.  Phosphoric. 

4   Perchloric.  12.  Hyposulphurous. 

5.  Chloro-carbonic.  13.  Sulphurous. 

6.  Nitrous.  14.  Sulphuric. 

7.  Nitric.  15.  Hyposulphuric. 

8.  lodic.  16.  Cyanic  ? 

Section 2d,  Oxygen  acids. —  Metallic. 

1.  Arsenic.  6.  Columbic. 

2.  Arsenious.  7.  Molybdic. 

3.  Antimonious.         8.  Molybdous. 

4.  Antimonic.  9.  Tungstic. 

5.  Chromic. 

Family  2d. — Hydrogen  acids. 

1.  Fluoric.  5.  Hydroprussic. 

2.  Hydriodic.        6.  Hydrosulphurous. 

3.  Hydrochloric.  7.  Hydrotellurous. 

4.  Ferroprussic.   8.  Sulphuroprussie. 

Family  3d. — Acids  without  oxygen 
or  hydrogen. 

1.  Chloriodic.  3.  Fluoboric. 

2.  Chloroprussic.       4.  Fluosilicic. 

Division  2d. — Acids  of  organic  origin. 

1.  Aceric.  20.  Margaric. 

2.  Acetic.  21.  Melassic. 

3.  Amniotic.  22.  Mellitic. 

4.  Benzoic.  23.  Moroxylic. 

5.  Boletic.  24.  Mucic. 

6.  Camphoric.  25.  Oleic. 

7.  Caseic.  26.  Oxalic. 

8.  Citric.  27.  Purpuric. 

9.  Formic.  28  Pyrolithic. 

10.  Fungic.  29.  Pyromalic. 

11.  Gallic.  30.  Pyrotartaric. 

12.  Kinic.  31.  Rosacic. 

13.  Laccic.  32.  Saclactic. 

14.  Lactic.  33.  Sebacic. 

15.  Lampic.  34.  Suberic. 

16.  Lithic.  35.  Succinic. 

17.  Malic.  36.  Sulphovinic  ? 

18.  Meconic.  37.  Tartaric. 

19.  Menispermic.  38.  Zumic. 

The  acids  of  the  last  division  are  all  decom- 
posable at  a  red  heat,  and  afford  general- 
ly carbon,  hydrogen,  oxygen,  and  in  some 
few  cases  also  nitrogen.  The  mellitic  is 
found  like  amber  in  wood  coal,  and  like  it, 
is  undoubtedly  of  organic  origin.  We  shall 
treat  of  them  all  in  alphabetical  order,  only 
joining  those  acids  together  which  gradu- 
ate, so  to  speak,  into  each  other,  as  hypo- 
sulphurous,  sulphurous  and  sulphuric.* 

*  ACID  (ACEUTC).  A  peculiar  acid  said  to 
exist  in  the  juice  of  the  maple.    It  is  de- 
composed by  heat,  like  the  other  vegetable 
acids.* 

*  ACID  (ACETIC).  The  same  acid  which, 
in  a  very  dilute  and  somewhat  impure  state, 
is  called  vinegar. 


AC1 


ACI 


This  acid  is  found  combined  with  potash 
in  the  juices  of  a  great  many  plants  ;  par- 
ticularly the  sambucus  nigra,  phoenix  dac- 
tilifera,  galium  verum,  and  rhus  typhinus. 
S\veat,urine.  and  even  fresh  milk  contain  it. 
It  is  frequently  generated  in  the  stomachs 
of  dyspeptic  patients.  Almost  all  dry  veg- 
etable substances,  and  some  animal,  sub- 
jected in  close  vessels  to  a  red  heat,  yield  it 
copiously,  it  is  the  result  likewise  of  a  spon- 
taneous fermentatioUjto  which  liquid  veget- 
able, and  animal  matters  are  liable.  Strong 
acids,  as  the  sulphuric  and  nitric,  develope 
the  acetic  by  their  action  on  vegetables.  It 
was  long  supposed,  on  the  authority  of 
Boerhaave,  that  the  fermentation  which 
forms  vinegar  is  uniformly  preceded  by  the 
vinous.  This  is  a  mistake.  Cabbages  sour 
in  water,  making  sour  crout  ;  starch  in 
starch-makers'  sour  waters  ;  and  dough  it- 
self, without  any  previous  production  of 
wine. 

The  varieties  of  acetic  acids  known  in 
commerce  are  four:  1st,  Wine  vinegar;  2d, 
Malt  vinegar;  3d,  Sugar  vinegar  ;  4th, 
Wood  vinegar.  We  shall  describe  first  the. 
mode  of  making  these  commercial  arti- 
cles, and  then  that  of  extracting  the  abso- 
lute acetic  acid  of  the  chemist,  eitherfrom 
these  vinegars,  or  directly  from  chemical 
compounds,  of  which  it  is  a  constituent. 

The  following  is  the  plan  of  making  vin- 
egar at  present  practised  in  Paris.  The 
wine  destined  for  vinegar  is  mixed  in  a  large 
tun  with  a  quantity  of  wine  lees,  and  the 
whole  being  transferred  into  cloth-sacks, 
placed  within  a  large  iron-bound  vat,  the 
liquid  matter  is  extruded  through  the 
sacks  by  superincumbent  pressure.  What 
passes  through  is  put  into  large  casks,  set 
upright,  having  a  small  aperture  in  their 
top.  In  these  it  is  exposed  to  the  heat  of 
the  sun  in  summer,  or  to  that  of  a  stove  in 
winter.  Fermentation  supervenes  in  a  few 
days.  If  the  heat  should  then  rise  too  high 
it  is  lowered  by  cool  air,  and  the  addition 
of  fresh  wine.  In  the  skilful  regulation  of 
the  fermentative  temperature  consists 
the  art  of  making  good  wine  vinegar.  In 
summer  the  process  is  generally  comple- 
ted in  a  fortnight;  in  winter  double  the 
time  is  requisite.  The  vinegar  is  then  run 
wffinto  barrels,  which  contain  several  chips 
of  birch-wood.  In  about  a  fortnight  it  is 
found  to  be  clarified,  and  is  then  fit  for  the 
market.  It  must  be  kept  in  close  casks. 

The  manufacturers  at  Orleans  prefer  wine 
of  a  year  old  for  making  vinegar.  But  if  by 
age  the  wine  has  lost  its  extractive  matter, 
it  does  not  readily  undergo  the  acetous  fer- 
mentation. In  this  case,  acetification,  as  the 
French  term  the  process,  may  be  deter- 
mined by  adding  slips  of  vines,  bunches  of 
grapes  or  green  woods.  It  has  been  asserted 
that  alcohol,  added  to  fermentable  liquor, 
does  not  increase  the  product  of  vinegar.But 


this  is  a  mistake.  Stahl  observed  long1  ag», 
that  if  we  moisten  roses,  or  lilies  with'al- 
cohol,  and  place  them  in  vessels  in  which 
they  are  stirred  from  time  to  time,  vinegar 
will  be  formed.  He  also  informs  us,  if  after 
abstracting  the  citric  acid  from  lemon  juice 
by  crabs'  eyes  (carbonate  of  lime),  we 
add  a  little  alcohol  to  the  supernatent  li- 
quid, and  place  the  mixture  in  a  proper 
temperature,  vinegar  will  be  formed. 

Chaptal  says,  that  two  pounds  of  weak 
spirits,  sp.  gr,  0.985,  mixed  with  300  grains 
of  beer  veast,  and  a  little  starch  water,  pro- 
duced extremely  strong  vinegar.  The  acid  ' 
was  developed  on  the  5th  day.  The  same 
quantity  of  starch  and  yeast,  without  the 
spirit,  fermented  more  slowly,  and  yielded 
a  weaker  vinegar.  A  slight  motion  is  found 
to  favour  the  formation  of  vinegar,  and  to 
endanger  its  decomposition  after  it  is  made. 
Chaptal  ascribes  to  agitation  the  operation 
of  thunder;  though  it  is  well  known,  that 
when  the  atmosphere  is  highly  electrified, 
beer  is  apt  to  become  suddenly  sour,  with- 
out the  concussion  of  a  thunder-storm.  In 
cellars  exposed  to  the  vibrations  occasioned 
by  the  rattling  of  carriages,  vinegar  does  not 
keep  well.  The  lees,  which  had  been  de- 
posited by  means  of  isinglass  and  repose, 
are  thus  jumbled  into  the  liquor,  and  make 
the  fermentation  recommence. 

Almost  all  the  vinegar  of  the  north  of 
France  being  prepared  at  Orleans,  the 
manufactory  of  that  place  has  acquired  such 
celebrity,  as  to  render  their  process  wor- 
thy of  a  separate  consideration. 

The  Orleans'  casks  contain  nearly  400 
pints  of  wine.  Those  which  have  been  al- 
ready used  are  preferred.  They  are  placed 
in  three  rows,  one  over  another,  and  in  the 
top  have  an  aperture  of  two  inches  diam- 
eter, kept  always  open.  The  wine  for  ace- 
tification is  kept  in  adjoining  casks,contain- 
ing  beech  shavings,  to  which  the  lees  ad- 
here. The  wine  thus  clarified  is  drawn  off 
to  make  vinegar.  One  hundred  pints  of 
good  vinegar,  boiling  hot,  are  first  poured 
into  each  cask,  and  left  there  for  eight 
days.  Ten  pints  of  wine  are  mixed  in,  every 
eight  days,  till  the  vessels  are  full.  The 
vinegar  is  allowed  to  remain  in  this  state 
fifteen  days,  before  it  is  exposed  to  sale. 

The  used  casks,  called  mothers,  are  never 
emptied  more  than  half,but  are  successively 
filled  again,  to  acetify  new  portions  of  wine. 
In  order  to  judge  if  the  mother  works,  the 
vinegar  makers  plunge  a  spatula  into  the 
liquid  ;  and  according  to  the  quantity  of 
froth  which  the  spatula  shows,  they  add 
more  or  less  wine.  In  summer,  the  atmos- 
pheric heat  is  sufficient.  In  winter,  stoves 
heated  to  about  75°  Fahr.  maintain  the 
requisite  temperature  in  the  manufactory. 

In  some  country  districts,  the  people 
keep  in  a  place,  where  the  temperature  is 
mild  and  equable,  a  'vinegar  cask,  into 


ACI 


ACI 


which  they  pour  such  wine  as  they  wish 
to  acetify  ;  and  it  is  always  preserved  full, 
by  replacing"  the  vinegar  drawn  off,  by  new 
wine.  To  establish  this  household  manu- 
facture, it  is  only  necessary  to  buy  at  first 
a  small  cask  of  good  vinegar.  At  Gand  a 
vinegar  from  beer  is  made,  in  which  the 
following  proportions  of  grain  are  found 
to  be  most  advantageous  :  — 

1880  Paris  Ibs.  malted  barley. 
700  wheat. 

500  buckwheat. 

These  grains  are  ground,  mixed,  and  boil- 
ed, along  with  twenty-seven  casks-full  of 
river  water,  for  three  hours.      Eighteen 
I    casks  of  good  beer  for  vinegar  are  obtain- 
|    ed.  By  a  subsequent  decoction,  more  fer- 
i    mentable  liquid  is  extracted,  which  is  mix- 
ed with  the   former.  The  whole  brewing 
yields  3000  English  quarts. 

In  this  country,  vinegar  is  usually  made 
from  malt.  By  mashing  with  hot  water, 
100  gallons  of  wort  are  extracted  in  less 
than  two  hours  from  1  boll  of  malt.  When 
the  liquor  has  fallen  to  the  temperature  of 
75°  Fahr.  4  gallons  of  the  barm  of  beer  are 
added.  After  thirty-six  hours  it  is  racked 
off  into  casks,  which  are  laid  on  their  sides, 
and  exposed,  with  their  bung-holes  loose- 
ly covered,  to  the  influence  of  the  sun  in 
summer ;  but  in  winter  they  are  arranged 
in  a  stove-room.  In  three  months  this 
vinegar  is  ready  for  the  manufacture  of  su- 
gar of  lead.  To  make  vinegar  for  domes- 
tic use,  however,  the  process  is  somewhat 
different.  The  above  liquor  is  racked  off 
into  casks  placed  upright,  having  a  false 
cover  pierced  with  holes  fixed  at  about  a 
foot  from  their  bottom.  On  this  n.  consid- 
erable quantity  of  rape,  or  the  refuse  from 
the  makers  of  British  wine,  or  otherwise  a 
quantity  of  low  priced  raisins,  is  laid.  The 
liquor  is  turned  into  another  barrel  every 
twenty-four  hours,  in  which  time  it  has 
begun  to  grow  warm.  Sometimes,  indeed^ 
the  vinegar  is  fully  fermented,  iu  above, 
without  the  rape,  which  is  added  towards 
the  end,  to  communicate  flavour.  Two 
large  casks  are  in  this  case  worked  togeth- 
er, as  is  described  long  ago  by  LJocrhaave, 
as  follows. 

"  Take  two  large  wooden  vats,  or  hogs- 
heads, and  in  each  cf  these  place  a  wooden 
grate  or  hurdle,  at  the  distance  of  a  foot 
from  the  bottom.  Set  the  vessel  upright, 
and  on  the  grate  place  a  moderately  close 
layer  of  green  twigs,  or  fresh  cuttings  of 
the  vine.  Then  fill  up  the  vessel  with  the 
footstalks  of  grapes,  commonly  called  the 
rape,  to  the  top  of  the  vessel,  which  must 
be  left  quite  open. 

"Having  thus  prepared  the  two  vessels, 
pour  into  them  the  wine  to  be  converted 
into  vinegar,  so  as  to  fill  one  of  them  quite 
up,  and  the  other  but  half  full.-  Leave 
them  thus  for  twenty-four  hours,  and  then 
Von.  I-.  F21 


fill  up  the  half  filled  vessel  with  liquor 
from  that  which  is  quite  full,  and  which 
will  now  in  its  turn  only  be  left  half  full. 
Four-and-twenty  hours  afterwards  repeat 
the  same  operation,  and  thus  go  on,  keep- 
ing the  vessels  alternately  full  and  half  full 
during  twenty-four  hours,  till  the  vinegar 
be  made.  On  the  second  or  third  day  there 
will  arise  in  the  half  filled  vessel,  a  fermen- 
tative motion,  accompanied  with  a  sensible 
heat,  which  will  gradually  increase  from 
day  to  day.  On  the  contrary,  the  ferment- 
ing motion  is  almost  imperceptible  in  the 
full  vessel ;  and  as  the  two  vessels  are  al- 
ternately full  and  half  full,  the  fermenta- 
tion is  by  this  means  in  some  measure  in- 
terrupted, and  is  only  renewed  every 
other  day  in  each  vessel. 

"  When  this  motion  appears  to  have  en- 
tirely ceased,  even  in  the  half  filled  vessel, 
it  is  a  sign  that  the  fermentation  is  finished; 
and  therefore  the  vinegar  is  then  to  be  put 
into  casks  close  stopped,  and  kept  in  a 
cool  place. 

"  A  greater  or  less  degree  of  warmth 
accelerates  or  checks  this,  as  well  as  the 
spirituous  fermentation.  In  France  it  is 
finished  in  about  fifteen  days,  during  the 
summer ;  but  if  the  heat  of  the  air  be  very 
great,  and  exceed  the  twenty -fifth  degree 
of  Reaumur's  thermometer,  (88^°  Fahr.) 
the  half  filled  vessel  must  be  filled  up  eve- 
ry twelve  hours  ;  because,  if  the  fermen- 
tation be  not  so  checked  in  that  time,  it 
will  become  violent,  and  the  liquor  will  be 
so  heated,  that  many  of  the  spirituous  parts, 
on  which  the  strength  of  the  vinegar  de- 
pends, will  be  dissipated,  so  that  nothing 
will  remain  after  the  fermentation  but  a 
vapid  liquor,  sour  indeed,  but  effete.  The 
better  to  prevent  the  dissipation  of  the 
spirituous  parts,  it  is  a  proper  and  usual 
precaution  to  close  the  mouth  of  the  half 
filled  vessel,  in  which  the  liquor  ferments, 
with  a  cover  made  of  oak  wood.  As  to 
the  full  vessel,  it  is  always  left  open,  that 
the  air  may  act  freely  on  the  liquor  it  con- 
tains ;  for  it  is  not  liable  to  the  same  in- 
conveniences, because  it  ferments  but  very 
slowly." 

Good  vinegar  may  be  made  from  a  weak 
sirup,  consisting  of  18  oz.  of  sugar  to  eve- 
ry gallon  of  water.  The  yeast  and  rape, 
are  to  be  here  used,  as  above  described. 
Whenever  the  vinegar  (from  the  taste  and 
flavour)  is  considered  to  be  complete,  it 
ought  to  be  decanted  into  tight  barrels  or 
bottles,  and  well  secured  from  access  of 
air.  A  momentary  ebullition  before  it  is 
bottled  is  found  favourable  to  its  preserva- 
tion. In  a  large  manufactory  of  malt  vine- 
gar, a  considerable  revenue  is  derived  from 
the  sale  of  yeast  to  the  bakers.  Vinegar 
obtained  by  the  preceding  methods  has 
more  or  less  of  a  brown  colour,  and  a  pe- 
culiar but  rather  gratpfi-H  smelt.  By  dts- 


ACI 


ACI 


tiilation  in  glass  vessels  the  colouring  mat- 
ter, which  resides  in  a  mucilage,  is  sepa- 
rated, but  the  fragrant  odour  is  generally 
replaced  by  an  empyreumatic  one.  The 
best  French  wine  vinegars,  and  also  some 
from  malt,  contain  a  little  alcohol,  which 
comes  over  early  with  the  watery  part, 
and  renders  the  first  product  of  distillation 
scarcely  denser,  sometimes  even  less  dense 
than  water.  It  is  accordingly  rejected. — 
Towards  the  end  of  the  distillation  the  em- 
pyreu ma  increases.  Hence  only  the  inter- 
mediate portions  are  retained  as  distilled 
vinegar.  Its  specific  gravity  varief  from 
1.005  to  1.015,  while  that  of  common  vin- 
egar of  equal  strength  varies  from  1.010  to 
1.025. 

A  crude  vinegar  has  been  long  prepared 
for  the  calico  printers,  by  subjecting  wood 
in  iron  retorts  to  a  strong  red  heat.  The 
following  arrangement  of  apparatus  has 
been  found  to  answer  well.  A  series  of 
cast-iron  cylinders,  about  4  feet  diameter, 
and  6  feet  long,  are  built  horizontally  in 
brick  work,  so  that  the  flame  of  one  fur- 
nace may  play  round  about  two  cylinders. 
Both  ends  project  a  little  from  the  brick 
work.  One  of  them  has  a  disc  of  cast-iron 
well  fitted  and  firmly  bolted  to  it,  from  the 
centre  of  which  disc  an  iron  tube  about  6 
inches  diameter  proceeds,  and  enters  at  a 
right  angle  the  main  tube  of  refrigeration. 
The  diameter  of  this  tube  may  be  from  9 
to  14  inches,  according  to  the  number  of 
cylinders.  The  other  end  of  the  cylinder 
is  called  the  mouth  of  the  retort.  This  is 
closed  by  a  disc  of  iron,  smeared  round  its 
edge  with  clay-lute,  and  secured  in  its 
place  by  wedges.  The  charge  of  wood  for 
such  a  cylinder  is  about  8  cvvt.  The  hard 
woods,  oak,  ash,  birch,  and  beech,  are 
alone  used.  Fir  does  not  answer.  The  heat 
is  kept  up  during  the  day-time,  and  the 
furnace  is  allowed  to  cool  during  the  night. 
Next  morning  the  door  is  opened,  the 
charcoal  removed,  and  a  new  charge  of 
wood  is  introduced.  The  average  product 
of  crude  vinegar  called  pyrolignous  acid 
is  35  gallons.  It  is  much  contaminated  with 
tar;  is  of  a  deep  brown  colour;  and  has 
a  sp.  gr.  of  1.025.  Its  total  weight  is  there- 
fore about  SOOlbs.  But  the  residuary  char- 
coal is  found  to  weigh  no  more  than  one- 
fifth  of  the  wood  employed.  Hence  nearly 
one  half  of  the  ponderable  matter  of  the 
wood  is  dissipated  in  incondensable  gases. 
Count  Rumford  states,  that  charcoal  is 
equal  in  weight  to  more  than  four-tenths 
of  the  wood  from  which  it  is  made.  And 
M.  Clement  says  that  it  is  equal  to  one- 
half.  The  Count's  error  seems  to  have 
arisen  from  the  slight  heat  of  an  oven  to 
which  his  wood  was  exposed  in  a  glass 
cylinder.  The  result  now  given  is  the  ex- 
perience of  an  eminent  manufacturing 
chemist  at  Glasgow.  The  crude  pyrolig- 


uous  acid  is  rectified  by  a  second  distilla- 
tion in  a  copper  still,  in  the  body  of  which 
about  20  gallons  of  viscid  tarry  matter  are 
left  from  every  100.  It  has  now  become  a 
transparent  brown  vinegar,  having  a  con- 
siderable empyreumatic  smell,  and  a  sp. 
gr.  of  1.013.  Its  acid  powers  are  superior 
to  those  of  the  best  household  vinegar,  in 
the  proportion  of  3  to  2.  By  redistilla'ion, 
saturation  with  quick-lime,  evaporation  of 
the  liquid  acetate  to  dry  ness,  and  gentle 
torrefaction,  the  empyreumatic  matier  is 
so  completely  dissipated,  that  on  decom- 
posing the  ca'careous  salt  by  sulphuric 
acid,  a  pure,  perfectly  colourless,  and 
grateful  vinegar  rises  in  distillation.  Its 
strength  will  be  proportional  to  the  con- 
centration of  the  decomposing  acid. 

The  acetic  acid  ot  the  chemist  may  be 
prepared  in  the  following  modes:  1st, 
Two  parts  of  fused  acetate  of  potash  with 
one  of  the  strongest  oil  of  vitriol  yield,  by 
slow  distillation  from  a  glass  retort  into  a 
refrigerated  receiver,  concentrated  acetic 
acid.  A  small  portion  of  sulphurous  acid, 
which  contaminates  it,  may  be  removed  by 
redistillation,  from  a  little  acetate  of  lead. 
2d,  Or  4  parts  of  good  sugar  of  lead,  with 
1  part  of  sulphuric  acid  treated  in  the  same 
way,  afford  a  slightly  weaker  acetic  acid. 
3d,  Gently  calcined  sulphate  of  iron,  or 
green  vitriol,  mixed  with  sugar  of  lead  in 
the  pi-oportion  of  1  of  the  former  to  2£  of 
the  latter,  and  carefully  distilled  from  a 
porcelain  retort  into  a  cooled  receiver, 
may  be  also  considered  a  good  economi- 
cal process.  Or  without  distillation,  if  100 
parts  of  well  dried  acetate  of  lime  be  cau- 
tiously added  to  60  parts  of  strong  sulphu- 
ric acid,  diluted  with  5  parts  of  water,  and 
digested  for  24  hours,  and  strained, a  good 
acetic  acid,  sufficiently  strong  for  every 
ordinary  purpose,  will  be  obtained. 

The  distillation  of  acetate  of  copper  or 
of  leader  se,  has  also  been  employed  for 
obtaining  strong  acid.  Here,  however,  the 
product  is  mixed  with  a  portion  of  the  fra- 
grant pyro-acetic  spirit,  which  it  is  trou- 
blesome to  get  rid  of.  Undoubtedly  the 
best  process  for  the  strong  acid  is  that  first 
described,  and  the  cheapest  the  second  or 
third.  When  of  the  utmost  possible 
strength  its  sp.  gravity  is  1.  062.  At  the 
temperature  of  50°  F.  it  assumes  the  solid 
form,  crystallizing  in  oblong  rhomboidal 
plates.  It  has  an  extremely  pungent 
odour,  affecting-  the  nostrils  and  eyes  even 
painfully,  when  its  vapour  is  incautiously 
snuffed  up.  lis  taste  is  eminently  acid  and 
acrid.  It  excoriates  and  inflames  tho 
skin. 

The  purified  wood  vinegar,  which  is 
used  for  pickles  and  culinary  purposes, 
has  commonly  a  specific  gravity  of  about 
1.009;  when  it  is  equivalent  in  acid 
strength  to  good  wine  or  malt  vinegar  of 


ACI 


ACI 


1.014.  It  contains  about  of^ff  its  weight 
of  absolute  acetic  acid,  and  ^  of  water. 
An  excise  duty  of  4d.  is  levied  on  every 
gallon  of  vinegar  of  the  above  strength. 
This,  however,  is  not  estimated  directly 
by  its  sp.  gr.  but  by  the  sp.  gr.  which  re- 
sults from  its  saturation  with  quick-lime. 
The  decimal  number  of  the  sp.  gr.  of  the 
calcareous  acetate,  is  nearly  double  that  of 
the  pure  wood  vinegar.  Thus  1.009  in 
vinegar,  becomes  1.018  in  liquid  acetate. 
But  the  vinegar  of  fermentation  =1.014 
will  become  only  1.023  in  acetate,  from 
which,  if  0.005  be  subtracted  for  mucilage 
or  extractive,  the  remainder  will  agree 
with  the  density  of  the  acetate  from  wood. 
A  glass  hydrometer  of  Fahrenheit's  con- 
struction is  used  for  finding  the  specific 
gravities.  It  consists  of  a  globe  about  3 
inches  diameter,  having  a  little  ballast  ball 
drawn  out  beneath,  and  a  stein  above  of 
about  3  inches  long,  containing  a  slip  of 
paper  with  a  transverse  line  in  the  middle, 
and  surmounted  with  a  little  cup  for  re- 
ceiving weights  or  poises.  The  experi- 
ments on  which  this  instrument,  called  an 
hectometer,  is  constructed,  have  been  de- 
tailed in  the  sixth  volume  of  the  Journal 
of  Science.  They  do  not  differ  essentially 
from  those  of  Mollerat.  The  following 
points  were  determined  by  this  chemist. 
The  acid  of  sp.  gr.  1.063  requires  2^  times 
its  weight  of  crystallized  subcarbonate  of 
soda  for  saturation,  whence  M.  Thenard 
regards  it  as  a  compound  of  11  of  water, 
and  89  of  real  acid  in  the  100  parts.  Com- 
bined with  water  in  the  proportion  of  100 
to  112.2,  it  does  not  change  its  density, 
but  it  then  remains  liquid  several  degrees 
below  the  freezing  point  of  water.  By  di- 
luting it  with  a  smaller  quantity  of  water, 
its  sp.  gr.  augments,  a  circumstance  pecu- 
liar to  this  acid.  It  is  1.079,  or  at  its  maxi- 
mum, when  the  water  forms  one-third  of 
the  weight  of  the  acid.  -Ann.  de  Chimie, 
torn.  66. 

The  following  table  is  given  by  Messrs 
Taylor  as  the  basis  of  their  acetome- 
ter:— 

Revenue  proof  acid,  called  by  the  man- 
ufacturer No.  24. 

sp.  gr.  1.0085  contains  real  acid  in  100,   5 

1.0170 10 

1.0257 15 

1.0320 20 

1.0470 30 

1.0580 40 

An  acetic  acid  of  very  considerable 
Strength  may  also  be  prepared  by  satu- 
rating perfectly  dry  charcoal  with  common 
vinegar,  and  then  distilling.  The  water 
easily  comes  off,  and  is  separated  at  first ; 
hut  a  stronger  heat  is  required  to  expel  the 


acid.  Or  by  exposing  vinegar  to  very  cold 
air,  or  to  freezing  mixtures,  its  water  sepa- 
rates in  the  state  of  ice,  the  interstices  of 
which  are  occupied  by  a  strong  acetic  acid, 
which  may  be  procured  by  draining.  The 
acetic  acid  or  radical  vinegar  of  the  apo- 
thecaries, in  which  they  dissolve  a  little 
camphor,  or  fragrant  essential  oil,  has  a 
specific  gravity  of  about  1.070.  It  contains 
fully  1  part  of  water  to  2  of  the  crystalliz- 
ed acid.  The  pungent  smelling  salt  con- 
sists  of  sulphate  of  potash  moistened  with 
that  acid.  Acetic  acid  acts  on  tin,  iron, 
zinc,  copper,  and  nickel;  and  it  combines 
readily  with  the  oxides  of  many  other  me- 
tals, by  mixing  a  solution  of  their  sulphates 
with  that  of  an  acetate  of  lead. 

This  acid,  as  it  exists  in  the  acetates  of 
barytes  and  lead,  has  been  analyzed  by  M. 
M.  Gay-Lussac  and  Thenard,  and  also  by 
Berzelius. 

Gay-Lussac  found  50.224  carbon,  5.629 
hydrogen,  and  44.147  oxygen  ;  or,  in  other 
terms,  50.224  carbon,  49.665  of  water,  or 
its  elementary  constituents,  and  0.111  hy- 
drogen in  excess. 

Berzelius.— 46.83  carb.  6.35  hydr.  and 
46.82  oxygen  in  the  hundred  parts. 

Their  methods  are  described  under  VE- 
GETABLE (AVALYSIS).  By  saturating  known 
weights  of  bases  with  acetic  acid,  and  as* 
certaining  the  quantity  of  acetates  obtain- 
ed after  cautious  evaporation  to  dryness, 
Berzelius  obtained  with  lime  (3.55)  6.5  for 
the  prime  equivalent  of  acetic  acid,  and 
with  yellow  oxide  of  lead  6.4  >2.  Recent  re- 
searches, which  will  be  published  in  a  de- 
tailed form,  induce  me  to  fix  the  prime  of 
acetic  acid  at  6.63.  It  would  seem  to  con,- 
sist,  by  Berzelius's  analysis,  of 

3  Primes  of  hydrogen      3.75      6.2 

4  carbon        30.        46.9 
3  oxygen        30.        46.9 

63,75  100.0 

The  quantity  of  hydrogen  is  probably 
much  underrated.  Acetic  acid  dissolves 
resins,  gum-resins,  camphor,  and  essential 
oils.  Its  odour  is  employed  in  medicine  to 
relieve  nervous  headaches,  faintingfits,  or 
sickness  occasioned  by  crowded  rooms.  In 
a  slightly  dilute  state,  its  application  has 
been  found  to  check  hemorrhagy  from  the 
nostrils.  Its  anticontagious  powers  are 
now  little  trusted  to.  It  is  very  largely 
used  in  calico  printing.  Moderately  rec- 
tified pyrolignous  acid  hasbeen  recommen- 
ded for  the  preservation  of  animal  food  ; 
but  the  empyreumatic  taint  it  communi- 
cates to  bodies  immersed  in  it,  is  not  quite 
removed  by  their  subsequent  ebullition  in 
water.  See  Acid,  (Pyrolignous). 

Acetic  acid  and  common  vinegar  are 
sometimes  fraudulently  mixed  with  sal- 


AC1 


ACI 


phuric  acid  to  give  them  strength.  This 
adulteration  may  be  detected  by  the  ad- 
dition of  a  little  chalk,  short  of  their  satu- 
ration. With  pure  vinegar  the  calcareous 
base  forms  a  limpid  solution,  but  with 
sulphuric  acid  a  white  insoluble  gypsum. 
Muriate  of  barytes  is  a  still  nicer  test. 
British  fermented  vinegars  are  allowed  by 
law  to  contain  a  little  sulphuric  acid,  but 
the  quantity  is  frequently  exceeded. 
Copper  is  discovered  in  vinegars  by  super- 
saturating them  with  ammonia,  when  a 
fine  blue  colour  is  produced  ;  and  lead  by 
sulphate  of  soda,  hydrosulphurets,  «ilph- 
uretted  hydrogen,  and  gallic  acid.  None 
of  these  sho-.ild  produce  any  change  on 
genuine  vinegar.  See  LKAD.* 

*  ACID  (OXY-ACETIC).  Acetic  acid  dis- 
solves deutoxide  of  barium  without  effer- 
vescence. By  precipitating  the  barytes 
with  sulphuric  acid,  there  remains  an  ox- 
ygenized acid,  which,  being  saturated 
with  potash,  and  heated,  allows  a  great 
quantity  of  oxygen  gas  to  escape.  There 
is  disengaged  at  the  same  time  a  notable 
quantity  of  carbonic  acid  gas.  This  shows 
that  the  oxygen,  when  assisted  by  heat, 
unites  in  part  with  the  carbon,  and  doubt- 
less likewise  with  the  hydrogen  of  the 
acid.  It  is  in  fact  acetic  deutoxide  of  hy- 
drogen. 

Salts  consisting  of  the  several  bases, 
united  in  definite  proportions  to  acetic 
acid,  are  called  acetates.  They  are  char- 
acterized by  the  pungent  smell  of  vinegar, 
which  they  exhale  on  the  affusion  of  sul- 
phuric acid ;  and  by  their  yielding  on  dis- 
tillation in  a  moderate  red  heat  a  very 
light,  odorous,  and  combustible  liquid 
called  pyro-acetic  (SPIRIT)  ;  which  see. 
They  are  all  soluble  in  water;  many  of 
them  so  much  so  as  to  be  uncrystallizable. 
About  30  different  acetates  have  been 
formed,  of  which  only  a  very  few  have 
been  applied  to  the  uses  of  life.* 

The  acetic  acid  unites  with  all  the  alka- 
lis and  most  of  the  earths,  and  with  these 
bases  it  forms  compounds,  some  of  which 
are  crystallizable,  and  others  have  not  yet 
been  reduced  to  a  regularity  of  figure.  The 
salts  it  forms  are  distinguished  by  their 
great  solubility;  their  decomposition  by 
fire,  which  carbonizes  them  ;  the  spontan- 
eous alteration  of  their  solution  ;  and  their 
decomposition  by  a  great  number  ofuc'.ds, 
which  extricate  from  them  the  acetic  acid 
in  a  concentrated  state,  it  unites  likewise 
with  most  of  the  metallic  oxides. 

With  barytes  the  saline  mass  formed  by 
the  acetic  acid  does  not  crystallize;  but, 
when  evaporated  to  dryness,  it  deliques- 
ces by  exposure  to  air.  This  mass  is  not 
decomposed  by  acid  of  arsenic.  By  spon- 
taneous evaporation,  however,  it  will 
crystallize  in  fine  transparent  prismatic 
of  a  bitterish  acid  taste,  which  do 


not  deliquesce  when  exposed  to  the  air, 
but  rather  effloresce. 

With  potash  this  acid  unites,  and  forms  a 
deliquescent  salt  scarcely  crystallizable, 
called  formerly  foliated  earth  of  tartar,  and 
regenerated  tartar.  The  solution  of  this 
salt,  even  in  closely  stopped  vessels,  is 
spontaneously  decomposed :  it  deposites  a 
thick,  mucous,  flocculent  sediment,  at  first 
gray,  and  at  length  black  ;  till  at  the  end 
of  a  few  months  nothing  remains  in  the 
liquor  but  carbonate  of  potash,  rendered 
impure  by  a  little  coaly  oil. 

With  soda  it  forms  a  crystallizable  salt, 
which  does  not  deliquesce.  This  salt  has 
very  improperly  been  called  mineral  foli- 
ated earth.  According  to  the  new  nomen- 
clature it  is  acetate  of  soda. 

The  salt  formed  by  dissolving  chalk  or 
other  calcareous  earth  in  distilled  vinegar, 
formerly  called  salt  of  chalk,  or  fixed  vege- 
table sal  ammoniac,  and  by  Bergman  calx 
acetata,  has  a  sharp  bitter  taste,  appears  in 
the  form  of  crystals  resembling  somewhat 
ears  of  corn,  which  remain  dry  when  ex- 
posed to  the  air,  unless  the  acid  has  been 
super-abundant,  in  which  case  they  deli- 
quesce. By  distilling  without  addition, 
the  acid  is  separated  from  the  earth,  and 
appears  in  the  form  of  a  white,  acid,  and  in- 
flammable vapour,  which  smells  like  acetic 
ether,  somewhat  empyreumatic,and  which 
condenses  into  a  reddish  brown  liquor. 

This  liquor,  being  rectified,  is  very  vola- 
tile and  inflammable  :  upon  adding  water 
it  acquires  a  milky  appearance,  and  drops 
of  oil  seem  to  swim  upon  the  surface. 
After  the  rectification,  a  reddish  brown  li- 
quor remains  behind  in  the  retort,  toge. 
ther  with  a  black  thick  oil.  When  this 
earthy  salt  is  mixed  with  a  solution  of  sul- 
phate of  soda,  the  calcareous  earth  is  pre- 
cipitated along  with  the  sulphuric  acid ;  the 
acetic  acid  uniting  with  the  soda,  makes  a 
crystallizable  salt,  by  the  calcination  of 
which  to  whiteness,  the  soda  may  be  ob- 
tained. This  acetic  calcareous  salt  is  not 
soluble  inspirit  of  wine. 

Of  the  acetate  of  strontian  little  is  known, 
but  that  it  has  a  sweet  taste,  is  very  solu- 
ble, and  is  easily  decomposed  by  a  strong 
heat. 

The  salt  formed  by  uniting  vinegar  with 
ammonia,  called  by  the  various  names  of 
spirit  of  Mindererus,  liquid  sal  ammoniac, 
acetous  sal  ammoniac,  and  by  Bergman  al- 
kali volatile  acctatum,  is  generally  in  a 
liquid  state,  and  is  commonly  believed  not 
to  be  crystallizable,  as  in  distillation  it  pass- 
es entirely  over  into  the  receiver.  It  ne- 
vertheless may  be  reduced  into  the  form 
of  small  needle-shaped  crystals,  when  this 
liquor  is  evaporated  to  the  consistence  of 
a  sirup. 

Westendorf,  by  adding1  his  concentrated 
vinegar  to  carbonate  of  ammonia,  obtained 


AC1 


ACI 


n  pellucid  liquid,  which  did  not  crystallize ; 
and  which  by  distillation  was  totally  expell- 
ed from  the  retort,  leaving-  only  a  white 
spot.  In  the  receiver,  under  'he  clear  fluid, 
a  transparent  saline  mass  appeared,  which 
being  separated  from  the  fluid,  and  expo- 
sed to  gentle  warmth,  melted  and  threw  out 
abundance  of  white  vapours,  and  in  a  few 
minutes  shot  into  sharp  crystals  resembling 
th;.-se  of  nitre.  Thf-se  crystals  remain  un- 
changed while  cold,  but  they  melt  at  120° 
and  evaporate  at  about  250°.  Their  taste 
at  first  is  sharp  and  then  sweet,  and  they 
possess  the  general  properties  of  neutral 
•salts, 

With  magnesia  the  acetic  acid  unites, 
and,  after  a  perfect  saturation,  forms  a  vis- 
cid saline  mass,  like  a  solution  of  gum  ara- 
ble, which  does  not  shoot  into  crystals,  but 
remains  deliquescent,  has  a  taste  sweetish 
at  first  and  afterwards  bitter,  and  is  soluble 
in  spirit  of  wine.  The  acid  of  this  saline 
mass  may  be  separated  by  distillation  with- 
out addition. 

Glucine  is  readily  dissolved  bv  acetic  acid. 
This  solution,  as  Vauquelin  informs  us,  does 
not  crystallize ;  but  is  reduced  by  evapora- 
tion to  a  gummy  substance,  which  slowly 
becomes  dry  and  brittle  ;  retaining  a  kind 
of  ductility  for  a  long  time.  It  has  a  sac- 
charine and  pretty  strongly  astringent  taste, 
in  which  that  of  vinegar  however,  is  distin- 
guishable. 

Yttria  dissolves  readily  in  acetic  acid,  and 
the  solution  yields  by  evaporation  crystals 
of  acetate  of  yttria.  These  have  common- 
ly the  form  of  thick  six-sided  plates,  and 
are  not  altered  by  exposure  to  the  air. 

Alumine,  obtained  by  boiling  alum  with 
alkali,  and  edulcorated  by  digesting  in  an 
alkaline  lixivium,  is  dissolved  by  distilled 
vinegar  in  a  very  inconsiderable  quantity. 
A  considerable  quantity  of  the  earth  of  al- 
um, precipitated  by  alkali,  and  edulcorated 
by  liot  water  in  MargrafPs  manner,  is  solu- 
ble in  vinegar,  and  a  whitish  saline  mass  is 
then  obtained,  which  is  not  crystallizable. 
Fro.n  this  mass  a  concentrated  acetic  acid 
may  be  obtained  by  distillation.  Or  to  a 
boiling  solution  of  alum  in  water  gradually 
add  a  solution  of  acetate  of  lead  till  no  fur- 
ther precipitate  ensues.  The  sulphate  of 
lead  having  subsided,  decant  the  superna- 
tant liquor,  evaporate,  and  the  acetnte  of 
alumine  may  be  obtained  in  small  needle- 
shaped  crystals,  having  a  strong  styptic  and 
acetous  taste.  This  salt  is  of  great  use  in 
dyeing  and  calico  printing.  See  ALU3HNA. 

Acetate  of  zircone  may  be  formed  by 
pouring  acetic  acid  on  newly  precipitated 
zircone.  It  has  an  astringent  taste.  It  does 
not  crystallize  ;  but,  when  evaporated  to 
dryness,  forms  a  powder,  which  does  not 
attract  moisture  from  the  air.  It  is  very 
soluble  both  in  water  and  alcohol ;  and  is 


not  so  easily  decomposed  by  heat  as  nitrate 
of  zircone. 

The  acetic  acid  has  no  action  upon  sili- 
ceous earth ;  for  the  needle-shaped  crys- 
tals observed  by  Durande  in  a  mixture  of 
vinegar  with  the  earth  precipitated  from  a 
liquor  of  flints,  do  not  prove  the  solubility 
of  siliceous  earth,  as  Leonhardi  observes. 

Concerning  the  action  of  vinegar  on  al-. 
cohol,  see  ETHER.  This  acid  has  no  effect 
upon  fat  oils,  except  that  when  distilled  to- 
gether, some  kind  of  mixture  takes  place, 
as  the  Abbe  Rozier  observes.  Neither  does 
distilled  vinegar  act  upon  essential  oils ;  but 
Westendorf 's  concentrated  acid  dissolved 
about  a  sixth  part  of  oil  of  rosemary,  or  one 
half  its  weight,  of  camphor ;  which  latter  so- 
lution was  inflammable  ;  and  the  camphor 
was  precipitated  from  it  by  adding  water. 
Vinegar  dissolves  the  true  gums,  and  part- 
ly the  gum-resins,  by  means  of  digestion. 

Boerhaave  observes,  that  vinegar  by  long 
boiling  dissolves  the  flesl^cartilag-es,  bones, 
and  ligaments  of  animals. 

Acin.  (AMNIOTIC).  On  evaporating  the 
liquor  amnii  of  the  cow  to  one-fourth,  Vau- 
quelin and  Buniva  found,  that  crystals  form 
in  it  by  cooling.  These  are  contaminated 
by  a  portion  of  extract)  ve  matter,from  which 
they  may  be  freed  by  washing  with  a  very 
small  quantity  of  water.  These  crystals  are 
white  and  shining,  slightly  acid  to  the  taste, 
redden  litmus  paper,  and  are  a  little  more 
soluble  in  hot  than  cold  water.  They  are 
likewise  soluble  in  alcohol.  On  ignited 
coals  they  swell,  turn  black,  give  out  am- 
monia and  prussic  acid,  and  leave  a  bulky 
coal.  With  the  alkalis  this  acid  forms  very 
soluble  salts,  but  it  does  not  decompose  the 
carbonate  without  the  assistance  of  heat.  It 
does  not  precipitate  the  earthy  salts,  or  the 
nitrates  of  mercury,  lead,  or  silver.  The 
acids  precipitate  it  from  its  combinations 
with  alkalis  in  a  white  crystaline  powder. 
Whether  it  exist  in  the  amniotic  liquor  of 
any  other  animal  is  not  known. 

ACID  (AKSENIC).  The  earlier  chemists 
were  embarrassed  in  the  determination  of 
the  nature  of  the  white  sublimate,  which  is 
obtained  during  the  roasting  of  cobalt  and 
other  metallic  ores,  known  in  commerce  by 
the  name  of  arsenic :  its  solubility  in  water, 
its  power  of  combining  with  metals  in  their 
simple  state,  together  with  other  apparent- 
ly heterogeneous  properties,  rendered  it 
difficult  to  determine  whether  it  ought  to 
be  classed  with  metals  or  salts.  Subse- 
quent discoveries  have  shown  the  relation 
it  bears  to  both.  When  treated  with  com- 
bustible matter,  in  close  vessels,  it  sublimes 
in  the  metallic  form,  (See  ANSEXIC)  ;  com- 
bustion, or  any  analogous  process,  converts 
it  into  an  oxide  ;  and  when  the  combustion, 
is  carried  still  further,  the  arsenical  basis 
becomes  itself  converted  into  an  acid. 


ACI 


ACI 


\Ve  arc  indebted  to  the  illustrious 
Scheele  for  the  discovery  of  this  acid, 
though  Macquer  had  before  noticed  its 
combinations.  It  may  be  obtained  by  va- 
rious methods.  If  six  parts  of  nitric  acid 
be  poured  on  one  of  the  concrete  arsenious 
acid,  or  white  arsenic  of  the  shops,  in  the 
pneumato-chemical  apparatus,  and  heat  be 
applied,  nitrous  gas  will  be  evolved,  and  a 
white  concrete  substance,  differing  in  its 
properties  from  the  arsenious  acid,  will  re- 
main in  the  retort.  This  is  the  arsenic 
acid.  It  may  equally  be  procured  by  means 
of  aqueous  chlorine,  or  by  heating  concen- 
trated nitric  acid  with  twice  its  weight  of 
the  solution  of  the  arsenious  acid  in  muri- 
atic acid.  The  concrete  acid  should  be  ex- 
posed to  a  dull  red  heat  for  a  few  minutes. 
In  either  case  an  acid  is  obtained,  that  does 
not  crystallize,  but  attracts  the  moisture  of 
the  air,  has  a  sharp  caustic  taste,  reddens 
blue  vegetable  colours,  is  fixed  in  the  fire, 
and  of  the  specific  gravity  of  3.391. 

If  the  arsenic  acid  be  exposed  to  a  red 
heat  in  a  glass  retort,  it  melts  and  becomes 
transparent,  but  assumes  a  milky  hue  on 
cooling.  If  the  heat  be  increased,  so  that 
the  retort  begins  to  melt,  the  acid  boils,  and 
sublimes  into  the  neck  of  the  retort.  If  a 
covered  crucible  be  used  instead  of  the 
glass  retort,  and  a  violent  heat  applied,  the 
acid  boils  strongly,  and  in  a  quarter  of  an 
.hour  begins  to  emit  fumes.  These,  on  be- 
ing received  in  a  glass  bell,  are  found  to  be 
arsenious  acid;  and  a  small  quantity  of  a 
transparent  glass,  difficult  to  fuse,  will  be 
found  lining  the  sides  of  the  crucible.  This 
is  arseniate  of  alumina. 

Combustible  substances  decompose  this 
acid.  If  two  parts  of  arsenic  acid  be  mixed 
with  about  one  of  charcoal,  the  mixture  in- 
troduced into  a  glass  retort,  coated,  and  a 
matrass  adapted  to  it ;  and  the  retort  then 
gradually  heated  in  areverberatory  furnace, 
till  the  bottom  is  red ;  the  mass  will  be  in- 
flamed violently,  and  the  acid  reduced,  and 
rise  to  the  neck  of  the  retort  in  the  metal- 
I'.c  state  mixed  with  a  little  oxide  and  char- 
coal powder.  A  few  drops  of  water,  de- 
void of  acidity,  will  be  found  in  the  receiv- 
er. 

With  sulphur  the  phenomena  are  differ- 
ent. If  a  mixture  of  six  parts  of  arsenic 
acid,  and  one  of  powdered  s'llphur,  be  di- 
gested together,  no  change  will  take  place  ; 
but  on  evaporating  to  dnness,  and  distill- 
ing in  a  glass  retort,  iitted  with  a  receiver, 
a  violent  combination  will  ensue,  as  soon  as 
the  mixture  is  sufficiently  heated  to  melt 
the  sulphur.  The  whole  mass  rises  almost 
at  once,  forming  ti  red  sublimate,  and  sul- 
phurous acid  passes  over  into  the  receiver. 
If  pure  arsenic  acid  be  diluted  with  a 
small  quantity  of  water,  and  hydrogen  gas, 
as  it  is  evolved  by  the  action  of  sulphuric 
prid  on  iron,  be  received  into  this  transpa- 


rent solution,  the  liquor  grows  turbid,  and 
a  blackish  precipitate  is  formed,  which,  be- 
ing well  washed  with  distilled  water,  ex- 
hibits all  the  phenomena  of  arsenic.  Some- 
times, too,  a  blackish  gray  oxide  of  arsenic 
is  found  in  this  process. 

If  sulphuretted  hydrogen  gas  be  employ- 
ed instead  of  simple  hydrogen  gas,  water 
and  a  sulphuret  of  arsenic  are  obtained. 

With  phosphorus,  phosphoric  acid  is  ob- 
tained, and  a  phosphuret  of  arsenic,  which 
sublimes. 

The  arsenic  acid  is  much  more  soluble 
than  the  arsenious.  According  to  Lagrange, 
two  parts  of  water  are  sufficient  for  this  pur- 
pose. It  cannot  be  crystallized  by  any 
means ;  but,  on  evaporation,  assumes  a  thick 
honey-like  consistence. 

No  acid  has  any  action  upon  it :  if  some 
of  them  dissolve  it  by  means  of  the  water 
that  renders  them  fluid,  they  do  nor  pro- 
duce any  alteration  in  it.  The  boi'acic  and 
phosphoric  are  verifiable  with  it  by  means 
of  heat,  but  without  any  material  alteration 
in  their  natures.  If  phosphorous  acid  be 
heated  upon  it  for  some  time,  it  saturates 
itself  with  oxygen,  and  becomes  phospho* 
ric  acid. 

1  he  arsenic  acid  combines  with  the  ear- 
thy and  alkaline  bases,  and  forms  salts  very 
different  from  those  furnished  by  the  ar- 
senious acid. 

All  these  arseniates  are  decomposable  by 
charcoal,which  separates  arsenic  from  them 
by  means  of  heat. 

*  Berzelius,  from  the  result  of  accurate 
experiments  on  the  arseniates  of  lead  and 
barytes,  infers  the  prime  equivalent  of  ar- 
senic acid  to  be  7/25,  oxygen  being  1.0 ; 
but  Dr.  Thomson,  from  his  experiments  on 
the  arseniates  of  potash  and  soda,  conceives 
that  the  double  of  the  above  number  ought 
to  be  preferred,  viz.  14.5.  Jinn,  of  Phil, 
vol.  xv. 

On  the  latter  supposition,  BerzeTius's  in- 
soluble salts  will  consist  of  two  primes  of 
base  and  one  of  acid ;  and  the  acid  itself  will 
be  a  compound  of  5  of  oxygen  =  5,  +  9.5. 
of  the  metallic  base  =  14.5  ;  for  direct  ex- 
periments have  shown  it  to  consist  of  100 
metal,  and  from  52  to  53  oxygen.  But 
152.5:  100::  14.5 :  9.5  nearly. 

All  its  salts,  with  the  exception  of  those 
of  potash,  soda,  and  ammonia,  are  insoluble 
in  water  ;  but  except  arseniate  of  bismuth, 
and  one  or  two  more,  very  soluble  in  an 
excess  of  arsenic  acid.  Hence,  after  ba- 
rytes or  oxide  of  lead  has  been  precipitated 
by  this  acid,  its  farther  addition  redissolves 
the  precipitate.  This  is  a  useful  criterion 
of  the  acid,  joined  to  its  reduction  to  the 
metallic  state  by  charcoal,  and  ihe  other 
characters  already  detailed.  Sulphuric 
acid  decomposes  the  arseniates  at  a  lou* 
temperature,  but  the  sulphates  are 'de- 
composed bv  arsenic  ac'd  at  a.  red  heat, 


ACI 


ACI 


owing-  to  the  greater  fixity  of  the  latter. 
Phosphoric,  nitric,  muriatic,  and  fluoric 
acids,  dissolve,  and  probably  convert  into 
subsalts  all  the  arseniates.  The  whole  of 
them,  as  well  as  arsenic  acid  itself  when 
decomposed  at  a  red  heat  by  charcoal, 
yield  the  characteristic  g:trlic  smell  of  the 
metallic  vapour.  JNitrate  of  silver  gives  a 
pulverulent  brick-coloured  precipitate,  or, 
according1  to  Dr.  Thomson,  a  flesh  red, 
with  arsenic  acid.  The  acid  itself  does  not 
disturb  the  transparency  of  a  solution  of 
sulphate  of  copper ;  but  a  neutral  arseni- 
ate  gives  with  it  a  bluish  green  precipitate; 
with  sulphate  of  cobalt,  a  dirty  red,  and 
with  sulphate  of  nickel,  an  apple  green 
precipitate.  These  precipitates  redissolve, 
on  adding  a  small  quantity  of  the  acid 
which  previously  held  them  in  solution. 
Orfila  says,  that  arsenic  acid  gives,  with 
acetate  of  copper,  a  bluish  white  precipi- 
tate, but  that  it  exercises  no  action  either 
on  the  muriate  or  acetate  of  cobalt ;  but 
with  the  ammonia-muriate  it  gives  a  rose- 
coloured  precipitate.  Arsenic  acid  ought 
to  be  accounted  a  more  violent  poison  than 
even  the  arsenious.  According  to  Mr. 
Brodie,  it  is  absorbed,  and  occasions  death 
by  acting  on  the  brain  and  the  heart.  * 

The  arseniate  of  barytes  is  insoluble, 
uncrystallizable,  soluble  in  an  excess  of  its 
acid,  and  decomposable  by  sulphuric  acid, 
which  precipitates  a  sulphate  of  barytes. 

Of  the  arseniate  of  strontian  nothing  is 
known,  but  no  doubt  it  resembles  that  of 
barytes. 

With  lime-water  this  acid  forms  a  pre- 
cipitate of  arseniate  of  lime,  soluble  in  an 
excess  of  its  base,  or  in  an  excess  of  its 
acid,  though  insoluble  alone.  The  acidu- 
fous  arseniate  of  lime  affords  on  evapora- 
tion little  crystals,  decomposable  by  sul- 
phuric acid.  The  same  salt  may  be  formed 
by  adding  carbonate  of  lime  to  the  solu- 
tion of  arsenic  acid.  This  acid  does  not 
decompose  the  nitrate  or  muriate  of  lime ; 
but  the  saturated  alkaline  arseniates  de- 
compose them  by  double  affinity,  precipi- 
tating the  insoluble  calcareous  arseniate. 

If  arsenic  acid  be  saturated  with  magne- 
sia, a  thick  substance  is  formed  near  the 
point  of  saturation.  This  arseniate  of  mag- 
nesia is  soluble  in  an  excess  of  acid  ;  and 
on  being  evaporated  takes  the  form  of  a 
jelly,  without  crystallizing.  Neither  the 
sulphate,  nitrate,  nor  muriate  of  magne- 
sia is  decomposed  by  arsenic  acid,  though 
they  are  by  the  saturated  alkaline  arseni- 
ates. 

Arsenic  acid  saturated  with  potash  does 
not  easily  crystallize.  This  arseniate.  be- 
ing evaporated  to  dryness,  attracts  the  hu- 
midity of  the  air,  and  turns  the  sirup  of 
violets  green,  without  altering  the  solu- 
tion of  litmus.  It  fiiscs  into  a  white  glass, 
and  with  a  strong1  fire,  is  converted  into  a-n 


acidule,  part  of  the  alkali  being  abstracted 
by  the  silex  and  alumina  of  the  crucible. 
If  exposed  to  a  red  heat  with  charcoal  in 
close  vessels  it  swells  up  very  much,  and 
arsenic  is  sublimed.  It  is  decomposed  by 
sulphuric  acid;  but  in  the  humid  way  the 
decomposition  is  not  obvious,  as  the  arse- 
nic acid  remains  in  solution.  On  evapora- 
tion, however,  this  acid  and  sulphate  of 
potash  are  obtained. 

If  arsenic  ucid  be  added  to  the  preceding 
salt,  till  it  ceases  to  have  any  effect  on  the 
sirup  of  violets,  it  will  redden  the  solu- 
tion of  litmus ;  and  in  this  state  it  afford* 
very  regular  and  very  transparent  crystals, 
of  the  figure  of  quadrangular  prisms,  ter- 
minated by  two  tetraedral  pyramids,  the 
angles  of  which  answer  to  those  of  the 
prisms.  These  crystals  are  the  arsenical 
neutral  salt  of  Macquer.  As  this  salt  dif- 
fers from  the  preceding  arseniate  by  its 
crystallizability,  its  reddening  solution  of 
litmus,  its  not  decomposing  the  calcareous 
and  magnesian  salts  like  it,  and  its  capa- 
bility of  absorbing  an  additional  portion  of 
potash,  so  as  to  become  neutral,  it  ought 
to  be  distinguished  from  it  by  the  term  of 
acidulous  arseniate  of  potash. 

With  soda  in  sufficient  quantity  to  satu- 
rate it,  arsenic  acid  forms  a  salt  crystalli- 
zable  like  the  acidulous  arseniate  of  pot- 
ash. Pelletier  says,  that  the  crystals  are 
hexaedral  prisms  terminated  by  planes 
perpendicular  to  their  axis.  This  neutral 
arseniate  of  soda,  however,  while  it  differs 
completely  from  that  of  potash  in  this  re- 
spect, and  in  becoming  deliquescent  in- 
stead of  crystallizable  on  the  addition  of  a 
surplus  portion  of  arsenic  acid,  resembles 
the  arseniate  of  potash  in  its  decomposi- 
tion by  charcoal,  by  acids,  and  by  the 
earths. 

Combined  with  ammonia,  arsenic  acid 
forms  a  salt  affording  rhomboida]  crystals 
analogous  to  those  of  the  nitrate  of  soda. 
The  arseniate  of  ammonia,  which  is  pro- 
duced likewise  in  the  decomposition  of 
nitrate  of  ammonia  by  arsenious  acid,  is 
decomposable  in  two  ways  by  the  action 
of  heat.  If  it  be  gently  heated,  the  ammo- 
nia is  evolved,  and  the  arsenic  acid  is  left 
pure.  If  it  be  exposed  to  a  violent  and 
rapid  heat,  part  of  the  ammonia  and  part 
of  the  acid  reciprocally  decompose  each 
other ;  water  is  formed ;  azotic  gas  is  given 
out ;  and  the  arsenic  sublimes  in  a  shining- 
metallic  form.  Magnesia  partly  decompo- 
ses the  arseniate  of  ammonia,  and  forms  a 
triple  salt  with  a  portion  of  it. 

Arsenic  acid  saturated  with  alumina 
forms  a  thick  solution,  which,  being  eva- 
porated to  dryness,  yields  a  salt  insoluble 
in  water,  and  decomposable  by  the  sul- 
phuric, nitric  and  muriatic  acids,  as  well 
as  by  all  the  other  earthy  and  alkaline  ba- 
ses. The,  arsenic  acid  readily  dissolves  the 


ACI 


ACI 


alumina  of  the  crucibles  in  which  it  is  re- 
duced to  a  state  of  fusion  ;  and  thus  it  at- 
tacks silex  also,  on  which  it  has  no  effect 
in  the  humid  way. 

We  know  nothing1  of  the  combination  of 
this  acid  with  zircone. 

By  the  assistance  of  a  strong"  fire,  as 
Fourcroy  asserts,  arsenic  acid  decompo- 
ses the  alkaline  and  earthy  sulphates,  even 
that  of  barytes  ;  the  sulphuric  acid  flying" 
off  in  vapour,  and  the  arseniate  remaining 
in  the  retort.  It  acts  in  the  same  manner 
on  the  nitrate,  from  which  it  expdts  the 
pure  acid.  It  likewise  decomposes  the 
muriates  at  a  high  temperature,  the  muri- 
atic acid  being  evolved  in  the  form  of  gas, 
and  the  arsenic  acid  combining  with  their 
bases,  which  it  saturates ;  while  the  arse- 
nious  acid  is  too  volatile  to  have  this  effect. 
It  acts  in  the  same  manner  on  the  fluates, 
and  still  more  easily  on  the  carbonates, 
with  which,  by  the  assistance  of  heat,  it 
excites  a  brisk  effervescence.  Lagrange, 
however,  denies  that  it  acts  on  any  of  the 
neutral  salts,  except  the  sulphate  of  pot- 
ash, and  soda,  the  nitrate  of  potash,  and  the 
muriates  of  soda  and  ammonia,  and  this  by 
means  of  heat.  It  does  not  act  on  the  phos- 
phates, but  precipitates  the  boracic  acid 
from  solutions  of  borates  when  heated. 

Arsenic  acid  does  not  act  on  gold  or 
platina;  neither  does  it  on  mercury  or 
silver  without  the  aid  of  a  strong  heat ;  but 
it  oxidizes  copper,  iron,  lead,  tin,  zinc, 
bismuth,  antimony,  cobalt,  nickel,  manga- 
nese, and  arsenic. 

This  acid  is  not  used  in  the  arts,  at  least 
directly,  though  indirectly  it  forms  a  part 
of  some  composition  used  in  dyeing.  It  is 
likewise  one  of  the  mineralizing  acids 
combined  by  nature  with  some  of  the  me- 
tallic oxides. 

ACID  (AnsENiors).  Fourcroy  was  the 
first  who  distinguished  by  this  name  the 
white  arsenic  of  the  shops,  which  Scheele 
had  proved  to  be  a  compound  of  the  metal 
arsenic  with  oxygen,  and  which  the  au- 
thors of  the  new  chemical  nomenclature 
had  consequently  termed  oxide  of  arsenic. 
As,  however,  it  manifestly  exhibits  the 
properties  of  an  acid,  though  in  a  slight 
degree,  it  has  a  fair  claim  to  the  title ;  for 
many  oxides  and  acids  are  similar  in  this, 
that  both  consist  of  a  base  united  with 
oxygen,  and  the  only  difference  between 
them  is,  that  the  compound  in  which  the 
acid  properties  are  manifest  is  termed  an 
acid,  and  that  in  which  they  are  not  is 
called  an  oxide. 

This  acid,  which  is  one  of  the  most  vi- 
rulent poisons  known,  frequently  occurs 
in  a  native  state,  if  not  very  abundantly ; 
and  it  is  obtained  in  roasting  several  ores, 
particularly  those  of  dobalt.  In  the  chim- 
neys of  the  furnaces  where  this  operation 
is  conducted,  it  generally  condenses  in 


thick  semi-transparent  masses ;  thougli 
sometimes  it  assumes  the  form  of  a  pow- 
der or  of  little  needles,  in  which  state  it 
was  formerly  called  flowers  of  arsenic. 

The  arsenious  acid  reddens  the  most 
sensible  blue  vegetable  colours,  though  it 
turns  the  sirup  of  violets  green.  On  ex- 
posure to  the  air  it  becomes  opaque,  and 
covered  with  a  slight  efflorescence. — 
Thrown  on  incandescent  coals,  it  evapo- 
rates in  white  fumes,  with  a  strong  smell 
of  garlic.  In  close  vessels  it  is  volatilized; 
and,  if  the  heat  be  strong,  vitrified.  The 
result  of  this  vitrification  is  a  transparent 
glass,  capable  of  crystallizing  in  tetraedra, 
the  angles  of  which  are  truncated.  It  is 
easily  altered  by  hydrogen  and  carbon, 
which  deprive  it  of  its  oxygen  at  a  red 
heat,  and  reduce  the  metal,  the  one  form- 
ing water,  the  other  carbonic  acid,  with 
the  oxygen  taken  from  it :  as  it  is  by  phos- 
phorus, and  by  sulphur,  which  are  in  part 
converted  into  acids  by  its  oxygen,  and  in 
part  form  an  arsenical  phosphuret  or  sul- 
phuret  with  the  ai'senic  reduced  to  the 
metallic  state.  Hence  Margraafand  Pel- 
letier,  who  particularly  examined  the 
phosphurets  of  metals,  have  asserted  they 
might  be  formed  with  arsenious  acid.  Its 
specific  gravity  is  3.7. 

It  is  soluble  in  thirteen  times  its  weight 
of  boiling  water,  but  requires  eighty  times 
its  weight  of  cold.  The  solution  crystal- 
lizes, and  the  acid  assumes  the  form  of  re- 
gular tetraedrons  according  to  Fourcroy  ; 
but,  according  to  Lagrange,  of  octaedrons, 
and  these  frequently  varying  in  figure  by 
different  laws  of  decrement.  It  crystallizes 
much  better  by  slow  evaporation  than  by 
simple  cooling. 

*  The  solution  is  very  acrid,  reddens 
blue  colours,  unites  with  the  earthy  bases, 
and  decomposes  the  alkaline  sulphurets. 
Arsenious  acid  is  also  soluble  in  oils,  spir- 
its, and  alcohol ;  the  last  taking  up  from  1 
to  2  per  cent.  It  is  composed  of  9.5  of  me- 
tal -t-  3  oxygen ;  and  its  prime  equivalent 
is  therefore  12.5.  Dr.  \Vollaston  first  ob- 
served, that  when  a  mixture  of  it  with 
quick-lime  is  heated  in  a  glass  tube,  at  a 
certain  temperature,  ignition  suddenly  per- 
vades the  mass,  and  metallic  arsenic  sub- 
limes. As  arseniate  of  lime  is  found  at  t  he- 
bottom  of  the  tube,  we  perceive  that  a 
portion  of  the  arsenious  acid  is  robbed  of 
its  oxygen,  to  complete  the  acidification 
of  the  rest.* 

There  are  even  some  metals,  which  act 
\ipon  the  solution,  and  have  a  tendency  to 
decompose  the  acid,  so  as  to  form  a  black- 
ish precipitate,  in  which  the  arsenic  is  very 
slightly  oxidized. 

The  action  of  the  other  acids  upon  the 
arsenious  is  very  different  from  that  which 
they  exert  on  the  metal  arsenic.  By  boil- 
ing, sulphuric  acid  dissolves  a  small  por- 


ACI 


ACI 


tion  of  it,  which  is  precipitated  as  the  so- 
lution cools.  The  nitric  acid  does  not  dis- 
solve it,  but  by  the  help  of  heat  converts 
it  into  arsenic  acid.  Neither  the  phospho- 
ric nor  the  carbonic  acid  acts  upon  it ;  yet 
it  enters  into  a  vitreous  combination  with 
the  phosphoric  and  boracic  acids.  The 
muriatic  acid  dissolves  it  by  means  of  heat, 
and  forms  with  it  a  volatile  compound, 
which  water  precipitates ;  and  aqueous 
chlorine  acidifies  it  completely,  so  as  to 
convert  it  into  arsenic  acid. 

The  arsenious  acid  combines  with  the 
earthy  and  alkaline  bases.  The  earthy  ar- 
seniafes  possess  little  solubility,  and  hence 
the  solutions  of  barytes,  strontian,  and 
]ime,  form  precipitates  with  that  of  arse- 
nious  acid. 

The  acid  enters  into  another  kind  of 
combination  with  the  earths,  that  formed 
by  vitrification.  Though  a  part  of  this  vola- 
tile acid  sublimes  before  the  glass  enters 
into  fusion,  part  remains  fixed  in  the  vitri- 
fied substance,  to  which  it  imparts  trans- 
parency, a  homogeneous  density,  and  con- 
siderable gravity.  The  arsenical  glasses 
appear  to  contain  a  kind  of  triple  salt, 
since  the  salt  and  alkalis  enter  into  an  in- 
timate combination  at  the  instant  of  fusion, 
jind  remain  afterwards  perfectly  mixed.  All 
of  them  have  the  inconvenience  of  quick- 
ly growing  dull  by  exposure  to  the  air. 

With  the  fixed  alkalis  the  arsenious  acid 
forms  thick  arsenites,  which  do  not  crys- 
tallize ;  which  are  decomposable  by  fire, 
the  arsenious  acid  being  volatilized  by  the 
heat ;  and  from  which  all  the  other  acids 
precipitate  this  in  powder.  These  saline 
compounds  were  formerly  termed  livers, 
because  they  were  supposed  to  be  analo- 
gous to  the  combinations  of  sulphur  with 
the  alkalis. 

With  ammonia  it  forms  a  salt  capable  of 
crystallization.  If  this  be  heated  a  little, 
the  ammonia  is  decomposed,  the  nitrogen 
is  evolved,  while  the  hydrogen,  uniting  with 
part  of  the  oxygen  of  the  acid,  forms  water. 

Neither  the  earthy  nor  alkaline  arsen- 
ites have  yet  been  much  examined  ;  what 
is  known  of  them  being  only  sufficient  to 
distinguish  them  from  the  arseniates. 

The  nitrates  act  on  the  arsenious  acid 
in  a  very  remarkable  manner.  On  treating 
the  nitrates  and  arsenious  acid  together, 
the  nitrous  acid,  or  nitrous  vapour,  is  ex- 
tricated  in  a  state  very  difficult  to  be  con- 
fined, as  Kunckel  long  ago  observed  ;  part 
of  its  oxygen  is  absorbed  by  the  arsenious 
acid ;  it  is  thus  converted  into  arsenic  acid, 
and  an  arseniate  is  left,  in  the  retort.  The 
same  phenomena  take  place  on  detonating 
nitrates  with  arsenious  acid  ;  for  it  is  still 
sufficiently  combustible  to  produce  a  de- 
tonation, in  which  no  spark*  are  seen,  it 
is  true,  but  with  commotion  and  efterves* 
cence  ;  and  a  true  arseniate  remains  at 
the  bottom  of  the  crucible.  It  was  in  this 

VOL.  I.  [3] 


way  chemists  formerly  prepared  their  fixed 
arsenic,  which  was  the  acidulous  arseni- 
ate of  potash.  The  nitrate  of  ammonia  ex- 
hibits different  phenomena  in  its  decom- 
position by  arsenious  acid,  and  requires 
considerable  precaution.  Pelletier,  having 
mixed  equal  quantities,  introduced  the 
mixture  into  a  large  retort  of  coated  glass, 
placed  in  a  reverberatory  furnace,  with  a 
globular  receiver.  He  began  with  a  very 
slight  fire  ;  for  the  decomposition  is  so  ra- 
pid, and  the  nitrous  vapours  issue  with 
such  force,  that  a  portion  of  the  arsenious 
acid  is  carried  off  undecomposed,  unless 
you  proceed  very  gently,  if  due  care  be 
taken  that  the  decomposition  proceeds 
more  slowly,  nitrous  acid  first  comes  over; 
if  the  fire  be  continued,  or  increased,  am- 
monia is  next  evolved ;  and  lastly,  if  the 
fire  be  urged,  a  portion  of  oxide  of  arsen- 
ic sublimes  in  the  form  of  a  white  pow- 
der, and  a  vitreous  mass  remains  in  the  re- 
tort, which  powerfully  attacks  and  cor- 
rodes it.  This  is  arsenic  acid.  The  chlo- 
rate of  potash,  too,  by  completely  oxidiz- 
ing the  arsenious  acid,  converts  it  into  ar- 
senic acid,  which  by  the  assistance  of  heat, 
is  capable  of  decomposing  the  muriate  of 
potash  that  remains. 

The  arsenious  acid  is  used  in  numerous 
instances  in  the  arts,  under  the  name  of 
white  arsenic,  or  of  arsenic  simply.  In 
many  cases  it  is  reduced,  and  acts  in  its 
metallic  state. 

Many  attempts  have  been  made  to  in- 
troduce it  into  medicine ;  but  as  it  is 
known  to  be  one  of  the  most  violent  poi- 
sons, it  is  probable  that  the  fear  of  its  bad 
effects  may  deprive  society  of  the  advan- 
tages it  might  afford  in  this  way.  An  ar* 
senite  of  potash  was  extensively  used  by 
the  late  l)r.  Fowler  of  York,  who  publish- 
ed a  treatise  on  it,  in  intermittent  and  re- 
mittent fevers.  He  likewise  assured  the 
writer,  that  he  had  found  it  extremely  effi- 
cacious in  periodical  headache,  and  as  a  to- 
nic in  nervous  and  other  disorders ;  and 
that  he  never  saw  the  least  ill  effect  from 
its  use,  due  precaution  being  employed  in 
preparing  and  administering  it.  Exter- 
nally it  has  been  employed  as  a  caustic  to 
extirpate  cancer,  combined  with  sulphur, 
with  bole,  with  antimony,  and  with  the 
leaves  of  crowfoot;  but  it  always  gives 
great  pain,  and  is  not  unattended  with 
danger.  Febure's  remedy  was  water  one 
pint,  extract  of  hemlock  5J,  Goulard's  ex- 
tract giij,  tincture  of  opium  gj,  arsenious 
acid  gr.  x.  With  this  the  cancer  was  wet- 
ted morning  and  evening ;  and  at  the  same 
time  a  small  quantity  of  a  weak  solution, 
was  administered  internally.  A  still  milder 
application  of  this  kind  has  been  made 
from  a  solution  of  one  grain  in  a  quart  of 
water,  formed  into  a  poultice  with  crumb 
of  bread. 

*  It  has  been  mere  lately  used  as  an  alv 


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terative  with  advantage  in  chronic  rheu~ 
matism.  The  symptoms  which  show  the 
system  to  be  arsenified  are  thickness,  red- 
ness, and  stiffness  of  t\\e  palpebr<e,  soreness 
of  the  gums,  ptyalism,  itching  over  the 
surface  of  the  body,  restlessness,  cough, 
pain  at  stomach,  and  headache.  When 
the  latter  symptoms  supervene,  the  admi- 
nistration of  the  medicine  ought  to  be  im- 
mediately suspended.  It  has  also  been  re- 
commended against  chincough;  and  has 
been  used  in  considerable  doses  with  suc- 
cess, to  counteract  the  poison  of  venemous 
serpents. 

Since  it  acts  on  the  animal  economy  as  a 
deadly  poison  in  quantities  so  minute  as  to 
be  insensible  to  the  taste  when  diffused  in 
water  or  other  vehicles,  it  has  been  often 
g-iven  with  criminal  intentions  and  fatal  ef- 
fects. It  becomes  therefore  a  matter  of  the 
utmost  importance  to  present  a  systematic 
view  of  the  phenomena  characteristic  of 
the  poison,  its  operation,  and  consequen- 
ces. 1st,  It  is  a  dense  substance,  subsiding 
speedily  after  agitation  in  water.  I  find  its 
sp.  gr.  to  vary  'rom  3.728  to  3.730,  which 
is  a  little  higher  than  the  number  given 
above ;  72  parts  dissolve  in  1000  of  boiling 
water,  of  which  30  remain  in  it,  after  it 
cools.  Cold  water  dissolves,  however,  on- 
ly -J-THTO  or  y\j  of  the  preceding  quanti- 
ty. This  water  makes  the  sirup  of  violets 
green,  and  reddens  litmus  paper.  T.ime 
water  gives  a  fine  white  precipitate  with 
it  of  arsenite  of  lime,  soluble  in  an  excess 
of  the  arsenious  solution.  Sulphuretted  hy- 
drogen gas,  and  hydrosulphu retted  water 
precipitate  a  golden  yellow  sulphuret  of 
arsenic.  By  this  means  TO^SOO  of  arsen- 
ious acid  may  be  detected  in  water.  This 
sulphuret  dried  on  a  filter,  and  heated  in 
a  glass  tube  with  a  bit  of  caustic  potash,  is 
decomposed  in  a  few  minutes,  and  con- 
verted into  sulphuret  of  potash,  which  re- 
mains at  the  bottom,  and  metallic  arsenic 
of  a  bright  steel  lustre,  which  sublimes, 
coating  the  sides  of  the  tube.  The  hydro- 
sulphurets  of  alkalis  do  not  affect  the  ar- 
senious solution,  unless  a  drop  or  two  of 
nitric  or  muriatic  acid  be  poured  in,  when 
the  characteristic  golden  yellow  precipi- 
tate falls.  Nitrate  of  silver  is  decomposed 
by  the  arsenious  acid,  and  a  very  peculiar 
yellow  arsenite  of  silver  precipitates,  which 
however,  is  apt  to  be  redissolved  by  nitric 
acid,  and  therefore  a  very  minute  addition 
of  ammonia  is  requisite.  Even  this  how- 
ever, also,  if  in  much  excess,  redissolves 
the  silver  precipitate. 

As  the  nitrate  of  silver  is  justly  regarded 
as  one  of  the  bestprecipitant  tests  of  arsen- 
ic, the  mode  of  using  it  has  been  a  sub- 
ject of  much  discussion.  The  presence  of 
muriate  of  soda  indeed,  in  the  arscnic-al  so- 


lution, obstructs,  to  a  certain  degree,  the 
operation  of  this  reagent.  But,  that  salt  is 
almost  always  present  in  the  prinKe  vice, 
and  is  a  usual  ingredient  in  soups,  and 
other  vehicles  of  the  poison.  If,  after  the 
water  of  ammonia  has  been  added,  by 
plunging  the  end  of  a  glass  rod  dipped  in 
it  into  the  supposed  poisonous  liquid,  we 
dip  another  rod  into  a  solution  of  pure 
nitrate  of  silver,  and  transfer  it  into  the 
arsenious  solution,  either  a  fine  yellow 
cloud  will  be  formed,  or  at  first  merely  a 
white  curdy  precipitate.  But  at  the  se- 
cond or  third  immersion  of  the  nitrate  rod, 
a  central  spot  of  yellow  will  be  perceived 
surrounded  with  the  white  muriate  of  sil- 
ver. At  the  next  immersion  this  yellow 
cloud  on  the  surface  will  become  very 
conspicuous.  Sulphate  of  soda  does  not 
interfere  in  the  least  with  the  silver  test. 
The  ammoniaco-sulphate,  or  rather  ammo- 
niaco-acetate  of  copper,  added  in  a  some- 
what dilute  state  to  an  arsenious  solution, 
gives  a  fine  grass  green  and  very  charac- 
teristic precipitate.  This  green  arsenite 
of  copper,  well  washed,  being  acted  on  by 
an  excess  of  sulphuretted  hydrogen  water, 
changes  its  colour  ai  id  becomes  of  a  brown- 
ish  red.  Ferro-Prussiate  of  potash  changes 
it  into  a  blood  red.  Nitrate  of  silver  con- 
verts it  into  the  yellow  arsenite  of  silver. 
Lastly,  if  the  precipitate  be  dried  on  a  fil- 
ter, and  placed  on  a  bit  of  burning  coal,  it 
will  diffuse  a  garlic  odour.  The  cupreous 

test  will  detect  frsW^  °^  ^ie  weight  of 
the  arsenic  in  water.  The  voltaic  battery, 
made  to  act  by  two  wires  on  a  little  arse- 
nious solution  placed  on  a  bit  of  window- 
glass,  developes  metallic  arsenic  at  the  ne- 
gative pole  ;  and  if  this  wire  be  copper,  it 
will  be  whitened  like  tombac.  We  may 
here  remark,  however,  that  the  most  ele- 
gant mode  of  using  all  these  precipitation 
reagents  is  upon  a  plane  of  glass,  a  mode 
practised  by  Dr.  Wollaston  in  general 
chemical  research,  to  an  extent,  and  with 
a  success,  which  would  be  incredible  in 
other  hands  than  his.  Concentrate  by  heat 
in  a  capsule  the  suspected  poisonous  so- 
lution, having  previously  filtered  it  if  ne- 
cessary. Indeed,  if  it  be  very  much  dis- 
guised with  animal  or  vegetable  matters, 
it  is  better  first  of  all  to  evaporate  to  dry- 
ness,  and  by  a  few  drops  of  nitric  acid  to 
dissipate  the  organic  products.  The  clear 
liquid  being  now  placed  in  the  middle  of 
the  bit  of  glass,  lines  are  to  be  drawn  out 
from  it  in  different  directions.  To  one  of 
these  a  particle  of  weak  ammoniacal  water 
being  applied,  the  weak  nitrate  of  silver 
may  then  be  brushed  over  it  with  a  hair 
pencil.  By  placing  the  glass  in  different 
lights,  either  over  white  paper  or  oblique- 
ly before  the  eye,  the  slightest  change  of 
tuit  will  be  perceived.  The  ammoniaco- 


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acetate  should  be  applied  to  another  fila- 
ment of  the  drop,  deut-acetate  of  iron  to  a 
third,  weak  ammoniaco-acetate  of  cobalt 
to  a  fourth,  sulphuretted  water  to  a  fifth, 
•lime  water  to  a  sixth,  a  drop  of  violet  sirup 
to  a  seventh,  and  the  two  galvanic  wires 
at  the  opposite  edges  of  the  whole.  Thus 
with  one  single  drop  of  solution  many 
exact  experiments  may  be  made.  But 
the  chief,  the  decisive  trial  or  experimentum 
crucis  remains,  which  is  to  take  a  little  of 
the  dry  matter,  mix  it  with  a  small  pinch 
of  dry  black  flux,  put  it  into  a  narrow  glass 
tube  sealed  at  one  end,  and  after  cleansing 
its  sides  with  a  feather,  urge  its  bottom 
with  a  blow-pipe  till  it  be  distinctly  red 
hot  for  a  minute.  Then  garlic  fumes  will 
be  smelt,  and  the  steel-lustred  coating  of 
metallic  arsenic  will  be  seen  in  the  tube 
about  one-fourth  of  an  inch  above  its  bot- 
tom. Cut  the  tube  across  at  that  point  by 
means  of  a  fine  file,  detach  the  scale  of 
arsenic  with  the  point  of  a  penknife  ;  put 
a  fragment  of  it  into  the  bottom  of  a  small 
wine  glass  along  with  a  few  drops  of  am- 
moniaco-acetate of  copper,  and  triturate 
them  well  together  for  a  few  minutes  with 
^.  round  headed  glass  rod.  The  mazarine 
blue  colour  will  soon  be  transmuted  into  a 
lively  grass  green,  while  the  metallic  scale 
will  vanish.  Thus  we  distinguish  perfect- 
ly between  a  particle  of  metallic  arsenic 
and  one  of  animalized  charcoal,  \nother 
particle  of  the  scale  may  be  placed  be- 
tween two  smooth  and  bright  surfaces  of 
copper,  with  a  touch  of  fine  oil ;  and  whilst 
they  are  firmly  pressed  together,  exposed 
to  a  red  heat.  The  tombac  alloy  will  ap- 
pear as  a  white  stain.  A  third  particle  may 
be  placed  on  a  bit  of  heated  metal,  and 
held  a  little  under  the  nostrils,  when  the 
garlic  odour  will  be  recognized.  No  dan- 
ger can  be  apprehended,  as  the  fragment 
need  not  exceed  the  tenth  of  a  grain.  It 
is  to  be  observed,  that  one  or  two  of  the 
precipitation  tests  may  be  equivocal  from 
admixtures  of  various  substances.  Thus 
tincture  of  ginger  gives  with  the  cupreous 
reagent  a  green  precipitate; — and  the 
writer  of  this  article  was  at  first  led  to  sus- 
pect from  that  appearance,  that  an  empi- 
rical tincture,  put  into  his  hands  for  ex- 
amination, did  contain  arsenic.  But  a  care- 
ful analysis  satisfied  him  of  its  genuineness. 
Tea  covers  arsenic  from  the  cupreous  test. 
Such  poisoned  tea  becomes  by  its  addi- 
tion of  an  obscure  olive  or  violet  red,  but 
yields  scarcely  any  precipitate.  Sulphu- 
retted hydrogen,  however,  throws  down  a 
fine  yellow  sulphuret  -of  arsenic. 

Another  way  of  obviating  all  these 
Sources  of  fallacy,  is  to  evaporate  careful- 
ly to  dryness,  and  expose  the  residue  to 
heat  in  a  glass  tube.  The  arsenic  sublimes, 
And  may  be  operated  on  without  ambigui- 
ty. Mr.  Orfila  has  gone  into  ample  details 


on  the  modifications  produced  by  wine* 
coffee,  tea,  broth,  &c.  on  arsenical  tests, 
of  which  a  good  tabular  abstract  is  given 
in  Mr.  Thomson's  London  Dispensatory. 
But  it  is  evident  that  the  differences  in 
these  menstrua,  as  also  in  beers,  are  so 
great  as  to  render  precipitations  and 
changes  of  colour  by  reagents  very  unsa- 
tisfactory witnesses,  in  a  case  of  life  and 
death.  Hence  the  method  of  evaporation 
above  described,  should  never  be  neglect- 
ed. Should  the  arsenic  be  combined  with 
oil,  the  mixture  ought  to  be  boiled  with 
water,  and  the  oil  then  separated  by  the 
capillary  action  of  wick-threads.  If  with 
resinous  substances,  these  may  be  remov- 
ed by  oil  of  turpentine,  not  by  alcohol,  (as 
directed  by  Dr.  Black,)  which  is  a  good 
solvent  of  arsenious  acid.  It  may  more- 
over be  observed,  that  both  tea  and  coffee 
should  be  freed  from  their  tannin  by  gela- 
tin, which  does  not  act  on  the  arsenic,  pre- 
vious to  the  use  of  reagents  for  the  poison. 
When  one  part  of  arsenious  acid  in  watery 
solution  is  added  to  10  parts  of  milk,  the 
sulphuretted  hydrogen  present  in  the  lat- 
ter, occasions  the  white  colour  to  pass  in- 
to a  canary  yellow  ;  the  cupreous  test  gives 
it  a  slight  green  tint,  and  the  nitrate  of  sil- 
ver produces  no  visible  change,  though 
even  more  arsenic  be  added;  but  the  hy- 
drosulphurets  throw  down  a  golden  yel- 
low, with  the  aid  of  a  few  drops  of  an  acid. 
The  liquid  contained  in  the  stomach  of  a 
rabbit  poisoned  with  a  solution  of  3  grains 
of  arsenious  acid,  afforded  a  white  preci- 
pitate with  nitrate  of  silver,  grayish  white 
with  lime  water,  green  with  the  ammoni- 
aco-sulphate,  and  deep  yellow  with  sul- 
phuretted hydrogen  water. 

The  preceding  copious  description  of 
the  habitudes  of  arsenious  acid  in  differ- 
ent circumstances,  is  equally  applicable  to 
the  soluble  arsenites.  Their  poisonous 
operation,  as  well  as  that  of  the  arsenic 
acid,  has  been  satisfactorily  referred  by 
Mr.  Brodie  to  the  suspension  of  the  func- 
tions of  the  heart  and  brain,  occasioned  by 
the  absorption  of  these  substances  into  the 
circulation,  and  their  consequent  determi- 
nation to  the  nervous  system  and  the  ali- 
mentary canal.  This  proposition  was  es- 
tablished by  numerous  experiments  on 
rabbits  and  dogs.  Wounds  were  inflicted, 
and  arsenic  being  applied  to  them,  it  was 
found  that  in  a  short  time  death  superve- 
ned with  the  same  symptoms  of  inflamma- 
tion of  the  stomach  and  bowels,  as  if  the 
poison  had  been  swallowed.  He  divides 
the  morbid  affections  into  three  classes: 
1st,  Those  depending  on  the  nervous  sys- 
tem, as  palsy  at  first  of  the  posterior  ex- 
tremities, and  then  of  the  rest  of  the  body, 
convulsions,  dilatation  of  the  pupils,  and 
general  insensibility  :  2d,  Those  which  in- 
dicate disturbance  in  the  organs  of  ch-cu* 


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lation  ;  for  example,  the  feeble,  slow,  and 
intermitting1  pulse,  weak  contractions  of 
the  heart  immediately  after  death,  and  the 
impossibility  of  prolonging  them,  as  may 
be  done  in  sudden  deaths  from  other 
causes,  by  artificial  respiration :  3d,  Lastly, 
Those  which  depend  on  lesion  of  the  ali- 
mentary canal,  as  the  pains  of  the  abdo- 
men, nauseas  and  vomitings,  in  those  ani 
mals  which  were  suffered  to  vomit.  At 
one  time  it  is  the  nervous  system  that  is 
most  remarkably  affected,  and  at  another 
the  organs  of  circulation.  Hence  inflam- 
mation of  the  stomach  and  intestines,  ought 
not  to  be  considered  as  the  immediate 
cause  of  death,  in  the  greater  number  of 
cases  of  poisoning  by  arsenic.  However, 
should  an  animal  not  sink  under  the  first 
violence  of  the  poison,  if  the  inflammation 
has  had  time  to  be  dereloped,  there  is  no 
doubt  that  it  may  destroy  life.  Mr.  Earle 
states,  that  a  woman  who  had  taken  arsenic 
resisted  the  alarming  symptoms  which  at 
first  appeared,  but  died  on  the  fourth  day, 
On  opening-  her  body  the  mucous  mem- 
brane of  the  stomach  and  intestines  was 
ulcerated  to  a  great  extent.  Authentic 
cases  of  poison  are  recorded,  where  no 
trace  of  inflammation  was  perceptible  on 
the  primae  vix. 

The  symptoms  of  a  dangerous  dose- of 
arsenic  have  been  graphically  represented 
by  Dr.  Black :  "  The  symptoms  produced 
by  a  dangerous  dose  of  arsenic  begin  to 
appear  in  a  quarter  of  an  hour,  or  not 
much  longer,  after  it  is  taken.  First  sick- 
ness, and  great  distress  at  stomach,  soon 
followed  by  thirst,  and  burning  heat  in  the 
bowels.  Then  come  on  violent  vomiting1, 
and  severe  cholic  pains,  and  excessive  and 
painful  purging.  This  brings  on  faintings, 
with  cold  sweats,  and  other  signs  of  great 
debility.  To  this  succeed  painful  cramps 
and  contractions  of  the  legs  and  thighs, 
and  extreme  weakness,  and  death."  Simi- 
lar results  have  followed  the  incautious 
sprinking  of  schirrous  ulcers  with  powder- 
ed arsenic,  or  the  application  of  arsenical 
pastes.  The  following  more  minute  spe- 
cification of  symptoms  is  given  by  Orfila  : 
«  An  austere  taste  in  the  mouth ;  frequent 
ptyalism  ;  continual  spitting;  constriction 
of  the  pharynx  and  oesophagus;  teeth  set  on 
edge ;  hiccups ;  nausea;  vomiting  of  brown 
or  bloody  matter ;  anxiety ;  frequent  faint- 
ing fits ;  burning  heat  at  the  precordia,-  in- 
flammation of  the  lips,  tongue,  palate, 
throat,  stomach ;  acute  pain  of  stomach, 
rendering  the  mildest  drinks  intolerable  ; 
black  stools  of  an  indescribable  foetor  ; 
pulse  frequent,  oppressed  and  irregular, 
sometimes  slow  and  unequal ;  palpitation 
of  the  heart ;  syncope  ;  unextinguishable 
thirst ;  burning  sensation  over  the  whole 
body,  resembling  a  consuming  fire  ;  at 
times  an  iey  coldness,  difficult  respiration, 


cold  sweats,  scanty  urine,  of  a  red  or 
bloody  appearance,  altered  expression  of 
countenance,  a  livid  circle  round  the  eye- 
lids, swelling  and  itching  of  the  whole 
body,  which  becomes  covered  with  livid 
spots,  or  with  a  miliary  eruption  ;  prostra- 
tion of  strength,  loss  of  feeling,  especially 
in  the  feet  and  hands ;  delirium,  convul- 
sions, sometimes  accompanied  with  an  in- 
supportable priapism,  loss  of  the  hair,  se- 
paration of  the  epidermis,  horrible  convul- 
sions, and  death." 

It  is  uncommon  to  observe  all  these 
frightful  symptoms  combined  in  one  indi- 
vidual ;  sometimes  they  are  altogether 
wanting1,  as  is  shown  by  the  following  case, 
related  by  M.  Chaussier:  A  robust  man  of 
middle  age,  swallowed  arsenious  acid  in 
large  fragments,  and  died  without  expe- 
riencing other  symptoms  than  slight  syn- 
copes.  On  opening  his  stomach,  it  was 
found  to  contain  the  arsenious  acid  in  the 
very  same  state  in  which  he  had  swallow- 
ed it.  There  was  no  appearance  what- 
ever of  erosion  or  inflammation  in  the  in- 
testinal canal.  Etmuller  mentions  a  young' 
girl's  being  poisoned  by  arsenic,  and 
whose  stomach  and  bowels  were  sound  to 
all  appearance,  though  the  arsenic  was 
found  in  them.  In  general,  however,  in- 
flammation does  extend  along-  the  whole 
canal  from  the  mouth  to  the  rectum.  The 
stomach  and  duodenum  present  frequently 
gangrenous  points,  escars,  perforations  of 
all  their  coats  ;  the  villous  coat  in  particu- 
lar, by  this  and  all  other  corrosive  poisons, 
is  commonly  detached,  as  if  it  were  scra- 
ped off  or  reduced  into  a  paste  of  a  reddish 
brown  colour.  From  these  considerations 
we  may  conclude,  that  from  the  existence 
or  non-existence  of  intestinal  lesions,  from 
the  extent  or  seat  of  the  symptoms  alone, 
the  physician  should  not  venture  to  pro- 
nounce definitively  on  the  fact  of  poison- 
ing. 

The  result  of  Mr.  Brodie's  experiments 
on  brutes,  teaches  that  the  inflammations 
of  the  intestines  and  stomach  are  more  se- 
vere when  the  poison  has  been  applied  to 
an  external  wound,  than  when  it  has  been 
thrown  into  the  stomach  itself.  The  best 
remedies  ag-ainst  this  poison  in  the  stomach 
are  copious  draughts  of  bland  liquids  of  a 
mucilaginous  consistence  to  inviscate  the 
powder,  so  as  to  procure  its  complete 
ejection  by  vomiting.  Sulphuretted  hy- 
drogen condensed  in  water,  is  the  only  di- 
rect antidote  to  its  virulence ;  Orfila  having- 
found,  that  when  clog-s  were  made  to  swal- 
low ihat  liquid,  after  getting  a  poisonous 
dose  of  arsenic,  they  recovered,  thoug-h 
their  oesophagus  was  tied  to  prevent  vo- 
miting; but  when  the  same  dose  of  poison 
was  administered  in  the  same  circumstan- 
ces, without  the  sulphuretted  water,  that, 
it  proved  fatal.  When  the  vise-era  are  to  be 


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subjected  aftei;  death  to  chemical  investi- 
gation, a  ligature  ought  to  be  thrown  round 
the  oesophagus  and  the  beginning  of  the 
colon,  and  the  intermediate  stomach  and 
intestines  removed.  Their  liquid  contents 
should  be  emptied  into  a  basin ;  and  there- 
after a  portion  of  hot  water  introduced  in- 
to the  stomach,  and  worked  thoroughly 
up  and  down  this  viscns,  as  well  as  the  in- 
testines. 

Alter  filtration,  a  portion  of  the  liquid 
should  be  concentrated  by  evaporation  in 
a  porcelain  capsule,  and  then  submitted  to 
the  proper  reagents  above  described.  We 
ma)  also  endeavour  to  extract  from  the 
stomach  by  digestion  in  boiling  water,  with 
a  little  ammonia,  the  arsenical  impregna- 
tion, which  has  been  sometimes  known  to 
adhere  in  minute  particles  with  wonderful 
pertinacity.  This  precaution  ought  there- 
fore to  be  attended  to.  The  heat  will  dis- 
sipate the  excess  of  ammonia  in  the  above 
operation ;  whereas  by  adding  potash  or 
soda,  as  prescribed  by  the  German  che- 
mists, we  introduce  animal  matter  in  alka- 
line solution,  which  complicates  the  inves- 
tigation. 

The  matters  rejected  from  the  patient's 
bowels  before  death  should  not  be  neglect- 
ed. These,  generally  speaking,  are  best 
treated  by  cautious  evaporation  to  dryness; 
but  we  must  beware  of  heating  the  resi- 
duum to  400°,  since  at  that  temperature, 
and  perhaps  a  little  under  it,  the  arsenious 
acid  itself  sublimes. 

Vinegar,  hydroguretted  alkaline  sulphu- 
rets,  and  oils,  are  of  no  use  as  counterpoi- 
sons.  Indeed,  when  the  arsenic  exists  in 
substance  in  the  stomach,  even  sulphu- 
retted hydrogen  water  is  of  no  avail,  how- 
ever effectually  it  neutralizes  an  arsenious 
solution.  Sirups,  linseed  tea,  decoction  of 
mallows,  or  tragacanth,  and  warm  milk 
should  be  administered  as  copiously  as  pos- 
sible, and  vomiting  provoked  by  tickling 
the  fauces  with  a  feather.  Clysters  of  a 
similar  nature  may  be  also  employed. 
Many  persons  have  escaped  death  by  hav- 
ing taken  the  poison  mixed  with  rich 
soups;  and  it  is  well  known,  that  when  it 
is  prescribed  as  a  medicine,  it  acts  most 
beneficially  when  taken  soon  after  a  meal. 
These  facts  have  led  to  the  prescription  of 
butter  and  oils,  the  use  of  which  is,  how- 
ever, not  advisable,  as  they  screen  the  ar- 
senical particles  from  more  proper  men- 
strua, and  even  appear  to  aggravate  its 
virulence.  Morgagni,  in  his  great  work  on 
the  seats  and  causes  of  disease,  states,  that 
at  an  Italian  feast,  the  dessert  was  pur- 
posely sprinkled  over  with  arsenic  instead 
of  flour.  Those  of  the  guests  who  had  pre- 
viously ate  and  drank  little  speedily  perish- 
ed; those  who  had  their  stomachs  well 
filled,  were  saved  by  vomiting.  He  also 
mentions  the  case  of  three  children  who  ate 


a  vegetable  soup  poisoned  with  arsenic. 
One  of  them,  who  took  only  two  spoons- 
full,  had  no  vomiting,  and  died ;  the  other 
two,  who  had  eaten  the  rest,  vomited,  and 
got  well.  Should  the  poisoned  patient  be 
incapable  of  vomiting,  a  tube  of  caout- 
chouc, capable  of  being  attached  to  a 
syringe,  may  be  had  recourse  to.  The 
tube  fr-st  serves  to  introduce  the  drink, 
and  to  withdraw  it  after  a  few  instants. 

The  following  te^ts  of  arsenic  and  corro- 
sive sublimate  have  been  lately  proposed 
by  Brugnatelli :  Take  the  starch  of  wheat 
boiled  in  water  until  it  is  of  a  proper  con- 
sistence, and  recen  \y  prepared;  to  this 
add  a  sufficient  quantity  of  iodine  to  make 
it  of  a  blue  colour;  it  is  afterwards  to  be 
diluted  with  pure  water  until  it  becomes 
of  a  beautiful  azure.  If  to  this,  some  drops 
of  a  watery  solution  of  arsenic  be  added, 
the  colour  changes  to  a  reddish  hue,  and 
finally  vanishes.  The  solution  of  corrosive 
sublimate  poured  into  iodine  and  starch, 
produces  almost  the  same  change  as  arsen- 
ic ;  but  if  to  the  fluid  acted  on  by  the  ar- 
senic we  add  some  drops  of  sulphuric  acid, 
the  original  blue  colour  is  restored  with 
more  than  its  original  brilliancy,  while  it 
does  not  restore  the  colour  to  the  corro- 
sive sublimate  mixture.* 

ACID  (BKXZOIC).  This  acid  was  first  de- 
scribed in  1608,  by  Blaise  de  Vigenere,  in 
his  Treatise  on  Fire  and  Salt,  and  has  been 
generally  known  since  by  the  name  of 
flowers  of  benjamin  or  benzoin,  because  it 
was  obtained  by  sublimation  from  the  re- 
sin of  this  name.  As  it  is  still  most  com- 
monly procured  from  this  substance,  it  has. 
preserved  the  epithet  of  benzoic,  though 
known  to  be  a  peculiar  acid,  obtainable 
not  from  benzoin  alone,  but  from  different 
vegetable  balsams,  vanello,  cinnamon,  am- 
bergris, the  urine  of  children,  frequently 
that  of  adults,  and  always,  according  ta 
Fourcroy  and  Yauquelin,  though  Giese 
denies  this,  that  of  quadrupeds  living  on 
grass  and  hay,  particularly  the  camel,  the 
horse,  and  the  cow.  There  is  reason  to 
conjecture  that  many  vegetables,  and 
among  them  some  of  the  grasses,  contain 
it,  and  that  it  passes  from  them  into  the 
urine.  Fourcroy  and  Vauquelin  found  it 
combined  with  potash  and  lime  in  the  li- 
quor of  dunghills,  as  well  as  in  the  iniiie 
of  the  quadrupeds  above  mentioned  ;  and 
they  strongly  svispect  it  to  exist  in  the 
anthoxanthum  odoratum,  or  sweet-scented 
vernal  grass,  from  which  hay  principally 
derives  its  fragrant  smell.  Giese,  however, 
could  find  none  either  in  this  grass  or  in 
oats. 

The  usual  method  of  obtaining  it  affords 
a  very  elegant  and  pleasing  example  of 
the  chemical  process  of  sublimation.  For 
this  purpose  a  thin  stratum  of  powdered 
benzoin  is  spread  over  the  bottom  of  a 


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glazed  earthen  pot,  to  which  a  tall  conical 
paper  covering1  is  fitted :  gentle  heat  is 
then  to  be  applied  to  the  bottom  of  the 
pot,  which  fuses  the  benzoin,  and  fills  the 
apartment  with  a  fragrant  smell,  arising 
from  a  portion  of  essential  oil  and  acid  of 
benzoin,  which  are  dissipated  into  the  air; 
at  the  same  time  the  acid  itself  rises  very 
suddenly  in  the  paper  head,  which  maybe 
occasionally  inspected  at  the  top,  though 
wuh  some  little  care,  because  the  fumes 
will  excite  coughing.  This  saline  subli- 
mate is  condensed  in  the  form^of  long 
needles,  or  straight  filaments  of  a  white 
colour,  crossing-  each  other  in  all  direc- 
tions. When  the  acid  ceases  to  rise,  the 
cover  may  be  chang-ed,  a  new  one  applied, 
and  the  heat  raised :  more  flowers  of  a 
yellowish  colour  will  then  rise,  which  re- 
quire a  secondsublimation  to  deprive  them 
of  the  empyreumatic  oil  they  contain. 

'I  he  sublimation  of  the  acid  of  benzoin 
may  be  conveniently  performed  by  substi- 
tuting- an  inverted  earthen  pan  instead  of 
the  paper  cone.  In  this  case  the  two  pans 
should  be  made  to  fit,  by  grinding-  on  a 
stone  with  sand,  and  they  must  be  luted 
tog-ether  with  paper  dipped  in  paste.  This 
method  seems  preferable  to  the  other, 
where  the  pi-esence  of  the  operator  is  re- 
quired elsewhere  ;  but  the  paper  head 
can  be  more  easily  inspected  and  changed. 
The  heat  applied  must  be  very  gentle, 
and  the  vessels  ought  not  to  be  separated 
till  they  have  become  cool. 

The  quantity  of  acid  obtained  in  these 
methods  differs  according  to  the  manage- 
ment, and  probably  also  from  difference  of 
purity,  and  in  other  respects  of  the  resin 
itself.  It  usually  amounts  to  no  more  than 
about  one-eighth  part  of  the  whole  weight. 
Indeed  Scheele  says,  not  more  than  a  tenth 
or  twelfth.  The  whole  acid  of  benzoin  is 
obtained  with  greater  certainty  in  the  hu- 
mid process  of  Scheele  :  this  consists  in 
boiling  the  powdered  resin  with  lime-wa- 
ter, and  afterwards  separating  the  lime  by 
the  addition  of  muriatic  acid.  Twelve  oun- 
ces of  water  are  to  be  poured  upon  four 
ounces  of  slaked  lime ;  and,  after  the 
ebullition  is  over,  eight  pounds,  or  ninety- 
six  ounces,  more  of  water  are  to  be  added; 
a  pound  of  finely  powdered  benzoin  being 
then  put  into  a  tin  vessel,  six  ounces  of  the 
lime-water  are  to  be  added,  and  mixed 
well  with  the  powder  ;  and  afterwards  the 
rest  of  the  lime-water  in  the  same  gradual 
manner,  because  the  benzoin  would  coag- 
ulate into  a  mass,  if  the  whole  were  added 
at  once.  This  mixture  must  be  gently 
boiled  for  half  an  hour  with  constant  agi- 
tation, and  afterwards  suffered  to  cool  and 
subside  during  an  hour.  The  supernatant 
liquor  must  be  decanted,  and  the  residuum 
boiled  with  eight  pounds  more  of  lime- 
\vatcr;  after  which  the  same  process  is  to 


be  once  more  repeated:  the  remaining" pow- 
der must  be  edulcorated  on  the  filter  by 
affusions  of  hot  water.  Lastly,  all  the  de- 
coctions, being  mixed  together,  must  be 
evaporated  to  two  pounds,  and  strained 
into  a  glass  vessel. 

This  fluid  consists  of  the  acid  of  benzoin 
combined  with  lime.  After  it  is  become 
cold,  a  quantity  of  muriatic  acid  must  be 
added,  with  constant  stirring,  until  the  flu- 
id tastes  a  little  sourish.  During  this  time 
the  last-mentioned  acid  unites  with  the 
lime,  and  forms  a  soluble  salt,  which  re- 
mains suspended,  while  the  less  soluble 
acid  of  benzoin,  being  disengaged,  falls  to 
the  bottom  in  powder.  By  repeated  affu- 
sions of  cold  water  upon  the  filter,  it  may 
be  deprived  of  the  muriate  of  lime  and 
muria  ic  acid,  with  which  it  may  happen 
to  be  mixed.  If  it  be  required  to  have  a 
shining  appearance,  it  may  be  dissolved 
in  a  small  quantity  of  boiling  water,  from 
which  it  will  separate  in  silky  filaments  by 
cooling.  By  this  process  the  benzoic  acid 
may  be  procured  from  other  substances, 
in  which  it  exists. 

*  Mr.  Hatchett  has  shown,  that  by  digest- 
ing benzoin  in  hot  sulphuric  acid,  very 
beautiful  crystals  are  sublimed.  This  is 
perhaps  the  best  process  for  extracting 
the  acid.  If  we  concentrate  the  urine  of 
horses  or  cows,  and  pour  muriatic  acid  in- 
to it,  a  copious  precipitate  of  benzoic  acid 
takes  place.  This  is  the  cheapest  source 
of  it.* 

As  an  economical  mode  of  obtaining 
this  acid,  Fourcroy  recommends  the  ex- 
traction of  it  from  the  water  that  drains 
from  dunghills,  cowhouses,  and  stables,  by 
means  of  the  muriatic  acid,  which  decom- 
poses the  benzoate  of  lime  contained  in 
them,  and  separates  the  benzoic  acid,  as 
in  Scheele's  process.  He  confesses  the 
smell  of  the  acid  thus  obtained  differs  a 
little  from  that  of  the  acid  extracted  from 
benzoin  ;  but  this,  he  says,  may  be  reme- 
died, by  dissolving  the  acid  in  boiling  wa- 
ter, filtering  the  solution,  letting  it  cool, 
and  thus  suffering  the  acid  to  crystallize, 
and  repeating  this  operation  a  second 
time. 

Mr.  Accum  found  the  benzoic  acid 
which  he  obtained  from  vanello-pods  con- 
taminated with  a  yellow  colouring  matter, 
from  which  it  could  not  be  freed  by  re- 
peated solutions  and  crystallizations ;  but 
by  boiling  with  charcoal  powder,  the  acid 
was  rendered  perfectly  pure. 

The  acid  of  benzoin  is  so  inflammable, 
that  it  burns  with  a  clear  yellow  flame 
without  the  assistance  of  a  wick.  The  sub- 
limed flowers  in  their  purest  state,  as 
white  as  ordinary  writing-paper,  were 
fused  into  a  clear  transparent  yellowish 
fluid,  at  the  two  hundred-and-thirtieth  de- 
gree of  Fahrenheit's  thermometer,  and  at 


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the  same  time  began  to  rise  in  sublima* 
,  tion.  It  is  probable  that  a  heat  somewhat 
greater  than  this  may  be  required  to  sepa- 
rate it  from  the  resin.  It  is  strongly  dis- 
posed to  take  the  crystalline  form  in  cool- 
ing1. The  concentrated  sulphuric  and  nitric 
acids  dissolve  this  concrete  acid,  and  it  is 
again  separated,  without  alteration,  by  add- 
ing1 water.  Other  acids  dissolve  it  by  the 
assistance  of  heat,  from  which  it  separates 
by  cooling,  unchanged,  it  is  plentifully 
soluble  in  ardent  spirit,  from  which  it 
may  likewise  be  separated  by  diluting  the 
spirit  with  water.  It  readily  dissolves  in 
oils,  and  in  melted  tallow.  If  it  be  added 
in  a  small  proportion  to  this  last  fluid, 
part  of  the  tallow  congeals  before  the 
rest,  in  the  form  of  white  opaque  clouds. 
If  the  quantity  of  acid  be  more  considera- 
ble, it  separates  in  part  by  cooling,  in  the 
form  of  needles  or  feathers.  It  did  not 
communicate  any  considerable  degree  of 
hardness  to  the  tallow,  which  was  the 
object  of  this  experiment.  When  the 
tallow  was  heated  nearly  to  ebullition,  it 
emitted  fumes  which  affected  the  respi- 
ration, like  those  of  the  acid  of  benzoin, 
but  did  not  possess  the  peculiar  and 
agreeable  smell  of  that  substance,  being 
probably  the  sebacic  acid.  A  stratum  of 
this  tallow,  about  one-twentieth  of  an  inch 
thick,  was  fused  upon  a  plate  of  brass, 
together  with  other  fat  substances,  with  a 
view  to  determine  its  relative  disposition 
to  acquire  and  retain  the  solid  state.  Af- 
ter it  had  cooled  it  was  left  upon  the  plate, 
and,  in  the  course  of  some  weeks,  it  gra- 
dually became  tinged  throughout  of  a 
bluish  green  colour.  If  this  circumstance 
be  not  supposed  to  have  arisen  from  a  so- 
lution of  the  copper  during  the  fusion,  it 
seems  a  remarkable  instance  of  the  mu- 
tual action  of  two  bodies  in  the  solid  state, 
i  contrary  to  that  axiom  of  chemistry  which 
affirms,  that  bodies  do  not  act  on  each 
other,  unless  one  or  more  of  them  be  in 
the  fluid  state.  Tallow  itself,  however, 
has  the  same  effect. 

Pure  benzoic  acid  is  in  the  form  of  a 
light  powder,  evidently  crystallized  in 
fine  needles,  the  figure  of  which  is  diffi- 
cult to  be  determined  from  their  smallness. 
It  has  a  white  and  shining  appearance ;  but 
when  contaminated  by  a  portion  of  vola- 
tile oil,  is  yellow  or  brownish.  It  is  not 
brittle  as  might  be  expected  from  its  ap- 
pearance, but  has  rather  a  kind  of  duc- 
tility and  elasticity,  and,  on  rubbing  in  a 
mortar,  becomes  a  sort  of  paste.  Its  taste 
is  acrid,  hot,  acidulous,  and  bitter.  It  red- 
dens the  infusion  of  litmus,  but  not  sirup 
of  violets.  It  has  a  peculiar  aromatic  smell, 
but  not  strong  unless  heated.  This,  how- 
ever, appears  not  to  belong  to  the  acid  ; 
for  Mr.  Giese  informs  us,  that  on  dissolving1 
ih.e  benzoic  acid  in  as  little  alcohol  as  pos- 


sible, filtering  the  solution,  and  precipi* 
tating  by  water,  the  acid  will  be  obtained 
pure,  and  void  of  smell,  the  odorous  oil 
remaining  dissolved  in  the  spirit.  Its  spe- 
cific gravity  is  0.667.  It  is  not  perceptibly 
altered  by  the  air,  and  has  been  kept  in  an 
open  vessel  twenty  years  without  losing 
any  of  its  weight.  None  of  the  combus- 
tible substances  have  any  effect  on  it ;  but 
it  may  be  refined  by  mixing  it  with  char- 
coal powder  and  subliming,  being  thus 
rendered  much  whiter  and  better  crystal- 
lized. It  is  not  very  soluble  in  water. 
Wenzel  and  Lichtenstein  say  four  hundred 
parts  of  cold  water  dissolve  but  one,  though 
the  same  quantity  of  boiling  water  dis- 
solves twenty  parts,  nineteen  of  which 
separate  on  cooling. 

The  benzoic  acid  unites  without  much 
difficulty  with  the  earthy  and  alkaline 
bases. 

The  benzoate  of  barytes  is  soluble, 
crystallizes  tolerably  well,  is  not  affected 
by  exposure  to  the  air,  but  is  decomposa- 
ble by  fire,  and  by  the  stronger  acids. 
That  of  lime  is  very  soluble  in  water, 
though  much  less  in  cold  than  in  hot,  and 
crystallizes  on  cooling.  It  is  in  like  man- 
ner decomposable  by  the  acids  and  by 
barytes.  The  benzoate  of  magnesia  is  so- 
luble, crystallizable,  a  little  deliquescent, 
and  more  decomposable  than  the  former. 
That  of  alumina  is  very  soluble,  crystal- 
lizes in  dendrites,  is  deliquescent,  has  an 
acerb  and  bitter  taste,  and  is  decomposa- 
ble by  fire,  and  even  by  most  of  the  ve- 
getable acids.  The  benzoate  of  potash 
crystallizes  on  cooling  in  little  compacted 
needles.  All  the  acids  decompose  it,  and 
the  solution  of  barytes  and  lime  form  with 
it  a  precipitate.  The  benzoate  of  soda  is 
very  crystallizable,  very  soluble,  and  not 
deliquescent  like  that  of  potash,  but  it  is 
decomposable  by  the  same  means.  It  is 
sometimes  found  native  in  the  urine  of 
graminivorous  quadrupeds,  but  by  no 
means  so  abundantly  as  that  of  lime.  The 
benzoate  of  ammonia  is  volatile,  and  de- 
composable by  all  the  acids  and  all  the 
bases.  The  solutions  of  all  the  benzoates, 
when  drying  on  the  sides  of  a  vessel  wet- 
ted with  them,  form  dendritical  crystalli- 
zations. 

Trommsdorf  found  in  his  experiments, 
that  benzoic  acid  united  readily  with  me- 
tallic oxides. 

From  the  chemical  properties  of  this 
acid,  it  appears  to  differ  from  the  other 
vegetable  acids  in  the  nature  and  proper- 
ties of  the  principles  that  constitute  its  ra. 
dical.  Its  odour,  volatility,  combustibili- 
ty, great  solubility  in  alcohol,  and  little 
solubility  in  water,  formerly  occasioned  it 
to  be  considered  as  an  oily  acid ;  and  have 
led  modern  chemists  to  conceive,  that  it 
contains  a  large  quantity  of  hydrogen  in 


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its  composition,  and  that  it  is  in  the  super- 
abundance  of  this  combustible  principle 
its  difference  from  the  other  vegetable 
acids  consists.  Its  solubility  in  the  power- 
ful acids,  and  its  subsequent  separation, 
indicate  that  its  principles  are  not  easily 
separable  from  each  other.  Attempts  have 
been  made  to  decompose  it  by  repeated 
abstraction  of  nitric  acid ;  the  nitric  acid 
rises  first,  scarcely  altered  except  toward 
the  end  of  the  process,  when  nitrous  gas 
comes  over;  and  the  acid  of  benzoin  is 
afterwards  sublimed  with  little  alteration. 
By  repeating1  the  process,  however,  it  is 
said  to  become  more  fixed,  and  at  length 
to  afford  a  few  drops  of  an  acid  resembling1 
the  oxalic  in  its  properties. 

*  Berzelius,  from  the  benzoate  of  lead, 
deduces  the  weight  of  the  prime  equiva- 
lent of  benzoic  acid  to  be  14.893 ;  and  it 
consists  per  cent  of  5.16  hydrogen,  74.41 
carbon,  and  20.43  oxygen. 

The  benzoates  are  all  decomposable  by 
heat,  which,  when  it  is  slowly  applied, 
first  separates  a  portion  of  the  acid  in  a 
vapour,  that  condenses  in  crystals.  The 
soluble  benzoates  are  decomposed  by  the 
powerful  acids,  which  separate  their  acid 
in  a  crvstalline  form.  The  benzoate  of 
ammonia  has  been  proposed  by  Berzelius 
as  a  reagent  for  precipitating  red  oxide  of 
iron  from  perfectly  neutral  solutions.  Ac- 
cording to  my  experiments,  21.3  of  am- 
monia take  15.7  of  crystallized  benzoic 
acid  for  neutralization.* 

The  benzoic  acid  is  occasionally  used  in 
medicine,  but  not  so  much  as  formerly ; 
and  enters  into  the  composition  of  the 
camphorated  tincture  of  opium  of  the  Lon- 
don college,  Ikiretofore  called  paregoric 
elixir. 

*  ACID  (TJoLETic).     An   acid  extracted 
from  the  expressed  juice   of  the    boletus 
psnido-igniarins   by  M.    Braconnot.     This 
juice   concentrated  to  a  sirup  by   a  very 
gentle  heat,  was  acted  on  by  strong  alco- 
hol.    What  remained  was  dissolved  in  wa- 
ter.    AVhen  nitrate   of  lead  was  dropped 
into  this  solution,  a  white  precipitate  fell, 
which,  after  being  well  washed  with  wa- 
ter, was  decomposed  by  a  current  of  sul- 
phuretted hydrogen  gas.     Two  different 
acids  were  found  in  the  liquid  after  filtra- 
tion and  evaporation.     One  in  permanent 
en  stals  was  BOLETIC  acid ;  the  other  was 
a   small  proportion    of  phosphoric    acid. 
The  former  was  purified  by  solution  in  al- 
cohol, and  subsequent  evaporation. 

It  consists  of  irregular  four-sided  prisms, 
of  a  white  colour,  and  permanent  in  the 
air.  Its  taste  resembles  cream  of  tartar; 
lit  the  temperature  of  68°  it  dissolves  in 
180  times  its  weight  of  water,  and  in  45 
of  alcohol.  Vegetable  blues  arc  reddened 
by  it,  Keel  oxide  of  iron,  and  the  oxides 
of  silver  and  mercury,  are  precipitated  by 


it  from  their  solutions  in  nitric  acid  ;  but 
lime  and  barytes  waters  are  not  affected. 
It  sublimes  when  heated,  in  white  vapours, 
and  is  con.lensed  in  a  white  powder.  Jinn, 
de  Chimie,  Ixxx.* 

Acin  (BORACIC).  The  salt  composed  of 
this  acid  and  soda,  had  long  been  used 
both  in  medicine  and  the  arts  under  the 
name  of  borax,  when  llomberg  first  ob- 
tained the  acid  separate  in  1702,  by  dis- 
tilling a  mixture  of  borax  and  sulphate  of 
iron.  He  supposed,  however,  that  it  was 
a  product  of  the  latter ;  and  gave  it  the 
name  of  volatile  narcotic  salt  of  vitriol,  or 
sedative  salt.  Lemery  the  younger  soon 
after  discovered,  that  it  could  be  obtained 
from  borax  equally  by  means  of  the  nitric 
or  muriatic  acid ;  Geoff  roy  detected  soda 
in  borax ;  and  at  length  Baron  proved  by  a 
number  of  experiments,  that  borax  is  a 
compound  of  soda  and  a  peculiar  acid. 
Cadet  has  disputed  this  ;  but  he  has  mere- 
ly shown,  that  the  borax  of  the  shops  is 
frequently  contaminated  with  copper;  and 
Struve  and  Exchaquet  have  endeavoured 
to  prove  that  the  boracic  and  phosphoric 
acids  are  the  same ;  yet  their  experiments 
only  show,  that  they  resemble  each  other 
in  certain  respects,  noi  in  all. 

To  procure  the  acid,  dissolve  borax  iu 
hot  water,  and  filter  the  solution ;  then 
add  sulphuric  acid  by  little  and  little,  till 
the  liquid  has  a  sensibly  acid  taste.  Lay 
it  aside  to  cool,  and  a  great  number  of 
small  shining  laminated  crystals  will  form. 
These  are  the  boracic  acid.  They  are  to 
be  washed  with  cold  \vater,  and  drained 
upon  brown  paper. 

Boracic  acid  thus  procured  is  in  the 
form  of  thin  irregular  hexagonal  scales,  of 
a  silvery  whiteness,  having  some  resem- 
blance to  spermaceti,  and  the  same  kind 
of  greasy  feel.  It  has  a  sourish  taste  at 
first,  then  makes  a  bitterish  cooling  im- 
pression, and  at  last  leaves  an  agreeable 
sweetness.  Pressed  between  the  teeth, 
it  is  not  brittle  but  ductile.  It  has  no 
smell;  but,  when  sulphuric  acid  is  poured 
on  it,  a  transient  odour  of  musk  is  pro- 
duced. Its  specific  gravity  in  the  form 
of  scales  is  1.479;  after  it  has  been  fused, 
1.803.  It  is  not  altered  by  light.  Exposed 
to  the  fire  it  swells  up,  from  losing  its  wa- 
ter of  crystallization,  and  in  this  state  is 
called  calcined  boracic  acid.  It  melts  a 
little  before  it  is  red-hot,  without  percep- 
tibly losing  any  water,  but  it  does  not  flow 
freely  till  it  is  red,  and  then  less  than  the 
borate  of  soda.  After  this  fusion  it  is  a 
hard  transparent  glass,  becoming  a  little 
opaque  on  exposure  to  the  air,  without 
abstracting  moisture  from  it,  and  unalter- 
ed in  its  properties,  for  on  being  dissolved 
in  boiling  water  it  crystallizes  as  before. 
This  glass  is  used  in  thq  composition  of 
false  gems. 


ACI 


ACI 


Boiling-  water  scarcely  dissolves  one  fif- 
tieth part,  and  cold  water  much  less. 
When  this  solution  is  distilled  in  close 
vessels,  part  of  the  acid  rises  with  the  wa- 
ter, and  crystallizes  in  the  receiver.  It  is 
more  soluble  in  alcohol,  and  alcohol  con- 
taining- it  burns  with  a  green  flame,  as  does 
paper  dipped  in  a  solution  of  boracic  acid. 

Neither  oxygen  gas,  nor  the  simple  com. 
bustibles,  nor  the  common  metals,  pro- 
duce any  change  upon  boracic  aciu,  as  far 
as  is  at  present  known.  If  mixed  with 
finely  powdered  charcoal,  it  is  neverthe- 
less capable  of  vitrification ;  and  with  soot 
it  melts  into  a  black  bitumen-like  mass, 
which  however  is  soluble  in  water,  and 
cannot  easily  be  burned  to  ashes,  but  sub- 
limes in  part.  With  the  assistance  of  a 
distilling  heat  it  dissolves  in  oils,  especial- 
ly mineral  oils ;  and  with  these  it  yields 
fluid  and  solid  products,  which  impart  a 
green  colour  to  spirit  of  wine.  When 
rubbed  with  phosphorus  it  does  not  pre- 
vent its  inflammation,  but  an  earthy  yellow 
matter  is  left  behind.  It  is  hardly  capa- 
fele  of  oxidizing  or  dissolving  any  of  the  me- 
tals except  iron  and  zinc,  and  perhaps 
copper;  but  it  combines  with  most  of  the 
metallic  oxides,  as  it  does  with  the  alka- 
lis, and  probably  with  all  the  earths, 
though  the  greater  part  of  its  combinations 
have  hitherto  been  little  examined.  It  is 
of  great  use  in  analyzing  stones  that  con- 
tain a  fixed  alkali. 

*  Crystallized  boracic  acid  is  a  compound 
of  57  parts  of  acid  and  43  of  water.  The 
honour  of  discovering  the  radical  of  bora- 
cic acid,  is  divided  between  Sir  H.  Davy 
and  M.  M.  Gay-Lussac  and  Thenard.  The 
first,  on  applying  his  powerful  voltaic  bat- 
tery to  it,  obtained  a  chocolate-coloured 
body  in  small  quantity  ;  but  the  two  latter 
chemists,  by  acting  on  it  with  potassium 
in  equal  quantities,  at  a  low  red  heat, 
formed  boron  and  subborate  of  potash. 
For  a  small  experiment  a  glass  tube  will 
serve,  but  on  a  greater  scale  a  copper 
tube  is  to  be  preferred.  The  potassium 
and  boracic  acid,  perfectly  dry,  should 
be  intimately  mixed  before  exposing  them 
to  heat.  On  withdrawing  the  tube  from 
the  fire,  allowing  it  to  cool,  and  removing 
the  cork  which  loosely  closed  its  mouth, 
we  then  pour  sviccessive  portions  of  water 
into  it,  till  we  detach  or  dissolve  the  whole 
matteiv  The  water  ought  to  be  heated 
each  time.  The  whole  collected  liquids 
are  allowed  to  settle  ;  when,  after  wash- 
ing the  precipitate  till  the  liquid  ceases  to 
affect  sirup  of  violets,  we  dry  the  boron 
in  a  capsule,  and  then  put  it  into  a  phial 
out  of  contact  of  air.  Boron  is  solid,  taste- 
less, inodorous,  and  of  a  greenish  brown 
colour.  Its  specific  gravity  is  somewhat 
greater  than  water.  The  prime  equiva- 
lent of  boracic  acid  has  been  inferred  from 
VOL,,  i,  [4] 


the  borate  of  ammonia,  to  be  about  2.7 
or  2.8;  oxygen  being  1.0;  and  it  probably 
consists  of  2.0  of  oxygen  -f-  0.8  of  boron. 
But  by  M.  M.  Gay-Lussac  and  Thenard,  the 
proportions  would  be  2  of  boron  to  1  of 
oxygen.* 

The  boracic  acid  has  a  more  powerful 
attraction  for  lime,  than  for  any  other  of 
the  bases,  though  it  does  not  readily  form 
borate  of  lime  by  adding  a  solution  of  it  to 
lime-water,  or  decomposing  by  lime-water 
the  soluble  alkaline  borates.  In  either 
case  an  insipid  white  powder,  nearly  inso- 
luble, which  is  the  borate  of  lime,  is  how- 
ever precipitated.  The  borate  of  barytes 
is  likewise  an  insoluble,  tasteless,  white 
powder. 

Bergmann  has  observed,  that  magnesia, 
thrown  by  little  and  little  into  a  solution  of 
boracic  acid,  dissolved  slowly,  and  the  li- 
quor on  evaporation  afforded  granulated 
crystals  without  any  regular  form  :  that 
these  crystals  were  fusible  in  the  fire  with- 
out being  decomposed  ;  but  that  alcohol 
was  sufficient  to  separate  the  boracic  acid 
from  the  magnesia.  If  however  some  of 
the  soluble  magnesian  salts  be  decom- 
posed by  alkaline  borates  in  a  state  of  so- 
lution, an  insipid  and  insoluble  borate  of 
magnesia  is  thrown  down.  It  is  probable, 
therefore,  that  Bergmann's  salt  was  a  bo- 
rate of  magnesia  dissolved  in  an  excess  of 
boracic  acid;  which  acid  being  taken  up 
by  the  alcohol,  the  true  borate  of  magne- 
sia was  precipitated  in  a  white  powder, 
and  mistaken  by  him  for  magnesia. 

One  of  the  best  known  combinations  of 
this  acid  is  the  native  magnesio-calcareous 
borate  of  Kalkberg,  near  Lunenburg  •  the 
tourfelstein  of  the  Germans,  cubic  quartz  of 
various  mineralogists,  and  boracite  of  Kir- 
wan.  It  is  of  a  grayish  white  colour, 
sometimes  passing  into  the  greenish  white, 
or  purplish.  Its  figure  is  that  of  a  cube, 
incomplete  on  its  twelve  edges,  and  at 
four  of  its  solid  angles ;  the  complete  and 
incomplete  anglesbeing  diametrically  op- 
posite to  each  other.  The  surfaces  gene- 
rally appear  corroded.  It  strikes  fire  with 
steel,  and  scratches  glass.  Its  specific 
gravity  is  2.566,  as  determined  by  M. 
Westrumb,  who  found  it  to  be  composed 
of  boracic  acid  0.68,  magnesia  0.1305, 
lime  0.11;  with  alumina  0.01,  silex  0.02, 
and  oxide  of  iron  0.0075,  all  of  which  he 
considers  as  casual.  Its  most  remarkable 
property,  discovered  by  Haiiy,  is,  that 
like  the  tourmalin  it  becomes  electric  by 
heat,  though  little  so  by  friction ;  and  it 
has  four  electric  poles,  the  perfect  angles 
always  exhibiting  negative  electricity,  and 
the  truncated  angles  positive. 

Since  the  component  parts  of  this  na- 
tive salt  have  been  known,  attempts  have- 
been  made  to  imitate  it  b^  art ;  but  no 
diemist  has  been  able,  by  mixing-  lime, 


ACI 


ALJ 


magnesia,  and  boracic  acid,  to  produce 
any  thing-  but  a  pulverulent  salt,  incapa- 
ble of  being  dissolved,  or  exhibited  in  the 
crystallized  form,  and  with  the  hardness 
of  the  bo  rate  of  Kalkberg. 

It  has  lately  been  denied,  however,  that 
this  compound  is  really  a  triple  salt.  Vau- 
quelin,  examining  this  substance  with  Mr. 
Smith,  who  had  a  considerable  quantity, 
found  the  powder  to  effervesce  with  acids  ; 
and  therefore  concluded  the  lime  to  be  no 
essential  part  of  the  compound.  They  at- 
tempted, by  using  weak  acids  much  dilu- 
ted, to  separate  the  carbonate  froTn  the 
borate;  but  they  did  not  succeed,  be- 
cause the  acid  attacked  the  borate  like- 
wise, though  feebly.  M.  Stromager  hav- 
ing afterwards  supplied  Vauquelin  with, 
some  transparent  crystals,  which  did  not 
effervesce  with  acids,  he  mixed  this  pow- 
der with  muriatic  acid,  and,  when  the  so- 
lution was  effected  by  means  of  heat, 
evaporated  to  dryness  to  expel  the  excess 
of  acid.  By  solution  in  a  small  quantity 
of  cold  distilled  water,  he  separated  most 
of  the  boracic  acid ;  and,  having  diluted 
the  solution,  added  a  certain  quantity  of 
oxalate  of  ammonia,  but  no  sign  of  the  ex- 
istence of  lime  appeared.  To  ascertain 
that  the  precipitation  of  the  lime  was  not 
prevented  by  the  presence  of  the  small 
quantity  of  boracic  acid,  he  mixed  with 
the  solution  a  very  small  portion  of  mu- 
riate of  lime,  and  a  cloudiness  immediate- 
ly ensued  through  the  whole.  Hence  he 
infers,  that  the  opacity  of  the  magnesian 
borate  is  occasioned  by  carbonate  of  lime 
interposed  between  its  particles,  and  that 
the  borate  in  transparent  crystals  contains 
none. 

The  borate  of  potash  is  but  little  known, 
though  it  is  said  to  be  capable  of  supplying 
the  place  of  that  of  soda  in  the  arts ;  but 
more  direct  experiments  are  required  to 
establish  this  effect.  Like  that,  it  is  ca- 
pable of  existing  in  two  states,  neutral 
and  with  excess  of  base,  but  it  is  not  so 
crystallizable,  and  assumes  the  form  of 
parallelepipeds. 

With  soda  the  boracic  acid  forms  two 
different  salts.  One,  in  which  the  alkali 
is  more  than  triple  the  quantity  necessary 
to  saturate  the  acid,  is  of  considerable  use 
in  the  arts,  and  has  long  been  known  by 
the  name  of  borax ;  under  which  its  his- 
tory and  an  account  of  its  properties  will 
be  given.  The  other  is  a  neutral  salt,  not 
changing  the  sirup  of  violets  green  like 
the  borate  with  excess  of  base  ;  differing 
from  it  in  taste  and  solubility  ;  crystallizing 
neither  so  readily,  nor  in  the  sanae  man- 
ner; not  efflorescent  like  it;  but  like  it 
fusible  into  a  glass,  and  capable  of  being 
employed  for  the  same  purposes.  This 
salt  may  be  formed  by  saturating  the  su- 
perabundant soda  in  borax  with  some  other 


acid,  and  then  separating  the  two  salts  r 
but  it  is  obviously  more  eligible,  to  satu- 
rate the  excess  of  soda  with  an  additional 
portion  of  the  boracic  acid  itself. 

Borate  ot  ammonia  forms  in  small  rhom- 
boidal  crystals,  easily  decomposed  by  fire  ; 
or  in  scales,  of  a  pungent  urinous  taste, 
which  lose  the  crystalline  form,  and  grow 
brown  on  exposure  to  the  air. 

It  is  very  difficult  to  combine  the  bora- 
cic acict  with  alumina,  at  least  in  the  direct 
way.  It  has  been  recommended,  for  this 
purpose,  to  add  a  solution  of  borax  to  a 
solution  of  sulphate  of  alumina ;  but  for 
this  process  the  neutral  borate  of  soda  is 
preferable,  since,  if  borax  be  employed,, 
the  soda  that  is  in  excess  ma\  throw  down 
a  precipitate  of  alumina,  which  might  be 
mistaken  for  an  earthy  borate. 

The  boracic  acid  unites  with  silex  by 
fusion,  and  forms  with  it  a  solid  and  per- 
manent vitreous  compound.  This  borate 
of  silex,  however,  is  neither  sapid,  nor 
soluble,  nor  perceptibly  alterable  in  the 
air;  and  cannot  be  formed  without  the 
assistance  of  a  violent  heat.  In  the  same 
manner  triple  compounds  may  be  formed 
with  silex  and  borates  already  saturated 
with  other  bases. 

The  boracic  acid  has  been  found  in  a 
disengaged  state  in  several  lakes  of  hot 
mineral  waters  near  Monte  Rotondo,  Ber- 
chiaio,  and  Castellonuovo  in  Tuscany,  in 
the  pi'oportion  of  nearly  nine  grains  in  a 
hundred  of  water,  by  M.  Hoefter.  M. 
Mascagni  also  found  it  adhering  to  schis- 
tus,  on  the  borders  of  lakes,  of  an  obscure 
white,  yellow,  or  greenish  colour,  and 
crystallized  in  the  form  of  needles.  He 
has  likewise  found  it  in  combination  with 
ammonia. 

ACID  (CAMPHOHTC).  M.  Kosegartcn 
found  some  years  ago,  that  an  acid  with 
peculiar  properties  was  obtained,  by  dis- 
tilling nitric  acid  eight  times  following 
from  camphor.  Bouillon  Lagrange  has 
since  repeated  his  experiments,  and  the 
following  is  the  account  he  gives  of  its 
preparation  and  properties. 

One  part  of  camphor  being  introduced 
into  a  glass  retort,  four  parts  of  nitric  acid 
of  the  strength  of  36  degrees  are  to  be 
poured  on  it,  a  receiver  adapted  to  the 
retort,  and  all  the  joints  well  luted.  The 
retort  is  then  to  be  placed  on  a  sand-bath, 
and  gradually  heated.  During  the  pro- 
cess a  considerable  quantity  of  nitrous  gas, 
and  of  carbonic  acid  gas,  is  evolved  ;  and 
part  of  the  camphor  is  volatilized,  while 
another  part  seizes  the  oxygen  of  the  ni- 
tric acid.  When  no  more  vapours  are  ex- 
tricated, the  vessels  are  to  be  separated, 
and  the  sublimed  camphor  added  to  the 
acid  that  remains  in  the  retort.  A  like 
quantity  of  nitric  acid  is  again  to  be 
poured" on  this,  and  the  distillation  repeat- 


ACI 


ACI 


ed.  This  operation  must  be  reiterated 
till  the  camphor  is  completely  acidified. 
Twenty  parts  of  nitric  acid  at  36  are  suf- 
ficient to  acidify  one  of  camphor. 

When  the  whole  of  the  camphor  is 
acidified,  it  crystallizes  in  the  remaining 
liquor.  The  whole  is  then  to  be  poured 
out  upon  a  filter,  and  washed  with  dis- 
tilled water,  to  cany  off  the  nitric  acid  it 
may  have  retained.  The  most  certain  in- 
dication of  the  acidification  of  the  cam- 
phor is  its  crystallizing1  on  the  cooling-  of 
die  liquor  remaining  in  the  retort. 

To  purify  this  acid  it  must  be  dissolved 
in  hot  distilled  water,  and  the  solution,  af- 
ter being  filtered,  evaporated  nearly  to 
Jialf,  or  till  a  slight  pellicle  forms  ;  when 
the  camphoric  acid  will  be  obtained  in 
-crystals  on  cooling. 

This  experiment  being  too  long  to  be 
exhibited  by  the  chemical  lecturer,  its 
place  may  be  supplied  by  the  following. 

A  jar  is  to  be  filled  over  mercury  with 
oxygen  gas  from  the  chlorate  of  potash, 
and  a  little  water  passed  into  it.  On  the 
other  hand,  a  bit  of  camphor  and  an  atom 
of  phosphorus  are  to  be  placed  in  a  little 
cupel;  and  then  one  end  of  a  curved  tube 
is  to  be  conveyed  under  the  jar,  and  the 
other  end  under  a  jar  filled  with  water  in 
the  pneumato-chemical  apparatus.  The 
•apparatus  being  thus  arranged,  the  phos- 
phorus is  to  be  kindled  by  means  of  a  red 
hot  iron.  The  phosphorus  inflames,  and 
afterwards  the  camphor.  The  flame  pro- 
duced by  the  camphor  is  very  vivid ;  much 
heat  is  given  out ;  and  the  jar  is  lined  with 
a  black  substance,  which  gradually  falls 
down,  and  covers  the  water  standing  on 
the  quicksilver  in  the  jar.  This  is  oxide 
of  carbon.  At  the  same  time  a  gas  is  col- 
lected, that  has  all  the  characters  of  car- 
bonic acid.  The  water  contained  in  the 
jar  is  very  fragrant,  and  contains  camphor- 
ic acid  in  solution. 

The  camphoric  acid  has  a  slightly  acid, 
Tsitter  taste,  and  reddens  infusion  of  litmus. 

It  crystallizes  ;  and  the  crystals  upon 
the  whole  resemble  those  of  muriate  of 
ammonia.  (Kosegarten  says  they  are  par- 
allelopipeds  of  a  snowy  whiteness.)  It 
effloresces  on  exposure  to  the  atmosphere; 
is  not  very  soluble  in  cold  water ;  when 
placed  on  burning  coals,  gives  out  a  thick 
aromatic  smoke,  and  is  entirely  dissipated  ; 
and  with  a  gentle  heat  melts,  and  is  sub- 
limed. The  mineral  acids  dissolve  it  en- 
tirely. It  decomposes  the  sulphate  and 
muriate  of  iron.  The  fixed  and  volatile  oils 
dissolve  it.  It  is  likewise  soluble  in  alcohol, 
and  is  not  precipitated  from  it  by  water ; 
a  property  that  distinguishes  it  from  the 
benzoic  acid.  It  unites  easily  with  the 
earths  and  alkalis. 

To  prepare  the  camphorates  of  lime, 
magnesia  and  alumina,  these  earths  must  be 


diffused  in  water,  and  crystallized  campho^ 
ric  acid  added.  The  mixture  must  then  be 
boiled,  filtered  while  hot,  and  the  solution 
•concentrated  by  evaporation. 

The  camphorate  of  barytes  is  prepared 
by  dissolving  the  pure  earth  in  water,  and 
then  adding  crystallized  camphoric  acid. 

Those  of  potash,  soda,  and  ammonia, 
should  be  prepared  with  their  carbonates 
dissolved  in  water:  these  solutions  are  to 
be  saturated  with  crystallized  camphoric 
acid,  heated,  filtered,  evaporated,  and  cool- 
ed, by  which  means  the  camphorates  will 
be  obtained. 

If  the  camphoric  acid  be  very  pure,  they 
have  no  smell ;  if  it  be  not,  they  have  al- 
ways a  slight  smell  of  camphor. 

The  camphorates  of  alumina  and  barytes 
leave  a  little  acidity  on  the  tongue ;  the; 
rest  have  a  slightly  bitterish  taste. 

They  are  all  decomposed  by  heat ;  the 
acid  being  separated  and  sublimed,  and  the 
base  remaining  pure ;  that  of  ammonia  ex- 
cepted,  which  is  entirely  volatilized. 

If  they  be  exposed  to  the  blow-pipe, 
the  acid  burns  with  a  blue  flame  :  that  of 
ammonia  gives  first  a  blue  flame ;  but  to- 
ward the  end  it  becomes  red. 

The  camphorates  of  lime  and  magnesia 
are  little  soluble,  the  others  dissolve  more 
easily. 

The  mineral  acids  decompose  them  all. 
The  alkalis  and  earths  act  in  the  order  of 
their  affinity  for  the  camphoric  acid ;  which 
is,  lime,  potash,  soda,  barytes,  ammonia, 
alumina,  magnesia. 

Several  metallic  solutions,  and  several 
neutral  salts,  decompose  the  camphorates ; 
such  as  the  nitrate  of  barytes,  most  of  the 
calcareous  salts,  &c. 

The  camphorates  of  lime,  magnesia, 
and  barytes,  part  with  their  acid  to  alco- 
hol.— Lagrange's  Manuel  d'un  Cours  de 
Chimie. 

ACID  (CARBONFC).  This  acid,  being  a 
compound  of  carbon  and  oxygen,  may  be 
formed  by  burning  charcoal ;  but  as  it  ex- 
ists in  great  abundance  ready  formed,  it  is 
not  necessary  to  have  recourse  to  this  ex- 
pedient. All  that  is  necessary  is  to  pour 
sulphuric  acid,  diluted  with  five  or  six 
times  its  weight  of  water,  on  common 
chalk,  which  is  a  compound  of  carbonic 
acid  and  lime.  An  effervescence  ensues  j 
carbonic  acid  is  evolved  in  the  state  of  gas, 
and  may  be  received  in  the  usual  manner. 

As  the  rapid  progress  of  chemistry  du- 
ring the  latter  part  of  the  18th  century, 
was  in  a  great  measure  owing  to  the  dis- 
covery of  this  acid,  it  may  be  worth  while 
to  trace  the  history  of  it  somewhat  par- 
ticularly. 

Paracelsus  and  Van  Helmont  were  ac- 
quainted with  the  fact,  that  air  is  extri- 
cated from  solid  bodies  during  certain  pro- 
cesses; and  the  latter  gave  to  air  thus 


ACI 


ACI 


produced  the  name  of  gas.  Boyle  called 
these  kinds  of  air  artificial  airs,  and  sus- 
pected that  they  might  be  different  from 
the  air  of  the  atmosphere.  Hales  ascer- 
tained the  quantity  of  air  that  could  be  ex- 
tricated from  a  great  variety  of  bodies,  and 
showed  that  it  formed  an  essential  part  of 
their  composition.  Dr.  Black  proved, 
that  the  substances  then  called  lime,  mag- 
nesia, and  alkalis,  were  compounds,  con- 
sisting of  a  peculiar  species  of  air,  and 
pure  lime,  magnesia,  and  alkali.  To  this 
species  of  air  he  gave  the  name  of  fixed 
air,  because  it  existed  in  these  bodies  in 
a  fixed  state.  This  air  or  gas  was  after- 
wards investigated,  and  a  great  number  of 
its  properties  ascertained,  by  Dr.  Priest- 
ley. From  these  properties  Mr.  Keir  first 
concluded  that  it  was  an  acid ;  and  this 
opinion  was  soon  confirmed  by  the  expe- 
riments of  Bergmann,  Fontana,  and  others. 
Dr.  Priestley  at  first  suspected  that  this 
acid  entered  as  an  element  into  the  com- 
position of  atmospherical  air ;  and  Berg- 
mann, adopting  the  same  opinion,  gave  it 
the  name  of  aerial  acid.  Mr.  Bewley 
called  it  mephitic  acid,  because  it  could 
not  be  respired  without  occasioning  death; 
and  this  name  was  also  adopted  by  Mor- 
veau.  Mr.  Keir  called  it  calcareous  acid; 
and  at  last  M.  Lavoisier,  after  discovering 
its  composition,  gave  it  the  name  of  car- 
bonic acid  gas. 

The  opinions  of  chemists  concerning  the 
composition  of  carbonic  acid  have  under- 
gone as  many  revolutions  as  its  name.  Dr. 
Priestley  and  Bergmann  seem  at  first  to 
have  considered  it  as  an  element;  and  seve- 
ral celebrated  chemists  maintained  that  it 
was  the  acidifying  principle.  Afterwards 
it  was  discovered  to  be  a  compound,  and 
that  oxygen  gas  was  one  of  its  component 
parts.  Upon  this  discovery  the  prevalent 
ppinion  of  chemists  was,  that  it  consisted 
of  oxygen  and  phlogiston  ;  and  when  hy- 
drogen and  phlogiston  came,  according  to 
Mr.  Kirwan's  theory,  to  signify  the  same 
thing,  it  was  of  course  maintained  that 
carbonic  acid  was  composed  of  oxygen 
and  hydrogen :  and  though  M.  Lavoisier 
demonstrated  that  it  was  formed  by  the 
combination  of  carbon  and  oxygen,  this 
did  not  prevent  the  old  theory  from  being 
maintained  ;  because  carbon  was  itself 
considered  as  a  compound,  into  which  a 
very  great  quantity  of  hydrogen  entered. 
But  after  M.  Lavoisier  had  demonstrated, 
that  the  weight  of  the  carbonic  acid  pro- 
duced was  precisely  equal  to  the  charcoal 
and  oxygen  employed ;  after  Mr.  Caven- 
dish had  discovered,  that  oxygen  and  hy- 
drogen when  combined  did  not  form  car- 
bonic acid,  but  water,  it  was  no  longer 
possible  to  doubt  that  this  acid  was  com- 

Eosed  of  carbon  and  oxygen.  According- 
/,  all  farther  dispute  about  it  is  at  an  end. 


If  any  thing  were  still  wanting,  to  put 
this  conclusion  beyond  the  reach  of  doubt, 
it  was  to  decompose  carbonic  acid,  and 
thus  to  exhibit  its  component  parts  by 
analysis  as  well  as  synthesis.  This  has 
been  actually  done  by  Mr.  Tennant.  Into 
a  tube  of  glass  he  introduced  a  bit  of 
phosphorus  and  some  carbonate  of  lime. 
He  then  sealed  the  tube  hermetically,  and 
applied  heat.  Phosphate  of  lime  was 
formed,  and  a  quantity  of  charcoal  depo- 
sited. Now  phosphate  of  lime  is  composed 
of  phosphoric  acid  and  lime,  and  phos- 
phoric acid  is  composed  of  phosphorus 
and  oxygen.  The  substances  introduced 
into  the  tube  were  phosphorus,  lime,  and 
carbonic  acid,  and  the  substances  found  in 
it  were  phosphorus,  lime,  oxygen,  and 
charcoal.  The  carbonic  acid,  therefore, 
must  have  been  decomposed,  and  it  must 
have  consisted  of  oxygen  and  charcoal. — 
This  experiment  was  repeated  by  Doctor 
Pearson,  who  ascertained  that  the  weight 
of  the  oxygen  and  charcoal  together  was 
equal  to  that  of  the  carbonic  acid  which 
had  been  introduced ;  and  in  order  to  show 
that  it  was  the  carbonic  acid  which  had 
been  decomposed,  he  introduced  pure 
lime  and  phosphorus ;  and,  instead  of 
phosphate  of  lime  and  ca-bon,  he  got  no- 
thing but  phosphuret  of  lime.  These  ex- 
periments were  also  confirmed  by  Four- 
croy,Vauquelin,Sylvestre,  and  Brongniart. 
Count  Mussin-Puschkin  too  boiled  a  solu- 
tion of  carbonate  of  potash  on  purified 
phosphorus,  and  obtained  charcoal.  This 
he  considered  as  an  instance  of  the  decom- 
position of  carbonic  acid,  and  as  a  confir- 
mation of  the  experiments  above  related. 

Carbonic  acid  abounds  in  great  quan- 
tities in  nature,  and  appears  to  be  produ- 
ced in  a  variety  of  circumstances.  It  com- 
poses -j^\y  of  the  weight  of  limestone, 
marble,  calcareous  spar,  and  other  natural 
specimens  of  calcareous  earth,  from  which 
it  may  be  extricated  either  by  the  simple 
application  of  heat,  or  by  the  superior  af- 
finity of  some  other  acid  ;  most  acids  hav- 
ing a  stronger  action  on  bodies  than  this. 
This  last  process  does  not  require  heat, 
because  fixed  air  is  strongly  disposed  to 
assume  the  elastic  state.  Water,  under 
the  common  pressure  of  the  atmosphere, 
and  at  a  low  temperature,  absorbs  some- 
what more  than  its  bulk  of  fixed  air,  and 
then  constitutes  a  weak  acid.  If  the  pres- 
sure be  greater,  the  absorption  is  aug- 
mented. It  is  to  be  observed,  likewise, 
that  more  gas  than  water  will  absorb, 
should  be  present.  Heated  water  absorbs 
less  ;  and  if  water,  impregnated  with  this 
acid,  be  exposed  on  a  brisk  fire,  the  rapid 
escape  of  the  aerial  bubbles  affords  an  ap- 
pearance as  if  the  water  were  at  the  point 
of  boiling,  when  the  heat  is  not  greater 
than  the  hand  can  bear.  Congelation  sev 


ACI 


ACI 


parates  it  readily  and  completely  from 
water;  but  no  degree  of  cold  or  pressure 
has  yet  exhibited  this  acid  in  a  dense  or 
concentrated  state  of  fluidity. 

Carbonic  acid  gas  is  much  denser  than 
common  air,  and  for  this  reason  occupies 
the  lower  parts  of  such  mines  or  caverns 
as  contain  materials  which  afford  it  by  de- 
composition. The  miners  call  it  choke- 
damp.  The  Grotto  del  Cano,  in  the  king- 
dom of  Naples,  has  been  famous  for  ages, 
on  account  of  the  effects  of  a  stratum  of 
fixed  air  which  covers  its  bottom.  It  is  a 
oave  or  hole  in  the  side  of  a  mountain, 
near  the  lake  Agnano,  measuring  not  more 
than  eighteen  feet  from  its  entrance  to  the 
inner  extremity ;  where  if  a  dog  or  other 
animal  that  holds  down  its  head  be  thrust, 
it  is  immediately  killed  by  inhaling  this 
noxious  fluid. 

Carbonic  acid  gas  is  emitted  in  large 
quantities  by  bodies  in  the  state  of  the 
vinous  fermentation,  (see  FOMENTATION), 
and  on  account  of  its  great  weight,  it  oc- 
cupies the  apparently  empty  space  or  up- 
per part  of  the  vessels  in  which  the  fer- 
menting process  is  going  on.  A  variety 
of  striking  experiments  may  be  made  in 
this  stratum  of  elastic  fluid.  Lighted  pa- 
per, or  a  candle  dippe^  into  it,  is  immedi- 
ately extinguished;  and  the  smoke  re- 
maining in  the  carbonic  acid  gas  renders 
its  surface  visible,  which  may  be  thrown 
into  waves  by  agitation  like  water.  If  a 
dish  of  water  be  immersed  in  this  gas,  and 
briskly  agitated,  it  soon  becomes  impreg- 
nated, and  obtains  the  pungent  taste  of 
Pyrmont  water.  In  consequence  of  the 
weight  of  the  carbonic  acid  gas,  it  may  be 
lifted  out  in  a  pitcher,  or  bottle,  which,  if 
well  corked,  may  be  used  to  convey  it  to 
great  distances,  or  it  may  be  drawn  out  of 
a  vessel  by  a  cock  like  a  liquid.  The  ef- 
fects produced  by  pouring  this  invisible 
fluid  from  one  vessel  to  another,  have  a 
very  singular  appearance  ;  if  a  candle  or 
small  animal  be  placed  in  a  deep  vessel,  the 
former  becomes  extinct,  and  the  latter  ex- 
pires in  a  few  seconds,  after  the  carbonic 
acid  gas  is  poured  upon  them,  though 
the  eye  is  incapable  of  distinguishing  any 
thing  that  is  poured.  If,  however  it  be 
poured  into  a  vessel  full  of  air,  in  the  sun- 
shine, its  density  being  so  much  greater 
than  that  of  the  air,  renders  it  slightly  visi- 
ble by  the  undulations  and  streaks  it  forms 
in  this  fluid,  as  it  descends  through  it. 
Carbonic  acid  reddens  infusion  of  lit- 
mus ;  but  the  redness  vanishes  by  expo- 
sure to  the  air,  us  the  acid  flies  off.  It  has 
a  peculiar  sharp  taste,  which  may  be  per- 
'Ceived  over  vats  in  which  wine  or  beer  is 
fermenting,  as  also  in  sparkling  Cham- 
paign, and  the  brisker  kinds  of  cider.  Light 
passing  through  it  is  refracted  by  it,  but 
do«s  not  effect  any  sensible  alteration  in  it, 


though  it  appears,  from  experiment,  that 
it  favours  the  separation  of  its  principles 
by  other  substances.  It  will  not  unite  with 
an  overdose  of  oxygen,  of  which  it  contains 
72  parts  in  100,  the  other  28  being  pure 
carbon.  It  not  only  destroys  life,  but  the 
heart  and  muscle  of  animals  killed  by  it 
lose  all  their  irritability,  so  as  to  be  insensi- 
ble to  the  stimulus  of  galvanism. 

Carbonic  acid  is  dilated  by  heat,  but  not 
otherwise  altered  by  it.  It  is  not  acted  up- 
on by  oxygen,  or  any  of  the  simple  com- 
bustibles. Charcoal  absorbs  it,  but  gives 
it  out  again  unchanged,  at  ordinary  tem- 
peratures ;  but  when  this  gaseous  acid  is 
made  to  traverse  charcoal  ignited  in  a 
tube,  it  is  converted  into  carbonic  oxide. 
Phosphorus  is  insoluble  in  carbonic  acid 
gas  ;  but,  as  already  observed,  is  capable 
of  decomposing  it  by  compound  affinity, 
when  assisted  by  sufficient  heat;  and 
Priestley  and  Cruickshank  have  shown 
that  iron,  zinc,  and  several  other  metals, 
are  capable  of  producing  the  same  effect. 
If  carbonic  acid  be  mixed  with  sulphur- 
etted, phosphuretted,  or  carburetted  gas, 
it  renders  them  less  combustible,  or  des- 
troys their  combustibility  entirely,  but 
produces  no  other  sensible  change.  Such 
mixtures  occur  in  various  analyses,  and 
particularly  in  the  products  of  the  decom- 
position of  vegetable  and  animal  substan- 
ces. The  inflammable  air  of  marshes  is 
frequently  carburetted  hydrogen  intimate- 
ly mixed  with  carbonic  acid  gas,  and  the; 
sulphuretted  hydrogen  gas  obtained  from 
mineral  waters  is  very  often  mixed  with 
it. 

Carbonic  acid  appears  from  various  ex- 
periments of  Ingenhousz  to  be  of  consider- 
able utility  in  promoting  vegetation.  It  is 
probably  decomposed  by  the  organs  of 
plants,  its  base  furnishing  part  at  least  of 
the  carbon  that  is  so  abundant  in  the 
vegetable  kingdom,  and  its  oxygen  con- 
tributing to  replenish  the  atmosphere 
with  that  necessary  support  of  life,  which 
is  continually  diminished  by  the  respiration 
of  animals  and  other  causes. 

*  The  most  exact  experiments  on  the 
neutral  carbonates  concur  to  prove,  that 
the  prime  equivalent  of  carbonic  acid  is 
2.  75;  and  that  it  consists  of  one  prime  of 
carbon  =  0.  75  -f-  2.0  oxygen.  This  pro- 
portion is  most  exactly  deduced  from  a 
comparison  of  the  specific  gravities  of 
carbonic  acid  gas  and  oxygen  ;  for  it  is 
well  ascertained  that  the  latter,  by  its 
combination  with  charcoal,  and  conversion 
into  the  former,  does  not  change  its  vol- 
ume. Now,  100  cubic  inches  of  oxygen 
weigh  33.8  gr.  and  100  cubic  inches  of 
carbonic  acid  46.5,  showing  the  weight  of 
combined  charcoal  in  that  quantity  to  be 
12.7.  But  the  oxide  of  carbon  contains 
only  half  the  quantity  qf  oxygen  which 


ACI 


AC1 


Carbonic  acid  does ;  and  we  hence  infer, 
that  the  oxide  of  carbon  consists  of  one 
prime  of  oxygen  united  to  one  of  carbon. 
This  a  priori  judgment  is  confirmed  by 
the  weight  2.75  deduced  from  the  carbon- 
ates, as  the  prime  equivalent  of  carbonic 
acid.  Therefore  we  have  this  propor- 
tion : 

If  33.8  represent  two  primes  of  oxygen, 
or  2 ;  12.7  will  represent  one  of  carbon. 
33.8  :  2.  :  :  12.7  :  0.751,  being,  as  above, 
the  prime  equivalent  or  first  combining- 
proportion  of  carbon.  If  the  specific 
gravity  of  atmospheric  air  be  called  1.0000, 
that  of  carbonic  acid  will  be  1,5236. 

We  have  seen  that  water  absorbs  about 
its  volume  of  this  acid  gas,  and  thereby 
acquires  a  specific  gravity  of  1.0015.  On 
freezing  it,  the  gas  is  as  completely  ex- 
pelled as  by  boiling.  By  artificial  pressure 
with  forcing  pumps,  water  may  be  made 
to  aborb  two  or  three  times  its  bulk  of 
carbonic  acid.  When  there  is  also  added 
a  little  potash  or  soda,  it  becomes  the 
aerated  or  carbonated  alkaline  waters,  a 
pleasant  beverage,  and  not  inactive  reme- 
dy in  several  complaints,  particularly 
dyspepsia,  hiccup,  and  disorders  of  the 
kidneys.  Alcohol  condenses  twice  its  vo- 
lume of  carbonic  acid.  The  most  beauti- 
ful analytical  experiment  with  carbonic 
acid,  is  the  combustion  of  potassium  in  it, 
the  formation  of  potash,  and  the  depos- 
ition of  charcoal.  Nothing  shows  the  pow- 
er of  chemical  research  in  a  more  favour- 
able light,  than  the  extraction  of  an  invisi- 
ble gas  from  Parian  marble  or  crystallized 
spar,  and  its  resolution  by  such  an  experi- 
ment into  oxygen  and  carbon ;  in  the  pro- 
portions above  stated,  5  gr.  of  potassium 
should  be  used  for  3  cubic  inches  of  gas. 
If  less  be  employed,  the  gas  will  not  all  be 
decomposed,  but  a  part  will  be  absorbed 
by  the  potash.  From  the  above  quanti- 
ties, 3-8ths  of  a  grain  of  charcoal  will  be 
obtained.  If  a  porcelain  tube,  containing 
a  coil  of  fine  iron  wire,  be  ignited  in  a  fur- 
nace, and  if  carbonic  acid  be  passed  back- 
wards and  forwards  by  means  of  a  full 
and  empty  bladder,  attached  to  the  ends  of 
the  tube,  the  gas  will  be  converted  into 
carbonic  oxide,  and  the  iron  will  be  oxi- 
dized.* 

In  point  of  affinity  for  the  earths  and 
alkalis,  carbonic  acid  stands  apparently 
low  in  the  scale.  Before  its  true  nature 
was  known,  its  compounds  with  them  were 
not  considered  as  salts,  but  as  the  earths 
and  alkalis  themselves,  only  distinguished 
by  the  names  of  mild,  or  effervescent,  from 
their  qualities  of  effervescing  with  acids, 
and  wanting  causticity. 

The  carbonates  are  characterized  by 
clTervescing  with  almost  all  the  acids,  even 
the  acetic,  when  they  evolve  their  gas- 
eous  acid,  which  passed  into  lime  water  by 


a  tube,  deprives  it  of  its  taste,  and  converts 
it  into  chalk  and  pure  water. 

The  carbonate  of  barytes  was  formed  arti- 
ficially by  Bergman  and  Scheele  in  1776; 
but  Dr.  Withering  first  found  it  native  at 
Alston  Moor  in  Cumberland  in  1783.  From 
this  circumstance  it  has  been  termed 
Witherite  by  Werner.  It  has  been  like- 
wise called  aerated  heavy  spar,  aerated 
baroselenite,  aerated  heavy  earth  or  barytes, 
barolite,  &c.  Its  crystals  have  been  ob- 
served to  assume  four  different  forms, 
double  six-sided,  and  double  four-sided 
pyramids;  six-sided  columns  terminated 
by  a  pyramid  with  the  same  number  of 
faces,  and  small  radiated  crystals,  half  an 
inch  in  length,  and  very  thin,  appearing 
to  be  hexagonal  prisms,  rounded  toward 
the  point.  The  hexaiidral  prism  is  pre- 
sumed to  be  its  primitive  form.  Its  spe- 
cific gravity,  when  native,  is  4.331,  when, 
prepared  artificially  it  scarcely  exceeds 
3,763. 

Itmay  be  prepared  by  exposing  a  solu- 
tion of  pure  barytes  to  the  atmosphere, 
when  it  will  be  covered  with  a  pellicle  of 
this  salt  by  absorbing  carbonic  acid ;  or 
carbonic  acid  may  be  received  into  this 
solution,  in  which  it  will  immediately  form 
a  copious  precipitate ;  or  a  solution  of 
nitrate  or  muriate  of  barytes  may  be  pre- 
cipitated by  a  solution  of  the  carbonate 
of  potash,  soda,  or  ammonia.  The  precipi- 
tate, in  either  of  these  cases,  being  well 
washed,  will  be  found  to  be  very  pure 
carbonate  of  barytes.  Itmay  likewise  be 
procured  by  decomposing  the  native  sul- 
phate of  barytes  by  the  carbonate  of  pot- 
ash, or  of  soda,  in  the  dry  way,  with  the 
assistance  of  fire  ;  but  in  this  way  the  sul- 
phate of  barytes  is  never  completely  de- 
composed, ,and  some  of  it  remains  mixed 
with  the  carbonate. 

The  carbonate  of  barytes  is  soluble  only 
in  4304  times  its  weight  of  cold  water,  and 
2304  of  boiling  water,  and  this  requires  a 
long  time ;  but  water  saturated  with  car- 
bonic acid  dissolves  1 -830th.  It  is  not  al- 
tered by  exposure  to  the  air,  but  is  decom- 
posed by  the  application  of  a  very  violent 
heat,  either  in  a  black  lead  crucible,  or 
when  formed  into  a  paste  with  charcoal 
powder.  Sulphuric  acid,  in  a  concentra- 
ted state,  or  diluted  with  three  or  four 
parts  of  water,  does  not  separate  the  car- 
bonic acid  with  effervescence,  unless  assis- 
ted by  heat.  Muriatic  acid  does  not  act 
upon  it  likewise,  unless  diluted  with  water, 
or  assisted  by  heat.  And  nitric  acid  does 
not  act  upon  it  at  all,  unless  diluted.  It 
has  no  sensible  taste,  yet  it  is  extremely 
poisonous. 

As  this  salt  has  lately  been  found,  in 
large  quantities,  near  Murton  in  Cumber- 
land, and  some  other  places  in  the  vicinity, 
it  might  probably  be  introduced  intt 


ACT 


ACI 


manufactures  with  advantage,  as  for  ex- 
tracting" the  bases  of  several  salts. 

It  is  composed  of  2.75  parts  of  acid,  and 
9.75  of  barytes.  Its  prime  equivalent  is 
therefore  the  sum  of  these  numbers  =  12.5. 

Carbonate  of  strontian  was  first  pointed 
out  as  distinct  from  the  preceding  species 
by  Dr.  Crawford  in  1790,  but  Dr.  Hope 
gave  the  first  accurate  account  of  it  in  the 
Edinburgh  Transactions.  It  has  been  found 
native  in  Scotland,  at  Strontian  in  Argyll- 
shire, and  at  Leadhills.  It  is  usually  in  fine 
striated  needless  or  prisms,  that  appear  to 
be  hexacdral,  semitransparent,  and  of  a 
white  colour  slightly  tinged  with  green. 
It  is  insipid  ;  requires  1536  parts  of  boiling 
water  to  dissolve  it ;  is  not  altered  by  ex- 

Sosure  to  the  air ;  but  when  strongly 
eated  iti  a  crucible  loses  part  of  its  acid ; 
and  this  decomposition  is  facilitated  by 
making  it  into  a  paste  with  charcoal  pow- 
der. When  the  fire  is  strongly  urged,  it 
attacks  the  crucible, and  melts  into  a  glass, 
resembling  the  colour  of  chrysolite,  or  py- 
ramidal phosphate  of  lime.  If  thrown  in 
powder  on  well  kindled  coals,  or  the  flame 
of  a  candle,  it  exhibits  red  sparks.  The 
same  phenomenon  occurs,  if  it  be  treated 
with  the  blow-pipe,  which  fuses  it  into  an 
opaque  vitreous  globule,  that  falls  to  pow- 
der in  the  open  air.  Its  specific  gravity  is 
only  3.66,  in  which  it  differs  strikingly 
from  the  carbonate  of  barytes  ;  as  it  does, 
in  not  being  poisonous,  according  to  the 
experiments  made  by  Pelletier  on  various 
animals. 

It  consists  of  6.5  strontian  -f-  2.75  car- 
bonic acid  =  9.25. 

Carbonate  of  lime  exists  in  great  abun- 
dance in  nature,  variously  mixed  with 
other  bodies,  under  the  names  of  marble, 
fhalk,  limestone,  stalactites,  &c.  in  which  it 
is  of  more  important  and  extensive  use 
than  any  other  of  the  salts,  except  per- 
haps the  muriate  of  soda.  It  is  often  found 
crystallized,  and  perfectly  transparent. 
The  primitive  form  of  its  crystals  is  the 
rhomboidal  prism,  with  angles  of  101^  and 
78£.  Its  integrant  particles  have  the  same 
form.  Beside  this,  however,  many  varieties 
of  its  crystals  have  been  discovered  and 
described  by  mineralogists.  The  specific 
gravity  of  the  marbles  is  from  2.65  to  2.85; 
of  the  crystallized  carbonates,  about  2.7  ; 
of  the  stalactites,  from  2.32  to  2.4-7  :  of  the 
limestones,  from  1.39  to  2.72. 

It  has  scarcely  any  taste ;  is  insoluble  in 
pifre  water,  but  water  saturated  with  car- 
bonic acid  takes  up  l-1500th,  though  as 
the  acid  flies  oft' this  is  precipitated.  It 
suffers  little  or  no  alteration  on  exposure 
to  the  air.  When  heated  it  decrepitates, 
its  water  flies  off',  and  lastly  its  acid  ;  but 
this  requires  a  pretty  strong  heat.  By 
this  process  it  is  burned  into  lime. 

It  te  composed  of  3.56  lime  -j-  2.75  cttr- 


bonie  acid  =  6.31  j  or  in  100  parts  of  56.4 
lime  and  43.6  acid. 

The  carbonate  or  rather  subcarbonate  of 
potash  was  long  known  by  the  name  of 
•vegetable  alkali.  It  was  also  called  fixed 
nitre,  salt  of  tartar,  salt  of  wormwood,  &c. 
according  to  the  different  modes  in  which 
it  was  procured ;  and  was  supposed  to 
retain  something  of  the  virtues  of  the  sub- 
stance from  which  it  was  extracted.  This 
error,  has  been  some  time  exploded,  but 
the  knowledge  of  its  true  nature  is  of  more 
recent  date. 

As  water  at  the  usual  temperature 
of  the  air  dissolves  rather  more  than  its 
weight  of  this  salt,  we  have  thus  a  ready 
mode  of  detecting  its  adulterations  in  gen- 
eral ;  and  as  it  is  often  of  consequence  in 
manufactures,  to  know  how  much  alkali  a 
particular  specimen  contains,  this  may  be 
ascertained  by  the  quantity  of  sulphuric 
acid  it  will  saturate. 

This  salt  is  deliquescent. 

It  consists  of  5.94  potash  -|-  2.75  car- 
bonic acid  =  8.69. 

The  bi-carbonate  of  potash  crystallizes, 
according  to  Fourcroy,  in  square  prisms, 
the  apices  of  which  are  quadrangular  py- 
ramids. According  to  Pelletier  they  are 
tetraedral  rhomboidal  prisms,  withdiedral 
summits.  The  complete  crystal  has  eight 
faces,  two  hexagons,  two  rectangles,  and 
four  rhombs.  It  has  a  urinous  but  not 
caustic  taste  ;  changes  the  sirup  of  violets 
green ;  boiling  water  dissolves  five-sixths 
of  its  weight,  and  cold  water  one-fourth ; 
alcohol,  even  when  hot,  will  not  dissolve 
more  than  l-1200th.  Its  specific  gravity 
is  2.012. 

When  it  is  very  pure  and  well  crystal- 
lized it  effloresces  on  exposure  to  a  dry 
atmosphere,  though  it  was  formerly  con- 
sidered as  deliquescent.  The  fact  is,  that 
the  common  salt  of  tartar  of  the  shops  is 
a  compound  of  this  carbonate  and  pure 
potash ;  the  latter  of  which,  being  very 
deliquescent,  attracts  the  moisture  of  the 
air  till  the  whole  is  dissolved.  From  its 
smooth  feel,  and  the  manner  in  which  it 
was  prepared,  the  old  chemists  called  this 
solution  oil  of  tartar  per  deliquium. 

The  bi-carbonate  of  potash  melts  with  a 
gentle  heat,  loses  its  water  of  crystalliza- 
tion, amounting  to  TWO'  and  gives  out  a 
portion  of  its  carbonic  acid ;  though  no- 
degree  of  heat  will  expel  the  whole  of  the 
acid.  Thus,  as  the  carbonate  of  potash  is 
always  prepared  by  incineration  of  veget- 
able substances,  and  lixiviation,  it  must  be 
in  the  intermediate  state ;  or  that  of  a  car- 
bonate with  excess  of  alkali :  and  to  obtain 
the  true  carbonate  we  must  saturate  thift 
salt  with  carbonic  acid,  which  is  best  done 
by  passing  the  acid  in  the  state  of  gas 
through  a  solution  of  the  salt  in  twice  its 
weight  of  water ;  or,  if  we  want  the  potasH 


ACI 


ACI 


'pure,  we  must  have  recourse  to  lime,  to 
separate  that  portion  of  acid  which  fire  will 
not  expel. 

Another  mode,  recommended  by  Ber- 
thollet,  and  which  may  be  of  use  on  some 
occasions,  is  to  add  solid  carbonate  of  am- 
monia to  a  solution  of  potash  not  saturated, 
and  distil  the  mixture  :  when  the  ammonia 
aiiay  be  obtained  in  the  form  of  gas,  or 
caustic  liquor,  while  the  carbonate  crystal- 
lizes in  the  retort. 

The  bi-carbonate  usually  called  super- 
carbonate  by  the  apothecaries,  consists  of 
2  primes  of  carbonic  acid  =5.500, 1  of  pot- 
nsh=  5.940,  and  1  of  water  =  1.125,  in  all 
12.565  . 

The  carbonate  of  soda  has  likewise  been 
long1  known,  and  distinguished  from  the 
preceding  by  the  name  of  mineral  alkali.  In 
commerce  it  is  usually  called  barilla  or 
soda ;  in  which  state,  however,  it  always 
contains  of  a  mixture  of  earthy  bodies  and 
usually  common  salt.  It  may  be  purified, 
by  dissolving  it  in  a  small  portion  of  water, 
filtering  the  solution,  evaporating  at  a  low 
heat,  and  skimming  off' the  crystals  of  mu- 
jiate  of  soda  as  they  form  on  its  surface. 
"When  these  cease  to  form,  the  solution 
may  be  suffered  to  cool,  and  the  carbonate 
ef  soda  will  crystallize.  To  obtain  this 
salt  perfectly  pure  Klaproth  dissolves  com- 
mon carbonate  of  soda  in  water,  and  satu- 
rates this  solution  with  nitric  acid,  taking 
care  that  the  acid  is  a  little  in  excess.  He 
then  separates  the  sulphuric  acid  by  ni- 
trate of  barytes,  and  the  muriatic  acid  by 
nitrate  of  silver.  The  fluid  thus  purified 
he  evaporates  to  dryness,  fuses  the  nitrate 
of  soda  obtained,  and  decomposes  it  by 
detonation  with  charcoal.  He  then  lix- 
iviates the  residue,  and  crystallizes  the 
carbonate  of  soda.  If  it  be  adulterated 
with  potash,  tartaric  acid  will  form  a  pre- 
cipitate in  a  pretty  strong  solution  of  it. 

It  is  found  abundantly  in  nature.  In 
Egypt,  where  it  is  collected  from  the  sur- 
face of  the  earth,  particularly  after  the  de- 
siccation of  temporary  lakes,  it  has  been 
known  from  time  immemorial  by  the  name 
of  nitrum,  natron,  or  natriim.  This  it  has 
been  proposed  to  retain  ;  and  accordingly 
the  London  college  has  adopted  the  term 
natron.  Dr.  Bostock  of  Liverpool  lately 
found,  that  the  efflorescence,  which  co- 
piously covered  the  decaying  parts  of  the 
plaster  of  the  salt  water  baths  in  that  town, 
consisted  of  carbonate  of  soda.  A  carbo- 
nate of  soda  exported  from  Tripoli,  which 
is  called  Tronn  from  the  name  of  the  place 
where  it  is  found,  and  analyzed  by  Klap- 
Toth,  contained  of  soda  37  parts,  carbon- 
ic acid  38,  water  of  crystallization  22.5, 
sulphate  of  soda  2.  This  does  not  efflor- 
esce. A  great  deal  is  prepared  in  Spain 
by  incinerating  the  maritime  plant  salsola; 
and  it  is  manufactured  in  this  country,  as 


well  as  in  France,  from  different  species 
of  sea- weeds.  It  is  likewise  found  in  min- 
eral waters  ;  and  also  in  some  animal  flu- 
ids. 

It  crystallizes  in  irregular  orrhomboidal 
decaedrons,  formed  by  two  quadrangular 
pyramids,  truncated  very  near  their  bases, 
frequently  it  exhibits  only  rhomboidal  la- 
minx.  Its  specific  gravity  is  1.3591.  Its 
taste  is  uriuous,  and  slightly  acrid,  without 
being  caustic.  It  changes  blue  vegetable 
colours  to  a  green.  It  is  soluble  in  less 
than  its  weight  of  boiling  water,  and  twice 
its  weight  of  cold.  It  is  one  of  the  most 
efflorescent  salts  known,  falling  complete- 
ly to  powder  in  no  long  time.  On  the  ap- 
plication of  heat  it  is  soon  rendered  fluid 
from  the  great  quantity  of  its  water  of  crys- 
tallization ;  but  is  dried  by  a  continuance 
of : he  heat,  and  then  melts.  It  is  some- 
what more  fusible  than  the  carbonate  of 
potash,  promotes  the  fusion  of  earths  in  a 
greater  degree,  and  forms  a  gl?ss  of  better 
quality.  Like  that,  it  is  very  tenacious  of 
a  certain  portion  of  its  carbonic  acid.  It 
consists  in  its  dry  state  of  3.94  soda,-f-  2.75 
acid,  =  6.69. 

*  But  the  crystals  contain  10  prime  pro- 
portions of  water.  They  are  composed  of 
22  soda,-}-  15.3  carbonic  acid,+  62.7  water 
in  100  parts,  or  of  1  prime  of  soda  =  3.94, 
1  of  carb.  acid  =  2.75,  and  10  of  water  «= 
11.25,  in  whole  17. 94. 

The  bi-carbonate  of  soda  mny  be  pre- 
pared by  saturating  the  solution  of  the 
preceding  salt  with  carbonic  acid  gas,  and 
then  evaporating  with  a  very  gentle  heat 
to  dryness,  when  a  white  irregular  saline 
mass  is  obtained.  The  salt  is  not  crystal- 
lizable.  Its  constituents  are  3.94  soda,  -f- 
5.50  carb.  acid,  +  1.125  water,  =  10.565  ; 
or  in  100  parts  37.4  soda,-f-  52  acid,-|-  10.6 
water.  The  intermediate  native  compound, 
the  African  trona,  consists,  according  to 
Mr.  It.  Phillips,  of  3  carbonic  acid,  -f-  2 
soda,  -f-  4  \\  ater  ;  or  in  100  parts  38  soda,, 
-f-  40  acid,  -f-  22  water.  *  See  the  article 
SODA. 

The  carbonate  of  magnesia,  in  a  state  of 
imperfect  saturation  with  the  acid,  has 
been  used  in  medicine  tor  some  time  un- 
der the  simple  name  of  magnesia.  It  is 
prepared  by  precipitation  from  the  sul- 
phate of  magnesia  by  means  of  carbonate 
of  potash.  Equal  parts  of  sulphate  of  mag- 
nesia and  carbonate  of  potash,  each  dis- 
solved in  its  own  weight  of  boiling  water, 
are  filtered  and  mixed  together  hot ;  the 
sulphate  of  potash  is  separated  by  copious 
washing  with  water  ;  and  the  carbonate  of 
magnesia  is  then  left  to  drain,  and  after- 
wards spread  thin  on  paper,  and  carried  to 
the  drying  stove.  When  once  dried  it  will 
be  in  friable  white  cakes,  or  a  fine  pow- 
der. 

Another  mode  of  preparing  it  in  the 


ACI 


ACI 


grate  will  be  found  under  the  article  An- 

i    MOXIA. 

To  obtain  carbonate  of  magnesia  satu- 
rated with  acid,  a  solution  of  sulphate  of 
i  magnesia  may  be  mixed  cold  with  a  solu- 
tion of  carbonate  of  potash ;  and  at  the  ex- 
piration of  a  few  hours,  as  the  superfluous 
carbonic  acid  that  held  it  in  solution  flies 
off,  the  carbonate  of  magnesia  will  crys- 
tallize in  very  regular  transparent  prisms 
of  six  equal  sides.  It  may  be  equally  ob- 
tained by  dissolving  magnesia  in  water  im- 
pregnated with  carbonic  acid,  and  expos- 
ing the  solution  to  the  open  air.  Dr. 
Thomson  says,  the  most  regular  crystals 
will  be  obtained  by  mixing  together  125 
parts  of  sulphate  of  magnesiaand  1  >6  parts 
of  carbonate  of  soda,  both  dissolved  in 
water,  filtering  the  solution,  and  then  set- 
ting it  aside  for  two  or  three  days. 

These  crystals  soon  lose  their  transparen- 
cy, and  become  covered  with  a  white  pow- 
der. Exposed  to  the  fire  in  a  crucible,  they 
decrepitate  slightly,  lose  their  water  and 
acid,  fall  to  powder,  and  are  reduced  to 
one-fourth  of  the  original  weight.  When 
the  common  carbonate  is  calcined  in  the 
great,  it  appears  as  if  boiling,  from  the  ex- 
trication of  carbonic  acid;  a  small  portion 
ascends  like  a  vapour,  and  is  deposited  in 
a  white  powder  on  the  cold  bodies  with 
which  it  comes  into  contact ;  and  in  a  dark 
place,  towards  the  end  of  the  operation,  it 
shines  with  a  bluish  phosphoric  light.  It 
thus  loses  half  its  weight,  and  the  magne- 
sia is  left  quite  pure. 

As  the  magnesia  of  the  shops  is  some- 
times adulterated  with  chalk,  this  may  be 
detected  by  the  addition  of  a  little  sulphu- 
ric acid  diluted  with  8  or  10  times  its 
weight  of  water,  as  this  will  form  with  the 
magnesia  a  very  soluble  salt,  while  the 
sulphate  of  lime  will  remain  undissolved. 
Calcined  magnesia  should  dissolve  in  this 
dilute  acid  without  any  effervescence. 

The  crystallized  carbonate  dissolves  in 
forty-eight  times  its  weight  of  cold  water; 
the  common  carbonate  requires  at  least 
ten  times  as  much,  and  first  forms  a  paste 
with  a  small  quantity  of  the  fluid. 

Guyton  Morveau  has  lately  found  the 
carbonate  of  magnesia  native,  near  Castel- 
la-Monte,  in  a  stone  considered  there  as  a 
clay  very  rich  in  alumina.  It  is  amorphous, 
as  white  as  ceruse,  and  as  compact  as  the 
hardest  chalk  ;  does  not  sensibly  adhere 
to  the  tongue  ;  and  has  no  argillaceous 
smell.  Its  specific  gravity,  when  all  the 
bubbles  of  air  it  contains  have  escaped,  is 
2.612.  In  the  fire  it  lost  0.585  of  its  weight, 
and  became  sufficiently  hard  to  scratch 
Bohemian  glass  slightly.  On  analysis  it  was 
found  to  contain  magnesia  26.3,  silex  14.2, 
carbonic  acid  46,  water  12,  iron  an  inap- 
preciable quantity. 

The  carbonate  of  ammonia,  once  vulgarly 
VOL.  i.  f51 


known  by  the  name  of  volatile  sal  ammo* 
niac,  and  abroad  by  that  of  English  volatile 
salt,  because  it  was  first  prepared  in  this 
country,  was  commonly  called  mild  volatile 
alkali,  before  its  true  nature  was  known. 

When  very  pure  it  is  in  a  crystalline 
form,  but  seldom  very  regular.  Its  crystals 
are  so  small,  that  it  is  difficult  to  deter- 
mine their  figure.  Bergmann  describes 
them  as  acute  octaedrons,  the  four  angles 
of  which  are  truncated.  Rom'  de  Lisle  had 
compressed  tetraedral  prisms,  terminated 
by  a  diedral  summit.  Bergmann  obtained 
his  by  saturating  warm  water  with  the 
salt,  stopping  the  bottle  closely,  and  ex- 
posing it  to  great  cold.  The  crystals  com- 
monly produced  by  sublimation  are  little 
bundles  of  needles,  or  very  slender  prisms, 
so  arranged  as  to  represent  herboriza- 
tions,  fern  leaves,  or  feathers.  The  taste 
and  smell  of  this  salt  are  the  same  with 
those  of  pure  ammonia,  but  much  weaker. 
It  turns  the  colour  of  violets  green,  and 
that  of  turmeric  brown.  It  is  soluble  in 
rather  more  than  twice  its  weight  of  cold 
water,  and  in  its  own  weight  of  hot  water* 
but  a  boiling  heat  volatilizes  it.  When 
pure,  and  thoroughly  saturated,  it  is  not 
perceptibly  alterable  in  the  air ;  but  when, 
it  lias  an  excess  of  ammonia,  it  softens  and 
grows  moist.  It  cannot  be  doubted,  how- 
ever,  that  it  is  soluble  in  air;  for  if  left  in 
an  open  vessel,  it  gradually  diminishes  in 
weight,  and  its  peculiar  smell  is  diffused 
to  a  certain  distance.  Heat  readily  sub- 
limes, but  does  not  decompose  it. 

It  has  been  prepared  by  the  destructive 
distillation  of  animal  substances,  and  some 
others,  in  large  iron  pots,  with  a  fire  in- 
creased by  degrees  to  a  strong  red  heat, 
the  aqueous  liquor  that  first  comes  over 
being  removed,  that  the  salt  might  not  be 
dissolved  in  it.  Thus  we  had  the  sat't  of 
hartshorn,  salt  of  soot,  essential  salt  of  vi- 
pers, &c.  If  the  salt  were  dissolved  in  the 
water,  it  was  called  spirit  of  the  substance 
from  which  it  was  obtained.  Thus,  how- 
ever, it  was  much  contaminated  by  a  fetid 
animal  oil,  from  which  it  required  to  be 
subsequently  purified,  and  is  much  better 
fabricated  by  mixing  one  part  of  muriate 
of  ammonia  and  two  of  carbonate  of  lime, 
both  as  dry  as  possible,  and  subliming  in 
an  earthen  retort. 

Sir  H.  Davy  has  shown  that  its  compo- 
nent parts  vary,  according  to  the  manner 
of  preparing  it.  The  lower  the  tempera- 
ture at  which  it  is  formed,  the  greater  the 
proportion  of  acid  and  water.  Thus,  if 
formed  at  the  temperature  of  300°,  it  con- 
tains more  than  fifty  per  cent  of  alkali ;  if 
at  60°,  not  more  than  twenty  per  cent. 

*  There  are  three  or  four  definite  com- 
pounds of  carbonic  acid  and  ammonia. 
The  1st  is  the  solid  sub-carbonate  of  the 
shops.  It  consists  of  55  carbonic  aci<3,  3Q 


AC1 


AC1 


ammonia,  and  15  water;  or  probably  of  3 
primes  carbonic  acid,  2  ammonia,  and  2 
water;  in  all  14.76  for  its  equivalent.  2. 
But  M.  Gay-Lussac  has  shown,  that  when 
100  volumes  of  ammoniacal  gas  are  mixed 
with  50  of  carbonic  acid,  the  two  gases 
precipitate  in  a  solid  salt,  which  must  con- 
sist by  weight  of  56 £  acid  -f  43 1  alkali, 
being  in  the  ratio  of  a  prime  equivalent  of 
each.  3.  When  the  pungent  sub-carbo- 
nate is  exposed  in  powder  to  the  air,  it  be- 
comes scentless  by  the  evaporation  of  a 
definite  portion  of  its  ammonia.  It  is  then 
a  compound  of  about  55  or  56  carbonic 
acid,  21.5  ammonia,  and  22.5  water,  (t  may 
be  represented  by  2  primes  of  acid,  1  of 
ammonia,  and  2  of  water,  =  12.  4.  Ano- 
ther compound,  it  has  been  supposed,  may 
be  prepared  by  passing  carbonic  acid 
through  a  solution  of  the  sub-carbonate 
till  it  be  saturated.  This,  however,  may  be 
supposed  to  yield  the  same  product  as  the 
last  salt.  M.  Gay-Lussac  infers  the  neutral 
carbonate  to  consist  of  equal  volumes  of 
the  two  gases,  though  they  will  not  direct- 
ly combine  in  these  proportions.  This 
•would  give  18.1  to  46.5;  the  very  propor- 
tions in  the  scentless  salt.  For  46.5  :  18.1 
: :  55 :  21.42.* 

It  is  well  known  as  a  stimulant  usually 
put  into  smelling-bottles,  frequently  with 
the  addition  of  some  odoriferous  oil. 

Fourcroy  has  found,  that  an  ammoniaco- 
magnesian  carbonate  is  formed  on  some 
occasions.  Thus,  if  carbonate  of  ammonia 
be  decomposed  by  magnesia  in  the  moist 
way,  leaving  these  two  substances  in  con- 
tact with  each  other  in  a  bottle  closely 
stopped,  a  complete  decomposition  will 
not  take  place,  but  a  portion  of  this  trisalt 
will  be  formed.  The  same  will  take  place, 
if  a  solution  of  carbonate  of  magnesia  in 
water,  impregnated  with  carbonic  acid,  be 
precipitated  by  pure  ammonia ;  or  if  am- 
moniaco-magnesian  sulphate,  nitrate,  or 
muriate,  be  precipitated  by  carbonate  of 
potash  or  of  soda. 

The  properties  of  this  triple  salt  are  not 
yet  \nown,  but  it  crystallizes  differently 
from  Mae  carbonate  of  either  of  its  bases, 
and  has  its  own  laws  of  solubility  and  de- 
compositioo. 

Tlw  carbonate  of  glucine  has  been  ex- 
amined by  Viviquelin,  and  is,  among  the 
salts  of  that  eavth,  that  of  which  he  has 
most  accurately  .ascertained  the  proper- 
ties. It  is  in  a  white,  dull,  clotty  powder, 
never  dry,  but  greasy,  and  soft  to  the  feel. 
It  is  not  sweet,  like  the  other  salts  of  glu- 
cine, but  insipid.  It  is  very  light,  insolu- 
ble in  water,  perfectly  unalterable  by  the 
air,  but  very  readily  decomposed  by  fire. 

A  saturated  solution  of  carbonate  of  am- 
Mjonia  takes  up  a  certain  portion  of  this 
carbonate,  and  forms  with  it  a  triple  salt. 
Tliis  property  enabled  Vauquelin  to  sepa- 


rate glucine  from  alumina,  and  was  one 
of  the  means  of  his  distinguishing  that 
earth. 

Carbonic  acid  does  not  appear  to  be 
much  disposed  to  unite  with  argillaceous 
earth.  Most  clays,  however,  afford  a 
small  quantity  of  this  acid  by  heat;  and 
Fourcroy  says,  that  the  fat  clays  effervesce 
with  acids.  The  snowy  white  substance 
resembling  chalk,  and  known  by  the  name 
of  lac  lun<e,  is  found  to  consist  almost 
wholly  of  alumina  saturated  with  carbonic 
acid.  A  saline  substance,  consisting  of 
two  six-sided  pyramids  joined  at  one  com- 
mon base,  weighing  five  or  six  grains,  and 
of  a  taste  somewhat  resembling"  alum,  was 
produced  by  leaving  an  ounce  phial  of  wa- 
ter impregnated  with  carbonic  acid,  and  a 
redundancy  of  alumina,  exposed  to  spon- 
taneous evaporation  for  some  months. 

Vauquelin  has  found,  that  carbonate  of 
zircone  may  be  formed  by  evaporating- 
muriate  of  zircone,  redissolving  it  in  wa- 
ter, and  precipitating  by  the  alkaline  car- 
bonates. He  also  adds,  that  it  very  readily 
combines  so  as  to  form  a  triple  salt  with 
either  of  the  three  alkaline  carbonates. 

*  ACID  (CASEIC).  The  name  given  by 
Proust  to  an  acid  found  in  cheese,  to  which 
he  ascribes  their  flavour. 

ACID  (CKTIC).  The  name  given  by  M. 
Chevreul  to  a  supposed  peculiar  principle 
of  spermaceti,  which  he  has  lately  found 
to  be  the  substance  he  has  called  Marga- 
rine, combined  "with  a  fatty  matter.* 

ACID  (CHLORIODIC).  See  ACID  (Hr- 
DBIODIC). 

ACID  (CHLOROCARBOXIC).  See  CHLO- 
RINE, and  CHLOROCARBOWOUS  ACID. 

ACID  (CHLOROCTANIC).  See  ACID  (Paus- 
sic). 

Acip  (CHROMIC).  This  acid  has  been 
examined  principally  by  Vauquelin,  who 
first  discovered  it,  and  by  count  Mussin 
Puschkin ;  yet  we  are  better  acquainted 
with  it  than  with  the  metal  that  forms  its 
basis.  However,  as  the  chromate  of  iron 
has  lately  been  found  in  abundance  in  the 
department  of  Var,  in  France,  and  in  some 
other  places,  we  may  expect  its  proper- 
ties to  be  more  amply  investigated,  and 
applied  with  advantage  in  the  arts,  as  the 
chromates  of  lead  and  iron  are  of  excellent 
use  in  painting  and  enamelling. 

It  was  extracted  from  the  red  lead  ore 
of  Siberia,  by  treating  this  ore  with  car- 
bonate of  potash,  and  separating  the  al- 
kali by  means  of  a  more  powerful  acid. 
In  this  state  it  is  a  red  or  orange-coloured 
powder,  of  a  peculiar  rough  metallic 
taste,  which  is  more  sensible  in  it  than  in 
any  other  metallic  acid.  If  this  powder 
be  exposed  to  the  action  of  light  and  heat, 
it  loses  its  acidity,  and  is  converted  into 
green  oxide  of  chrome,  giving  out  pure 
oxygen  gas.  The  chromic  tvcid  is  the  first 


ACI 


ACI 


that  has  been  found  to  de-oxygenate  itself 
easily  by  the  action  of  heat,  and  afford  oxy- 
gen "gas  by  this  simple  operation.  It  ap- 
pears that  several  of  its  properties  are  ow- 
ing to  the  weak  adhesion  of  a  part  at  least 
of  its  oxygen.  The  green  oxide  of  chrome 
cannot  be  brought  back  to  the  state  of  an 
acid,  unless  its  oxygen  be  restored  by 
treating  it  with  some  other  acid. 

The  chromic  acid  is  soluble  in  water, 
and  crystallizes,  by  cooling  and  evapora- 
tion, in  longish  prisms  of  a  ruby  red.  Its 
taste  is  acrid  and  styptic.  Its  specific  gra- 
vity is  not  exactly  known ;  but  it  always 
exceeds  that  of  water.  It  powerfully  red- 
dens the  tincture  of  turnsole. 

Its  action  on  combustible  substances  is 
little  known.  If  it  be  strongly  heated 
with  charcoal,  it  grows  black  and  passes 
to  the  metallic  state  without  melting. 

Of  the  acids,  the  action  of  the  muriatic 
on  it  is  the  most  remarkable.  If  this  be 
distilled  with  the  chromic  acid,  by  a  gentle 
heat,  it  is  readily  converted  into  chlorine. 
It  likewise  imparts  to  it  by  mixture  the 
property  of  dissolving  gold ;  in  which  the 
chromic  resembles  the  nitric  acid.  This 
is  owing  to  the  weak  adhesion  of  its  oxy- 
gen, and  it  is  the  only  one  of  the  metallic 
acids  that  possesses  this  property. 

*  The  extraction  of  chromic  acid  from 
the  French  ore,  is  performed  by  igniting 
it  with  ite  own  weight  of  nitre  in  a  cruci- 
ble. The  residue  is  lixiviated  with  water, 
which  being  then  filtered,  contains  the 
ehromate  of  potash.  On  pouring  into  this 
a  little  nitric  acid  and  muriate  of  barytes, 
an  instantaneous  precipitate  of  the  chro- 
rnate  of  barytes  takes  place.  After  having 
procured  a  certain  quantity  of  this  salt,  it 
must  be  put  in  its  moist  state  into  a  cap- 
sule, and  dissolved  in  the  smallest  possible 
quantity  of  weak  nitric  acid.  The  barytes 
is  to  be  then  precipitated  by  very  dilute 
sulphuric  acid,  taking  care  not  to  add  an 
excess  of  it.  When  the  liquid  is  found  by 
trial  to  contain  neither  sulphuric  acid  nor 
barytes,  it  must  be  filtered.  It  now  con- 
sists of  water,  with  nitric  and  chromic 
acids.  The  whole  is  to  be  evaporated  to 
dryness,  conducting  the  heat  at  the  end, 
so  as  not  to  endanger  the  decomposition 
of  the  chromic  acid,  which  will  remain  in 
the  capsule  under  the  form  of  a  reddish 
matter.  It  must  be  kept  in  a  glass  phial 
well  corked. 

Chromic  acid,  heated  with  a  powerful 
acid,  becomes  chromic  oxide ;  while  the 
latter,  heated  with  the  hydrate  of  an  alka- 
li, becomes  chromic  acid.  As  the  solution 
of  the  oxide  is  green,  and  that  of  the  acid 
yellow,  these  transmuta:ions  become  very 
remarkable  to  the  eye.  From  Berzelius's 
experiments  on  the  combinations  of  the 
chromic  acid  with  barytes,  and  oxide  of 
lead,  its  prime  equivalent  seems  to  be  6.5 ; 


consisting  of  3.5  chromium,  and  3.0  oxy- 
gen.* See  CHROMIUM. 

It  readily  unites  with  alkalis,  and  is  the 
only  acid  that  has  the  property  of  colouring 
its  salts,  whence  the  name  of  chromic  has 
been  given  it.  If  two  parts  of  the  red  lead 
ore  of  Siberia  in  fine  powder  be  boiled 
with  one  of  an  alkali  saturated  with  car- 
bonic acid,  in  forty  parts  of  water,  a  car- 
bonate of  lead  will  be  precipitated,  and 
the  ehromate  remain  dissolved.  The  so- 
lutions are  of  a  lemon  colour,  and  afford 
crystals  of  a  somewhat  deeper  hue.  Those 
of  ehromate  of  ammonia  are  in  yellow  la- 
minae, having  the  metallic  lustre  of  gold. 

The  ehromate  of  barytes  is  very  little 
soluble,  and  that  of  lime  still  less.  They 
are  both  of  a  pale  yellow,  and  when  heat- 
ed give  out  oxygen  gas,  as  do  the  alkaline 
chromates. 

If  the  chromic  acid  be  mixed  with  filings 
of  tin  and  the  muriatic  acid,  it  becomes  at 
first  yellowish  brown,  and  afterwards  as- 
sumes a  bluish  green  colour,  which  pre- 
serves the  same  shade  after  desiccation. 
Ether  alone  gives  it  the  same  dark  colour. 
With  a  solution  of  nitrate  of  mercury,  it 
gives  a  precipitate  of  a  dark  cinnabar  co- 
lour. With  a  solution  of  nitrate  of  silver 
it  gives  a  precipitate,  which,  the  moment 
it  is  formed,  appears  of  a  beautiful  carmine 
colour,  but  becomes  purple  by  exposure 
to  the  light.  This  combination,  exposed 
to  the  heat  of  the  blow-pipe,  melts  before 
the  charcoal  is  inflamed,  and  assumes  a 
blackish  and  metallic  appearance.  If.it  be 
then  pulverized,  the  powder  is  still  pur- 
ple ;  but  after  the  blue  flame  of  the  lamp 
is  brought  into  contact  with  this  powder, 
it  assumes  a  green  colour,  and  the  silver 
appears  in  globules  disseminated  through 
its  substance. 

With  nitrate  of  copper  it  gives  a  chesnut 
red  precipitate.  With  the  solution  of  sul- 
phate of  zinc,  muriate  of  bismuth,  muriate 
of  antimony,  nitrate  of  nickel,  and  muriate 
of  platina,  it  produces  yellowish  precipi- 
tates, when  the  solutions  do  not  contain 
an  excess  of  acid.  With  muriate  of  gold 
it  produces  a  greenish  precipitate. 

When  melted  with  borax,  or  glass,  or 
acid  of  phosphorus,  it  communicates  to  it 
a  beautiful  emerald  green  colour. 

If  paper  be  impregnated  with  it,  and  ex- 
posed to  the  sun  a  few  days,  it  acquires  a 
green  colour,  which  remains  permanent 
in  the  dark. 

A  slip  of  iron,  or  tin,  put  into  its  solu- 
tion, imparts  to  it  the  same  colour. 

The  aqueous  solution  of  tannin  produces 
a  flocculent  precipitate  of  a  brown  fawn 
colour. 

Sulphuric  acid,  when  cold,  produces  no 
effect  on  it ;  but  when  warm  it  makes  it 
assume  a  bluish  green  colour. 

ACID  (CiTHic).    Theguice  of 


ACI 

o*  limes,  has  all  the  characters  of  an  acid 
of  considerable  strength;  but  on  account 
of  the  mucilaginous  matter  with  which  it 
is  mixed,  it  is  very  soon  altered  by  spon- 
taneous decomposition.  Various  methods 
have  been  contrived  to  prevent  this  effect 
from  taking  place,  in  order  that  this  whole- 
some and  agreeable  acid  might  be  pre- 
served for  use  in  long  voyages,  or  other 
domestic  occasions.  The  juice  may  be 
kept  in  bottles  under  a  thin  stratum  of  oil, 
which  indeed  prevents,  or  greatly  retards, 
its  total  decomposition ;  though  th^e  origi- 
nal fresh  taste  soon  gives  place  to  one 
which  is  much  less  grateful.  In  the  East 
Indies  it  is  evaporated  to  the  consistence 
of  a  thick  extract.  If  this  operation  be 
carefully  performed  by  a  very  gentle  heat, 
it  is  found  to  be  very  effectual.  When  the 
juice  is  thus  heated,  the  mucilage  thickens, 
and  separates  in  the  form  of  flocks,  part  of 
which  subsides,  and  part  rises  to  the  sur- 
face ;  these  must  be  taken  out.  The  va- 
pours which  arise  are  not  acid.  If  the 
evaporation  be  not  carried  so  far  as  to  de- 
prive the  liquid  of  its  fluidity,  it  may  be 
long  preserved  in  well  closed  bottles;  in 
which,  after  some  weeks'  standing,  a  far- 
ther portion  of  mucilage  is  separated, 
without  any  perceptible  change  in  the 
acid. 

Of  all  the  methods  for  preserving  le- 
mon-juice, that  of  concentrating  it  by  frost 
appears  to  be  the  best,  though  in  the 
warmer  climates  it  cannot  conveniently  be 
practised.  Lemon-juice,  exposed  to  the 
air,  in  a  temperature  between  50°  and 
60°,  deposites  in  a  few  hours  a  white  semi- 
transparent  mucilaginous  matter,  which 
leaves  the  fluid,  after  decantation  and  fil- 
tration, much  less  alterable  than  before. 
This  mucilage  is  not  of  a  gummy  nature, 
but  resembles  the  gluten  of  wheat  in  its 
properties:  it  is  not  soluble  in  water  when 
dried.  More  mucilage  is  separated  from 
lemon-juice  by  standing  in  closed  vessels. 
If  this  depurated  lemon-juice  be  exposed 
to  a  degree  of  cold  of  about  seven  or  eight 
degrees  below  the  freezing  point,  the 
aqueous  part  will  freeze,  and  the  ice  may 
be  taken  away  as  it  forms ;  and  if  the  pro- 
cess be  continued  until  the  ice  begins  to 
exhibit  signs  of  acidity,  the  remaining 
acid  will  be  found  to  be  reduced  to  about 
one -eighth  of  its  original  quantity,  at  the 
same  time  that  its  acidity  will  be  eight 
times  as  intense,  as  is  proved  by  its  re- 
quiring eight  times  the  quantity  of  alkali 
to  saturate  an  equal  portion  of  it.  This 
concentrated  acid  may  be  kept  for  use,  or, 
.if  preferred,  it  may  be  made  into  a  dry  le- 
monade, by  adding  six  times  its  weight  of 
fine  loaf  sugar  in  powder. 

The  above  processes  mav  be  used  when 
the  sicid  of  lemons  is  wanted  for  domestic 
purpases,  because  they  leave  it  in  posses- 


ACI 

sion  of  the  oils,  or  other  principles,  on 
which  its  flavour  peculiarly  depends  ;  but 
in  chemical  researches,  where  the  acid  it- 
self is  required  to  be  had  in  the  utmost 
purity,  a  more  elaborate  process  must  be 
used.  Boiling  lemon-juice  is  to  be  satu- 
rated with  powdered  chalk,  the  weight  of 
which  is  to  be  noted,  and  the  powder 
must  be  stirred  up  from  the  bottom,  or 
the  vessel  shaken  from  time  to  time.  The 
neutral  saline  compound  is  scarcely  more 
soluble  in  water  than  selenite ;  it  there- 
fore falls  to  the  bottom,  while  the  mucil- 
age remains  suspended  in  the  watery  fluid, 
which  must  be  decanted  oflf;  the  remain- 
ing precipitate  must  then  be  washed  with 
warm  water  until  it  comes  oflT  clear.  To 
the  powder  thus  edulcorated,  a  quantity 
of  sulphuric  acid,  equal  the  chalk  in 
weight,  and  diluted  with  ten  parts  of  wa- 
ter, must  be  added,  and  the  mixture  boil- 
ed a  few  minutes.  The  sulphuric  acid 
combines  with  the  earth,  and  forms  sul- 
phate of  lime,  which  remains  behind  when 
the  cold  liquor  is  filtered,  while  the  disen- 
gaged acid  of  lemons  remains  dissolved  in 
the  fluid.  This  last  must  be  evaporated 
to  the  consistence  of  a  thin  sirup,  which 
yields  the  pure  citric  acid  in  little  needle- 
like  crystals.  It  is  necessary  that  the  sul- 
phuric acid  should  be  rather  in  excess, 
because  the  presence  of  a  small  quantity  of 
lime  will  prevent  the  crystallization.  This 
excess  is  allowed  for  above. 

M.  Dize,  a  skilful  apothecary  in  Paris, 
who  has  repeated  this  process  of  Scheele 
on  a  very  extensive  scale,  asserts,  that  an 
excess  of  sulphuric  acid  is  necessary,  not 
only  to  obtain  the  citric  acid  pure,  but  to 
destroy  the  whole  of  the  mucilage,  part  of 
which  would  otherwise  remain,  and  occa- 
sion its  spoiling.  It  is  not  certain,  how- 
ever, but  the  sulphuric  acid  may  act  on 
the  citric  itself,  and  by  decomposing  it, 
produce  the  charcoal  that  M.  Dize  as- 
cribes to  the  decomposition  of  mucilage ; 
and  if  so,  the  smaller  the  excess  of  sulphu- 
ric acid  the  better.  He  also  adds,  that  to 
have  it  perfectly  pure  it  must  be  repeated- 
ly crystallized,  and  thus  it  forms  very  large 
and  accurately  defined  crystals  in  rhom- 
boidal  prisms,  the  sides  of  which  are  in- 
clined in  angles  of  60°  and  120°,  termina- 
ted at  each  end  by  tetraedral  summits, 
which  intercept  the  solid  angles.  These, 
however,  will  not  be  obtained  when  ope- 
rating on  small  quantities., 

Its  taste  is  extremely  sharp,  so  as  to  ap- 
pear caustic.  Distilled  in  a  retort,  part 
rises  without  being  decomposed ;  it  ap- 
pears to  give  out  a  portion  of  vinegar;  it 
then  evolves  carbonic  acid  gas,  and  a  little 
carburetted hydrogen;  and  a  light  coal  re- 
mains. It  is  among  the  vegetable  acids 
the  one  which  most  powerfully  resists  de- 
composition by  fire. 


ACI 


AC1 


Tn  a  dry  and  warm  air  it  seems  to  efflo- 
resce ;  but  it  absorbs  moisture  when  the 
air  is  damp,  and  at  length  loses  its  crystal- 
line form.  A  hundred  parts  of  this  acid 
are  soluble  in  seventy-five  of  water  at 
60°,  according1  to  Vauquelin.  Though  it 
is  less  alterable  than  most  other  solutions 
of  vegetable  acids,  it  will  undergo  decom- 
position when  lonjr  kept.  Fourcroy  thinks 
it  probable  that  it  is  converted  into  acetic 
acid  before  its  final  decomposition. 

It  is  not  altered  by  any  combus  ible  sub- 
stance; charcoal  alone  appears  to  be  capa- 
ble of  whitening  it.  The  most  powerful 
acids  decompose  it  less  easily  than  they 
do  other  vegetable  acids  ;  but  the  sulphu- 
ric evidently  converts  it  into  acetic  acid. 
The  nitric  acid  likewise,  according  to 
Fourcroy  and  Vauquelin,  if  employed  in 
large  quantity,  and  heated  on  it  a  long 
time,  converts  the  greater  part  of  it  into 
acetic  acid,  and  a  small  portion  into  oxalic. 
Scheele  indeed  could  not  effect  this ;  but 
Westrumb  supposes  that  it  was  owing  to 
his  having  used  too  much  nitric  acid  ;  for 
on  treating  60  grains  of  citric  acid  with 
200  of  nitric  he  obtained  30  grains  of  oxalic 
acid ;  with  300  grains  of  nitric  acid  he  got 
15  ;  and  with  600  grains  no  vestige  of  oxa- 
lic acid  appeared 

If  a  solution  of  barytes  be  added  gradu- 
ally to  a  solution  of  citric  acid,  a  flocculent 
precipitate  is  formed,  soluble  by  agitation, 
till  the  whole  of  the  acid  is  saturated. 
This  salt  at  first  falls  down  in  powder,  and 
then  collects  in  •  silky  tufts,  and  a  kind  of 
very  beautiful  and  shining  silvery  bushes. 
It  requires  a  large  quantity  of  water  to 
dissolve  it. 

The  citrate  of  lime  has  been  mentioned 
already  in  treating  of  the  mode  of  purify- 
ing the  acid. 

The  citrate  of  potash  is  very  soluble  and 
deliquescent. 

The  citrate  of  soda  has  a  dull  saline 
taste ;  dissolves  in  less  than  twice  its 
weight  of  water  ;  crystallizes  in  six-sided 
prisms  with  flat  summits ;  effloresces 
slightly,  but  does  not  fall  to  powder; 
boils  up,  swells,  and  is  reduced  to  a  coal 
on  the  fire.  Lime-water  decomposes  it, 
but  does  not  render  the  solution  turbid, 
notwithstanding  the  little  solubility  of  ci- 
trate of  lime. 

Citrate  of  ammonia  is  very  soluble ;  does 
not  crystallize  unless  its  solution  be  great- 
ly concentrated;  and  forms  elongated 
prisms. 

Citrate  of  magnesia  does  not  crystallize. 
When  its  solution  had  been  boiled  down, 
and  it  had  stood  some  days,  on  being 
slightly  shaken  it  fixed  in  one  white  opaque 
mass,  which  remained  soft,  separating 
from  the  sides  of  the  vessel,  contracting 
its  dimensions,  and  rising  in  the  middle 
like  a  kind  of  mushroom. 


Its  combination  with  the  other  earths 
has  not  been  much  examined;  and  its  ac- 
tion upon  metals  has  been  little  studied. 
Scheele  however  found,  that  it  did  not 
precipitate  the  nitric  solutions  of  metals, 
as  the  malic  acid  does. 

\11  the  citrates  are  decomposed  by  the 
powerful  acids,  which  do  not  form  a  pre- 
cipitate with  them,  as  with  the  oxalates 
and  tartnttes.  The  oxalic  and  tartaric 
acids  decompose  them,  and  form  crystal- 
lized or  insoluble  precipitates  in  their  so- 
lutions. All  afford  traces  of  acetic  acid, 
or  a  product  of  the  same  nature,  on  being 
exposed  to  distillation  :  this  character 
exists  particularly  in  the  metallic  citrates. 
Placed  on  burning  coals  they  melt,  swell 
tip,  emit  an  empyreumatic  sniell  of  acetic 
acid,  and  leave  alight  coal.  All  of  them, 
if  dissolved  in  water,  and  left  to  stand  for 
a  time,  undergo  decomposition,  depositea 
flocculent  mucus  which  grows  black,  and 
leave  their  bases  combined  with  carbonic 
acid,  one  of  the  products  of  the  decompo- 
sition. Before  they  are  completely  de- 
composed, they  appear  to  pass  to  the 
state  of  acetates. 

The  affinities  of  the  citric  acid  are  ar- 
ranged by  Vauquelin  in  the  following  or- 
der :  barytes,  lime,  potash,  soda,  strontian, 
magnesia,  ammonia,  alumina.  Those  for 
zircone,  glucine,  and  the  metallic  oxides, 
are  not  ascertained. 

The  citric  acid  is  found  in  many  fruits 
united  with  the  malic  acid  ;  which  see  for 
the  process  of  separating  them  in  this 
case. 

*  From  the  composition  of  the  citrate  of 
lead,  as  determined  by  Berzelius,  it  ap- 
pears that  dry  citric  acid  has  for  its  prime 
equivalent  7.368,  compared  to  yellow 
oxide  of  lead  14,  and  oxygen  1.0.  The 
crystals,  according  to  the  same  accurate 
chemist,  consist  of  79  real  acid,  and  21 
water,  in  100  parts.  This  would  make 
the  equivalent  of  the  crystallized  acid  9.3. 
Its  ultimate  constituents  are,  by  the  analy- 
sis of 

Hydrog.  Carbon.  Oxyg. 

6-330+33.811-f.59.859 


Berzelius,  3.800+41.369+54.831 

Citric  acid  being  more  costly  than  tar- 
taric, may  be  occasionally  adulterated 
with  it.  This  fraud  is  discovered,  by  add- 
ing slowly  to  the  acid  dissolved  in  water  a 
solution  of  sub  -carbonate  of  potash,  which 
will  give  a  white  pulverulent  precipitate 
of  tartar,  if  the  citric  be  contaminated  witk 
the  tartaric  acid.  When  one  part  of  the 
citric  acid  is  dissolved  in  19  of  water,  the 
solution  may  be  used  as  a  substitute  for 
lemon-juice.  If  before  solution  the  crys-r 
tals  be  triturated  with  a  little  sugar  and  a 
few  drops  of  the  oil  of  lemons,  the  resem- 


ACI 


ACI 


Wance  to  the  native  juice  will  be  com- 
plete. It  is  an  antidote  against  sea  scurvy; 
but  the  admixture  of  mucilage  and  other 
vegetable  matter  in  the  recent  fruit  of  the 
lemon,  has  been  supposed  to  render  it 
preferable  to  the  pure  acid  of  the  che- 
mist.* 

ACID  (CHLORIC).  See  ASID  (MURIATIC.) 
*  ACID  (COLTTMBIG).  The  experiments 
of  Mr.  Hatchett  have  proved,  that  a  pecu- 
liar mineral  from  Massachusetts,  deposited 
in  the  British  Museum,  consisted  of  one 
part  of  oxide  of  iron,  and  somewhat  more 
than  three  parts  of  a  white  coloured  sub- 
stance, possessing  the  properties  of  an 
acid.  Its  basis  was  metallic.  Hence  he 
named  this  i  olumbium,  and  the  acid  the 
Columbic.  Dr.  Wollaston,  by  very  exact 
analytical  comparisons,  proved,  that  the 
acid  of  Mr.  Hatchett,  was  the  oxide  of  the 
metal  lately  discovered  in  Sweden  by  Mr. 
Ekeberg,  in  the  mineral  yttrotantalite,  and 
thence  called  tantalum.  Dr.  Wollaston's 
method  of  separating  the  acid  from  the 
mineral  is  peculiarly  elegant.  One  part 
of  tantalite,  five  parts  of  carbonate  of  pot- 
ash, and  two  parts  of  borax,  are  fused  to- 
gether in  a  platina  crucible.  The  mass, 
after  being  softened  in  water,  is  acted  on 
by  muriatic  acid.  The  iron  and  manga- 
nese dissolve,  while  the  columbic  acid  re- 
mains at  the  bottom.  It  is  in  the  form  of 
a  white  powder,  which  is  insoluble  in  ni- 
tric and  sulphuric  acids,  but  partially  in 
muriatic.  It  forms  with  barytes  an  insolu- 
ble salt,  of  which  the  proportions,  accord- 
ing to  Berzelius,  are  24.4  acid,  and  9.75 
barytes.  By  oxidizing  a  portion  of  the  re- 
vived tantalum  or  columbium,  Berzelius 
infers  the  composition  of  the  acid  to  be 
100  metal  and  5.485  oxygen. 

ACID  (CYANIC).  See  ACID  (Pnussic). 
ACID  (FLUOUTC).  The  fusible  spar  which 
is  generally  distinguished  by  the  name  of 
Derbyshire  spar,  consists  of  calcareous 
earth  in  combination  with  the  acid  at  pre- 
sent under  our  consideration.  If  the  pure 
fluor,  or  spar,  be  placed  in  a  retort  of  lead 
or  silver,  with  a  receiver  of  the  same  me- 
tal adapted,  and  its  weight  of  sulphuric 
acid  be  then  poured  upon  it,  the  fluoric 
acid  will  be  disengaged  by  the  application 
of  a  moderate  heat.  This  acid  gas  readily 
combines  with  water ;  for  which  purpose 
it  is  necessary  that  the  receiver  should 
previously  be  half  filled  with  that  fluid. 

*  If  the  receiver  be  cooled  with  ice,  and 
no  water  put  in  it,  then  the  condensed 
acid  is  an  intensely  active  liquid,  first  pro- 
cured by  M.  Gay-Lussac.  The  best  account 
of  it,  however,  has  been  given  by  Sir  H. 
Davy.  It  has  the  appearance  of  sulphuric 
acid,  but  is  much  more  volatile,  and  sends 
oft*  white  fumes  when  exposed  to  air.  Its 
specific  gravity  is  only  1.0609.  It  must  be 
examined  with  great  caution,  for  when 


applied  to  the  skin  it  instantly  disorganizes 
it,  and  produces  very  painful  wounds. 
When  potassium  is  introduced  into  it,  it 
acts  with  intense  energy,  and  produces 
hydrogen  gas  and  a  neutral  salt;  when 
lime  is  made  to  act  upon  it,  there  is  a  vio- 
lent heat  excited,  water  is  formed,  and 
the  same  substance  as  fluor  spar  is  pro- 
duced. With  water  in  a  certain  propor- 
tion, its  density  increases  to  1.25.  When 
it  is  dropped  into  water,  a  hissing  noise  is 
produced  with  much  heat,  and  an  acid 
fluid  not  disagreeable  to  the  taste  is  form- 
ed if  the  water  be  in  sufficient  quantity.  It 
instantly  corrodes  and  dissolves  glass. 

It  appears  extremely  probable,  from  all 
the  facts  known  respecting  the  fluoric 
combinations,  that  fluor  spar  contains  a 
peculiar  acid  matter;  and  that  this  acid 
matter  is  united  to  lime  in  the  spar,  seems 
evident  from  the  circumstance,  that  gyp- 
sum or  sulphate  of  lime  is  the  residum  of 
the  distillation  of  fluor  spar  and  sulphuric 
acid.  The  results  of  experiments  on  fluor 
spar  have  been  differently  stated  by  chem- 
ists. Sir  H.  Davy  states,  that  100  fluor 
spar  yield  175.2  sulphate  of  lime;  whence 
we  deduce  the  prime  equivalent  of  fluoric 
acid  to  be  1.3260,  to  lime,  3.56,  and  oxygen 
1.00.  From  fluate  of  potash  the  equiva- 
lent comes  out  for  the  acid,  =  1.2495, 
potash  being  reckoned  5.95.  Berzelius  in 
his  last  series  of  experiments  gives  from 
fluate  of  lime,  1.374  for  the  equivalent  of 
fluoric  acid.  The  dense  fluid  obtained  in 
silver  vessels,  may  be  regarded  as  hydro- 
fluoric acid ;  and,  supposing  all  the  water  in 
oil  of  vitriol  transferred  to  it,  would  con- 
sist of  1.326  or  1.374  acid,+  1.125  water; 
which  is  a  prime  of  each. 

Dr.  Thomson,  in  his  System  of  Chemistry 
fifth  edition,  vol.  i.  p.  203,  deduces  the 
equivalent  of  fluoric  acid  from  the  decom- 
position of  fluate  of  lime  by  sulphuric  acid, 
to  be  1.0095;  and,  from  the  lowness  of 
this  number,  he  afterwards  endeavours  to 
prove  that  fluoric  acid  cannot  be  a  com- 
pound of  oxygen  with  a  base.  Now 
taking  his  own  data  of  100  parts  of  fluor 
spar  yielding,  according  to  Sir  H.  Davy's 
latest  experiments,  175.2  sulphate  of  lime  ; 
and  admitting  that  these  contain  73.582  of 
lime;  leaving  consequently  26.418  for  the 
proportion  of  acid  in  100  of  fluor  spar,  we 
shall  find  1.3015  to  be  the  equivalent  or 
atom  of  fluoric  acid.  For  73.582 :  3.625  : 
i6.418:  1.3015,  taking  his  own  number 
3.625  for  the  atom  of  lime.  Hence  the 
whole  difficulties  stated  by  him  in  the  fol- 
lowing passage,  page  206,  disappear : — "  If 
we  suppose  fluate  of  lime  to  be  a  com- 
pound of  fluoric  acid  and  lime,  its  compo- 
sition will  be,  Fluoric  acid,  1.0095. 

Lime.  3.625 

From  this  we  see  that  the  weight  of  an 
integrant  particle  of  fluoric  acid  must  be 


ACI 

|    1.0095.    If  it  be  supposed  a  compound  of 

I    one  atom  of  oxygen,  and  one  atom  of  an 

|    unknown  inflammable  basis,  then  as  the 

[    weight  of  an  atom   of  oxygen  is  1,  the 

|    weight  of  an  atom  of  the  inflammable  base 

>    can   be   only  0.0095,   which  is  only  the 

thirteenth  part  of  the  weight  of  an  atom 

of  hydrogen.     On  that  supposition,  fluoric 

acid  would  be  composed  of 

Inflammable  basis,          1.00 
Oxygen,  105.67. 

So  very  light  a  body,  being  contrary  to 
all  analogy,  cannot  be  admitted  to   exist 
without  stronger  proofs  than  have  hitherto 
been  adduced.      On  the   other  hand,  if 
fluor  spar  be  in  reality  a  fluoride  of  calci- 
um, then  its  composition  will  be, 
Fluorine,          2.0095 
Calcium,  2.625 

So  that  the  weight  of  an  atom  of  fluorine 
would  be  2.0095,  or  almost  exactly  twice 
the  weight  of  an  atom  of  oxygen.  This  is 
surely  a  much  more  probable  supposition 
than  the  former.*' 

It  is  not  possible  to  find  a  more  instruc- 
tive example  than  the  one  now  afforded  by 
this  systematic  chemist,  of  the  danger  of 
prosecuting,  on  slippery  grounds,  hy- 
pothetical analogies.  The  atom  of  fluoric 
acid,  when  rightly  computed  with  his  own 
data,  is  not  1.0095,  but  1.3015,  and  hence 
none  of  his  consequences  need  be  consi- 
dered. It  may  consist  of  1  of  oxygen 
combined  with  0.3015  of  an  unknown  rad- 
ical ;  or  there  may,  for  aught  we  know, 
be  a  substance  analogous  to  chlorine  and 
iodine,  to  be  called  therefore  fluorine, 
whose  prime  equivalent' will  be  2.3015. 
From  the  mode  in  which  liquid  fluoric 
acid  is  produced  viz.  from  a  mixture  of 
fluor  spar,  and  oil  of  vitriol,  it  may  obvious- 
ly contain  water,  and  may  consist,  as  we 
have  seen,  probably  of  a  prime  or  atom  of 
j  real  acid,  and  an  atom  of  water.  Hence 
the  phenomena  occasioned  by  adding  pot- 
assium to  it,  present  nothing  different 
from  those  exhibited  by  the  same  metal 
added  to  concentrated  hydro-nitric  or 
hydro-sulphuric  acid.  Sir  H.  Davy  indeed 
i  has  been  induced  in  his  last  researches  to 
infer,  from  the  action  of  ammoniacal  gas 
on  the  liquid  fluoric  acid,  that  it  contains 
no  water. 

On  this  subject  Dr.  Thomson  has  the 
following  aphorism :  "  When  any  acid 
that  contains  water  is  combined  in  this 
manner  with  ammoniacal  gas,  if  we  heat 
the  salt  formed,  water  is  always  disengag- 
ed. Thus  sulphuric  acid,  or  nitric  acid,  or 
phosphorous  acid,  when  saturated  with 
ammoniacal  gas  and  heated,  give  out 
always  abundance  of  water.  But  fluate  of 
ammonia,  when  thus  treated,  gave  out 
no  water.  Hence  we  have  no  evidence 
that  fluoric  acid  contains  any  water." 
The  whole  of  this  reasoning  is  visionary. 


ACI 

It  has  been  proved  in  my  experimented 
researches  on  the  ammoniacal  salts,  in- 
serted in  the  tenth  volume  of  the  Annals 
of  Philosophy,  that  the  sulphate  and  ni- 
trate of  ammonia,  in  the  driest  state  to 
which  they  can  be  brought  by  heat,  short 
of  their  decomposition,  contain  one  atom 
or  prime  equivalent  of  water,  which  is  in- 
deed essential  to  their  very  existence,  and 
which  water  cannot  be  separated  by  heat 
alone.  If  concentrated  oil  of  vitriol  be  sa- 
turated with  dry  ammoniacal  gas,  a  solid 
salt  will  be  obtained,  from  which  heat 
alone  will  not  separate  the  proportion  of 
water  it  contains,  and  which  amounts  to 
13.6  percent.  A  stronger  heat  will  merely 
separate  a  portion  of  the  ammonia  from 
the  acid,  or  volatilize  both.  In  the  former 
case  the  acid  retains  its  atom  of  water. 
Hence  we  see,  that  no  inference  whatever 
can  be  drawn  from  the  ammoniacal  com- 
bination with  liquid  fluoric  acid,  to  nega- 
tive the  probability  that  it  may  contain, 
from  the  mode  of  its  extraction,  combined 
water,  like  the  sulphuric  and  nitric  acids. 
The  inferences  from  the  analogous  ac- 
tions of  potassium  on  the  muriate  and  fluate 
of  ammonia,  are  all  liable  to  the  same 
fallacy.  If  the  combined  water  of  the 
fluoric  acid  pass  into  the  salt,  as  with 
sulphuric  acid  it  undoubtedly  does,  then 
hydrogen  and  fluate  of  potash  ought  to 
result,  from  the  joint  actions  of  potassium 
and  the  hydro-fiuoric  acid. 

The  chocolate  powder  which  is  evolved 
at  the  positive  pole,  and  the  hydrogen  at 
the  negative,  when  liquid  fluoric  acid  was 
subjected  by  Sir  H.  Davy  to  the  voltaic 
power,  can  justify  no  decisive  opinion  on 
this  intricate  research.  The  mere  coating 
of  the  platinum  wire  may  as  well  be  re- 
garded as  the  fluate  of  platinum,  as  a  fluor- 
ide. Nor  does  the  decomposition  of  the 
fluates  of  silver  and  mercury,  when  heated 
in  glass  vessels  with  chlorine,  seem  to 
prove  any  thing  whatever.  The  oxygen 
evolved,  is  obviously  separated  from  the 
oxides  of  silver  or  mercury  when  acted  on 
by  chlorine ;  and  the  dry  fluoric  acid 
unites  to  the  silica  of  the  glass,  forming- 
silicated  fluoric  gas,  or  fluo-silicic  acid. 

[n  thus  showing  the  inconclusiveness  of 
Dr.  Thomson's  four  different  arguments, 
to  prove  that  fluoric  acid  is  a  compound  of 
an  unknown  radical,  fluorine,  with  hydro- 
gen, and  not  of  an  unknown  radical,  which 
might  be  termed  fluor,  with  oxygen ;  one 
cannot  help,  however,  expressing  a  high 
admiration  of  Sir  H.  Davy's  experimental 
researches  on  fluoric  acid,  which  were 
published  in  the  second  part  of  the  Phil- 
osophical Transactions  for  1813.  He  did 
all  which  the  existing  resources  of  science 
could  enable  genius  and  judgment  to  ac- 
complish. The  mystery  in  which  the 
subject  obvionsly  and  confessedly  remains. 


ACI 


ACI 


must  be  removed  by  further  investigations, 
and  not  by  analogical  assumptions.  These, 
indeed,  by  giving  resting  points  to  the 
imagination,  of  which  it  becomes  found, 
powerfully  tend  to  obstruct  the  advance- 
ment of  truth. 

The  principal  reason  for  considering 
fluoric  acid  as  a  compound  of  fluorine  with 
hydrogen,  seems  on  the  whole  to  be  the 
analogy  of  chlorine.  But  the  analogy  is  in- 
complete. Certainly  it  is  consonant  to  the 
true  logic  of  chemical  science  to  regard 
chlorine  as  a  simple  body,  since  ^'ery  at- 
tempt to  resolve  it  into  simpler  forms  of 
matter  has  failed.  But  fluorine  has  not 
been  exhibi'ed  in  an  insulated  state  like 
chlorine  ;  and  here  therefore  the  analogy 
does  not  hold. 

With  the  view  of  separating  its  hydro- 
yen,  Sir  H,  Davy  applied  the  power  of  the 
great  voltaic  batteries  of  the  royal  Institu- 
tion to  the  liquid  fluoric  acid.  "  In  this 
case,  gas  appeared  to  be  produced  from 
both  the  negative  and  positive  surfaces; 
but  it  was  probably  only  the  undecom- 
pounded  acid  rendered 'gaseous,  which 
was  evolved  at  the  positive  surface  ;  for 
during  the  operation  the  fluid  became 
very  hot,  and  speedly  diminished."  "  In 
the  course  of  these  investigations  I  made 
several  attempts  to  detach  hydrogen  from 
the  liquid  fluoric  acid,  by  the  agency  of 
oxygen  and  chlorine.  It  was  not  decom- 
posed when  passed  through  a  platinatube 
heated  red  hot  with  chlorine,  nor  by  being 
distilled  from  salts  containing  abundance 
of  oxygen,  or  those  containing  abundance 
of  chlorine."  By  the  strict  rules  of  chem- 
ical logic,  therefore,  fluoric  acid  ought  to 
be  regarded  as  a  simple  body,  for  we  have 
no  evidence  of  its  ever  haviag  been  de- 
composed ;  and  nothing  but  analogy  with 
the  other  acid  bodies  has  given  rise  to  the 
assumption  of  its  being  a  compound. 

There  is  no  difficulty  in  imagining  a 
radical  to  exist,  whose  saturating  powers 
are  exactly  one-third  of  those  of  hydrogen; 
for  0.375' is  precisely  thrice  0.125,  the 
weight  of  the  prime  equivalent  of  hydro- 
gen; and  one-half  of  0.750,  the  equivalent 
of  carbon.  Those  who  are  allured  by  the 
harmony  of  numbers,  might  possibly  con- 
sider these  examples  of  accordance,  as  of 
some  value  in  the  discussion. 

The  marvellous  activity  of  fluoric  acid 
may  be  inferred  from  the  following-  re- 
marks of  Sir  H.  Davy,  from  which  also 
may  be  estimated  in  some  measure  the 
prodigious  difficulty  attending  refined  in- 
vestigations on  this  extraordinary  sub- 
stance. 

"  I  undertook  the  experiment  of  elec- 
trizing pure  liquid  fluoric  acid  with  con- 
siderable interest,  as  it  seemed  to  offer  the 
most  probable  method  of  ascertaining  its 
real  nature ;  but  considerable  difficulties 


occurred  in  executing  the  process.  The 
liquid  fluoric  acid  immediately  destroys 
glass,  and  all  animal  and  vegetable  sub- 
stances ;  it  acts  on  all  bodies  contain- 
ing metallic  oxides ;  and  1  know  of  no  sub- 
stances which  are  not  rapidly  dissolved 
or  decomposed  by  it,  except  metals,  char- 
coal, phosphorus,  sulphur,  and  certain 
combinations  of  chlorine.  1  attempted  to 
make  tubes  of  sulphur,  of  muriates  of  lead 
and  of  cop  per  containing  metallic  wires,  by 
which  it  might  be  electrized,  but  with- 
out success.  I  succeeded,  however,  in  bor- 
ing a  piece  of  horn  silver  in  such  a  man- 
ner that  I  was  able  to  cement  a  platina 
wire  into  it  by  means  of  a  spirit  lamp  ;  and 
by  inverting  this  in  a  tray  of  platina,  filled 
with  liquid  fluoric  acid,  I  contrived  to 
submit  the  fluid  to  the  agency  of  elec- 
tricity in  such  a  manner,  tha%  in  succes- 
sive experiments,  it  was  possible  to  col- 
lect any  elastic  fluid  that  might  be  pro- 
duced Operating  in  this  way  with  a 
very  weak  voltaic  power,  and  keeping 
the  apparatus  cool  by  a  freezing  mixture 
I  ascertained  that  the  pla  ina  wire  at  the 
positive  pole  rapidly  corroded,  and  be- 
came covered  with  a  chocolate  powder; 
gaseous  matter  separated  at  the  negative 
pole,  which  I  could  never  obtain  in  suffi- 
cient quantities  to  analyze  with  accuracy, 
but  it  inflamed  like  hydrogen.  No  other 
inflammable  matter  was  produced  when 
the  acid  was  pure."  We  beg  to  refer  the 
reader  to  the  Philosophical  Transactions 
for  1813  and  1814;  or  the  42d  and  43d 
vols.  of  Tilloch's  Magazine,  where  he  will 
see  philosophical  sagacity  and  experimen- 
tal skill  in  their  utmost  variety  and  vigour, 
struggling  with  the  most  mysterious  and 
intractable  powers  of  matter 

If  instead  of  being  distilled  in  metallic 
vessels,  the  mixture  of  fluor  spar  and  oil 
of  vitriol  be  distilled  in  glass  vessels,  little 
of  the  corrosive  liquid  will  be  obtained ; 
but  the  glass  will  be  acted  upon,  and  a 
peculiar  gaseous  substance  will  be  pro- 
duced, which  must  be  collected  over  mer- 
cury. The  best  mode  of  pi-ocuring  this 
gaseous  body  is  to  mix  the  fluor  spar  with 
pounded  glass  or  quartz;  and  in  this  case, 
the  glass  retort  may  be  preserved  from 
corrosion,  and  the  gas  obtained  in  greater 
quantities.  This  gas,  which  is  called  sili- 
cated  fluoric  gas,  is  possessed  of  very  ex- 
traordinary properties. 

It  is  very  heavy  ;  100  cubic  inches  of  it 
weigh  110.77  gr.  and  hence  its  sp.  gr  is 
to  that  of  air,  as  3.6 32  is  to  1.000.  It  is 
about  48  times  denser  than  hydrogen. 
When  brought  into  contact  with  water,  it 
instantly  deposites  a  white  gelatinous  sub- 
stance, which  is  hydrate  of  silica ;  it  pro- 
duces white  fumes  when  suffered  to  pass 
into  the  atmosphere.  It  is  not  affected  by 
any  of  the  common  combustible  bodies; 


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feut  when  potassium  is  strongly  heated  in 
it,  it  takes  fire  and  burns  with  a  deep  red 
fight ;  the  gas  is  absorbed,  and  a  fawn-co- 
loured substance  is  formed,  which  yields 
alkali  to  water  with  slight  effervescence, 
and  contains  a  combustible  body.  The 
washings  afford  potash  and  a  salt,  from 
which  the  strong  acid  fluid  previously  de- 
scribed, may  be  separated  by  sulphuric 
acid. 

The  gas  formed  by  the  action  of  liquid 
sulphuric  acid  on  a  mixture  containing 
silica  and  fluor  spar,  the  silicated  fluoric 
gas  or  fluo-silicic  acid,  may  be  regarded  as 
a  compound  of  fluoric  acid  and  silica.  It 
affords,  when  decomposed  by  solution  of 
ammonia,  61.4  per  cent  of  silica;  and 
hence  was  at  first  supposed  by  Sir  H.  Da- 
vy to  consist  of  two  prime  proportions  of 
acid  =  2.652  and  one  of  silica  =  4. 066,  the 
sum  of  which  numbers  may  represent  its 
equivalent  =  6.718.  One  volume  of  it  con- 
denses two  volumes  of  ammonia,  and  they 
form  together  a  peculiar  saline  substance 
which  is  decomposed  by  water.  The  com- 
position of  this  salt  is  easily  reconciled  to 
the  numbers  given  as  representing  silica 
and  fluoric  acid,  on  the  supposition  that  it 
contains  1  prime  of  ammonia  to  1  of  the 
fluosilicic  gas ;  for  200  cubic  inches  of  am- 
monia weigh  36. 2  gr.  and  100  of  the  acid 
gas  110.77.  Now  36.2  :  2.13  :  :  110.77  : 
6.52. 

Dr.  John  Davy  obtained,  by  exposing 
this  gas  to  the  action  of  water,-^^.  of  its 
weight  of  silica ;  and  from  the  action  of 
water  of  ammonia  he  separated  -6~*~L  of  its 
weight.  Hence  100  cubic  inches  consist 
by  weight  of  68  silica  and  42  of  unknown 
fluoric  matter,  the  gas  which  holds  the 
silica  in  solution.  Sir  H.  Davy,  however, 
conceives  that  this  gas  is  a  compound  of 
the  basis  of  silica,  or  silicon,  with  fluorine, 
the  supposed  basis  of  fluoric  acid. 

If,  instead  of  glass  or  silica,  the  fluor  spar 
be  mixed  with  dry  vitreous  boracic  acid, 
and  distilled  in  a  glass  vessel  with  sulphu- 
ric acid,  the  proportions  being  one  part 
boracic  acid,  two  fluor  spar,  and  twelve 
oil  of  vitriol,  the  gaseous  substance  formed 
is  of  a  different  kind,  and  is  called  thefluo- 
boric  gas.  100  cubic  inches  of  it  weigh 
73.5  gr.  according  to  Sir  H.  Davy,  which 
makes  its  density  to  that  of  air  as  2.41  is  to 
1.00;  but  M.  Thenard,  from  Dr.  John 
Davy,  states  its  density  to  that  of  air  as 
2.371  to  1.000.  It  is  colourless ;  its  smell 
is  pungent,  and  resembles  that  of  muriatic 
acid;  it  cannot  be  breathed  without  suf- 
focation ;  it  extinguishes  combustion ;  and 
reddens  strongly  the  tincture  of  turnsole. 
It  has  no  manner  of  action  on  glass ;  but  a 
very  powerful  one  on  vegetable  and  ani- 
mal matter:  It  attacks  them  with  as  much 
force  as  concentrated  sulphuric  acid,  and 
Appears  to  operate  on  these  bodies  by 
Voi.  i.  [  6  ] 


the  production  of  water;  for  while  it  cat* 
bonizesthem,  or  evolves  carbon,  they  may 
be  touched  without  any  risk  of  burning. 
Exposed  to  a  high  temperature,  it  is  not 
decomposed;  it  is  condensed  by  cold 
without  changing  its  form.  When  it  is  put 
in  contact  with  oxygen,  or  air,  either  at  a 
high  or  low  temperature,  it  experiences 
no  change,  except  seizing,  at  ordinary 
temperatures,  the  moisture  which  these 
gases  contain,  [t  becomes  in  consequence 
a  liquid  which  emits  extremely  dense  va- 
pours It  operates  in  the  same  way  with 
all  the  gases  which  contain  hygrometric 
water.  However  little  they  may  contain, 
it  occasions  in  them  very  perceptible  va- 
pours. It  may  hence  be  employed  with  ad- 
vantage to  show  whether  or  not  a  gas  con- 
tains moisture. 

No  combustible  body,  simple  or  com- 
pound, attacks  fluoboric  gas,  if  we  except 
the  alkaline  metals.  Potassium  and  sodi- 
um with  the  aid  of  heat,  burn  in  this  gas, 
almost  as  brilliantly  as  in  oxygen.  Boron 
and  fluate  of  potash,  are  the  products  of 
this  decomposition.  It  might  hence  be  in- 
ferred that  the  metal  seizes  the  oxygen  of 
the  boracic  acid,  sets  the  boron  at  liberty, 
and  is  itself  oxidized  and  combined  with 
the  fluoric  acid.  According  to  Sir  H.  Da- 
vy's views,  the  fluoboric  gas  being  a  com- 
pound of  fluorine  and  boron,  the  potassium 
unites  to  the  former,  giving  rise  to  the 
fluoride  of  potassium,  while  the  boron  re- 
mains disengaged. 

Fluoboric  gas  is  very  soluble  in  water; 
Dr.  John  Davy  savs,  water  can  combine 
with  700  times  its  own  volume,  or  twice 
its  weight  at  the  ordinary  temperature  and 
pressure  of  the  air.  The  liquid  has  a  spe- 
cific gravity  of  1.770.  If  a  bottle  contain- 
ing this  gas  be  uncorked  under  water,  the 
liquid  will  rush  in  and  fill  it  with  explosive 
violence.  Water  saturated  with  this  gas  is 
limpid,  fuming  and  very  caustic.  By  heat, 
about  one-fifth  of  the  absorbed  gas  may  be 
expelled;  but  it  is  impossible  to  abstract 
more.  It  then  resembles  concentrated  sul- 
phuric acid,  and  boils  at  a  temperature 
considerably  above  212°.  It  afterwards 
condenses  altogether,  in  stricc,  although  it 
contains  still  a  very  large  quantity  of  gas. 
It  unites  with  the  bases,  forming  salts,  call- 
ed fluoborates,  none  of  which  has  been 
applied  to  any  use.  The  most  important 
will  be  described  under  their  respective 
bases. 

The  2d  part  of  the  Phil.  Transactions 
for  1812,  contains  an  excellent  paper  by 
Dr.  John  Davy  on  fluosilicic  and  fluoboric 
gases,  and  the  combinations  of  the  latter 
with  ammoniacal  gas.  When  united  in 
equal  volumes,  a  pulverulent  salt  is  form- 
ed; a  second  volume  of  ammonia,  howev- 
er, gives  a  liquid  compound;  and  a  third 
of  ammonia,  which  is  the  limit  of  combi- 


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of  "about  68°  F.  was  reduced  from  103 
grains  to  91,  and  rendered  white  through- 
out. Some  parts  of  it  were  rendered  fria- 
ble. White  Carrara  marble  in  twenty  four 
hours,  at  77°,  lost  l-30th  of  its  weight,  but 
the  shining  surface  of  its  crystallized  tex- 


affords  still  a  liquid;  both  of  them  with  efflorescent  white  spots,  and  partly 
curious  on  many  accounts.  "  They  are,"  covered  with  the  common  white  crust,  be- 
says  he,  "  the  first  salts  that  have  been  ob-  ing  exposed  five  days  to  the  gas  at  a  heat 
served  liquid  at  the  common  temperature 
of  the  atmosphere.  And  they  are  addition- 
al facts  in  support  of  the  doctrine  of  defi- 
nite proportions,  and  of  the  relation  of  vol- 
umes." The  fluosilicic  acid  also  unites  to 
bases  forming  fluos-.licates. 

If  we  regard  fluoric  acid  as  capable  of  ture  was  distinguishable.  Black  marble 
combining,  like  the  sulphuric,  nitric,  and  was  not  affected,  either  in  weight  or  co- 
carbonic  acids,  with  the  oxidized  bases,  lour,  and  agate  was  not  attacked.  Trans- 
the  weight  of  its  prime  equivalent  is^.. 375;  parent  foliated  gypsum  fell  into  white 
whence  all  its  neutral  compounds  may  be  powder  on  its  surface,  in  a  few  hours ;  but 
inferred  ;  but  if  we  suppose  that  it  is  fluo-  this  powder  was  not  soluble  in  dilute  ni- 
tric acid, — so  that  the  fluoric  acid  had  not 
destroyed  the  combination  of  its  princi- 
ples ;  but  deprived  it  of  its  water  of  crys- 
tallization. A  striated  zeolite,  weighing 


nne  alone  which  unites  to  the  metallic 
bases,  then  the  prime  of  oxygen  must  be 
subtracted  from  them  and  added  to  its 
weight,  which  will  make  it  2.375.  This  is 
exactly  like  a  man  taking  a  piece  of  money 
out  of  the  one  pocket,  an«l  putting  it  in 


102  grains,  was  rendered  friable  on  its  sur- 
face in  forty-eight  hours,  and  weighed  only 


the  other.  All  the  proper  ions  experimen-     85|  grains.    On  being  immersed  in  water, 
tally  associated   with  the  compound,  re 
main  essentially  the  same.* 


and  then   dried,  it  gained  2£   grains,  but 
did  not  recover  its  lustre.    Barvtes  of  a  fi- 


From  the  remarkable  property  fluoric  brous  texture  remained  unchanged.  A  thin, 
acid  possesses  of  corroding  glass,  it  has  plate  of  Venetian  talc,  weighing  124  gr. 
been  employed  for  etching  on  it,  both  in  was  reduced  to  81  grains  in  forty-eight 
the  gaseous  state  and  combined  with  wa-  hours,  and  had  fallen  into  a  soft  powder, 
ter;  and  an  ingenious  apparatus  for  this  which  floated  on  water.  M.  Kortum  pour- 
purpose  is  given  by  Mr.  Richard  Knight,  ed  water  on  the  residuum  in  the  appara- 
in  the  Philosophical  Magazine,  vol.  xvii.  p.  tus,  and  the  next  day  the  sides  were  in- 
357.  crusted  with  small  crystalline  glittering 

M.  Kortum,  of  Warsaw,   having  found  flakes,  adhering  in  detached  masses,  which 

that  some  pieces  of  glass  were  more  easily  could  not  be  washed  off  with  dilute  ni- 

acted  upon  by  it  than  others,  tried  its  ef-  trous  acid. 

feet  on  various  stones.  Rock  cr\  stal,  ruby.         Of  the  combinations  of  this  acid  with 

sapphire,  lux  sapphire,  emerald,  oriental  most  of  the  bases  little  is  known, 
garnet,  amethyst,  chrysolite,   aventurine,        The  native  fluate  of  lime,  the  fluor  spar 

cirasol,   a  Saxon  topaz,  a   Brazilian  topaz  already  mentioned,  is  the  most  common 


burnt,  and  an  opal,  being  exposed  to  the 
fluoric  gas  at  a  temperature  of  122°  F 
was  not  acted  upon.  Diamond  exposed 
to  the  vapour  on  a  common  German  stove 
for  four  days,  was  unaffected.  Of  polished 
granite,  neither  the  quarts  nor  mica  ap- 
peared to  be  attacked,  but  the  feldspar 
was  rendered  opaque  and  muddy,  and  co- 
vered with  a  white  powder.  Chrysoprase. 


It  is  rendered  phosphorescent  by  heat,  but 
this  property  gradually  goes  off,  and  can- 
not be  produced  a  second  time.  With  a 
strong  heat  it  decrepitates.  At  a  heat  of 
130° 'of  Wedgwood,  it  enters  into  fusion 
in  a  clay  crucible.  It  is  not  acted  upon  by 
the  air,*  and  is  insoluble  in  water.  Concen- 
trated sulphuric  acid  deprives  it  of  the  flu- 
oric acid  with  effervescence,  at  the  com- 


an  opal  from   Hungary,  onyx,  a  carnelian    mon  temperature,  but  heat  promotes  its 

rf»  *-»•  _  1    "    1  1  __C1*  .-  n  -1  *j__  _       £• _j_      *       • *.\^  *~ 


from  Persia,  agate,  chalcedony,  green  Si- 
berian jasper,  and  common  flint,  were 
etched  by  it  in  twenty-four  hours ;  the 
chrysoprase  near  half  a  line  deep,  the 
onyx  pretty  deeply,  the  opal  with  the 
finest  and  most  regular  strokes,  and  all 
the  rest  more  or  less  irregularly.  The  un- 
covered part  of  the  b"o\vn  flint  had  be- 
come white,  but  was  still  compact :  water, 
alcohol,  and  other  liquids,  rendered  the 
whiteness  invisible,  but  as  soon  as  the  flint 
became  dry,  it  appeared  again.  The  same 
effect  was  produced  on  carnelian,  and  on 


action.  Besides  its  use  for  obtaining  this 
acid,  it  is  much  employed  in  chimney  or- 
naments, and  as  a  flux  for  some  ores  and 
stones. 

The  fluoric  acid  takes  barytes  from  the 
nitric  and  muriatic,  and  forms  a  salt  very 
little  soluble,  that  effloresces  in  the  air. 

With  magnesia,  it  precipitates,  accord- 
ing to  Scheele,  in  a  gelatinous  mass.  But 
Bergmann  says,  that  a  part  remains  in  so- 
lution, and  by  spontaneous  evaporation, 
shoots  on  the  sides  of  the  vessel  into  crys- 
talline threads,  resembling  a  transparent 


a  dark  brown  jasper,  if  the  operation  of  mass.  The  bottom  of  the  vessel  affords  al- 

the  acid  were  stopped,   as  soon  as  it  had  so  crystals  in  hexagonal  prisms,  ending  in 

whitened  the   part  exposed,  without  de-  a  low  pyramid  of  three  rhombs.  He  adds, 

stroying- its  texture.  A  piece  of  black  flint,  that  no  acid  decomposes  it  in  the  moist 


ACI 


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•Way,  and  that  it  is  unalterable  by  the  most 
violent  fire. 

The  fluate  of  potash  is  not  crystalliza- 
ble  ;  and  if  it  be  evaporated  to  dryness,  it 
soon  deliquesces.  Its  taste  is  somewhat 
acrid  and  saline.  It  melts  with  a  strong 
heat,  is  afterward  caustic,  and  attracts 
moisture. 

This  fluate,  as  well  as  those  of  soda  and 
ammonia,  are  commonly  obtained,  as  Four- 
croy  conceives,  in  the  state  of  triple  sails, 
being  combined  with  siliceous  earth. 

The  fluate  of  soda  affords  small  crystals 
in  cubes  and  parallelograms,  of  a  bitterish 
and  astringent  taste,  decrepitating  on  burn- 
ing coals,  and  melting  into  semitransparent 
globules  with  the  blowpipe,  without  losing 
their  acid.  It  is  not  deliquescent,  and  dif- 
ficultly soluble.  The  concentrated  acids 
disengage  its  acid  with  effervesence. 

The  fluate  of  ammonia  may  be  prepared 
By  adding  carbonate  of  ammonia  to  diluted 
fluoric  acid  in  a  leaden  vessel,  observing, 
that  there  is  a  small  excess  of  acid.  This  is 
a  very  delicate  test  of  lime. 

Fourcroy  informs  us,  that  ammonia  and 
magnesia  form  a  triple  salt  with  the  fluoric 
acid. 

Scheele  observed,  that  the  fluor  acid 
united  with  alumina  into  a  salt  that  could 
not  be  crystallized,  but  assumed  a  gela- 
tinous form.  Fourcroy  adds,  that  the  solu- 
tion is  always  acid,  astringent,  decompo- 
sable and  precipitabie  by  all  the  earthy 
and  alkaline  bases,  but  capable  of  uniting 
with  silex  and  the  alkalis  into  various  triple 
salts.  A  native  combination  of  alumina  and 
soda  with  fluoric  acid,  has  been  found  late- 
ly in  a  semitransparent  stone  from  Green- 
land. See  CRYOLITE. 

The  affinity  of  the  fluoric  acid  for  silex, 
has  already  appeared.  If  the  acid  solution 
of  fluate  of  silex,  obtained  by  keeping  the 
solution  of  the  acid  in  glass  vessels,  be 
evaporated  to  dryness,  the  fluoric  acid  may 
be  disengaged  from  the  solid  salt  remain- 
ing, as  Fourcroy  informs  us,  either  by  the 
powerful  acids,  or  by  a  strong  heat ;  and 
if  the  solution  be  kept  in  a  vessel  that  ad- 
mits of  a  slow  evaporation,  small  brilliant 
crystals,  transparent,  hard,  and  apparently 
of  a  rhomboidal  figure,  will  form  on  the 
bottom  of  the  vessel,  as  Bergmann  found 
in  the  course  of  two  years'  standing. 

Besides  the  fluor  spar  and  cryolite,  in 
which  it  is  abundant,  fluoric  acid  has  been 
detected  in  the  topaz  ;  in  wavellite,  in 
which,  however,  it  is  not  rendered  sensi- 
ble by  sulphuric  acid ;  and  in  fossil  teeth 
and  fossil  ivory,  though  it  is  not  found  in 
cither  of  these  in  their  natural  state. 

ACIDS  (FERROPRUSSIC  and  FKRRUBETTED 
CHTAZIC).  See  ACID  (Paussic). 

ACID  (FORMIC).  It  has  longbeen  known, 
that  ants  contain  a  strong  acid,  which  they 
occasionally  emit ;  and  which  may  be  ob- 


tained from  the  ants,  either  by  simple  dis- 
tillation, or  by  infusion  of  them  in  boiling 
water,  and  subsequent  distillation  of  as 
much  of  the  water  as  can  be  brought  over 
without  burning  the  residue.  After  this  it 
may  be  purified  by  repeated  rectifications, 
or  by  boiling  to  separate  the  impurities  ;  or 
after  rectification  it  may  be  concentrated 
by  frost. 

*  This  acid  has  a  very  sour  taste,  *nd 
continues  liquid  even  at  very  low  temper- 
atures. Its  specific  gravity  is  1.1 168  at  68°, 
which  is  much  denser  than  acetic  acid  ever 
is.    Berzelius  finds,  that  the  formiate  of 
lead  consists  of  4.696  acid,  and  14  oxide 
of  lead  ;  and  that  the  ultimate  constituents 
of  the  dry  acid  are  hydrogen  2.84  -{-  car- 
bon 32.40 -f  oxygen  64.76  =  100.* 

We  have  been  informed,  that  it  has  been 
employed  among  quacks,  as  a  wonderful 
remedy  for  the  toothach,  by  applying  it  to 
the  tooth  with  the  points  of  the  forefinger 
and  thumb. 

*  ACID  (FUNGIC).  The  expressed  juice 
of  the  boletus  juglandis,  boletus  pseiido-igni- 
arius,  the  phallus  impudicus,  merulius  can- 
tharellus,  or  the  pepiza  nigra,  being  boiled 
to  coagulate  the  albumen,  then  filtered, 
evaporated  to  the   consistence  of  an  ex- 
tract, and  acted  on  by  pure  alcohol,  leaves 
a  substance   which  has    been   called  by 
Braconnot  Fungic  Jlcid.  He  dissolves  that 
residue  in  water,  added  solution  of  acetate 
of  lead,  whence  resulted  fungate  of  lead, 
which  he  decomposed  at  a  gentle  heat  by 
dilute  sulphuric  acid.    The  evolved  fun- 
gic  acid  being  saturated  with  ammonia, 
yielded  a  crystallized  fungate  of  ammonia, 
which  he   purified  by  repeated  solution 
and  crystallization.    From  this  salt  by  ace- 
tate of  lead,  and  thereafter  sulphuric  acid 
as  above  detailed,  he  procured  the  pure 
fungicacid. 

It  is  a  colourless,  uncrystallizable,  and 
deliquescent  mass,  of  a  very  sour  taste. 
The  fungates  of  potash  and  soda,  are  un- 
crystallizable ;  that  of  ammonia  forms  re- 
gular six-sided  prisms ;  that  of  lime  is 
moderately  soluble,  and  is  not  affected  by 
the  air ;  that  of  barytes  is  soluble  in  15 
times  its  weight  of  water,  and  crystallizes 
with  difficulty ;  that  of  magnesia  appears 
in  soluble  granular  crystals.  This  acid  pre- 
cipitates from  the  acetate  of  lead  a  white 
flocculent  fungate,  which  is  soluble  in  dis- 
tilled vinegar.  When  insulated,  it  does 
not  affect  solution  of  nitrate  of  silver ;  but 
the  fungates  decompose  this  salt.* 

ACID  (GALLIC).  This  acid  is  found  in 
different  vegetable  substances  possessing 
astringent  properties,  but  most  abundant- 
ly in  the  excrescences  termed  galls,  or  nut- 
galls,  whence  it  derives  its  name.  It  may 
be  obtained  by  macerating  galls  in  water, 
filtering,  and  suffering  the  liquor  to  stand 
exposed  to  the  air.  It  will  grow  mouldy, 


AUI 


ACI 


be  covered  with  a  thick  glutinous  pellicle, 
abundance  of  glutinous  flocks  will  full 
down,  and,  in  the  course  of  two  or  three 
months,  the  sides  of  the  vessel  will  appear 
covered  with  small  yellowish  crystals, 
abundance  of  which  will  likewise  be  found 
on  the  under  surface  of  the  supernatant 
pellicle.  These  crystals  may  be  purified 
by  solution  in  alcohol,  and  evaporation  to 
dryness. 

Or  muriate  of  tin  may  be  added  to  the 
infusion  of  galls,  till  no  more  precipitate 
falls  down  ;  the  excess  of  oxide  o^tin  re- 
maining in  the  solution,  may  then  be  pre- 
cipitated by  sulphuretted  hydrogen  gas, 
and  the  liquor  will  yield  crystals  of  gallic 
acid  by  evaporation. 

A  more  simple  process,  however,  is  that 
of  M.  Fiedler.  Boil  an  ounce  of  powdered 
galls  in  sixteen  ounces  of  water  to  eight, 
and  strain.  Dissolve  two  ounces  of  alum 
in  water,  precipitate  the  alumina  by  car- 
bonate of  potash  ;  and,  after  edulcorating 
it  completely  by  repeated  ablutions,  add  it 
to  the  decoction,  frequently  stirring  the 
mixture  with  a  glass  rod.  The  next  day 
filter  the  mixture  ;  wash  the  precipitate 
with  warm  water,  till  this  will  no  longer 
blacken  sulphate  of  iron  ;  mix  the  wash- 
ings with  the  filtered  liquor,  evaporate, 
and  the  gallic  acid  will  be  obtained  in  fine 
needled  crystals. 

These  crystals  obtained  in  any  of  these 
ways,  however,  according  to  Sir  H.  Davy, 
are  contaminated  with  a  small  portion  of 
extractive  matter  ;  and  to  purify  them  they 
may  be  placed  in  a  glass  capsule  in  a  sand 
heat,  and  sublimed  into  another  capsule, 
inverted  over  this  and  kept  cool.  M.  De- 
yeux  indeed  recommends  to  procure  the 
acid  by  sublimation  in  the  first  instance  ; 
putting  the  powdered  galls  into  a  glass 
retort,  and  applying  heat  slowly  and  cau- 
tiously ;  when  the  acid  will  rise,  and  be 
condensed  in  the  neck  of  the  retort.  This 
process  requires  great  care,  as,  if  the  heat 
be  earned  so  far  as  to  disengage  the  oil, 
the  crystals  will  be  dissolved  immediately. 
The  crystals  thus  obtained  are  pretty  large, 
laminated,  and  brilliant. 

The  gallic  acid,  placed  on  a  red-hot 
iron,  burns  with  flame,  and  emits  an  aro- 
matic smell,  not  unlike  that  of  benzole  acid. 
It  is  soluble  in  20  parts  of  cold  water,  and 
in  3  parts  at  a  boiling  heat.  It  is  more  so- 
luble in  alcohol,  which  takes  up  an  equal 
•weight  if  heated,  and  one-fourth  of  its 
weight  cold. 

*  It  has  an  acido-astringent  taste,  and 
reddens  tincture  of  litmus.  It  does  not  at- 
tract humidity  from  the  air. 

From  the  gallate  of  lead,  Berzelius  infers 
the  equivalent  of  this  acid  to  be  8.00.  Its 
ultimate  constituents  are,  hydrogen  5.00 
4-  carbon  56  64  +  oxygen  38.36  =  100. 

This  acid,  in  its  combinations  with  the 


salifiable  bases,  presents  some  remarkable 
phenomena.  If  we  pour  its  aqueous  solu- 
tion by  slow  degrees  into  lime,  bar)  tes,  or 
strontian  water,  there  will  first  be  formed 
a  greenish  white  precipitate.  As  the  quan- 
tity of  acid  is  increased,  the  precipitate 
changes  to  a  violet  hue,  and  eventually 
disappears.  The  liquid  has  then  acquired 
a  reddish  tint.  Among  the  salts  those  only 
of  black  oxide,  and  red  oxide  of  iron,  are 
decomposed  by  the  pure  gallic  acid.  It 
forms  a  blue  precipitate  with  the  first, 
and  a  brown  with  the  second.  But  when 
this  acid  is  united  with  tannin,  it  decom> 
poses  almost  all  the  salts  of  the  permanent 
metals.* 

Concentrated  sulphuric  acid  decompo- 
ses and  carbonizes  it  ;  and  the  nitric  acid 
converts  it  into  malic  and  oxalic  acids. 

United  with  barytes,  strontian,  lime,  and 
magnesia,  it  forms  salts  of  a  dull  yellow 
colour,  which  are  little  soluble,  but  mora 
so  if  their  base  be  in  excess.  With  alkalis, 
it  forms  salts  that  are  not  very  soluble  in 
general. 

Its  most  distinguishing  characteristic  is 
its  great  affinity  for  metallic  oxides,  so  as, 
when  combined  with  tannin,  to  take  them 
from  powerful  acids.  The  more  readily 
the  metallic  oxides  part  with  their  oxy- 
gen, the  more  they  are  alterable  by  the 
gallic  acid.  To  a  solution  of  gold,  it  im- 
parts a  green  hue ;  and  a  brown  precipi- 
tate is  formed,  which  readily  passes  to 
the  metallic  state,  and  covers  the  solution 
with  a  shining  golden  pellicle.  With  ni- 
tric solution  of  silver,  it  produces  a  similar 
effect.  Mercury  it  precipitates  of  an  orange 
yellow ;  copper,  brown  ;  bismuth,  of  a  le- 
mon colour;  lead,  white;  iron,  black.  Pla- 
tina,  zinc,  tin,  cobalt,  and  manganese,  are 
not  precipitated  by  it. 

The  gallic  acid  is  of  extensive  use  in  the 
art  of  dyeing,  as  it  constitutes  one  of  the 
principal  ingredients  in  all  the  shades  of 
black,  and  is  employed  to  fix  or  improve 
several  other  colours.  It  is  well  known 
as  an  ingredient  in  ink.  See  GALLS,  DYE- 
ING and  IKK. 

*  ACID     (HYDROCYANIC).      See     ACID 
(Pnussic). 

*  ACID  (HvDTuoDic).    This  acid  resem- 
bles the  muriatic  in  being  gaseous  in  its 
insulated  state.     If  four  parts  of  iodine  be 
mixed  with  one  of  phosphorus,  in  a  small 
glass  retort,  applying  a  gentle  heat,  and 
adding  a  few  drops  of  water  from  time  to 
time,  a  gas  comes  over,  which  must   be 
received  in  the  mercurial  bath.     Its  spe- 
cific  gravity  is  4.4;    100    cubic    inches, 
therefore,  weigh  134  2  grains.     It  is  elas- 
tic and  invisible,  but  has  a  smell  some- 
what similar  to  that  of  muriatic  acid.  Mer- 
cury after  some  time  decomposes  it,  seiz- 
ing its  iodine,  and  leaving  its  hydrogen 
equal  to  one-half  the  original  bulk,  at  li 


ACI 


AC1 


berty.  Chlorine,  on  the  other  hand, 
unites  to  its  hydrogen,  and  precipitates 
the  iodine.  From  these  experiments,  it 
evidently  consists  of  vapour  of  iodine  and 
hydrogen,  which  combine  in  equal  vo- 
lumes, without  change  of  their  primitive 
bulk.  Us  composition  by  weight,  is  there- 
fore 8.61  of  iodine  -f  0.0694  hydrogen, 
which  is  the  relation  of  their  gasiform 
densities;  and  if  8.61  be  divided  by  0.0694, 
it  will  give  the  prime  of  iodine  124  times 
greater  than  hydrogen ;  and  as  the  prime 
of  oxygen  is  eight  times  more  than  that  of 
hydrogen,  on  dividing  124  by  8,  we  have 
15.5  for  the  prime  equivalent  of  iodine  ; 
to  which,  if  we  add  0.125,  the  sum  15.625 
represents  the  equivalent  of  hydriodic 
acid.  The  number  deduced  for  iodine, 
from  the  relation  of  iodine  to  hydrogen  in 
Volume,  approaches  very  nearly  to  15.621, 
which  was  obtained  in  the  other  experi- 
ments of  M.  Gay-Lussac.  Hydriodic  acid 
is  partly  decomposed  at  a  red  heat,  and 
the  decomposition  is  complete,  if  it  be 
mixed  with  oxygen.  Water  is  formed  and 
iodine  separated. 

M.  Gay-Lussac,  in  his  admirable  memoir 
•n  iodine  and  its  combinations,  published 
in  the  Ann.  de  Chimie,  vol.  xci.  says,  that 
the  specific  gravity  he  there  gives  for  hy- 
driodic gas,  viz.  4.443,  must  be  a  little  too 
great,  for  traces  of  moisture  were  seen  in 
the  inside  of  the  bottle.  In  fact,  if  we 
take  15.621  as  the  prime  of  iodine  to  oxy- 
gen, whose  specific  gravity  is  1.1111; 
and  multiply  one-half  of  this  number  by 
15  621,  as  he  does,  we  shall  have  a  pro- 
duct of  8.6696,  to  which  adding  0.0694 
for  the  density  of  hydrogen,  we  get  the 
sum  8.7390,  one-half  of  which  is  obvious- 
ly the  density  of  the  hydriodic  gas  = 
4.3695.  When  the  prime  of  iodine  is  ta- 
ken at  15.5,  then  the  density  of  the  gas 
comes  out  4.3. 

We  can  easily  obtain  an  aqueous  hy- 
driodic acid  very  economically,  by  pass- 
ing sulphuretted  hydrogen  gas  through  a 
mixture  of  water  and  iodine  in  a  Woolfe's 
bottle.  On  heating  the  liquid  obtained, 
the  excess  of  sulphur  flies  off,  and  leaves 
liquid  hydriodic  acid.  At  temperatures 
below  262°,  it  parts  with  its  water ;  and 
becomes  of  a  density  =  1.7.  At  262°  the 
acid  distils  over.  When  exposed  to  the 
air,  it  is  speedily  decomposed,  and  iodine 
is  evolved.  Concentrated  sulphuric  and 
nitric  acids  also  decompose  it.  When 
poured  into  a  saline  solution  of  lead,  it 
throws  down  a  fine  orange  precipitate. 
"With  solution  of  perexide  of  mercury,  it 
gives  a  red  precipitate  ;  and  with  that  of 
silver,  a  white  precipitate  insoluble  in  am- 
monia. Hydriodic  acid  may  also  be  form- 
ed, by  passing  hydrogen  over  iodine  at  an 
elevated  temperature. 

The  compounds  of  hydriodic  acid  with 


the  salifiable  bases  may  be  easily  fortnecl, 
either  by  direct  combination,  or  by  acting 
on  the  basis  in  water,  with  iodine.  The 
latter  mode  is  most  economical.  Upon  a 
determinate  quantity  of  iodine,  pour  solu- 
tion of  potash  or  soda,  till  the  liquid  ceases 
to  be  coloured.  Evaporate  to  dryness, 
and  digest  the  dry  salt  in  alcohol  of  the 
specific  gravity  0.810,  or  0.820.  As  the 
iodate  is  not  soluble  in  this  liquid,  while 
the  hydriodate  is  very  soluble,  the  two 
salts  easily  separate  from  each  other.  Af- 
ter having  washed  the  iodate  two  or  three 
times  with  alcohol,  dissolve  it  in  water, 
and  neutralize  it  with  acetic  acid.  Eva- 
porate to  dryness;  and  digest  the  dry  salt 
in  alcohol,  to  remove  the  acetate.  After 
two  or  three  washings,  the  iodate  is  pure. 
As  for  the  alcohol  containing  the  hydrio- 
date, distil  it  off,  and  then  complete  the 
neutralization  of  the  potash,  by  means  of 
a  little  hydriodic  acid  separately  obtained, 
Sulphurous  and  muriatic  acids,  as  well  as 
sulphuretted  hydrogen,  produce  no  change 
on  the  hydriodates,  at  the  usual  tempera- 
ture of  the  air. 

Chlorine,  nitric  acid,  and  concentrated 
sulphuric,  instantly  decompose  them,  and 
separate  the  iodine. 

With  solution  of  silver,  they  give  a  white 
precipitate  insoluble  in  ammonia ;  with  the 
pernitrate  of  mercury,  a  greenish  yellow 
precipitate ;  with  corrosive  sublimate,  a 
precipitate  of  a  fine  orange  red,  very  so- 
luble in  an  excess  of  hydriodate;  and  with 
nitrate  of  lead,  a  precipitate  of  an  orange 
yellow  colour.  They  dissolve  iodine,  and 
acquire  a  deep  reddish  brown  colour. 

Hydriodate  of  potash*  or  in  the  dry  state, 
iodide  of  potassium,  yields  crystals  like 
sea-salt,  which  melt  and  sublime  at  a  red 
heat.  This  salt  is  not  changed  by  being- 
heated  in  contact  with  air.  100  parts  of 
water  at  64°,  dissolve  143  of  it.  It  con- 
sists of  15.5  iodine,  and  4.95  potassium. 

Hydriodate  of  soda,  called  in  the  dry 
state  iodide  of  sodium,  may  be  obtained  in 
pretty  large  flatrhomboidal  prisms.  These 
prisms  unite  together  with  larger  ones, 
terminated  in  echellon,  and  striated  long- 
ways, like  those  of  sulphate  of  soda. 
This  is  a  true  hydriodate,  for  it  contains 
much  water  of  crystallization.  It  consists, 
when  dry,  of  15.5  iodine  -f-  2'95  so- 
dium. 

Hydnodate  ofbarytes  crystallizes  in  fine 
prisms,  similar  to  muriate  of  strontian.  In 
its  dry  state,  it  consists  of  15.5  iodine  -\-. 
8.7  or  8.75  barium. 

The  hydriodates  of  lime  and  strontian  are 
very  soluble;  and  the  first  exceedingly 
deliquescent. 

Hydnodate  of  ammonia  results  from  the 
combination  of  equal  volumes  of  ammonia- 
cal  and  hydriodic  gases ;  though  it  is  usual- 
ly prepared  by  saturating  the  liquid  acid 


ACI 


ACI 


with  ammonia.  It  is  nearly  as  volatile  as 
gal  ammoniac ;  but  it  is  more  soluble  and 
more  deliquescent.  It  crystallizes  in  cubes. 
From  this  compound,  we  may  infer  the 
prime  of  hydriodic  acid,  from  the  specific 
gravity  of  the  hydriodic  gas;  or  having 
the  prime,  we  may  determine  the  sp.  gr. 
If  we  call  15.625  its  equivalent,  then  we 
have  this  proportion :—  As  a  prime  of  am- 
monia, to  a  prime  of  hydriodic  acid,  so  is 
the  density  of  ammoniacal,  to  that  of  hy- 
driodic gas. 

2.13  :  15.625  :  :  0.59  :  4.32* 

This  would  make  100  cubic  inches 
weigh  exactly  132  grains. 

Hydriodate  of  magnesia  is  formed  by  unit- 
ing its  constituents  together;  it  is  deli- 
quescent, and  crystallizes  with  difficulty. 
It  is  decomposed  by  a  strong  heat. 

Hydriodate  of  zinc  is  easily  obtained,  by 
putting  iodine  into  water  with  an  excess  of 
zinc,  and  favouring1  their  action  by  heat. 
When  dried  it  becomes  an  iodide. 

All  the  hydriodates  have  the  property 
of  dissolving  abundance  of  iodine;  and 
thence  they  acquire  a  deep  reddish  brown 
colour.  They  part  with  it  on  boiling,  or 
when  exposed  to  the  air  after  being 
dried.* 

*  ACID  (IOTHC).  When  barytes  water  is 
made  to  act  on  iodine,  a  soluble  hydrio- 
date,  and  an  insoluble  iodate  of  barytes, 
are  formed.  On  the  latter,  well  washed, 
pour  sulphuric  acid  equivalent  to  the  ba- 
rytes present,  diluted  with  twice  its 
weight  of  water,  and  heat  the  mixture. 
The  iodic  acid  quickly  abandons  a  portion 
of  its  base,  and  combines  with  the  water; 
fmt  though  even  less  than  the  equivalent 
proportion  of  sulphuric  acid  has  been 
used,  a  little  of  it  will  be  found  mixed 
with  the  liquid  acid.  If  we  endeavour  to 
separate  this  portion,  by  adding  barytes 
water,  the  two  acids  precipitate  together. 

The  above  economical  process  is  that  of 
M.  Gay-Lussac ;  but  Sir  H.  Davy,  who  is 
the  first  discoverer  of  this  acid,  invented 
one  more  elegant,  and  which  yields  a 
purer  acid.  Into  a  long  glass  tube,  bent 
like  the  letter  L  inverted  (rj),  shut  at  one 
end,  put  100  grains  of  chlorate  of  potash, 
and  pour  over  it  400  grains  of  muriatic 
acid,  specific  gravity  1.105.  Put  40  grains 
of  iodine  into  a  thin  long-necked  receiver. 
Into  the  open  end  of  the  bent  tube  put 
some  muriate  of  lime,  and  then  connect 
it  with  the  receiver.  Apply  a  gentle  heat 
to  the  sealed  end  of  the  former.  Pro- 
toxide of  chlorine  is  evolved,  which,  as 
it  comes  in  contact  with  the  iodine,  pro- 
duces combustion,  and  two  new  com- 
pounds, a  compound  of  iodine  and  oxy- 
gen, and  one  of  iodine  and  chlorine.  The 
latter  is  easily  separable  by  heat,  while 
the  former  remains  in  a  state  of  purity. 

The  iodic  acid  of  Sir  H,  Davy  is  a  white 


semi-transparent  solid.  It  has  a  strong 
acido-as'ringent  tas'e,  but  no  smell.  Its 
density  is  considerably  greater  than  that 
of  sulphuric  acid,  in  which  it  rapidly  sinks. 
It  melts,  and  is  decomposed  into  iodine 
and  oxygen,  at  a  temperature  of  about 
620°.  A  grain  of  iodic  acid  gives  out 
176.1  grain  measures  of  oxygen  gas.  It 
would  appear  from  this,  that  iodic  acid 
consists  of  15.5  iodine,  to  5  oxygen. 
This  agrees  with  the  determination  of  M. 
Gay-Lussac,  obtained  from  much  greater 
quantities ;  and  must  therefore  excite  ad- 
miration at  the  precision  of  result  derived 
by  sir  H.  from  the  very  minute  proper- 
tions  which  he  used.  176.1  grain  mea- 
sures, are  equal  to  0.7  of  a  cubic  inch; 
winch,  calling  100  cubic  inches  33.88, 
will  weigh  0  237  of  a  g.ain,  leaving  0.763 
for  iodine.  And  0.763  .-  0.2 .>7  :  :  15.5  :  5.0. 
Iodic  acid  deliquesces  in  the  air,  and  is, 
of  course,  very  soluble  in  \vaer.  It  first 
reddens,  and  then  destroys  the  blues  of 
vegetable  infusions.  It  blanches  other  ve- 
getable colours.  By  concen  ration  of  the 
liquid  acid  of  Gay-Lussac,  it  acquires  the 
consistence  of  sirup.  Had  not  the  happy 
genius  of  Sir  H.  Davy  produced  it  in  the 
solid  state,  his  celebrated  French  rival 
would  have  persuaded  us  to  suppose  that 
slate  impossible.  "  Hitherto,5'  says  M. 
Gay-Lussac,  "iodic  acid  has  only  been 
obtained  in  combination  with  water  and 
it  is  very  probable  that  this  liquid  is  as 
necessary  as  a  base,  to  keep  the  elements 
of  this  acic.  united,  as  we  see  is  the  case 
with  sulphuric  acid,  nitric  acid,"  8tc.  M. 
Gay-Lussac's  Memoir  was  read  to  the 
Institute  on  the  1st  August  1814 ;  and,  on 
the  10th  February  following,  Sir  H.  dates 
at  Rome  his  communication  to  the  Uo}  al 
Society,  written  before  he  had  seen  the 
French  paper.  When  the  temperature 
of  inspissated  iodic  acid  is  raised  to  about 
392°,  it  is  resolved  into  iodine  and  oxygen. 
Here  we  see  the  influence  of  water  is  ex- 
actly the  reverse  of  what  M.  Gay-Lussac 
assigns  to  it;  for,  instead  of  giving  fixity 
like  a  base  to  the  acid,  it  favours  its  de- 
composition. The  dry  acid  may  be  raised 
to  upwards  of  600y  without  being  decom- 
posed. Sulphurous  acid,  and  sulphuret- 
ted hydrogen  immediately  separate  iodine 
from  it.  Sulphuric  and  nitric  acids  have 
no  action  on  it.  With  solution  of  silver, 
it  gives  a  white  precipitate,  very  soluble 
in  ammonia.  It  combines  with  all  the 
bases,  produces  all  the  iodates  which  we 
can  obtain  by  making  the  alkaline  bases 
act  upon  iodine  in  water.  It  likewise 
forms  with  ammonia  a  salt,  which  fulmin- 
ates when  heated.  Between  the  acid 
prepared  by  M.  Gay-Lussac,  and  that  of 
Sir  H.  Davy,  there  is  one  important  dif- 
ference. The  latter  being  dissolved,  may, 
by  evaporation  of  the,  water,  pass  not  only 


ACT 


ACI 


the  inspissated  sirupy  state,  but  can 
made  to  assume  a  pasty  consistence  ; 
ind  finally,  by  a  stronger  heat,  yields  the 
solid  substance  unaltered.  When  a  mix- 
:ure  of  it,  with  charcoal,  sulphur,  rosin, 
sugar,  or  the  combusrible  metals,  in  a 
finely  divided  state,  is  heated,  detonations 
are  produced;  and  its  solution  rapidly 
[corrodes  all  the  metals  to  which  Sir  H. 
Davv  exposed  it,  both  gold  and  platinum, 
but  much  more  intensely  the  first  of  these 
metals. 

It  appears  to  form  combinations  with  all 
the  fluid  or  solid  acids  which  it  does  not 
decompose.  When  sulphuric  acid  is  drop- 
ped into  a  concentra.ed  solution  of  it  in 
hot  water,  a  solid  substance  is  precipita- 
ted, which  consists  of  the  acids  in  com- 
I  bination ;  for,  on  evaporating  the  s  lu- 
tion  by  a  gentle  heat,  nothing  rises  but 
i  water.  On  increasing  the  heat  in  an  ex- 
penment  of  this  kind,  the  solid  substance 
formed  fused  ;  and  on  cooling  the  mixture, 
rhomboidal  cr-stals  formed  of  a  pale  yel- 
low colour,  which  were  very  fusible,  and 
which  did  not  change  at  the  heat  at  which 
the  compound  of  oxygen  and  iodine  de- 
composes, but  sublimed  unaltered.  When 
urged  by  a  much  stronger  heat,  it  par- 
tiall  sublimed  and  partially  decomposed, 
affording  oxygen,  iodine,  and  sulphuric 
acid. 

With  hydro  phosphoric,  the  compound 
presents  phenomena  precisely  similar,  and 
they  form  together  a  solid,  yellow,  crys- 
talline combination. 

With  hydro-nitric  acid,  it  yields  white 
crystals  in  rhomboidal  plates,  which,  at  a 
lower  heat  than  the  preceding  acid  com- 
pounds, are  resolved  into  hydro-nitric 
acid,  oxygen,  and  iodine.  By  liquid  mu- 
riatic acid,  the  substance  is  immediately 
decomposed,  and  the  compound  of  chlo- 
'jine  and  iodine  is  formed.  All  these  acid 
compounds  redden  vegetable  blues,  taste 
sour,  and  dissolve  gold  and  platinum. 
From  these  curious  researches,  Sir  H. 
Davy  infers,  that  M.  Gay-Lussac's  iodic 
acid,  is  a  sulpho-iodic  acid,  and  probably  a 
'definite  compound.  However  minute  the 
quantity  of  sulphuric  acid  made  to  act  on 
the  iodide  of  barium  may  be,  a  part  of  it 
is  always  employed  to  form  the  compound 
acid  ;  and  the  residual  fluid  contains  both 
the  compound  acid  and  a  certain  quantity 
of  the  original  salt. 

In  treating  of  hydriodic  acid,  we  have 
already  described  the  method  of  forming 
the  iodates,  a  class  of  salts  distinguished 
chiefly  for  their  property  of  deflagrating 
when  heated  with  combustibles.* 

*Acin  (CHLORTODTC).  The  discovery  of 
this  interesting  compound,  constitutes  an- 
other of  Sir  H.  Davy's  contributions  to  the 
advancement  of  science.  In  a  communi- 
cation from  Florence  to  the  Royal  Socie- 


ty, in  March  1814,  he  gives  a  curious  de« 
tail  of  its  preparation  and  properties.  He 
formed  it,  by  admitting  chlorine  in  excess 
to  known  quantities  of  iodine,  in  vessels 
exhausted  of  air,  and  repeatedly  heating 
the  sublimate.  Operating  in  this  way,  he 
found  that  iodine  absorbs  less  than  one- 
third  of  its  weight  of  chlorine. 

Chloriodic  acid  is  a  very  volatile  sub- 
stance, and  in  consequence  of  its  action 
upon  mercury,  he  was  not  able  to  deter- 
mine the  elastic  force  of  its  vapour.  In  the 
most  considerable  experiment  which  he 
made  to  determine  proportions,  20  grains 
caused  the  disappearance  of  9.6  cubical 
inches  of  chlorine.  These  weigh  7.296 
grains.  And  20  :  7.296  : :  15.5  :  5.6,  a  num. 
ber  certainly  not  far  from  4.5,  the  prime 
equivalent  of  chlorine ;  and  in  the  very 
delicate  circumstances  of  the  experiment, 
an  approximation  not  to  be  disparaged. 
Indeed,  the  first  result  in  close  vessels, 
giving  less  than  one-third  of  the  weight 
of  chlorine  absorbed,  comes  sufficiently 
near  4.5,  which  is  just  a  little  less  than 
one-third  of  15.5,  the  prime  equivalent  of 
iodine. 

The  chloriodic  acid  formed  by  the  sub- 
limation of  iodine  in  a  great  excess  of 
chlorine,  is  of  a  bright  yellow  colour; 
when  fused  it  becomes  of  a  deep  orange, 
and  when  rendered  elastic,  it  forms  a  deep 
orange  coloured  gas.  It  is  capable  of 
combining  with  much  iodine  when  they 
are  heated  together,  its  colour  becomes,  in 
consequence,  deeper,  and  the  chloriodio 
acid  and  the  iodine  rise  together  in  the 
elastic  state.  The  solution  of  the  chlo- 
riodic acid  in  water,  likewise  dissolves 
large  quantities  of  iodine,  so  that  it  is  pos- 
sible to  obtain  a  fluid  containing  very  dif- 
ferent proportions  of  iodine  and  chlorine. 

When  two  bodies  so  similar  in  their 
characters,  and  in  the  compounds  they 
form  as  iodine  and  chlorine,  act  upon  sub- 
stances at  the  same  time,  it  is  difficult,  Sip 
H.  observes,  to  form  a  judgment  of  the 
different  parts  that  they  play  in  the  new- 
chemical  arrangement  produced.  It  ap- 
pears most  probable,  that  the  acid  pro- 
perty of  the  chloriodic  compound  de- 
pends upon  the  combination  of  the  two 
bodies ;  and  its  action  upon  solutions  of 
the  alkalis  and  earths  may  be  easily  ex- 
plained, when  it  is  considered  that  chlo- 
rine has  a  greater  tendency  than  iodine  to 
form  double  compounds  with  the  metals, 
and  that  iodine  has  a  greater  tendency 
than  chlorine  to  form  triple  compounds 
with  oxygen  and  the  metals. 

A  triple  compound  of  this  kind  with  so- 
dium may  exist  in  sea  water,  and  would 
be  separated  with  the  first  crystals  that 
are  formed  by  its  evaporation.  Hence,  it 
may  exist  in  common  salt.  Sir  H.  Davy 
ascertained,  by  feeding  birds  with  brea4 


ACI 


ACI 


snaked  with  water,  holding  some  of  it  in 
solution,  that  it  is  not  poisonous  like  iodine 
itself.* 

ACID  (HrDROTHiowic).  Some  of  the 
German  chemists  distinguish  sulphuretted 
hydrogen  by  this  name,  on  account  of  its 
properties  resembling  those  of  an  acid. 

*  Acm  (Kimc).     A   peculiar  acid  ex- 
tracted by  M.  Vauquelin  from  cinchona. 
Let  a  watery  extract  from  hot  infusions  of 
the  bark  in  powder  be  made.   Alcohol  re- 
moves the  resinous  part  of  this  ^xtract, 
and  leaves  a  viscid  residue,  of  a  brown  co- 
lour, which  has  hardly  any  bitter  taste, 
and  which  consists  of  kinite  of  lime  and  a 
mucilaginous  matter.     This  residue  is  dis- 
solved in  water,  the  liquor  is  filtered  and 
left  to  spontaneous  evaporation,  in  a  warm 
place.    It  becomes  thick  like  sirup,  and 
then    deposites    by   degrees    crystalline 
plates,  sometimes  hexahedral,  sometimes 
rhomboidal,  sometimes    square,  and    al- 
ways coloured  slightly  of  a  reddish  brown. 
These  plates  of  kinate  of  lime  must  be  pu- 
rified by  a  second  crystallization.     They 
are  then  dissolved  in  10  or  12  times  their 
weight  of  water,  and  very  dilute  aqueous 
oxalic  acid  is  poured  into  the  solution,  till 
no  more  precipitate  is  formed.     By  filtra- 
tion, the  oxalate  of  lime  is  separated,  and 
the  kinic  acid  being  concentrated  by  spon- 
taneous evaporation,  yields  regular  crys- 
tals.    It  is  decomposed  by  heat.    While  it 
forms  a  soluble  salt  with  lime,  it  does  not 
precipitate  lead  or  silver  from  their  solu- 
tions.   These  are  characters  sufficiently 
distinctive.     The    kinates    are    scarcely 
known ;  that  of  lime  constitutes  7  per  cent 
ef  cinchona.* 

ACZD  (LACCIC)  of  Dr.  John. 

*  This  chemist  made  a  watery  extract 
of  powdered  stick  lac,  and  evaporated  it 
to  dryness.     He  digested  alcohol  on  this 
extract,  and  evaporated  the  alcoholic  ex- 
tract to  dryness.     He  then  digested  this 
mass  in  ether,  and  evaporated  the  etlierial 
solution ;  when  he  obtained  a  sirupy  mass 
of  a  light  yellow  colour,  which  was  again 
dissolved  in  alcohol.     On  adding  water  to 
this  solution  a  little  resin  fell.     A  peculiar 
acid  united  to  potash  and  lime  remains  in 
the  solution,  which  is  obtained  free,  by 
forming  with  acetate  of  lead  an  insoluble 
laccate,   and  decomposing  this  with  the 
equivalent    quantity    of   sulphuric    acid. 
Laccic  acid  crystallizes;  it  has  a  wine  yel- 
low colour,  a  sour  taste,  and  is  soluble,  as 
we  have  seen,  in  water,  alcohol,  and  ether. 
It  precipitates  lead  and  mercury  white; 
but  it  does  not  affect  lime,  barytes,  or  sil- 
ver, in  their  solutions.  It  throws  down  the 
salts  of  iron  white.    With  lime,  soda,  and 
potash,  it  forms  deliquescent  salts,  soluble 
in  alcohol.* 

ACID  (LACTIC).  Ey  evaporating  sour 
whey  to  one-eighth,  filtering,  precipitating 


with  lime-water,  and  separating  the  lime 
by  oxalic  acid,  Scheele  obtained  an 
aqueous  solution  of  what  he  supposed  to 
be  a  peculiar  acid,  which  has  accordingly 
been  termed  the  lactic.  To  procure  it 
separate,  he  evaporated  the  solution  to 
the  consistence  of  honey,  poured  on  it  al- 
cohol, filtered  this  solution,  and  evapora- 
ted the  alcohol.  The  residuum  was  an 
acid  of  a  yellow  colour,  incapable  of  being 
crystallized,  attracting  the  humidity  of 
the  air,  and  forming  deliquescent  salts 
with  the  earths  and  alkalis. 

Bouillon  Lagrange  since  examined  it 
more  narrowly ;  and  from  a  series  of  ex- 
periments concluded,  that  it  consists  of 
acetic  acid,  muriate  of  potash,  a  small  por- 
tion of  iron  probably  dissolved  in  the  ace» 
tic  acid,  and  an  animal  matter. 

*  This  judgment  of  M.  Lagrange  was 
afterwards  supported  by  the  opinions  of 
MM.  Fourcroy  and  Vauquelin.  But  since 
then  Berzelius  has  investigated  its  nature 
very  fully,  and  has  obtained,  by  means  of 
a  long  and  often  repeated  series  of  differ- 
ent experiments,  a  complete  conviction 
that  Scheele  was  in  the  right,  and  that 
the  lactic  acid  is  a  peculiar  acid,  very  dis- 
tinct from  all  others.  The  extract  which 
is  obtained  when  dried  whey  is  digested 
with  alcohol,  contains  uncombined  lactic 
acid,  lactate  of  potash,  muriate  of  potash, 
and  a  proper  animal  matter.  As  the  elimi- 
nation of  the  acid  affords  an  instructive 
example  of  chemical  research,  we  shall 
present  it  at  some  detail,  from  the  2d  vo- 
lume of  Berzelius's  Animal  Chemistry. 

He  mixed  the  above  alcoholic  solution 
with  another  portion  of  alcohol,  to  which 
7J_  of  concentrated  sulphuric  acid  had  been 
added,  and  continued  to  add  fresh  por- 
tions of  this  mixture  as  long  as  any  saline 
precipitate  was  formed,  and  until  the  fluid 
had  acquired  a  decidedly  acid  taste.  Some 
sulphate  of  potash  was  precipitated,  and! 
there  remained  in  the  alcohol,  muriatic 
acid,  lactic  acid,  sulphuric  acid,  and  a  mi- 
nute portion  of  phosphoric  acid,  detached 
from  some  bone  earth  which  had  been 
held  in  solution.  The  acid  liquor  was 
filtered,  and  afterwards  digested  with  car- 
bonate of  lead,  which  with  the  lactic  acid 
affords  a  salt  soluble  in  alcohol.  As  soon 
as  the  mixture  had  acquired  a  sweetish 
taste,  the  three  mineral  acids  had  fallen 
down  in  combination  with  the  lead,  and 
the  lactic  acid  remained  behind,  imper- 
fectly saturated  by  a  portion  of  it,  from 
which  it  was  detached  by  means  of  sul- 
phuretted hydrogen,  and  then  evaporated 
to  the  consistence  of  o  thick  varnish,  of  a 
dark-brown  colour,  and  sharp  acid  taste, 
but  altogether  without  smell. 

In  order  to  free  it  from  the  animal  matter 
which  might  remain  combined  with  it,  he 
boiled  itwith  a  mixture  of  a  large  quantity 


ACI 


ACI 


I:  Of  fresh  lime  and  water,  so  that  the  ani- 
I  mal  substances  were  precipitated  and  de- 
I  stroyed  by  the  lime.  The  lime  became 
I  yellow  brown,  and  the  solution  almost 
colourless,  while  the  mass  emitted  a  smell 
of  soap  lees,  which  disappeared  as  the 
boijing  was  continued.  The  fluid  thus 
obtained  was  filtered  and  evaporated,  until 
a  great  part  of  the  superfluous  lime  held 
in  solution  was  precipitated.  A  small  por- 
tion of  it  was  then  decomposed  by  oxalic 
acid,  and  carbonate  of  silver  was  dissolved 
in  the  uncombined  lactic  acid,  until  it  was 
fully  saturated.  With  the  assistance  of  the 
lactate  of  silver  thus  obtained,  a  further 
quantity  of  muriatic  acid  was  separated 
from  the  lactate  of  lime,  which  was  then 
decomposed  by  pure  oxalic  acid,  free 
from  nitric  acid,  taking-  care  to  leave  it  in 
such  a  state  that  neither  the  oxalic  acid 
nor  lime  water  afforded  a  precipitate.  It 
was  then  evaporated  to  dryness,  and  dis- 
solved again  in  alcohol,  a  small  portion  of 
oxalate  of  lime,  before  retained  in  union 
with  the  acid,  now  remaining  undissolved. 
The  alcohol  was  evaporated  until  the  mass 
was  no  longer  fluid  while  warm ;  it  be- 
came a  brown  clear  transparent  acid, 
which  was  the  lactic  acid,  free  from  all 
substances  that  we  have  hitherto  had 
reason  to  think  likely  to  contaminate  it. 

The  lactic  acid,  thus  purified,  has  a 
brown  yellow  colour,  and  a  sharp  sour 
taste,  which  is  much  weakened  by  dilu- 
ting it  with  water.  It  is  without  smell  in 
the  cold,  but  emits,  when  heated,  a  sharp 
sour  smell,  not  unlike  that  of  sublimed 
oxalic  acid.  It  cannot  be  made  to  crystal- 
lize, and  does  not  exhibit  the  slightest  ap- 
pearance of  a  saline  substance,  but  dries 
into  a  thick  and  smooth  varnish,  which 
slowly  attracts  moisture  from  the  air.  It 
is  very  easily  soluble  in  alcohol.  Heated  in 
a  gold  spoon  over  the  flame  of  a  candle, 
it  first  boils,  and  then  its  pungent  acid 
smell  becomes  very  manifest,  but  extreme- 
ly distinct  from  that  of  the  acetic  acid  ; 
afterwards  it  is  charred,  and  has  an  empy- 
reumatic,  but  by  no  means  an  animal 
smell.  A  porous  charcoal  is  left  behind, 
which  does  not  readily  burn  to  ashes. 
When  distilled,  it  gives  an  empyreumatic 
oil,  water,  empyreumatic  vinegar,  carbon- 
ic acid,  and  inflammable  gases.  With 
alkalis,  earths,  and  metallic  oxides,  it  af- 
fords peculiar  salts  :  and  these  are  distin- 
guished by  being  soluble  in  alcohol,  and 
in  general  by  not  having  the  least  disposi- 
tion to  crystallize,  but  drying  into  amass 
like  gum,  which  slowly  becomes  moist  in 
the  air. 

Lactate  of  potash  is  obtained,  when  the 
lactate  of  lime,  purified  as  has  been  men- 
tioned, is  mixed  warm  with  a  warm  solu- 
tion of  carbonate  of  potash.  It  forms,  in 
drying,  a  gummy,  light  vellmv  brown, 
Voi.  T.  [71 


transparent  mass,  which  cannot  easily  be 
made  hard.  If  it  is  mixed  with  concentra- 
ted sulphuric  acid,  no  smell  ot  acetic  acid 
is  perceived  ;  but  if  the  mixture  is  heated, 
it  acquires  a  disagreeable  pungent  smell, 
which  is  observable  in  all  animal  substan- 
ces mixed  with  the  sulphuric  acid.  The 
extract  which  is  obtained  direct;y  from 
milk,  contains  this  salt ;  but  this  affords, 
when  mixed  with  sulphuric  acid,  a  sharp 
acid  smell,  not  unlike  that  of  the  acetic 
acid.  This,  however,  depends  not  on 
acetic  but  on  muriatic  acid,  which  in  its 
concentrated  state  introduces  this  modifi- 
cation into  the  smell  of  almost  all  organic 
bodies.  The  pure  lactate  of  potash  is  easily 
soluble  in  alcohol ;  that  which  contains  au 
excess  of  potash,  or  is  still  contaminated 
with  the  animal  matter  soluble  in  alcohol, 
which  is  destroyed  by  the  treatment  with 
lime,  is  slowly  soluble,  and  requires  about 
14  parts  of  warm  alcohol  for  its  solution. 
It  is  dissolved  in  boiling  alcohol  more 
abundantly  than  in  cold,  and  separates 
from  it,  while  it  is  cooling,  in  the  form  of 
hard  drops. 

The  lactate  of  soda  resembles  that  of 
potash,  and  can  only  be  distinguished  from 
it  by  analysis. 

Lactate  of  ammonia.  If  concentrated 
lactic  aoid  is  saturated  with  caustic  am- 
monia in  excess,  the  mixture  acquires  a 
strong  volatile  smell,  not  unlike  that  of 
the  acetate  or  formiate  of  ammonia,  which, 
however,  soon  ceases.  The  salt  which  is 
left  has  sometimes  a  slight  tendency  to 
shoot  into  crystals.  It  affords  a  gummy 
mass,  which  in  the  air  acquires  an  excess 
of  acidity.  When  heated,  a  great  part  of 
the  alkali  is  expelled,  and  a  very  acid  salt 
remains,  which  deliquesces  in  the  air. 

The  lactate  ofbarytes  may  be  obtained 
in  the  same  way  as  that  of  lime;  but  it* 
then  contains  an  excess  of  the  base.  When 
evaporated,  it  affords  a  gummy  mass, 
soluble  in  alcohol.  A  portion  remains 
undissolved,  which  is  a  sub-salt,  is  doughy, 
and  has  a  browner  colour.  That  which  is 
dissolved  in  the  alcohol  affords  by  evapo- 
ration an  almost  colourless  gummy  mass, 
which  hardens  into  a  stiff'  but  not  a  brittle 
varnish.  It  does  not  show  the  least  tenden- 
cy to  crystallize.  The  salt,  which  is  less 
soluble  in  alcohol,  may  be  further  purified 
from  the  animal  matter  adhering  to  it,  by 
adding  to  it  more  barytes,  and  then  be- 
comes more  soluble. 

The  lactate  of  lime  is  obtained  in  the 
manner  above  described.  It  affords  a 
gummy  mass,  \rhichis  also  divided  by  alco- 
hol into  two  portions.  The  larger  portion 
is  soluble,  and  gives  a  shining  varnish 
inclining  to  a  light  yellow  colour,  which, 
when  slowly  dried,  cracks  all  over,  and 
becomes  opaque.  This  is  pure  lactate  of 
lime.  That  which  is  insoluble  in  alcohol  is 


AC1 


ACI 


a  powder,  with  excess  of  the  base ;  re- 
ceived on  a  filter,  it  becomes  smooth  in 
the  aif  like  gum,  or  like  malate  of  lime. 
By  boiling  with  more  lime,  and  by  the 
precipitation  of  the  superfluous  base  upon 
exposure  to  the  air,  it  becomes  pure  and 
soluble  in  alcohol. 

Lactate  of  magnesia,  evaporated  to  the 
consistence  of  a  thin  sirup,  and  leit  in  a 
warm  place,  shoots  into  small  granular 
crystals.  When  hastily  evaporated  to 
dryness,  it  affords  a  gummy  mass.  With 
regard  to  alcohol,  its  properties  resemble 
those  of  the  two  preceding  salts. 


The  lactate  of  lead  may  be  obtained  in 
several  different  degrees  of  saturation.  If 
the  lactic  acid  is  digested  with  the  carbon- 
ate of  lead,  it  becomes  browner  than  be- 
fore, but  cannot  be  fully  saturated  with 
the  oxide  ;  and  we  obtain  an  acid  salt, 
which  does  not  crystallize,  but  dries  into 
a  sirup-like  brown  mass,  with  a  sweet 
austere  taste.  When  a  solution  of  lactic 
acid  in  alcohol  is  digested  with  finely  pow- 
dered litharge,  until  the  solution  becomes 
sweet,  and  is  then  slowly  evaporated  to 
the  consistence  of  honey,  the  neutral  lac- 
tate of  lead  crystallizes  in  small  grayish 


Jlmmoniaco-muffnesian  lactate  is  obtained     grains,  which  may  be  rinsed  with  alcohol, 


by  mixing-  the  preceding  salt  with  caustic 
ammonia,  as  long  as  any  precipitation  con- 
tinues. By  spontaneous  evaporation  this 
salt  shoots  into  needle-shaped  prisms, 
which  are  little  coloured,  and  do  not 
change  in  the  air.  Berzelius  has  once 
seen  these  crystals  form  in  the  alcoholic 


to  wash  off  the  viscid  mass  that  adheres  to 
them,  and  will  then  appear  as  a  gray  granu* 
lar  salt,  which  when  dry  is  light  and 
silvery. 

This  silver  grained  salt  is  not  changed 
in  the  air ;  treated  with  sulphuretted  hy- 
drogen it  affords  pure  lactic  acid.  If  the 


extract  of  milk  boiled  to  dryness;    but    lactic  acid  is  digested  with  a  greater  por 


this  is  by  no  means  a  common    occur 
rence. 

The  lactate  of  silver  is  procured  by  dis- 
solving the  carbonate  in  the  lactic  acid. 
The  solution  is  of  a  light  yellow,  somewhat 
inclining  to  green,  and  has  an  unpleasant 
taste  of  verdigris.  When  evaporated  in  a 
flat  vessel,  it  dries  into  a  very  transparent 
greenish  yellow  varnish,  which  has  exter- 
nally an  unusual  splendour  like  that  of  a 
looking-glass.  If  the  evaporation  is  con- 
ducted in  a  deeper  vessel,  and  with  a 
stronger  he?it,  a  part  of  the  salt  is  decom- 
posed, and  remains  brown  from  the  reduc 

i*  j_i_  _    _*i i /%  Ai_  •_   __ij_   •       iv i   __ 


tion  of  levigated  litharge  than  is  required 
for  its  saturation,  the  fluid  acquires  first  a 
browner  colour,  and  as  the  digestion  is 
continued  the  colour  becomes  more  and 
more  pale,  and  the  oxide  swells  into  a 
bulky  powder,  of  a  colour  somewhat 
lighter  than  before.  If  the  fluid  is  evapo- 
rated, and  water  is  then  poured  on  the 
dry  mass,  a  very  small  portion  of  it  only  is 
dissolved ;  the  solution  is  not  coloured, 
and  when  it  is  exposed  to  the  air,  a  pellicle 
of  carbonate  of  lead  is  separated  from  it. 
If  the  dried  salt  of  lead  be  boiled  with 
water,  and  the  solution  be  filtered  while 


tion  of  the  silver.     If  this  salt  is  dissolved    hot.  a  great  part  of  that  which  had  been 

•  • 'J l_  1  _       .      a.* _£••*.! T  1     *~      1  '11       1  '       *  j       j.         1          ___l.!1_       "A. 


in  water,  no  inconsiderable  portion  of  the 
silver  is  reduced  and  deposited,  even 
when  the  salt  has  been  transparent ;  »and 
the  concentrated  solution  has  a  fine  green- 
ish yellow  colour,  which  by  dilution  be- 
comes yellow.  If  we  dissolve  the  oxide 
of  silver  in  an  impure  acid,  the  salt  be- 
comes brown,  and  more  silver  is  revived 
during  the  evaporation. 

The  lactate  of  the  protoxide  of  mercury  is 
obtained  when  the  lactic  acid  is  saturated 
with  black  oxidated  mercury.  It  has  a 
light  yellow  colour,  which  disappears  by 
means  of  repeated  solution  and  evapora- 
tion. The  salt  exhibits  acid  properties, 
deliquesces  in  the  air,  and  is  partially  dis- 
solved in  alcohol,  but  is  at  the  same  time 


dissolved  will  be  precipitated  while  it 
cools,  in  the  form  of  a  white,  or  light  yellow 
powder,  which  is  a  sublactate  of  lead. 
This  salt  is  of  a  light  flame  colour;  when 
dried,  it  remains  mealy,  and  soft  to  the 
touch,  and  it  is  decomposed  by  the  weak- 
est acids,  while  the  acid  salt  is  dissolved 
in  water,  exhibiting  a  sweet  taste  and  a 
brown  colour.  When  moistened  with 
water,  it  undergoes  this  change  from  the 
operation  of  the  carbonic  acid  diffused  in 
the  air.  If  this  salt  is  warmed  and  then 
set  on  fire  at  one  point,  it  burns  like  tin- 
der, and  leaves  the  lead  in  great  measure 
reduced.  A  hundred  parts  of  this  saltj 
dissolved  in  nitric  acid,  and  precipitated 
with  carbonate  of  potash,  gave  exactly 


decomposed    and  deposites  carbonate  of    100  parts  of  carbonate  of  lead;  conseq 


mercury,  while  the  mixture  acquires 
slight  smell  of  ether.  The  lactic  acid  dis- 
solves also  the  red  oxide  of  mercury,  and 
gives  with  it  a  red  gummy  deliquescent 
salt.  If  it  is  left  exposed  to  a  warm  and 
moist  atmosphere,  it  deposites,  afterthe  ex- 
piration of  some  weeks,  a  light  semi-crys- 
talline powder,  which  he  has  not  examin- 


uent 

ly  its  component  parts,  determined  frorr. 
those  of  the  carbonate,  must  be  83  of  the 
oxide  of  lead,  and  17  of  the  lactic  acid 
At  the  same  time  we  cannot  wholly  de 
pend  on  this  proportion,  and  it  certain!) 
makes  the  quantity  of  lead  somewhat  to< 
great.  The  relation  of  the  lactic  acid  tc 
lead  affords  one  of  the  best  methods  o 


ed,  but  which  probably  must  be  acetate  of    recognizing    it,    and    Berzelius    alwayi 
mercury,  principally  employed  it  in  extracting  thi: 


ACI 


AGI 


-ic;cl  from  animal  fluids;  it  gives  the 
clearest  distinction  between  the  lactic  acid 
and  the  acetic. 

The  lactate  of  iron  is  of  a  red  brown  co- 
lour, does  not  crystallize,  and  is  not  solu- 
ble in  alcohol.  The  lactate  of  zinc  crystal- 
zes.  LJoth  these  metals  are  dissolved 
by  the  lactic  acid,  with  an  extrication  of 
hydrog'en  gas.  The  lactate  of  copper,  ac- 
cording1 to  its  different  degrees  of  satura- 
tion, varies  from  blue  to  green  and  dark 
blue,  it  does  not  crystallize. 

It  is  only  necessary  to  compare  the  de- 
scriptions* of  these  salts  with  what  we 
know  of  the  salts  which  are  formed  with 
the  same  bases  by  other  acids,  for  example, 
the  acetic,  the  malic,  and  others,  in  order 
to  be  completely  convinced  that  the  lactic 
acid  must  be  a  peculiar  acid,  perfectly  dis- 
tinct from  all  others.  Its  prime  equivalent 
mav  be  called  5.8. 

The  nanceic  acid  of  Braconnot resembles 
the  lactic  in  many  respects.* 

*  ACID  (LAMPIC).  Sir  H.  Davy,  during 
his  admirable  researches  on  the  nature  and 
properties  of  flame,  announced  the  singu- 
lar fact,  that  combustible  bodies  might  be 
made  to  combine  rapidly  with  oxygen,  at 
temperatures  below  what  were  necessary 
to  their  visible  inflammation,  Among  the 
phenomena  resulting  from  these  new 
;  combinations,  he  remarked  the  production 
of  a  peculiar  acid  and  pungent  vapour 
from  the  slow  combustion  of  ether;  and 
from  its  obvious  qualities  he  was  led  to 
suspect,  that  it  might  be  a  product  yet 
new  to  the  chemical  catalogue.  Mr.  Fara- 
day, in  tue  3d  volume  of  the  Journal  of 
Science  and  the  Arts,  has  given  some  ac- 
count of  the  properties  of  this  new  acid ; 
bui  from  the  very  small  quantities  in  which 
he  was  able  to  collect  it,  was  prevented 
j  from  performing  any  decisive  experiments 
upon  it, 

In  the  6th  volume  of  the  same  Journal, 
we  have  a  pretty  copious  investigation  of 
the  properties  and  compounds  of  this  new 
acid,  by  Mr.  Daniell.  From  the  slow 
i  combustion  of  ether  during  six  weeks,  by 
means  of  a  coil  of  platina  wire  sitting  on 
the  cot  on  wick  of  the  lamp,  (See  F-.AME), 
he  condensed  with  the  head  of  an  alembic, 
whose  beak  was  inserted  in  a  receiver,  a 
pint  and  a  half  of  the  lampic  acid  liquor. 

When  first  collected  it  is  a  colourless 
fluid  of  an  intensely  sour  taste,  and  pun- 
gent odour.  Its  vapour,  when  heated,  is 
extremely  irritating  and  disagreeable,  and 
when  received  into  the  lungs  produces  an 
oppression  at  the  chest  very  much  resem- 
bling the  effect  of  chlorine.  Its  specific 
gravity  varies  according  to  the  care  with 
which  it  has  been  prepared,  from  less 
than  1.000  to  1.008.  It  may  be  purified  by 
careful  evaporation ;  and  it  is  worthy  of 


remark,  that  the  vapour  which  rises  from  " 
it  is  that  of  alcohol,  with  which  it  is  slightly 
contaminated,  and  not  of  ether.      Thus 
rectified,  its  specific  gravity  is  1.015.     It 
reddens  vegetable  blues,  and  decomposes 
all  the  earthy  and   alkaline  carbonates, 
forming   neutral   salts   with   their   bases, 
which    are    more  or    less   deliquescent. 
Lampate  of  soda  is  a  very  deliquescent 
salt,  of  a  not  unpleasant  saline  tas'.e.     It  is 
decomposed  by  heat.     It  consists  of  62^1 
acid  and   37.9    soda.      Hence  its  prime 
equivalent  comes  out  6.47.     Lampate  of 
potash    is    not    quite     so    deliquescent. 
Lampate  of  ammonia  evaporates  at  a  tem- 
perature below  212°.     It  is  a  brown  salt. 
Lampate  of  barytes  crystallizes  in  colour- 
less transparent  needles.    Its  composition 
is  39.5  acid  and  60.5  base ;  and  hence  the 
prime  is   6.365,   barytes  being  reckoned 
9.75,  with  Dr.  Wollaston.  Lampate  of  lime 
is  deliquescent,  and  has  a  caustic  bitter 
taste.     Lampate  of  magnesia  has  a  sweet, 
astringent  taste,  like  sulphate  of  iron.  All 
these  salts  burn  with  flame.    Lampic  acid 
reduces  gold  from  the  muriate  instantly  ; 
and  the  lampates  of  potash  and  ammonia 
produce  the  same  effect  more  slowly.    A 
mixture  of  these    two  lampates,   throws 
down  metallic  platinum  from  its  solution. 
Nitrate  of  silver  also  gives  a  metallic  preci- 
pitate ;   but  what  is  singular,  the  oxide  of 
silver  is  soluble  in  lampic  acid,   but  at  a 
boilingheat  falls  down  in  the  metallic  state. 
A  hot  solution  of  nitrated  protoxide  of 
mercury   exhibits   a  very  beautiful  phe- 
nomenon, when  mixed  with  the  acid.     A 
shower  of  mercurial  globules  falls  down 
through  the  liquid.  Red  oxide  forms  with 
lampic  acid  a  bulky  white  salt,  of  sparing 
solubility,  from  which,  after  a  few  days, 
metallic  mercury  separates.     Lampate  of 
copper  affords  by   evaporation  under  an 
exhausted  receiver,  blue  rhomboidal  crys- 
tals.    When  the  solution  is  boiled,  metal- 
lic copper  falls.      Lampate   of  lead  is  a 
white,  sweetish,  and  easily  crystallized  salt, 

By  analysis  of'  the  lampate  of  barytes  in 
M.  M.  G.  Lussac  and  Thenard's  apparatus, 
(See  VEGETABLE  ANALYSIS),  Mr.  Daniell 
infers  the  composition  of  the  acid  to  be 
40.7  carbon,  -f-  7.7  hydrogen,  -}-  51.6  of 
oxygen  and  hydrogen,  in  their  aqueous 
ratio  =  100.  These  numbers  correspond, 
lie  says,  with  what  we  may  suppose  to  re- 
sult from  I  atom  of  carbon,  1  of  hydrogen, 
and  1  of  water,  or  its  elements.  The 
excess  of  hydrogen  explains,  he  imagines, 
the  property  which  the  acid  possesses  of 
reviving  the  metals,  whence  it  may  be 
usefully  applied  in  the  arts,  to  plate  deli- 
cate works  with  gold  and  platinum. 

The  weight  of  its  equivalent,  and  some 
of  the  properties  of  the  salts,  mig'ht  lead 
tp  the  opinion  of  the  lampic  acid  of  Mr. 


ACI 


ACI 


Baniell  being1  merely  the  acetic,  combined 
with  some  etherous  matter.  This  conjec- 
ture must  be  left  for  future  verification.* 

Acn>  (LTTHIC).  This  was  discovered 
about  the  year  1776  by  Scheele,  in  analy- 
zing human  calculi,  of  many  of  which  it 
constitutes  the  greater  part  and  of  some, 
particularly  that  which  resembles  wood 
in  appearance,  it  forms  almost  the  whole. 
It  is  likewise  present  in  human  urine,  and 
in  that  of  the  camel;  and  Dr.  Pearson 
found  it  in  those  arthritic  concretises  com- 
monly called  chalkstones,  which  Mr.  Ten- 
nanthas  since  confirmed.  It  is  often  called 
uric  acid. 

The  following-  are  the  results  of  Scheele's 
experiments  on  calculi,  which  were  found 
to  consist  almost  wholly  of  this  acid  : 

1.  Dilute  sulphudc  acid  produced  no  ef- 
fect on  the  calculus,  but  the  concentrated 
dissolved  it;  and  the  solution  distilled  to 
dryness  left  a  black  coal,  giving-  off' sulphu- 
rous acid  fumes.     2.  The  muriatic  acid, 
either  dimted  or  concentrated,  had  no  ef- 
fect on  it  even  with  ebullition.    3.  Dilute 
nitric  acid  attacked  it  cold ;  and  with  the 
assistance  of  heat  produced  an  efferves- 
cence and  red  vapour,  carbonic  acid  was 
evolved,  and  the  calculus  was  entirely  dis- 
solved. The  solution  was  acid,  even  when 
saturated  with  the  calculus,  and  gave  a 
beautiful  red  colour  to  the  skin  in  half  an 
hour  after  it  was  applied ;  when  evaporat- 
ed, it  became  of  a  blood  red,  but  the  co- 
lour was  destroyed  by  adding  a  drop  of 
acid  :  it  did  not  precipitate  muriate  of  ba- 
rytes,  or  metallic  solutions,  even  with  the 
addition  of  an  alkali ;  alkalis  rendered  it 
more  yellow,  and,  if  superabundant,  chang- 
ed it  by  a  strong  digesting  heat  to  a  rose 
colour :  and  this  mixture  imparts  a  similar 
colour  to  the  skin,  and  is  capable  of  pre- 
cipitating sulphate  of  iron  black,  sulphate 
of  copper  green,  nitrate  of  silver  gray,  su- 
per-oxygenated muriate  of  mercury,  and 
solutions  of  lead  and  zinc,  white.     Lime- 
water  produced  in  the  nitric  solution  a 
white  precipitate,  which  dissolved  in  the 
nitric  and  muriatic  acids  without  efferves- 
cence, and  without  destroying  their  acidi- 
ty.    Oxalic  acid  did  not  precipitate  it.     4. 
Carbonate  of  potash  did  not  dissolve  it, 
either  cold  or  hot,  but  a  solution  of  per- 
fectly pure  potash  dissolved  it  even  cold. 
The  solution  was  yellow;  sweetish  to  the 
taste ;  precipitated  by  all  the  acids,  even 
the  carbonic;  did  not  render  lime-water 
turbid ;  decomposed  and  precipitated  so- 
lution of  iron  brown,  of  copper  gray,  of 
silver  black,  of  zinc,  mercury,  and  lead, 
white ;  and  exhaled  a  smell  of  ammonia. 
5.  About  200  parts  of  lime-water  dissolved 
the  calculus  by  digestion,  and  lost  its  acrid 
taste.    The  solution  was  partly  precipita- 
ted by  acids.     6.  Pure  water  dissolved  it 
entirely,  but  it  was  necessary  to  boil  for 


some  time  360  parts  with  one  of  the  cal- 
culus in  powder.  This  solution  reddened  . 
tincture  of  litmus,  did  not  render  lime-| 
water  turbid,  and  on  cooling  deposited  in ; 
small  crystals  almost  the  whole  of  what  it  j 
had  taken  up.  7.  Seventy -two  grains  dis-1 
tilled  in  a  small  glass  retort  over  an  open 
fire,  and  gradually  brought  to  a  red  heat, 
produced  water  of  ammonia  mixed  with  a 
little  animal  oil,  and  a  brown  sublimate 
weighing  28  grains,  and  12  grains  of  coal 
remained,  which  preserved  its  black  co- 
lour on  red  hot  iron  in  the  open  air.  The 
brown  sublimate  was  rendered  white  by  a 
second  sublimation;  was  destitute  of  smell, 
even  when  moistened  by  an  alkali;  was 
acid  to  the  taste ;  dissolved  in  boiling  wa- 
ter, and  also  in  alcohol,  but  in  less  quanti- 
ty; did  not  precipitate  lime-water;  and 
appeared  to  resemble  succinic  acid. 

Fourcroy  has  found,  that  this  acid  is  al- 
most entirely  soluble  in  20GO  times  its 
weight  of  cold  water,  when  the  powder  is 
repeatedly  treated  with  it.  From  his  ex- 
periments he  infers,  that  it  contains  azote, 
with  a  considerable  portion  of  carbon,  and 
but  little  hydrogen,  and  little  oxygen. 

Of  its  combinations  with  the  bases  we 
know  but  little.  The  lithate  of  lime  is 
more  soluble  than  the  acid  itself;  but  on 
exposure  to  the  air  it  is  soon  decomposed, 
the  carbonic  acid  in  the  atmosphere  com- 
bining with  the  lime,  and  precipitating1 
both  the  lithic  acid  and  new  formed  car- 
bonate of  lime  separate  from  each  other. 
The  lithate  of  soda  appears  from  the  ana- 
lysis of  Mr.  Tennant  to  constitute  the  chief 
part  of  the  concretions  formed  in  the  joints 
of  gouty  persons.  The  lithate  of  potash 
is  obtained  by  digesting  calculi  in  caustic 
lixivium  ;  and  Fourcroy  recommends  the 
precipitation  of  the  lithic  acid  from  this 
solution  by  acetic  acid,  as  a  good  process 
for  obtaining  the  acid  pure  in  small,  white, 
shining,  and  almost  pulverulent  needles. 

*  Much  additional  information  has  been 
obtained  within  these  few  years  on  the  na- 
ture and  habitudes  of  the  lithic  acid.  Dr. 
Henry  wrote  a  medical  thesis,  and  after- 
wards published  a  paper,  on  the  subject, 
in  the  second  volume  of  the  new  series  of 
the  Manchester  Memoirs,  both  of  which 
contain  many  important  facts.  He  pro- 
cured the  acid  in  the  manner  above  pre- 
scribed by  Fourcroy.  It  has  the  form  of 
white  shining  plates,  which  are  denser 
than  water.  Has  no  taste  nor  smell.  It 
dissolves  in  about  1400  parts  of  boiling 
water.  It  reddens  the  infusion  of  litmus. 
AVhen  dissolved  in  nitric  acid,  and  evapo- 
rated to  dryness,  it  leaves  a  pink  sediment. 
The  dry  acid  is  not  acted  on  nor  dissolved 
by  the  alkaline  carbonates,  or  sub-carbo- 
nates. It  decomposes  soap  when  assisted 
by  heat;  as  it  does  also  the  alkaline  sul- 
phurets,  and  hydjosulphurets.  No  acid 


ACI 


ACI 


acts  on  it,  except  those  that  occasion  its 
decomposition.  It  dissolves  in  hot  solu- 
tions of  potash  and  soda,  and  likewise  in 
ammonia,  but  less  readilv .  The  lithates 
may  be  formed,  either  by  mutually  satura- 
ting- the  two  constituents,  or  we  may  dis- 
solve the  acid  in  an  excess  of  base,  and  we 
may  then  precipitate  by  carbonate  of  am- 
monia. The  lithates  are  all  tasteless,  and 
resemble  in  appearance  lithic  acid  itself. 
They  are  not  altered  by  exposure  to  the 
atmosphere.  They  are  very  sparingly  so- 
luble in  water.  They  are  decomposed  by 
a  red  heat,  which  destroys  the  acid.  The 
lithic  acid  is  precipitated  from  these  salts, 
by  all  the  acids  except  the  prussic  and  car- 
bonic. They  are  decomposed  by  the  ni- 
trates, muriates,  and  acetates  of  barytes, 
strontites,  lime,  magnesia,  and  alumina. 
They  are  precipitated  by  all  the  metallic 
solutions  except  that  of  gold.  When  li- 
thic acid  is  exposed  to  heat,  the  products 
are  carburetted  hydrogen,  and  carbonic 
acid,  prussic  acid,  carbonate  of  ammonia, 
a  sublimate,  consisting  of  ammonia  com- 
bined with  a  peculiar  acid,  which  has  the 
following  properties : — 

Its  colour  is  yellow,  and  it  has  a  cooling 
bitter  taste.  It  dissolves  readily  in  water, 
and  in  alkaline  solutions,  from  which  it  is 
not  precipitated  by  acids.  It  dissolves  al- 
so sparingly  in  alcohol,  It  is  volatile,  and 
when  sublimed  a  second  time,  becomes 
much  whiter.  The  watery  solution  red- 
dens vegetable  blues,  but  a  very  small 
quantity  of  ammonia  destroys  this  proper- 
ty. It  does  not  cause  effervescence  with 
alkaline  carbonates.  By  evaporation  it 
yields  permanent  crystals,  but  ill  defined, 
from  adhering  animal  matter.  These  red- 
den vegetable  blues.  Potash  when  added 
to  these  crystals,  disengages  ammonia. 
"When  dissolved  in  nitric  acid,  they  do  not 
leave  a  red  stain,  as  happens  with  uric  acid; 
nor  does  their  solution  in  water  decom- 
pose the  earthy  salts,  as  happens  with  al- 
kaline lithates  (or  urates.)  Neither  has  it 
any  action  on  the  salts  of  copper,  iron, 
gold,  platinum,  tin,  or  mercury.  With  ni- 
trates of  silver,  and  mercury,  and  acetate 
of  lead,  it  forms  a  white  precipitate,  solu- 
ble in  an  excess  of  nitric  acid.  Muriatic 
acid  occasions  no  precipitate  in  the  solu- 
tion of  these  crystals  in  water.  These 
properties  show,  that  the  acid  of  the  sub- 
limate is  different  from  the  uric,  and  from 
eveiy  other  known  acid.  Dr.  Austin  found, 
that  by  repeated  distillations,  lithic  acid 
was  resolved  into  ammonia,  nitrogen,  and 
prussic  acid.  See  ACID  (PXROLITHIC.) 

When  lithic  acid  is  projected  into  a  flask 
with  chlorine,  there  is  formed,  in  a  little 
time,  muriate  of  ammonia,  oxalate  of  am- 
monia, carbonic  acid,  muriatic  acid,  and 
malic  acid;  the  same  results  are  obtained 


by  passing  chlorine  through  water,  hold- 
ing this  acid  in  suspension. 

M.  Gay-Lussac  mixed  lithic  acid  with  20 
times  its  weight  of  oxide  of  copper,  put 
the  mixture  into  a  glass  tube,  and  covered 
it  with  a  quantity  of  copper  filings.  The 
copper  filings  being  first  heated  to  a  dull 
red  heat,  was  applied  to  the  mixture.  The 
gas  which  came  over,  was  composed  of 
0.69  carbonic  acid,  and  0.31  nitrogen.  He 
conceives,  that  the  bulk  of  the  carbonic 
acid  would  have  been  exactly  double  that 
of  the  nitrogen,  had  it  not  been  for  the 
formation  of  a  little  carbonate  of  ammonia. 
Hence,  uric  acid  contains  two  prime  equi- 
valents of  carbon,  and  one  of  nitrogen. 
This  is  the  same  proportion  as  exists  in 
cyanogen.  Probably,  a  prime  equivalent 
of  oxygen  is  present.  Dr.  Prout,  in  the 
eighth  vol.  of  the  Med.  Chir.  Trans,  de- 
scribes the  result  of  an  analysis  of  lilhic 
acid,  effected  also  by  ignited  oxide  of  cop- 
per, but  so  conducted  as  to  determine  the 
product  of  oxygen  and  hydrogen.  Four 
grains  of  lithic  acid  yielded,  water  1.05, 
carbonic  acid  11.0  c.  inches,  nitrogen  5.5 
do.  Hence,  it  consisted  of 

Hydrogen    2.857  or  1  prime  =  0.125 
Carbon       34.286      2  «=  1.500 

Oxygen      22.857       1  =  1.000 

Nitrogen    40.000      1  =  1.750 

100.000  4.375 

M.  Berard  has  published  an  analysis  of 
lithic  acid  since  Dr.  Prout,  in  which  he  al- 
so employed  oxide  of  copper. 

The  following  are  the  results : — 
Carbon         33.61  r"2  Carbon 

Oxygen         18.89  which  ap-J  1  Oxygen 
Hydrogen       8.34  proach  to  j  4  Hydrogen 
Nitrogen       39.16  \_1  Nitrogen 

100.00 

Here  we  find  the  nitrogen  and  carbon 
nearly  in  the  same  quantity  as  by  Dr.  Prout, 
but  there  is  much  more  hydrogen  and  less 
oxygen.  By  urate  of  barytes,  we  have  the 
prime  *equivalent  of  uric  acid  equal  to 
15.67 ;  and  by  urate  of  potash  it  appears  to 
be  14.0.  It  is  needless  to  try  to  accom- 
modate an  arrangement  of  prime  equiva- 
lents to  these  discrepancies.  The  lowest 
number  would  require,  on  the  Daltonian 
plan,  an  association  of  more  than  twenty 
atoms,  the  grouping  of  which  is  rather  a 
spoil  of  fancy,  than  an  exercise  of  reason. 
For  what  benefit  could  accrue  to  chemical 
science,  by  stating,  that  if  we  consider  the 
atom  of  lithic  acid  to  be  16.75,  then  it 
would  probably  consist  of 

7  atoms  Carbon      =  5.25        31.4 

3  Oxygen      =  3.00        17.90 
12  Hydrogen  =  1.500        8.90 

4  Nitrogen   =  7.00        41.80 


26 


16,75      100.0* 


ACI 


ACI 


*  ACID  (MALIC.  )     The  acid  of  apples ; 
the  same  wilh  that  which  is  extracted  from 
the  fruit  of  the  mountain  ash.     See  ACID 

(SORBIC.*) 

*  ACID  (MARGARIC.)   When  we  immerse 
soap  made  of  pork-grease  and  potash,  in  a 
large  quantity  of  water,  one  part  is  dissolv- 
ed, while  another  part  is  precipitated,  in 
the  form  of  several  brilliant  pellets.  These 
are  separated,  dried,  washed  in  a  large 
quantity  of  water,  and  then  dried  on  a  fil- 
ter.    They  are  now  dissolved  in  "boiling 
alcohol,  sp.  gr.  0.820,  from  which,  as  it 
cools,  the  pearly  substance  falls  down  pure. 
On  acting  on  this  with  dilute  muriatic  acid, 
a  substance  of  a  peculiar  kind,  which  M. 
Chevreul,  the  discoverer,  calls  margarine, 
or  margaric  acid,  is  separated.     It  must  be 
Well  washed  with  water  dissolved  in  boil- 
ing alcohol,  from  which  it  is  recovered  in 
the  same  crystalline  pearly  form,  when  the 
solution  cools. 

Margaric  acid  is  pearly  white,  and  taste- 
less. Its  smell  is  feeble,  and  a  little  simi- 
lar to  that  of  melted  wax.  Its  specific  gra^ 
vity  is  inferior  to  water.  It  melts  at  134° 
F.  into  a  very  limpid,  colourless  liquid, 
which  crystallizes  on  cooling,  into  brilliant 
needles  of  the  finest  white.  It  is  insoluble 
in  water,  but  very  soluble  in  alcohol,  sp. 
gr.  0.800.  Cold  margaric  acid  has  no  ac- 
tion on  the  colour  of  litmus ;  but  when 
heated  so  as  to  soften  without  melting, 
the  blue  was  reddened.  It  combines  with 
the  salifiable  bases,  and  forms  neutral  com- 
pounds. 100  parts  of  it  unite  to  a  quantity 
of  base  containing  three  parts  of  oxygen, 
supposing  that  100  of  potash  contain  17  of 
oxygen.  Two  orders  of  margarates  are 
formed,  the  margarates,  and  the  supcr- 
margarates,  the  former  being  converted 
into  the  latter,  by  pouring  a  large  quanti- 
ty of  water  on  them.  Other  fats  besides 
that  of  the  hog  yield  this  substance. 

Jlcid.  Jlase. 

Margarate  of  potash  consists  of  100  17  77 
Supermargarate  -  -  -  -  100  8.88 
Margarate  of  soda  -  -  -  -  100*  12.72 

Barytes 100     28.93 

Strontites 100    20.23 

Lime 100     11.06 

Potash 

Supermargarate  of  Human  fat  100      8.85 

Sheep  fat     100      8.68 

Ox  fat  100      8.78 

Jaguar  fat    100       8.60 

Goose  fat     100       8.77 

If  we  compare  the  above  numbers,  we 

shall  find  35  to  be  the  prime  equivalent  of 

margaric  acid. 

That  of  man  is  obtained  under  three  dif- 
ferent ^forms.  1st,  In  very  fine  long  nee- 
dles, disposed  in  fiat  stars,  *2d,  In  very  fine 
and  rery  short  needles,  fyrming  waved 
figures,  like  those  of  the  margaric  acid  of 
carcasses.  3d,  In  very  large  brilliant  crys- 


tals  disposed  in  stars,  similar  to  the 
garic  acid  of  the  hog.  The  margaric  acids 
of  man  and  the  hog  resemble  eacti  other ; 
as  do  those  of  the  ox  and  the  sheep  ;  and 
of  the  goose  and  the  jaguar.  The  com- 
pounds with  the  bases,  are  real  soaps.  The 
solution  of  alcohol  affords  the  transparent 
soap  of  this  country. — Annales  de  Chimie, 
several  volumes.* 

*  ACID  (MKCOJHC).  This  acid  is  a  consti- 
tuent of  opium.  It  was  discovered  by  M. 
Sertuerner,  who  procured  it  in  the  follow- 
ing way :  After  precipitating  the  morphia, 
from  a  solution  of  opium,  by  ammonia,  he 
added  to  the  residual  fluid  a  solution  of 
the  muriate  of  harytes.  A  precipitate  is  in 
this  way  formed,  which  is  supposed  to  be 
a  quadruple  compound,  of  barytes,  mor- 
phia, extract,  and  the  meconic  acid.  The 
extract  is  removed  by  alcohol,  and  the 
barytes  by  sulphuric  acid ;  when  the  me- 
conic acid  is  left,  merely  in  combination 
with  a  portion  of  the  morphia ;  and  from 
this  it  is  purified  by  successive  solutions 
and  evaporations.  The  acid,  when  sub- 
limed, forms  long  colourless  needles ;  it 
has  a  strong  affinity  for  the  oxide  of  iron, 
so  as  to  take  it  from  the  muriatic  solution, 
and  form  with  it  a  cherry-red  precipitate 
It  forms  a  crystallizable  salt  with  lime, 
which  is  not  decomposed  by  sulphuric 
acid  ;  and  what  is  curious,  it  seems  to  pos« 
sess  no  particular  power  over  the  human 
body,  when  received  into  the  stomach. 
The  essential  salt  of  opium,  obtained  in 
M.  Derosne's  original  experiments,  was 
probably  the  meconiate  of  morphia. 

Mr.  Robiquet  has  made  a  useful  modifi- 
cation of  the  process  for  extracting  mecon- 
ic acid.  He  treats  the  opium  witli  magne- 
sia, to  separate  the  morphia,  while  me- 
coniate of  magnesia  is  also  formed.  The 
magnesia  is  removed  by  adding  muriate  of 
barytes,  and  the  barytes  is  afterwards  se- 
parated by  dilute  sulphuric  acid.  A  lar- 
ger proportion  of  meconic  acid  is  thus  ob- 
tained. 

Mr.  Robiquet  denies  that  meconic  acid 
precipitates  iron  from  the  muriate  ;  but, 
according'  to  M.  Vogel,  its  power  of  red- 
dening solutions  of  iron  is  so  gTeat,  as  to 
render  it  a  more  delicate  test  of  this  metal, 
than  even  the  prussiate  of  potash. 

To  obtain  pure  meconic  acid  from  the 
meconiate  of  barytes,  M.  Choulant  tritu- 
rated it  in  a  mortar,  with  its  own  weight 
of  glassy  boracic  acid.  This  mixture  being 
put  into  a  small  glass  flask,  which  was 
surrounded  with  sand  in  a  sand  pot,  in  the 
usual  manner,  and  the  red  heat  being 
gradually  raised,  the  meconic  acid  sublimed, 
in  the  state  of  fine  white  scales  or  plates. 
It  has  a  strong  sour  taste,  which  leaves  be- 
hind it  an  impression  of  bitterness.  It  dis- 
solves readily  in  water,  alcohol,  and  ether. 
It  reddens  the  greater  number  of  vegeta- 


ACI 


\   ble  blues,  and  changes  the  solutions  of 
f-  iron  to  a  cherry-red  colour.    When  these 
solutions  are  heated,  the  iron  is  precipi- 
'    tated  in  the  state  of  protoxide. 

The  meconiates  examined  by  Choulant, 
are  the  following: — 

1st,  VIecouiate  of  potash.   Tt  crystallizes 
in  four  sided  tables,  is  soluble  in  twice  its 
weight  of  wafer,  and  is  composed  of 
Meconic  acid  27         2.7 
Potash  60         6.0 

Water  13 

100 

It  is  destroyed  by  heat. 
2d,  Meconiate  of  soda.     It  crystallizes 
in  soft  prisms,  is  soluble  in  five  times  its 
weight  of  water,  and  seems  to  effloresce. 
It  is  destroyed  by  heat.     It  consists  of 
Acid     '       32  3.2 

Soda  40  4.0 

Water         28 

100 

3d  Meconiate  of  ammonia.  It  crystal- 
Mzes  in  star-form  needles,  which,  when 
sublimed,  lose  their  water  of  crystalliza- 
tion, and  assume  the  shape  of  scales.  The 
crystals  are  soluble  in  1£  their  weight  of 
water,  and  are  composed  of 

Acid  40  2.03 

Ammonia    42  2.13 

Water          18 

100 

If  two  parts  of  sal  ammoniac  be  tritura- 
ted with  3  parts  of  meconiate  of  barytes, 
and  heat  be  applied  to  the  mixture,  me- 
coniate of  ammonia  sublimes,  and  muriate 
of  barytes  remains. 

4th,  Meconiate  of  lime.     It  crystallizes 
in  prisms,  and  is  soluble  in  eight  times  its 
i     weight  of  water.     It  consists  of 

Acid  34  2  882 

Lime  42  3.560 

Water         24 

100 

As  the  potash  and  lime  compounds  give 
nearly  the  same  acid  ratio,  we  may  take 
their  mean  of  it,  as  the  true  prime  =  2.8.* 

*  ACTD  (MKI.ASSIC).  The  acid  present 
in  melasses,  which  has  been  thought  a  pe- 
culiar acid  by  some,  by  others,  the  acetic.* 

ACID  (MELLITIC).  M.  Klaproth  disco- 
vered in  the  mellite,  or  honey-stone, 
what  he  conceives  to  be  a  peculiar  acid  of 
the  vegetable  kind,  combined  with  alu- 
mina. This  acid  is  easily  obtained  by  re- 
ducing the  stone  to  powder,  and  boiling  it 
in  about  70  times  its  weight  of  water; 
when  the  acid  will  dissolve,  and  may  be 
separated  from  the  alumina  by  filtration. 
By  evaporating  the  solution,  it  may  be  ob- 
tained in  the  form  of  crystals.  The  fol- 
lowing are  its  characters :— 


ACI 

It  crystallizes  in  fine  needles  or  globules 
by  the  union  of  these,  or  small  prisms.  Its 
taste  is  at  first  a  sweetish  sour,  which 
leaves  a  bitterness  behind.  On  a  plate  of 
hot  metal  it  is  readily  decomposed,  and 
dissipated  in  copious  gray  fumes,  which 
affect  not  the  smell;  leaving  behind  a 
small  quantity  of  ashes,  that  do  not  change 
either  red  or  blue  tincture  of  litmus.  Neu- 
tralized by  potash  it  cr-,  stalli/es  in  groups 
of  long  prisms :  by  soda,  in  cubes,  or  tri- 
angular laminx,  sometimes  in  groups, 
sometimes  single ;  and  by  ammonia,  in 
beautiful  prisms  with  six  planes,  which 
soon  lose  their  transparency,  and  acquire 
a  silvery  white  hue.  If  tl>e  mellitic  acid 
be  dissolved  in  lime-water,  and  a  solution 
of  calcined  strontian  or  barytes  be  drop- 
ped into  it,  a  white  precipitate  is  thrown 
down,  which  is  redissolved  on  adding  mu- 
riatic acid.  With  a  solution  of  acetate  of 
barytes,  it  produces  likewise  a  white  pre- 
cipitate, which  nitric  acid  redissolves. 
With  solution  of  muriate  of  barytes,  it  pro- 
duces no  precipitate,  or  even  cloud ;  but 
after  standing-  some  time,  fine  transparent 
needly  crvstals  are  deposited.  The  mel- 
litic acid  produces  no  change  in  a  solution 
of  nitrate  of  silver.  From  a  solution  of 
nitrate  of  mercury,  either  hot  or  cold,  it 
throws  down  a  copious  white  precipitate, 
which  an  addition  of  nitric  acid  imme- 
diately redissolves.  With  nitrate  of  iron 
it  gives  an  abundant  precipitate  of  a  dun 
yellow  colour,  which  may  be  redissolved 
by  muriatic  acid.  With  a  solution  of  ace- 
tate of  lead,  it  produces  an  abundant  pre- 
cipitate, immediately  redissolved  on  add- 
ing nitric  acid.  With  acetate  of  copper, 
it  produces  a  grayish-green  precipitate; 
but  it  does  not  affect  a  solution  of  muriate 
of  copper.  Lime-water  precipitated  by 
it,  is  immediately  redissolved  on  adding1 
nitric  acid. 

M.  Klaproth  was  never  able  to  convert 
this  acid  into  the  oxalic  by  means  of  nitric 
acid,  which  only  changed  its  brownish  co- 
lour to  a  pale  yellow. 

*  The  mellite,  or  native  mellate  of  alu- 
mina, consists,  according  to  Klaproth,  of 
46  acid  -\-  16  alumina  -f-  38  water  ==  100; 
from  which,  calling-  the  prime  of  alumina 
3.2,  that  of  mellitic  acid  appears  to  be 
9.2.* 

*  ACID  (MEXISPKRMTC).     The  seeds  of 
menispermum  cocci/his  being  macerated  for 
24  hours  in  5  times  their  weight  of  water, 
first  cold,  and  then  boiling  hot,  yield  an 
infusion,  from  which  solution  of  subacetate 
of  lead  throws  down  a  menispermate  of 
lead.     This  is  to  be  washed  and  drained, 
diffused  through  water,  and  decomposed 
by  a  current  of  sulphuretted  hydrogen 
gas.     The  liquid  thus  freed  from  lead,  is 
to  be  deprived  of  sulphuretted  hydrogen 
by  heat,  and  tfeen  forms  solution  of  minis- 


ACI 


ACI 


permic  acid.  By  repeated  evaporations 
and  solutions  in  alcohol,  it  loses  its  bitter 
taste,  and  becomes  a  purer  acid.  It  occa- 
sions no  precipitate  with  lime-water ;  with 
nitrate  of  barytes  it  yields  a  gray  precipi- 
tate ;  with  nitrate  of  silver,  a  deep  yellow; 
and  with  sulphate  of  magnesia,  a  copious 
precipitate.* 

*  Ar<  r  ( vio^YBDic).  The  native  sulphu- 
ret  of  molybdenum  being1  roasted  for  some 
time,  and  dissolved  in  water  of  ammonia, 
when  nitric  acid  is  added  to  this  solution, 
the  molybdic  acid  precipitates  "in  fine 
white  scales,  which  become  yellow,  on 
melting  and  subliming  them.  It  changes 
the  vegetable  blues  to  red,  but  less  readi- 
ty  and  powerfully  than  the  following  acid. 
M.  Bucholz  found  that  100  parts  of  the 
sulphuret  gave  90  parts  of  molybdic  acid, 
tn  other  experiments  in  which  he  oxidized 
molybdenum,  he  found  that  100  of  the 
metal  combined  with  from  49  to  50  of  oxy- 
gen. Berzelius,  after  some  vain  attempts 
to  analyze  the  molybdates  of  lead  and  ba- 
rytes, found  that  the  only  method  of  ob- 
taining an  exact  result  was  to  form  a  mo- 
lybdate  of  lead.  He  dissolved  10  parts  of 
neutral  nitrate  of  lead  in  water,  and  pour- 
ed an  excess  of  solution  of  crystallized 
molybdate  of  ammonia  into  the  liquid. 
The  molybdate  of  lead,  washed,  dried  and 
heated  to  redness,  weighed  11.068.  No 
traces  of  lead  were  found  in  the  liquid  by 
sulphate  of  ammonia;  hence  these  11.068 
of  lead,  evince  67.3  per  cent  of  oxide  of 
tead.  This  salt  then  is  composed  of 

Molybdic  acid  39.194  9.0 

Oxide  of  lead   60.806  14.0 

100.000 

And  from  Bucholz  we  infer,  that  this 
prime  equivalent  9,  consists  of  3  of  oxy- 
gen _j.  6  metal;  while  molybdotis  acid 
will  be  2  oxygen  -f  6  metal  =  8.0. 

Molybdic  acid  has  a  specific  gravity  of 
3.460.  In  an  open  v«ssel  it  sublimes  into 
brilliant  yellow  scales ;  960  parts  of  boiling 
water  dissolve  one  of  it,  affording  a  pale 
yellow  solution,  which  reddens  litmus, 
but  has  no  taste.  Sulphur,  charcoal,  and 
several  metals  decompose  the  molybdic 
acid.  Molybdate  of  potash  is  a  colourless 
salt.  Molybdic  acid  gives,  with  nitrate  of 
lead,  a  white  precipitate,  soluble  in  nitric 
acid ;  with  the  nitrates  of  mercury  and 
silver,  a  white  flaky  precipitate ;  with  ni- 
trate of  copper,  a  greenish  precipitate; 
with  solutions  of  the  neutral  sulphate  of 
zinc,  muriate  of  bismuth,  muriate  of  anti- 
mony, nitrate  of  nickel,  muriates  of  gold 
and  platinum,  it  produces  white  precipi- 
tates. When  melted  with  borax,  it  yields 
a  bluish  colour ;  and  paper  dipped  in  its 
solution  becomes,  in  the  sun,  of  a  beauti- 
ful blue.* 

The  neutral  alkaline  molybdates  preci- 


pitate all  metallic  solutions.  Gold,  roti- 
riate  of  mercury,  zinc,  and  manganese, 
are  precipitated  in  the  form  of  a  white 
powder;  iron  and  tin,  from  their  solutions 
in  muriatic  acid,  of  a  brown  colour ;  cobalt, 
of  a  rose  colour ;  copper,  blue ;  and  the 
solutions  of  alum  and  quicklime,  white. 
If  a  dilute  solution  of  recent  muriate  of  tin 
be  precipitated  by  a  dilute  solution  of 
molybdate  of  potash,  a  beautiful  blue 
powder  is  obtained. 

The  concentrated  sulphuric  acid  dis- 
solves a  considerable  quantity  of  the  mo- 
lybdic acid,  the  solution  becoming  of  a 
fine  blue  colour  as  it  cools,  at  the  same 
time  that  it  thickens ;  the  colour  disap- 
pears again  on  the  application  of  heat, 
but  returns  again  by  cooling.  A  strong 
heat  expels  the  sulphuric  acid.  The  nitric 
acid  has  no  effect  on  it ;  but  the  muriatic 
dissolves  it  in  considerable  quantity,  and 
leaves  a  dark  blue  residuum  when  dis- 
tilled. With  a  strong  heat  it  expels  a  por- 
tion of  sulphuric  acid  from  sulphate  of 
potash.  It  also  disengages  the  acid  from 
nitre  and  common  salt  by  distillation.  It 
has  some  action  upon  the  filings  of  the  me- 
tals in  the  moist  way. 

The  molybdic  acid  has  not  yet  been  em- 
ployed in  the  arts. 

*  ACID  (MOLYBDOUS).  The  deutoxide 
of  molybdenum  is  of  a  blue  colour,  and 
possesses  acid  properties.  Triturate  2 
parts  of  molybdic  acid,  with  1  part  of  the 
metal,  along  with  a  little  hot  water,  in  a 
porcelain  mortar,  till  the  mixture  assumes 
a  blue  colour.  Digest  in  10  parts  of  boil- 
ing water,  filter,  and  evaporate  the  liquid 
in  a  heat  of  120°.  The  blue  oxide  sepa- 
rates. It  reddens  vegetable  blues,  and 
forms  salts  with  the  bases.  Air  or  water, 
when  left  for  some  time  to  act  on  molyb- 
denum, convert  it  into  this  acid.  It  con- 
sists of  about  100  metal  to  34  oxygen,* 

ACIP  (MonoxYLtc).  In  the  botanic  gar- 
den at  Palermo,  Mr.  Thompson  found  an 
uncommon  saline  substance  on  the  trunk 
of  a  white  mulberry  tree.  It  appeared  as 
a  coating  on  the  surface  of  the  bark  in  lit- 
tle granulous  drops  of  a  yellowish  and 
blackish  brown  colour,  and  had  likewise 
penetrated  its  substance.  M.  Klaproth, 
who  analyzed  it,  found  that  its  taste  was 
somewhat  like  that  of  succinic  acid ;  on 
burning  coals  it  swelled  up  a  little,  emit- 
ted a  pungent  vapour  scarcely  visible  to 
the  eye,  and  left  a  slight  earthy  residuum. 
Six  hundred  grains  of  the  bark  loaded 
with  it  were  lixiviated  with  water,  and 
afforded  320  grains  of  a  light  salt,  resem- 
bling in  colour  a  light  wood,  and  compos- 
ed of  short  needles  united  in  radii.  It  was 
not  deliquescent ;  and  though  the  crystals 
did  not  form  till  the  solution  was  greatly 
condensed  by  evaporation,  it  is  not  very 


ACI 


ACI 


soluble,  since  1000  parts  of  water  dissolve 
but  35  with  heat,  and  15  cold. 

This  salt  was  found  to  be  a  compound 
of  lime  and  a  peculiar  vegetable  acid,  with 
some  extractive  matter. 

To  obtain  the  acid  separate,  M.  Klap- 
roth  decomposed  the  calcareous  salt  by 
acetate  of  lead,  and  separated  the  lead  by 
sulphuric  acid.     He  likewise  decomposed 
I  it  directly  by  sulphuric  acid.     The  pro- 
l  duct  was  still  more  like  succinic  acid  in 
I  taste ;   was  not  deliquescent ;   easily  dis- 
solved both  in  water  and  alcohol ;  and  did 
i  not  precipitate  the  metallic  solutions,  as 
it  did  in  combination  with  lime.     Twenty 
grains  being-  slightly  heated  in   a  small 
>  glass  retort,  a  number  of  drops  of  an  acid 
liquor  first  came  over ;  next  a  concrete 
salt  arose,  that  adhered  flat  against  the 
top  and  part  of  the  neck  of  the  retort  in 
the  form  of  prismatic  crystals,  colourless 
and  transparent ;  and  a  coaly  residuum  re- 
mained.    The  acid  was  then  washed  out, 
and  crystallized  by  spontaneous  evapora- 
tion.    Thus  sublimation  appears  to  be  the 
best  mode  of  purifying  the  salt,  but  it  ad- 
hered too  strongly  to  the  lime  to  be  sepa- 
rated from  it  directly  by  heat  without  be- 
ing decomposed. 

Not  having  a  sufficient  quantity  to  de- 
termine its  specific  characters,  though  he 
conceives  it  to  be  a  peculiar  acid,  coming 
nearest  to  the  succinic  both  in  taste  and 
ether  qualities,  Mr.  Klaproth  has  pro- 
visionally given  it  the  name  of  moroxylic, 
and  the  calcareous  salt  containing  it  that 
of  moroxylate  of  lime. 

ACID  (Mucic).  This  acid  has  been  gene 
rally  known  by  the  name  of  saccholactic, 
because  it  was  first  obtained  from  sugar  of 
inilk  ;  but  as  all  the  gums  appear  to  afford 
it,  and  the  principal  acid  in  sugar  of  milk 
;is  the  oxalic,  chemists  in  general  now  dis- 
tinguish it  by  the  name  of  mucic  acid. 

It  was  discovered  by  Scheele.  Having 
poured  twelve  ounces  of  diluted  nitric 
acid  on  four  ounces  of  powdered  sugar  of 
milk  in  a  glass  retort  on  a  sand  bath,  the 
mixture  became  gradually  hot,  and  at 
length  effervesced  violently,  and  contin- 
ued to  do  so  for  a  considerable  time  after 
the  retort  was  taken  from  the  fire.  It  is 
necessary  therefore  to  use  a  large  retort, 
and  not  to  lute  the  receiver  too  tight.  The 
effervescence  having  nearly  subsided,  the 
retort  was  again  placed  on  the  sand  heat, 
and  the  nitric  acid  distilled  off,  till  the 
mass  had  acquired  a  yellowish  colour. 
This  exhibiting  no  crystals,  eight  ounces 
more  of  the  same  acid  were  added,  and 
the  distillation  repeated,  till  the  yellow 
colour  of  the  fluid  disappeared.  As  the 
fluid  was  inspissated  by  cooling,  it  was 
redissolved  in  eight  ounces  of  water,  and 
filtei-ed.  The  filtered  liquor  held  oxalic 
acid  in  solution,  and  seven  drams  and  a 
Von.  i  [8] 


half  of  a  white  powder  remained  on  the 
filter.  This  powder  was  the  acid  under 
consideration. 

If  one  part  of  gum  be  heated  gently  with 
two  of  nitric  acid,  till  a  small  quantity  of 
nitrous  gas  and  of  carbonic  acid  is  disen- 
gaged, the  dissolved  mass  will  deposite  on 
cooling  the  mucic  acid.  According  to 
Fourcroy  and  Vauquelin,  different  gums 
yield  from  14  to  26  hundredths  of  this 
acid. 

This  pulverulent  acid  is  soluble  in  about 
60  parts  of  hot  water,  and  by  cooling,  a 
fourth  part  separates  in  small  shining 
scales,  that  grow  white  in  the  air.  It  de- 
composes the  muriate  of  barytes,  and  both 
the  nitrate  and  muriate  of  lime.  It  acts 
very  little  on  the  metals,  but  forms  with 
their  oxides  salts  scarcely  soluble.  It  pre- 
cipitates the  nitrates  of  silver,  lead,  and 
mercury.  With  potash  it  forms  a  salt  solu- 
ble in  eight  parts  of  boiling  water,  and 
crystallizable  by  cooling.  That  of  soda  re- 
quires but  five  parts  of  water,  and  is  equal- 
ly crystallizable.  Both  these  salts  are  still 
more  soluble  when  the  acid  is  in  excess. 
That  of  ammonia  is  deprived  of  its  base  by 
heat.  The  salts  of  barytes,  lime,  and  mag- 
nesia, are  nearly  insoluble. 

*  Mucic  or  saccholactic  acid  has  been 
analyzed  recently  with  much  care ; 

Hydrogen.  Carbon.  Oxygen. 
Gay-Lussac,  3.62  -f-  33.69  -f  62.69  =100 
Berzelius,  5.105  -f  33.430 -f  61.465=100 
From  saclactate  of  lead,  Berzelius  has 
inferred  the  prime  equivalent  of  the  acid 
to  be  13.1.* 

*  ACID  (MURIATIC).  Let  6  parts  of  pure 
and  well  dried  sea  salt  be  put  into  a  glass 
retort,  to  the  beak  of  which  is  luted,  in  a 
horizontal  direction,  a  long  glass  tube  arti- 
ficially refrigerated,  and  containing  a  quan- 
tity of  ignited  muriate  of  lime.    Upon  the 
salt  pour  at  intervals  5  parts  of  concentrat- 
ed oil  of  vitriol,  through  a  syphon  funnel, 
fixed,  air-tight,  in  the  tubulure  of  the  re- 
tort. The  free  end  of  the  long  tube  being 
recurved,  so  as  to  dip  into  the  mercury  of 
a  pneumatic  trough,  a  gas  will  issue,  which 
on  coming  in  contact  with  the  air,  will  form 
a  visible  cloud,  or  haze,  presenting,  when 
viewed  in  a  vivid  light,  prismatic  colours. 
This  gas  is  muriatic  acid.   When  received 
in  glass  jars  over  dry  mercury,  it  is  invisi- 
ble, and  possesses  all  the  mechanical  pro- 
perties of  air.    Its  odour  is  pungent  and 
peculiar.  Its  taste  acid  and  corrosive.    Its 
specific  gravity,  according  to  Sir  H.  Davy, 
is  such,  that  100  cubic  inches  weigh  39 
grains,  while  by  estimation,  he  says,  they 
ought  to  be  38.4  gr.    By  the  latter  num- 
ber the  specific  gravity,  compared  to  air, 
becomes  1.2590.    By  the  former  number 
the  density  comes  out  1.2800.     M.  Gay- 
Lussac  states  the  sp.  gr.  at  1.2780.  Sir  H.'s 
second  number  makes  the  prime  equiva- 


AC1 


AC1 


lent  of  chlorine  4.43,  which  comes  near  to 
Berzelius's  latest  result;  while  his  first 
number  makes  it  4.48,  (See  Cnr.oniNK). 
As  the  attraction  of  muriatic  acid  gas  for 
hygrometric  water  is  very  strong,  it  is  very 
probable  that  38.4  grs.  may  be  the  more 
exact  weight  of  100  cubic  inches,  regard- 
ing *he  same  bulk  of  air  as  =  30.5.  If  an 
inflamed  taper  be  immersed  in  it,  it  is  in- 
stantly extinguished.  It  is  destructive  of 
animal  life  ;  but  the  irritation  produced  by 
it  on  the  epiglottis  scarcely  permits^its  de- 
scent into  the  lungs.  It  is  merely  changed 
in  bulk  by  alterations  of  temperature  ;  it 
experiences  no  change  of  state.  When 
potassium,  tin,  or  zinc,  is  heated  in  con- 
tact with  this  gas  over  mercury,  one-half 
of  the  volume  disappears,  and  the  remain- 
der is  pure  hydrogen.  On  examining  the 
solid  residue,* it  is  found  to  be  a  metallic 
chloride.  Hence  muriatic  acid  gas  con- 
sists of  chlorine  and  hydrogen,  united  in 
equal  volumes.  This  view  of  its  nature 
was  originally  given  by  Scheele,  though 
obscured  by  terms  derived  from  the  vague 
and  visionary  hypothesis  of  phlogiston. 
The  French  school  afterwards  introduced 
the  belief  that  muriatic  acid  gas  was  a 
compound  of  an  unknown  radical  and 
water ;  and  that  chlorine  consisted  of  this 
radical  and  oxygen.  Sir  H.  Davy  has  the 
distinguished  glory  of  refuting  the  French 
hypothesis,  and  of  proving  by  decisive  ex- 
periments, that  in  the  present  state  of  our 
knowledge,  chlorine  must  be  regarded  as 
a  simple  substance ;  and  muriatic  acid  gas 
as  a  compound  of  it  with  hydrogen. 

This  gaseous  acid  unites  rapidly,  and  in 
large  quantity,  with  water.  The  following 
table  of  its  aqueous  combinations,  was  con- 
structed after  experiments  made  by  Mr. 
E.  Davy,  in  the  laboratory  of  the  Royal  In- 
stitution, under  the  inspection  of  Sir  H. 
Davy. 

At  temperature  45°,  barometer  30. 
100  parts  of  solution 

of  muriatic  gas,   in          Of  muriatic  acid 
water,  of  sp.  gravity         gas,  parts. 
1  -21        contain        42.43 
1.20  40.80 

1.19  38.38 

1.17  34.34 

1.16  32.32 

1.15  30.30 

l.U  28.28 

1.13  26.26 

1  12  24.24 

1.11  22.30 

1.10  20.20 

1.09  18.18 

1.08  16.16 

1.07  14.14 

106  12.12 

1 05  10.10 

1.04  8.08 

1.03  6.06 


100  parts  of  solution 

of  muriatic  gas,    in          Of  muriatic  acid 
water,  of  sp.  gravity  gas,  parts. 

1.02        contain          4.04 
1.01  2.02 

At  the  temperature  of  40°  Fahrenheit, ; 
water  absorbs  about  480  times  its  bulk  of 
gas,  and  forms  solution  of  muriatic  acid  | 
gas  in  water,  the  specific  gravity  of  which 
is  1.2109.— Sir  H.  Davy's  Elements. 

In  the  Annals  of  Philosophy  for  Octo-  i 
ber  and  November  1817,  there  are  two 
papers  on  the  constitution  of  liquid  muri- 
atic acid  with  tables,  by  Dr.  Ure,  which 
coincide  nearly  with  the  preceding  results. 
They  were  founded  on  a  great  number  of 
experiments  carefully  performed,  which 
are  detailed  in  the  October  number.  In  \ 
mixing  strong  liquid  acid  with  water,  he 
found  that  some  heat  is  evolved,  and  a 
small  condensation  of  volume  is  experien- 
ced, contrary  to  the  observ?tion  of  Mr. 
Kirvvan.  Hence  this  acid  forms  no  longer 
an  exception,  as  that  eminent  chemist 
taught,  to  the  general  law  of  condensa- 
tion of  volume,  which  liquid  acids  obey  in 
their  progressive  dilutions.  Hitherto  in- 
deed many  chemists  have,  without  due 
consideration,  assumed  the  half-sum  or 
arithmetical  mean  of  two  specific  gravities, 
to  be  the  truly  computed  mean  ;  and  on 
comparing  the  number  thus  obtained  with 
that  derived  from  experiment,  they  have 
inferred  the  change  of  volume,  occasion- 
ed by  chemical  combination.  The  errors 
into  which  this  false  mode  of  computation 
leads  are  excessively  great,  when  the  two 
bodies  differ  considerably  in  their  specific 
gravities.  A  view  of  these  erroneous  re- 
sults was  given  in  Dr.  Ure's  third  table  of 
sulphuric  acid,  published  in  the  7th  num- 
ber of  the  Journal  of  Sciences  and  the 
Arts,  and  reprinted  in  this  Dictionary,  ar- 
ticle SPECIFIC  GRAVITY.  "When,  however, 
the  two  specific  gravities  do  not  differ 
much,  the  errors  become  less  remarkable. 
It  is  a  singular  fact,  that  the  arithmetical 
mean,  which  is  always  greater  than  the 
rightly  computed  mean  specific  gravity, 
gives  in  the  case  of  liquid  muriatic  acid, 
an  error  in  excess,  very  nearly  equal  to 
the  actual  increase  of  density.  The  curious 
coincidence  thus  accidentally  produced, 
between  accurate  experiments  and  a  false 
mode  of  calculation  is  very  instructive,  and 
ought  to  lead  chemists  to  verify  every 
anomalous  phenomenon,  by  independent 
modes  of  research.  Had  Mr.  Kirwan,  for 
example,  put  into  a  nicely  graduated 
tube  50  measures  of  strong  muriatic  acid, 
and  poured  gently  over  it  50  measures  of 
water,  he  would  have  found  after  agita- 
tion, and  cooling  the  mixture  to  its  former 
temperature,  that  there  was  a  decided 
diminution  of  volume,  as  Dr.  Ure  experi- 
mentally ascertained.* 


ACI 


ACI 


TABLE  of  real  Muriatic  Aeid,  8tc.  in  100  of  the  Liquid  Acid,  by  Dr.  UHE, 


Sp.Gr. 

Dry 
Add. 

Acid 
Gas. 

Chlo- 
rine. 

Sp.Gr. 

Dry 
Acid. 

Acid  Chlo- 
Gas.  rine. 

Sp.Gr. 

Dry 
Acid. 

Ada 
Gas. 

Chlo- 
rine. 

1.1920 

28.3 

37.60 

36.50 

1.1272 

18.68 

24.82',  24.09 

\  1.0610 

9.05 

1203 

11.68 

1.1900 

28.02 

37.22 

36.13 

1.1253 

18.39 

24.4423.72 

.0590 

8.77 

11.65 

11.31 

1.1881 

27.73 

36.85 

35.77 

1.1233 

18.11 

24.06!  23.36 

.0571 

8.49 

11.28 

10.95 

1.1863 

27.45 

36.47 

35.40 

1.1214 

17.83 

23.69  22.99 

.0552 

8.21 

1J.90 

10.58 

1.1845 

27.17 

36.10 

35.04 

1.1194 

17.55 

23.31)22.63 

.05)3 

7.92 

10.53 

10.22 

1.1827 

26.88 

35.72 

34.67 

1.117.; 

17.26 

22.93 

22.26 

.0514 

7.64 

10.15 

9.85 

1.1808 

26.60 

35.34 

34.31 

1.1155 

16.98 

22.56 

21.90 

.0495 

7.36 

9.77 

9.49 

1.1790 

26.32 

34.97 

33.94 

1.1134 

16.70 

22.18 

21.53 

.0477 

7.07 

9.40 

9.12 

1.1772 

26.04 

34.59 

33.58 

1.1115 

16.41 

21.81 

21.17 

.0457 

6.79 

9.02 

8.76 

1.1753 

25.75 

34.22 

33.21 

1.1097 

16.13 

21.43 

20.80 

.0438 

6.51 

8.65 

8.39 

1.1735 

25.47 

53.84 

32.85 

1.1077 

15.85 

21.05 

20.44 

.0418 

6.23 

8.27 

8.03 

1.1715 

25.19 

33.46 

32.48 

1.1058 

15.56 

20.68 

19.07 

1.0399 

5.94 

7.89 

7.66 

1.1698 

24.90 

33.09 

32.12 

1.1037 

15.28 

20.30 

19.71 

1.0380 

5.66 

7.52 

7.30 

1.1679 

24.62 

32.71 

31.75 

1.1018 

1500 

19.93 

19.34 

1.0361 

5.38 

7.14 

6.93 

1.1661 

24.34 

33.34 

31.39 

1.0999 

14.72 

19.55 

18.9^ 

1.0342 

5.09 

6.77 

6.57 

1.1642 

24.05 

31.96 

31.02 

1.0980 

14.43 

19.17 

18.61 

1.0324 

4.81 

6.39 

6.20 

1.1624 

23.77 

31.58 

30.66 

1.0960 

14.15 

18.80 

18.25 

1.0304 

4.53 

6.02 

5.84 

1.1605 

23.49 

31.21 

30.29 

1.0941 

13.87 

18.42 

17.88 

1.0285 

4.24 

5.64 

5.47 

1.1587 

23.20 

30.83 

29.93 

1.0922 

13.58 

18.04 

17.52 

1.0266 

3.96 

5.26 

5.11 

1.1568 

22.92 

30.46 

29.56 

1.0902 

13.30i17.67 

17.15 

1.0247 

3.68 

4.89 

4.74 

1.1550 

22.64 

30.08 

29.20 

1.0883 

13.02il7.29 

16.79 

1.0228 

3.39 

4.51 

4.38 

1.1531 

22.36 

29.7U 

28.83 

1.0863 

12.73ll6.92 

16.42 

1.0209 

3.11 

4.14 

4.01 

1.1510 

22.07 

2933 

28.47 

1.0844 

12.45|16.54 

16.06 

1.0190 

2.83 

3.76 

3.65 

1.1491 

21.79 

29.95 

28.10 

1.0823 

12.17 

16.17 

15.69 

1.0171 

2.55 

3.38 

3.28 

1.1471 

21.51 

28.57 

27.74 

1.0805 

11.88 

15.79 

15.33 

1.0152 

2.26 

3.01 

2.92 

1.1452 

21.22 

28.20 

27.37 

1.0785 

11.60 

15.42 

14.96 

1.0133 

1.98 

2.63 

2.55 

1.1431 

20.94 

27.82 

27.01 

1.0765 

11.32 

15.04 

14.60 

1.0114 

1.70 

2.26 

2.19 

1.1410 

20.66 

27.45 

26.64 

1.0746 

11.04 

14.66 

14.23 

1.0095 

1.41 

1.88 

1.82 

1.1391 

20.37 

27.07 

26.28 

1.0727 

10.75 

14.29 

13.87 

1.0076 

1.13 

1.50 

1.46 

1.1371 

20.09 

26.69 

25.91 

1.0707 

10.47 

13.91 

13.50 

1.0056 

0.85 

1.13 

109 

1.135119.81 

26.32 

25.55 

1.0688 

10.19 

13.54 

13.14 

1.0037 

0.56 

0.752 

0.73 

1.133219,53 

29.94 

25.18 

1.0669 

9.90 

1.3.16 

12.77 

1.0019 

0.28 

0.376 

0.365 

1.131219.24 

25.57 

24.82 

1.0649 

9.62 

12.78 

12.41 

1.000 

0.00 

0.000 

0.000 

1.1293(18.96 

25.19 

24.45      1.0629 

9.34 

12.41 

12.04 

The  fundamental  density  of  the  acid  of 
:he  preceding  table  is  1.1920,  which  is  as 
strong1  as  it  is  comfortable  to  make  or  to 
use  in  chemical  researches.  To  find  the 
quantity  of  real  acid  in  that  possessed  of 
greater  density,  we  have  only  to  dilute  it 
!with  a  known  proportion  of  water,  till  it 
come  within  the  range  of  the  table.  The 
short  memoir  in  the  Annals  for  November, 
contains  the  logarithmic  series  correspon- 
ding to  the  range  of  densities  and  acid 
strengths;  but  for  all  ordinary  purposes 
the  following  simple  rule  will  serve : 
Multiply  the  decimal  part  of  the  number 
denoting  the  specific  gravity  by  147,  the 
product  will  be  very  nearly  the  per-cen- 
tage  of  dry  acid,  or  by  197  when  we  wish 
to  know  the  per-centage  of  the  acid 

Sas- 

EXAMPLES.  1.  The  specific  gravity  is 
1.141 ;  required  the  proportion  of  dry  acid 
in  100  parts. 

0.141  X  147  =*  20.72,  Bv  the  table  it 
«s  20.66. 


2.  The  specific  gravity  is  1.096;  the 
quantity  of  acid  gas  is  sought. 

0.096  X  197  =  18.9.  By  the  table  it  is 
18.8. 

According  to  the  new  doctrine  of  Sir 
H.  Davy  there  is  no  such  substance  as  the 
dry  acid ;  and  therefore  in  a  theoretical 
point  of  view,  the  column  containing  it 
might  have  been  expunged.  But  for 
practical  purposes  it  is  very  useful,  for  it 
shows  directly  the  increase  of  weight  which 
any  alkaline  or  earthy  base  will  acquire, 
by  combining  with  the  liquid  acid.  Thus, 
if  we  unite  100  grs.  of  liquid  acid  sp. 
gravity  1.1134  with  quicklime,  we  see  that 
the  base  will,  on  evaporation  to  dryness, 
be  heavier  by  16.7  grains.  We  would 
require  a  little  calculation  to  determine 
this  amount  from  the  other  columns.  We 
have  seen  it  stated  that  water,  in  absorb- 
ing 480  times  its  bulk  of  the  acid  gas,  be- 
comes of  specific  gravity  1.2109.  If  we 
compute  from  these  data  the  increase  of 
its  bulk,  we  shall  find  it  equal  to  1.42,  or 


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nearly  one  and  a  half  the  volume  of  the 
water.  481  parts  occupy  only  1.42  in  bulk, 
a  condensation  of  about  340  into  one.  The 
consequence  of  this  approximation  of  the 
particles,  is  the  evolution  of  their  latent 
heat ;  and  accordingly  the  heat  produced 
in  the  condensation  of  the  gas  is  so  great 
that  it  melts  ice  almost  as  rapidly  as  the 
steam  of  boiling  water  does.  Hence  also 
in  passing  the  gas  from  the  beak  of  a  retort 
into  a  Woulfe's  apparatus  containing  water 
to  be  impregnated,  it  is  necessary  to  sur- 
round the  bottles  with  cold  water  or  ice, 
if  we  wish  a  considerable  condensation. 

Dr.  Thomson,  in  the  second  volume  of 
his  System  of  Chemistry,  5th  edition,  has 
committed  some  curious  mistakes  in  treat- 
ing of  the  aqueous  combination  of  muriatic 
acid  gas.  He  says,  "  A  cubic  inch  of 
water  at  the  temperature  of  60°,  barome- 
ter 29.4,  absorbs  515  cubic  inches  of  muri- 
atic acid  gas,  which  is  equivalent  to  308 
grains  nearly.  Hence  water  thus  impreg- 
nated contains  0.548,  or  more  than  half  of 
its  weight  of  muriatic  acid,  in  the  same 
state  of  purity,  as  when  gaseous.  I  caused 
a  current  of  gas  to  pass  through  water, 
till  it  refused  to  absorb  any  more.  The 
specific  gravity  of  the  acid  thus  obtained 
was  1.203.  If  we  suppose  that  the  water 
in  this  experiment  absorbed  as  much  gas 
as  in  the  last,  it  will  follow  from  it  that  6 
parts  of  water,  being  saturated  with  this 
gas,  expanded  so  as  to  occupy  very 
nearly  the  bulk  of  11  parts;  but  in  all 
my  trials  the  expansion  was  only  to  9 
parts.  This  would  indicate  a  specific 
gravity  of  1.477;  yet  upon  actually  trying 
water  thus  saturated,  its  specific  gravity 
was  only  1.203.  Is  this  difference  owing 
to  the  gas  that  escapes  during  the  taking 
of  the  specific  gravity  ?"  page  232. 

\Ve  are  here  presented  with  a  puzzle 
for  the  chemical  student ;  and  an  instruc- 
tive example,  when  one  takes  the  trouble 
of  unravelling  the  hank,  of  a  contest  be- 
tween experimental  results  and  false 
computation.  Granting  all  the  experimen- 
tal statements  to  be  exact,  none  of  the 
consequences  follow.  For,  in  the  first 
place,  515  cubic  inches  of  muriatic  acid 
gas  do  not  weigh  308  grains  nearly,  but 
only  201  grains  ;  and  hence,  secondly,  his 
liquid  acid  could  contain  at  utmost  only 
0.443  of  its  weight  of  gas,  instead  of  0.548 ; 
and,  in  the  third  place,  the  calculated  en- 
largement of  bulk  is  1.5,  or  from  6  to  9, 
and  not  to  11 ;  so  that  the  quere  with 
which  he  concludes  is  superseded.  But 
another  quere  may  here  be  started,  about 
the  experimental  results  themselves.  Dr. 
Thomson  says,  that  a  cubic  inch  of  water 
absorbs  515  cubic  inches  of  gas,  and  ac- 
quires the  specific  gravity  by  experiment 
of  1.203.  Sir  II.  Davy  states,  that  a  cubic 
inch  of  water  absorbs  about  480  cubic 


inches  of  gas,  and  forms  a  liquid  of  specific 
gravity  1.2109.  Now  it  is  remarkable  that 
Dr.  Thomson's  additional  condensation  of 
35  inches  of  gas  gives  a  less  specific  gravity 
than  we  have  in  the  stronger  acid  of  Sir 
H.  Davy. 

But  farther,  the  table  constructed  by 
Sir  H.  and  E.  Davy  presents  for  its  funda- 
mental  density  the  number  1.20  of  Dr. 
Thomson.  Now  this  particular  acid  of 
1.20  was  carefully  analyzed  by  nitrate  of 
silver,  and  is  stated  by  Sir  H.  to  contain 
in  100  grains  40.8  grains  of  condensed  gas. 
Of  course  we  have  a  remainder  of  59.2 
grains  of  water.  40.8  gr.  of  g'as  have  a  vol- 
ume at  the  ordinary  pressure  and  temper- 
ature of  104  cubic  inches,  reckoning  the 
weight  of  100  cubic  inches  to  be  39.162 
gr.  with  Dr.  Thomson-  And  as  59.2  gr. 
of  water  have  absorbed  104  cubic  inches, 
we  have  the  following  proportion,  59.2: 
104 : :  252.5 : 443.  Thus  a  cubic  inch  has  con- 
densed  only  443  cubic  inches,  instead  of 
515.  as  by  Dr.  Thomson.  And  whatever 
error  may  be  supposed  to  be  in  their 
table,  it  is  but  minute,  and  undoubtedly 
does  not  consist  in  underrating  the  quan- 
tity  of  condensed  gas. 

By  uniting  the  base  of  this  gas  with 
silver,  and  also  with  potassium,  Berzelius 
has  lately  determined  the  prime  equivalent 
of  muriatic  acid  to  be  3.4261,  whence 
chlorine  comes  out  4.4261,  and  muriatic 
gas  4.4261 -f-  0.125  (the  prime  of  hydro- 
gen) =  4.5511.  But  if  we  take  1.278  as 
the  specific  gravity  of  this  acid  gas,  then 
the  specific  gravity  of  chlorine  will  be 
twice  that  number,  minus  the  specific 
gravity  of  hydrogen,  or  (1.278  X  2) 
—0.0694  =  2.4866 ;  and  as  chlorine  and 
hydrogen  unite  volume  to  volume,  then 
the  relation  of  the  prime  of  chlorine  will 
2.4866 

be  to  that  of  hydrogen  == =  35.83. 

0.0694 

If  we  divide  this  by  8,  we  shall  have  4.48, 
to  represent  the  prime  equivalent  of  chlo- 
rine, and  4.48-4-0.125  =  4.605  for  that 
of  muriatic  acid  gas. 

But  if  we  call  the  specific  gravity  of 
dry  muriatic  acid  gas  1.2590,  as  Sir  H. 
Davy  says  it  should  be  by  calculation, 
then  the  sp.  gravity  of  chlorine  becomes 
2.4486,  and  its  prime  4.42,  a  number 
agreeing  nearly  with  the  latest  researches 
of  Berzelius. 

Muriatic  acid,  from  its  composition,  has 
been  termed  by  M.  Gay-Lussac  the  hydro- 
chloric acid ;  a  name  objected  to,  on  good 
grounds,  by  Sir  II.  Davy.  It  was  prepar- 
ed by  the  older  chemists  in  a  very  rude 
manner,  and  was  called  by  them  spirit  of 
salt.* 

In  the  ancient  method,  common  salt  was 
previously  decrepitated,  then  ground 
with  dried  clay,  and  kneaded  or  wrought 


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with  water  to  a  moderately  stiff  consis- 
tence, after  which  it  was  divided  into 
balls  of  the  size  of  a  pigeon's  egg:  these 
balls,  being  previously  well  dried,  were 
put  into  a  retort,  so  as  to  fill  the  vessel 
two-thirds  full ;  distillation  being  then 
proceeded  upon,  the  muriatic  acid  came 
over  when  the  heat  was  raised  to  ignition. 
In  this  process  eight  or  ten  parts  of  clay 
to  one  of  salt  are  to  be  used.  The  retort 
must  be  of  stone-ware  well  coated,  and 
the  furnace  must  be  of  that  kind  called 
reverberatory. 

It  was  formerly  thought,  that  the  salt 
was  merely  divided  in  this  operation  by 
the  clay,  and  on  this  account  more  readily 
gave  out  its  acid;  but  there  can  be  little 
doubt,  that  the  effect  is  produced  by  the 
siliceous  earth,  which  abounds  in  large 
proportions  in  all  natural  clays,  and  de- 
tains the  alkali  of  the  salt  by  combining 
with  it. 

*  Sir  H.  Davy  first  gave  the  just  ex- 
planation of  this  decomposition.  Common 
salt  is  a  compound  of  sodium  and  chlorine. 
The  sodium  may  be  conceived  to  combine 
with  the  oxygen  of  the  water  in  the  earth, 
and  with  the  earth  itself,  to  form  a  vitreous 
compound ;  and  the  chlorine  to  unite 
with  the  hydrogen  of  the  water,  forming 
muriatic  acid  gas.  "  It  is  also  easy,"  adds 
lie,  "  according  to  these  new  ideas,  to  ex- 
plain the  decomposition  of  salt  by  moisten- 
ed litharge,  the  theory  of  which  has  so 
much  perplexed  the  most  acute  chemists. 
It  may  be  conceived  to  be  an  instance  of 
compound  affinity  ;  the  chlorine  is  attrac- 
ted by  the  lead,  and  the  sodium  combines 
with  the  oxygen  of  the  litharge,  and  with 
water,  to  form  hydrate  of  soda,  which 
gradually  attracts  carbonic  acid  from  the 
air.  When  common  salt  is  decomposed 
by  oil  of  vitriol,  it  was  usual  to  explain  the 
phenomenon  by  saying,  that  the  acid  by  its 
superior  affinity,  aided  by  heat,  expelled 
the  gas,  and  united  to  the  soda.  But  as 
neither  muriatic  acid  nor  soda  exists  in 
common  salt,  we  must  now  modify  the 
explanation,  by  saying  that  the  water  of 
the  oil  of  vitriol  is  first  decomposed,  its 
oxygen  unites  to  the  sodium  to  form  soda, 
which  is  seized  on  by  the  sulphuric  acid, 
while  the  chlorine  combines  with  the  hy- 
drogen of  the  water,  and  exhales  in  the 
form  of  muriatic  acid  gas." 

As  100  parts  of  dry  sea  salt,  are  capable 
of  yielding  62  parts  by  weight  of  muriatic 
acid  gas,  these  ought  to  afford  by  econo- 
mical management  nearly  221  parts  of 
liquid  acid,  specific  gravity  1.142,  as  pre- 
scribed by  the  London  College,  or  200 
parts  of  acid  sp.  gr.  1.160,  as  directed  by  the 
Edinburgh  and  Dublin  Pharmacopeias. 

The  fluid  ounce  of  the  London  College 
feeing  .jig  of  a  wine  pint,  is  equal  in  weight 
fo  1.265817  Ibs.  Troy,  divided  by  16, 


which  gives  453.7  grains  Troy.  This 
weight  multiplied  by  1.142  =  the  specific 
gravity  of  their  standard  acid,  gives  the 
product  520.4 ;  which  being  multiplied 
by  0.2763,  the  muriatic  gas  in  1.00  by  Dr. 
Ure's  table,  we  have  143.8  or  144  for  the 
acid  gas  in  the  liquid  ounce,  of  the  above 
density.  We  find  this  quantity  equivalent 
to  200  gr.  of  carbonate  of  lime.  Had  the 
fundamental  number  28.3  of  Dr.  Ure's 
table  been  made  28.6,  as  one  of  his  ex- 
periments related  in  the  Annals  of  Philoso- 
phy indicates,  then  a  liquid  ounce  of  the 
above  acid  would  have  dissolved  upwards 
of  202  grains  of  pure  calcareous  carbonate. 
But  when  the  results  fluctuate  between 
28.3  and  28.6,  they  become  exceedingly 
difficult  to  decide  upon.  As  the  difference 
is  altogether  unimportant  in  practice,  he 
does  not  feel  himself  justified  in  making 
any  alteration  in  his  table.  The  limit  of  its 
error  is  certainly  a  fraction  of  one  per  cent. 
Were  29.0  the  leading  number,  then  a 
liquid  oz.  of  acid  of  1.142,  would  dissolve 
205  grains  of  calc  spar.  It  is  obvious  that 
the  series  of  specific  gravities  given  in  the 
above  table,  is  altogether  independent  of 
this  question.  If  28.6  should  be  prefer- 
red by  any  person,  let  him  multiply  this 
number  by  0.9,  0.8,  0.7,  0.6,  &c.  and  he 
will  have  a  series  of  numbers  represen- 
ting the  quantities  of  dry  acids  correspon- 
ding to  the  specific  gravities  1.190, 1.1735, 
1.1550,  1.1351,  &c.  for  these  densities  are 
opposite  to  90,  80,  70,  60,  &c.  per  cent  of 
the  strong  acid.  When  this  acid  is  con- 
taminated with  sulphuric  acid,  it  affords 
precipitates  with  muriates  of  barytes  and 
strontites.* 

We  have  described  the  ancient  method 
of  extracting  the  gas  from  salt,  which  is 
now  laid  aside. 

The  English  manufacturers  use  iron  stills 
for  this  distillation,  with  earthen  heads: 
the  philosophical  chemist,  in  making  the 
acid  of  commerce,  will  doubtless  prefer  glass. 
Five  parts,  by  weight,  of  strong  sulphuric 
acid  are  to  be  added  to  six  of  decrepitated 
sea  salt,  in  a  retort,  the  upper  part  of  which 
is  furnished  with  a  tube  or  neck,  through 
which  the  acid  is  to  be  poured  upon  the 
salt.  The  aperture  of  this  tube  must  be 
closed  with  a  ground  stopper  immediately 
after  the  pouring.  The  sulphuric  acid  im- 
mediately combines  with  the  alkali,  and 
expels  the  muriatic  acid  in  the  form  of  a 
peculiar  air,  which  is  rapidly  absorbed  by 
water.  As  this  combination  and  disen- 
gagement take  place  without  the  applica- 
tion of  heat,  and  the  aerial  fluid  escapes 
very  rapidly,  it  is  necessary  to  arrange  and 
lute  the  vessels  together  before  the  sul- 
phuric acid  is  added,  and  not  to  make  any 
fire  in  the  furnace  until  the  disengagement 
begins  to  slacken ;  at  which  time  it  must 
be  very  gradually  raised.  Be/ore  the  mo- 


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dcrn  improvements  in  chemistry  were 
made,  a  great  part  of  the  acid  escaped  for 
want  of  water  to  combine  with ;  but  by  the 
use  of  Woulfe's  apparatus,  (See  LABORA- 
TORY,) the  acid  air  is  made  to  pass  through 
water,  in  which  it  is  nearly  condensed,  and 
forms  muriatic  acid  of  double  the  weight 
of  the  water,  though  the  bulk  of  this  fluid 
is  increased  one-half  only.  The  acid  con- 
densed in  the  first  receiver,  which  con- 
tains no  water,  is  of  a  yellow  colour,  aris- 
ing from  the  impurities  of  the  salt. 

The  marine  acid  in  commerce  has  a  straw 
colour:  but  this  is  owing  to  accidental  im- 
purity ;  for  it  does  not  obtain  in  the  acid 
produced  by  the  impregnation  of  water 
with  the  pure  aeriform  acid. 

The  muriatic  acid  is  one  of  those  longest 
known,  and  some  of  its  compounds  are 
among  those  salts  with  which  we  are  most 
familiar. 

*  The  muriates,  when  in  a  state  of  dry- 
ness,  are  actually  chlorides,  consisting  of 
chlorine  and  the  metal ;  but  since  moisture 
makes  them  instantly  pass  to  the  state  of 
muriates,  we  shall  describe  them  under 
this  article.  The  sulphates  and  nitrates, 
•when  destitute  of  water,  may  in  like  man- 
ner be  regarded  as  containing  neither  acid 
nor  alkali,  and  might  therefore  be  trans- 
ported to  some  new  department  of  classi- 
fication, to  be  styled  sulphides  and  nitrides, 
as  we  shall  see  in  treating  of  salts.* 

The  muriate  of  barytes  crystallizes  in  ta- 
bles bevelled  at  the  edges,  or  in  octaedral 
pyramids  applied  base  to  base.  It  is  solu- 
ble in  five  parts  of  water  at  60P,  in  still  less 
at  a  boiling  heat,  and  also  in  alcohol.  It 
is  not  altered  in  the  air,  and  but  partly  de- 
composable by  heat.  The  sulphuric  acid 
separates  its  base ;  and  the  alkaline  carbo- 
nates and  sulphates  decompose  it  by  dou- 
ble affinity.  It  is  best  prepared  by  dis- 
solving the  carbonate  in  dilute  muriatic 
acid ;  and  if  contaminated  with  iron  or  lead, 
which  occasionally  happens,  these  may  be 
separated  by  the  addition  of  a  small  quan- 
tity of  liquid  ammonia,  or  by  boiling  and 
stirring  the  solution  with  a  little  barytes. 
Mr.  Goettling  recommends  to  prepare  it 
from  the  sulphate  of  barytes :  eight  parts 
of  which  in  fine  powder  are  to  be  mixed 
with  two  of  muriate  of  soda,  and  one  of 
charcoal  powder.  This  is  to  be  pressed 
hard  into  a  Hessian  crucible,  and  exposed 
for  an  hour  and  a  half  to  a  red  heat  in  a 
wind  furnace.  The  cold  mass,  being  pow- 
dered, is  to  be  boiled  a  minute  or  two  in 
sixteen  parts  of  water,  and  then  filtered. 
To  this  liquor  muriatic  acid  is  to  be  added 
by  little  and  little,  till  sulphuretted  hydro- 
gen censes  to  be  evolved;  it  is  then  to  be 
filtered,  a  little  hot  water  to  be  poured  on 
the  residuum,  the  liquor  evaporated  to  a 
pellicle,  filtered  again,  and  then  set  to  crys- 
•  iallize.  As  the  muriate  of  soda  is  much 


more  soluble  than  the  muriate  of  baryta?, 
and  does  not  separate  by  cooling,  the  mu- 
riate of  barytes  will  crystallize  into  a  per- 
fectly white  salt,  and  leave  the  muriate  of 
soda  in  the  mother  water,  which  may  be 
evaporated  repeatedly  till  no  more  muriate 
of  barytes  is  obtained.  This  salt  was  first 
employed  in  medicine  by  Dr.  Crawford, 
chiefly  in  scrofulous  complaints  and  can- 
cer, beginning  with  doses  of  a  few  drops 
of  the  saturated  solution  twice  a-day,  and 
increasing  it  gradually,  as  far  as  forty  or 
fifty  drops  in  some  instances.  In  large  do- 
ses it  excites  nausea,  and  has  deleterious 
effects.  Fourcroy  says  it  has  been  found 
very  successful  in  scrofula  in  France.  It 
has  likewise  been  recommended  as  a  ver- 
mifuge ;  and  it  has  been  given  with  much 
apparent  advantage,  even  to  very  young 
children,  where  the  usual  symptoms  of 
worms  occurred,  though  none  were  ascer- 
tained to  be  present.  As  a  test  of  sulphu- 
ric acid  it  is  of  great  use. 

The  muriate  of  potash,  formerly  known 
by  the  names  of  febrifuge  salt  of  Sylvius, 
digestive  salt,  and  regenerated  sea  salt,  crys- 
tallizes in  regular  cubes,  or  in  rectangular 
parallelopipedons ;  decrepitating  on  the 
fire,  without  losing  much  of  their  acid,  and 
acquiring  a  little  moisture  from  damp  air, 
and  giving  it  out  again  in  dry.  Their  taste 
is  saline  and  bitter.  They  are  soluble  in 
thrice  their  weight  of  cold  water,  and  in 
but  little  less  of  boiling  water,  so  as  to  re- 
quire spontaneous  evaporation  for  crystal- 
lizing. Fourcroy  recommends,  to  cover 
the  vessel  with  gauze,  and  suspend  hairs 
in  it,  for  the  purpose  of  obtaining  regular 
crystals. 

It  is  sometimes  prepared  in  decompo- 
sing sea  salt  by  common  potash  for  the 
purpose  of  obtaining  soda;  and  may  be 
formed  by  the  direct  combination  of  its 
constituent  parts. 

It  is  decomposable  by  the  sulphuric  and 
nitric  acids.  Barytes  decomposes  it,  though 
not  completely.  And  both  silex  and  alu- 
mina decomposed  it  partially  in  the  dry 
way.  It  decomposes  the  earthy  nitrates^ 
so  that  it  might  be  used  in  saltpetre  manu- 
factories to  decompose  the  nitrate  of  lime. 

Muriate  of  soda,  or  common  salt,  is  of  con- 
siderable use  in  the  arts,  as  well  as  a  ne- 
cessary ingredient  in  our  food.  It  crystal- 
lizes in  cubes,  which  are  sometimes  group- 
ed together  in  various  ways,  and  not  unfre- 
quently  form  hollow  quadrangular  pyra- 
mids. In  the  fire  it  decrepitates,  melts, 
and  is  at  length  volatilized.  When  pure 
it  is  not  deliquescent.  One  part  is  soluble 
in  2$  of  cold  water,  and  in  little  less  of  hot, 
so  that  it  cannot  be  crystallized  but  by  eva- 
poration. According  to  M.  Chenevix,  it  is 
soluble  in  alcohol  also,  particularly  when 
it  is  mixed  with  the  chlorate. 

Common  salt  is  found  in  large  masses,  or 


ACI 

i  in  rocks  under  the  earth,  in  England  and 
elsewhere.  In  the  solid  form  it  is  called 
sal  gem  or  rock  salt.  If  it  be  pure  and  trans- 
parent, it  may  be  immediately  used  in  the 
state  in  which  it  is  found ;  but  if  it  contain 
any  impure  earthy  particles,  it  should  be 
previously  freed  from  them.  In  some 
countries  it  is  found  in  incredible  quanti- 
ties, and  dug  up  like  metals  from  the  bow- 
els of  the  earth.  In  this  manner  has  this 
salt  been  dug  out  of  the  celebrated  salt 
mines  near  Bochnia  and  Wieliczka,  in  Po- 
land, ever  since  the  middle  of  the  13th 
century,  consequently  above  these  500 
years,  in  such  amazing  quantities,  that 
sometimes  there  have  been  20,000  tons 
ready  for  sale.  In  these  mines,  which  are 
said  to  reach  to  the  depth  of  several  hun- 
dred fathoms,  500  men  are  constantly  em- 
ployed. The  pure  and  transparent  salt 
needs  no  other  preparation  than  to  be 
beaten  to  small  pieces,  or  ground  in  a  mill. 
But  that  which  is  more  impure  must  be 
elutriated,  purified,  and  boiled.  That 
which  is  quite  impure,  and  full  of  small 
stones,  is  sold  under  the  name  of  rock  salt, 
and  is  applied  to  ordinary  uses;  it  may 

;  likewise  be  used  for  strengthening  weak 
and  poor  brine-springs. 

Though  the  salt  mines  of  Wieliczka, 

|    near  Cracow  in  Poland,  have  long  asto- 

|  rushed  the  philosopher  and  traveller,  yet 
it  deserves  to  be  remarked,  that  the  quan- 
tity of  rock  salt  obtained  from  the  mines 

i  of  Northwich  is  greatly  superior  to  that 
obtained  at  Cracow.  The  bishop  of  Llan- 
daff  affirms,  that  a  single  pit,  into  which 
he  descended,  yielded  at  a  medium  4000 

I  tons  of  salt  in  a  year,  which  alone  is  about 
two-thirds  of  that  raised  in  the  Polish 
mines.  This  rock  salt  is  never  used  on 
our  tables  in  its  crude  state,  as  the  Polish 
I  rock  salt  is ;  and  though  the  pure  transpa- 
rent salt  might  be  used  with  our  food,  with- 
out any  danger,  yet  it  is  prohibited  under 
a  penalty  of  40s.  for  every  pound  of  rock 
salt  so  applied.  It  is  partly  purified  in 
i  water,  and  a  great  part  of  it  is  sent  to  Li- 
verpool and  other  places,  where  it  is  used 
either  for  strengthening  brine-springs  or 
sea  water. 

Beside  the  salt  mines  here  mentioned, 
where  the  common  salt  is  found  in  a  con- 
crete state,  under  the  name  of  rock  salt, 
there  is  at  Cordova,  in  the  province  of  Ca- 
talonia in  Spain,  a  remarkable  solid  moun- 
tain of  rock  salt ;  this  mountain  is  between 
four  and  five  hundred  feet  in  height,  and  a 
league  in  circuit;  its  depth  below  the  sur- 
face of  the  earth  is  not  known.  This 
mountain  contains  the  rock  salt  without 
the  least  admixture  of  any  other  matter. 

The  waters  of  the  ocean  every  where 
abound  with  common  salt,  though  in  diffe- 
rent proportions.  The  water  of  the  Bal- 
trc  sea  is  said  to  contain  one  sixty-fourth 


ACI 

of  its  weight  of  salt ;  that  of  the  sea  be- 
tween England  and  Flanders  contains  one 
thirty-second  part;  that  on  the  coast  of 
Spain  one  sixteenth  part;  and  between 
the  tropics  it  is  said,  erroneously,  to  con- 
tain from  an  eleventh  to  an  eighth  part. 

The  water  of  the  sea  contains,  besides 
the  common  salt,  a  considerable  propor- 
tion of  muriate  of  magnesia,  and  some  sul- 
phate of  lime,  of  soda,  and  potash.  The 
former  is  the  chief  ingredient  of  the  re- 
maining liquid  which  is  left  after  the  ex- 
traction of  the  common  salt,and  is  called  the 
mother  water.  Sea  water,  if  taken  up  neav 
the  surface,  contains  also  the  putrid  re- 
mains of  animal  substances,  which  render 
it  nauseous,  and  in  a  long  continued  calm 
cause  the  sea  to  stink. 

The  whole  art  of  extracting  salt  from 
waters  which  contain  it,  consists  in  evapo- 
rating the  water  in  the  cheapest  and  most 
convenient  manner.  In  England,  a  brine 
composed  of  sea  water,  with  the  addition 
of  rock  salt,  is  evaporated  in  large  shallow 
iron  boilers ;  and  the  crystals  of  salt  are 
tak  en  out  in  baskets.  In  Russia,  and  pro- 
bably in  other  northern  countries,  the  sea 
water  is  exposed  to  freeze  ;  and  the  ice, 
which  is  almost  entirely  fresh,  being  taken 
out,  the  remaining  brine  is  much  stronger, 
and  is  evaporated  by  boiling.  In  the 
southern  parts  of  Europe  the  salt-makers 
take  advantage  of  spontaneous  evapora- 
tion. A  flat  piece  of  ground  near  the  sea 
is  chosen,  and  banked  round,  to  prevent 
its  being  overflowed  at  high  water.  The 
space  within  the  banks  is  divided  by  low 
walls  into  several  compartments,  which 
successively  communicate  with  each  other. 
At  flood  tide,  the  first  of  these  is  filled 
with  sea  water;  which,  by  remaining  a 
certain  time,  deposites  its  impurities,  and 
loses  part  of  its  aqueous  fluid.  The  resi- 
due is  then  suffered  to  run  into  the  next 
compartment;  and  the  former  is  again 
filled  as  before.  From  the  second  com- 
partment, after  a  due  time,  the  water  is 
transferred  into  a  third,  which  is  lined 
with  clay  well  rammed  and  levelled.  At 
this  period  the  evaporation  is  usually 
brought  to  that  degree,  that  a  crust  of  salt 
is  formed  on  the  surface  of  the  water, 
which  the  workmen  break,  and  it  imme- 
diately falls  to  the  bottom.  They  continue 
to  do  this,  until  the  quantity  is  sufficient 
to  be  raked  out,  and  dried  in  heaps.  This 
is  called  bay  salt. 

In  some  parts  of  France,  and  also  on  the 
coast  of  China,  they  wash  the  dried  sand3 
of  the  sea  with  a  small  proportion  of  wa- 
ter, and  evaporate  this  brine  in  leaden 
boilers. 

There  is  no  difference  between  this  salt 
and  the  lake  salt  extracted  from  different 
lakes,  excepting  such  as  may  be  occasion- 
ed bv  the  casual  intervention  of  some  sub- 


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stances.  In  this  respect  the  Jeltonic  salt 
water  lake,  in  the  Russian  dominions,  near 
Saratov?  and  Dmitrewsk,  deserves  our  at- 
tention. In  the  year  1748,  when  the  Rus- 
sians first  fetched  salt  thence,  the  lake 
was  almost  solid  with  salt;  and  that  to 
such  a  degree,  that  they  drove  their  heavy 
wagons  over  it,  as  over  a  frozen  river, 
and  broke  up  the  salt.f  But  since  the 
year  1757  the  water  has  increased  so 
much,  that  at  this  time  it  is  nothing  more 
than  a  lake  very  strongly  impregnated 
with  salt.  The  Jeltonic  lake  salt  contains 
at  the  same  time  alum  and  sulphate  of 
magnesia. 

At  several  places  in  Germany,  and  at 
Montmarot  in  France,  the  waters  of  salt 
springs  are  pumped  up  to  a  large  reser- 
voir at  the  top  of  a  building  or  shed  ;  from 
which  it  drops  or  trickles  through  small 
apertures  upon  boards  covered  with  brush- 
wood. The  large  surface  of  the  water 
thus  exposed  to  the  air  causes  a  very  con- 
siderable evaporation  ;  and  the  brine  is  af- 
terward conveyed  to  the  boilers  for  the 
perfect  separation  of  the  salt. 

To  free  common  salt  from  those  mix- 
tures that  render  it  deliquescent,  and  less 
fit  for  the  purposes  to  which  it  is  applied, 
it  may  be  put  into  a  conical  vessel  with  a 
small  aperture  at  the  point,  and  a  satura- 
ted solution  of  the  muriate  of  soda  boiling 
hot  be  poured  on  if.  This  solution  will 
dissolve  and  carry  oil  any  other  salt  mix- 
ed with  the  muriate  of  soda,  and  leave  it 
quite  pure,  by  repeating  the  process  three 
l>r  four  times. 

From  this  salt,  as  already  observed,  the 
muriatic  acid  is  extracted;  and  of  late 
years  to  obtain  its  base  separate,  in  the 
most  economical  mode,  for  the  purposes 
of  the  arts,  has  been  an  object  of  research. 
The  process  of  Scheele,  which  consists  in 
mixing  the  muriate  of  soda  with  red  oxide 
of  lead,  making  this  into  a  soft  paste  with 
water,  and  allowing1  it  to  stand  thus  for 
some  time,  moistening  it  with  water  as  it 
gets  dry,  and  then  separating  the  soda 
from  the  muriate  of  lead  by  lixiviation,  has 
been  resorted  to  in  this  country.  Mr. 
Turner  some  years  ago  had  a  patent  for 
it;  converting  the  muriate  of  lead  into  a 
a  pigment,  which  was  termed  mineral  or 
patent  yeko-w,  by  heating  it  to  fusion.  The 
oxide  of  lead  should  be  at  least  twice  the 
weight  of  the  salt.  This  would  have  an- 
swered extremely  well,  had  there  been 
an  adequate  and  regular  demand  for  the 
pigment.  At  present,  we  understand, the 
greater  part  of  the  carbonate  of  soda  in 
the  market  is  furnished  by  decomposing 
the  sulphate  of  soda  left  after  the  muriatic 

f  Why  did  it  not  sink?  Does  salt  swim 
like  ice  ?  I  question  the  truth  of  this  ac- 
co  ant. 


acid  is  expelled  in  the  usual  way  of  manu- 
facturing it  from  common  salt.  Various 
processes  for  this  purpose  were  tried  in 
France  and  made  public  by  the  French 
government,  all  depending  on  the  princi- 
ple of  decomposing  the  acid  of  the  sul- 
phate, by  charcoal,  and  at  the  same  time 
adding  some  other  material  to  prevent 
the  soda  from  forming  a  sulphuret.  What 
they  consider  as  the  best,  is  to  mix  the  sul- 
phate of  soda  with  an  equal  weight  of  chalk 
and  rather  more  than  half  its  weight  oi 
charcoal  powder,  and  to  expose  the  mix- 
ture  in  a  reverberatory  furnace  to  a  heat 
sufficient  to  bring  them  to  a  state  of  im- 
perfect liquefaction.  Much  of  the  sulphuz 
formed  will  be  expelled  in  vapour  and 
burned,  the  mixture  being  frequently 
stirred  to  promote  this ;  and  this  is  conti- 
nued till  the  mass  on  cooling  assumes  a 
fine  grain.  It  is  then  left  exposed  to  a 
humid  atmosphere,  and  the  carbonate  of 
soda  may  be  extracted  by  lixiviation,  the 
sulphur  not  consumed  having  united  with 
the  lime.  Tinmen's  shreds,  or  old  iron, 
may  be  employed  instead  of  chalk,  in  the 
proportion  of  65  parts  to  200  of  sulphate 
of  soda,  and  62  of  charcoal ;  or  chalk  and 
iron  may  be  used  at  the  same  time  in  dif- 
ferent proportions.  The  muriate  of  soda 
might  be  decomposed  in  the  first  instance 
by  the  sulphate  of  iron,  instead  of  the  sul- 
phuric acid.  The  carbonate  of  soda  thus 
prepared,  however,  is  not  free  from  sul- 
phur, and  Dize  recommends  the  abstrac- 
tion of  it  by  adding  litharge  to  the  lixi- 
vium in  a  state  of  ebullition,  which  will 
render  the  alkali  pure.  Oxide  of  manga- 
nese was  substituted  in  the  same  way  with 
equal  success ;  and  this  may  be  used  re- 
peatedly, merely  by  calcining  it  after  each 
time  to  expel  the  sulphur. 

.Mr.  Accum  gives  the  following  method, 
as  having  answered  extremely  well  in  a 
soda  manufactory  in  which  he  was  em- 
ployed : — Five  hundred  pounds  of  sulphate 
of  soda,  procured  from  the  bleachers,  who 
make  a  large  quantity  in  preparing  their 
muriatic  acid  from  common  salt,  were  put 
into  an  iron  boiler  with  a  sufficient  quan- 
tity of  soft  water.  Into  another  boiler  were 
put  560  Ibs.  of  good  American  potash,  or 
570,  if  the  potash  were  indifferent,  dis- 
solved in  about  30  pails  of  water,  or  as  lit- 
tle as  possible.  When  both  were  brought 
to  boil,  the  solution  of  potash  was  ladled 
into  that  of  sulphate  of  soda,  agitating  the, 
mixture,  and  raising  the  fire  as  quickly  as 
possible.  When  the  whole  boiled,  it  \vas 
ladled  into  a  wooden  gutter,  that  convey- 
ed it  to  a  wooden  cistern  lined  with  lead 
near  half  an  inch  thick,  in  a  cool  place. 
Sticks  were  placed  across  the  cistern, 
from  which  slips  of  sheet  lead,  two  or 
three  inches  wide,  hung  down  into  the 
fluid  about  four  inches  distant  from  each 


ACI 


AGI 


other.  When  the  whole  was  cold,  which 
in  winter  was  in  about  three  days,  the  fluid 
was  drawn  off,  the  crystalized  salt  was  de- 
tached from  the  slips  of  lead,  and  the 
rock  of  salt  fixed  to  the  bottom  was  separ- 
ated by  a  chisel  and  mallet.  The  salt  being 
washed  in  the  same  cistern,  to  free  it  from 
impurities,  was  then  returned  to  the  boil- 
er, dissolved  in  clear  water,  and  evaporat- 
ed till  a  strong1  pellicle  formed.  Letting1  it 
cool  till  the  hand  could  be  dipped  into  it, 
it  was  kept  at  this  temperature  as  long-  as 
pellicles  would  form  over  the  whole  sur- 
face, and  fall  to  the  bottom.  When  no 
more  pellicles  appeared  without  blowing 
on  the  surface,  the  fire  was  put  out,  and 
the  solution  returned  into  the  cistern  to 
crystallize.  If  the  solution  be  suffered  to 
cool  pretty  low,  very  little  sulphate  of 
potash  will  be  found  mixed  with  the  soda; 
but  the  rocky  masses  met  with  in  the  mar- 
ket generally  contain  a  pretty  large  quan- 
tity. Tn  the  process  above  described,  the 
produce  of  the  mixed  salt  from  100  Ibs.  of 
sulphate  of  soda  was  in  general  from  136 
i  to  139  Ibs. 

Besides  its  use  in  seasoning1  our  food, 
and  preserving-  meat  both  for   domestic 
|i  consumption  and  during"  the  longest  voy- 
j:  ages,  and  in  furnishing  us  with  the  muri- 
|  atic  acid  and  soda,  salt  forms  a  glaze  for 
i  coarse  pottery,  by  being  thrown  into  the 
I  oven  where  it  is  baked ;  it  improves  the 
whiteness  and  clearness  of  glass  ;  it  gives 
i  greater  hardness  to  soap  ;  in  melting  me- 
j  tals  it  preserves  their  surface  from  calci- 
nation, by  defending  them  from  the  air, 
and  is  employed  with  advantage  in  some 
assays  ;  it  is  used  as  a  mordant,  and  tor  im- 
proving certain  colours,  and  enters  more 
or  less  into  many  other  processes  of  the 
,  arts. 

The  muriate  of  strontian  has  not  long 
been  known.  Dr.  Hope  first  distinguished 
it  from  muriate  of  barytes.  It  crystallizes 
in  very  slender  hexagonal  prisms,  has  a 
cool  pungent  taste,  without  the  austerity 
{  of  the  muriate  of  barytes,  or  the  bitterness 
1  of  the  muriate  of  lime  ;  is  soluble  in  0.75 
of  water  at  60°,  and  to  almost  any  amount 
in  boiling  water ;  is  likewise  soluble  in 
alcohol,  and  gives  a  blood-red  colour  to  its 
flame. 

It  has  never  been  found  in  nature,  but 
1  may  be  prepared  in  the  same  way  as  the 
muriate  of  barytes. 

The  muriate  of  lime  has  been  known  by 
the  names  of  marine  selenite,  calcareous 
marine  salt,  muria,  and  fixed  sal  ammoniac, 
It  crystallizes  in  hexaedral  prisms,  termi- 
nated by  acute  pyramids ;  but  if  the  solu- 
tion be  greatly  concentrated,  and  exposed 
to  a  low  temperature,  it  is  condensed  in 
confused  bundles  of  neeclly  crystals.  Its 
taste  is  acrid,  bitter,  and  very  disagreea- 
ble. It  is  soluble  in  half  its  weight  of  cold 
Vox.  i,  [  9  ] 


water,  and  by  heat  in  its  own  water  of 
crystallization.  It  is  one  of  the  most  de- 
liquescent salts  known  ;  and  when  deli- 
quesced has  been  called  oil  of  lime.  It 
exists  in  nature,  but  neither  very  abun- 
dantly nor  very  pure.  It  is  formed  in 
chemical  laboratories,  in  the  decomposi- 
tion of  muriate  of  ammonia;  andHomberg 
found,  that,  if  it  were  urged  by  a  violent 
heat,  till  it  condensed,  on  cooling,  into  a 
vitreous  mass,  it  emitted  a  phosphoric 
light  upon  being  struck  by  any  hard  body, 
in  which  state  it  was  called  ffombei^g's  phos- 
phorus. 

Hitherto  it  has  been  little  used  except 
for  frigorific  mixtures ;  and  with  snow  it 
produces  a  very  great  degree  of  cold. 
Fourcroy,  indeed,  says  he  has  found  it  of 
great  utility  in  obstructions  of  the  lym- 
phatics, and  in  scrofulous  affections. 

The  muriate  of  ammonia  has  long  been 
known  by  the  name  of  sal  ammonia,  or  am- 
monia. It  is  found  native  in  the  neigh- 
bourhood of  volcanoes,  where  it  is  sub- 
limed sometimes  nearly  pure,  and  in  dif- 
ferent parts  of  Asia  and  Africa.  A  great 
deal  is  carried  annually  to  Russia  and  Si- 
beria from  Bucharian  Tartary ;  and  we 
formerly  imported  large  quantities  from, 
Egypt,  but  now  manufacture  it  at  home. 
See  AMMONIA. 

This  salt  is  usually  in  the  form  of  cakes, 
with  a  convex  surface  on  one  side,  and 
concave  on  the  other,  from  being  sub- 
limed into  large  globular  vessels  ;  but  by 
solution  it  may  be  obtained  in  regular 
quadrangular  crystals.  It  is  remarkable 
for  possessing  a  certain  degree  of  ductili- 
ty, so  that  it  is  not  easily  pulverable.  It 
is  soluble  in  3|  parts  of  water  at  60°,  and 
in  little  more  than  its  own  weight  of  boil- 
ing water.  Its  taste  is  cool,  acrid,  and  bit- 
terish. Its  specific  gravity  is  1.42.  It 
attracts  moisture  from  the  air  but  very 
slightly. 

Muriate  of  ammonia  has  been  more  em- 
ployed in  medicine  than  it  is  at  present. 
It  is  sometimes  useful  as  an  auxiliary  to 
the  bark  in  intermittents ;  in  gargles  it  is 
beneficial,  and  externally  it  is  a  good  dis- 
cutient.  In  dyeing  it  improves  or  height- 
ens different  colours.  In  tinning  and  sol- 
dering it  is  employed  to  preserve  the  sur- 
face of  the  metals  from  oxidation.  In  as- 
saying it  discovers  iron,  and  separates  it 
from  some  of  its  combinations. 

The  muriate  of  magnesia  is  extremely 
deliquescent,  soluble  in  an  equal  weight  of 
water,  and  difficultly  crystallizable  It  dis- 
solves also  in  five  parts  of  alcohol.  It  is 
decomposable  by  heat,  which  expels  its 
acid.  Its  taste  is  intensely  bitter. 

With  ammonia  this  muriate  forms  a  tri- 
ple salt,  crystallizable  in  little  polyedrons, 
which  separate  quickly  from  the  water, 
but  are  not  very  regularly  formed.  Us 


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AC1 


taste  partakes  of  that  of  both  the  prece- 
ding- salts.  The  best  mode  of  preparing1 
it,  is  by  mixing  a  solution  of  27  parts  of 
muriate  of  ammonia  with  a  solution  of  73 
of  muriate  of  magnesia;  but  it  may  be 
formed  by  a  semi-decomposition  of  either 
of  these  muriates  by  the  base  of  the  other. 
It  is  decomposable  by  heat,  and  requires 
six  or  seven  times  its  weight  of  water  to 
di  'Solve  it. 

Of  the  muriate  of  glucine  we  know  but 
little.  It  appears  to  crystallize  *n  very 
small  crystals;  to  be  decomposable  by 
heat ;  and,  dissolved  in  alcohol  and  diluted 
with  water,  to  form  a  pleasant  saccharine 
liquor. 

Muriate  of  alumina  is  scarcely  crystal- 
lizable,  as  on  evaporation  it  assumes  the 
state  of  a  thick  jelly.  It  has  an  acid,  styp- 
tic, acrid  taste.  It  is  extremely  soluble 
in  water,  and  deliquescent.  Fire  decom- 
poses it.  It  may  be  prepared  by  directly 
combining  the  muriatic  acid  with  alumina, 
but  the  acid  always  remains  in  excess. 

The  muriate  of  zircon  crystallizes  in 
small  needles,  which  are  very  soluble,  at- 
tract moisture,  and  lose  their  transparency 
In  the  air.  It  has  an  austere  taste,  with 
somewhat  of  acrimony.  It  is  decomposa- 
ble by  heat.  The  gallic  acid  precipitates 
from  its  solution,  if  it  be  free  from  iron,  a 
white  powder.  Carbonate  of  ammonia, 
if  added  in  excess,  redissolves  the  preci- 
pitate it  had  before  thrown  down. 

Muriate  of  yttria  does  not  crystallize 
when  evaporated,  but  forms  a  jelly :  it 
dries  with  difficulty,  and  deliquesces. 

Fourcroy  observes,  that  when  siliceous 
stones,  previously  fused  with  potash,  are 
treated  with  muriatic  acid,  a  limpid  solu- 
tion is  formed,  which  may  be  reduced  to 
a  transparent  jelly  by  slow  evaporation. 
But  a  boiling  heat  decomposes  the  sili- 
ceous muriate,  and  the  earth  is  deposited. 
The  solution  is  always  acid. 

*  ACID  (MURIATIC,  OXYGENATED).     See 
CHLORIXE.* 

*  ACID  (MURIATIC,  OXYGEXIZKD).  This 
supposed  acid  was  lately  described  by  M. 
Thenard.     Fie  saturated  common  muriatic 
acid  of  moderate  strength  with  deutoxide 
of  barium,  reduced  into   a  soft  paste  by 
trituration  with  water.     He  then  precipi- 
tated the  barytes  from  the  liquid,  by  ad- 
ding the  requisite   quantity  of   sulphuric 
acid.     He  next  took  this  oxygenized  mu- 
riatic acid,  and  treated  it  with  deutoxide 
of  barium  and  sulphuric  acid,  to  oxygenate 
it  anew.     In  this  way  he  charged'  it  with 
oxygen  as  often  as  15  times.     He  thus  ob- 
tained a  liquid  acid  which  contained  32 
times  its  volume  of  oxygen  at  the  tempe- 
rature of  68°  Fahr.  and  at   the   ordinary 
atmospherical  pressure,  and  only  4£  times 
its  volume  of  muriatic  acid,  which  gives 
about  28  equivalent  primes  of  oxygen  to 


one  of  muriatic  acid.  For  the  ratio  of 
oxygen  to  the  acid,  by  weight,  is  1.  to  4.6 ; 
b.ut  by  measure  the  ratio  will  be  as  these 
two  numbers  respectively  divided  by  the 
specific  gravity  of  the  gases,  or  as  y.7TT 
to  -j-.TT^'Which  by  reduction  makes  near; 
ly  one  volume  of  oxygen,  equivalent  to 
four  of  muriatic  acid.  Now,  the  oxygen 
in  the  above  result,  instead  of  being  1  4th 
of  the  volume  of  the  acid  gas,  was  seven 
times  greater,  whence  we  derive  the  num- 
ber 28.  Still  more  oxygen  may  however 
be  added.  On  putting  the  above  oxygen- 
ized acid  in  contact  with  sulphate  of  sil- 
ver, an  insoluble  chloride  of  this  metal 
subsides,  and  the  liquid  is  oxygenized 
sulphuric  acid.  When  this  is  passed 
through  the  filter,  muriatic  acid  is  added 
to  it,  but  in  smaller  quantity  than  existed 
in  the  original  oxygenized  acid.  A  quan- 
tity of  barytes,  just  sufficient  to  precipi- 
tate the  sulphuric  acid,  is  then  added.  In- 
stantly the  oxygen,  leaving  the  sulphuric 
acid  to  unite  with  the  muriatic  acid,  brings 
that  acid  to  the  highest  point  of  oxygena- 
tion.  Thus  we  see  that  we  can  transfer 
the  whole  of  the  oxygen  from  one  of 
these  acids  to  the  other ;  and  on  a  little 
reflection  it  will  be  evident,  that  to  obtain 
sulphuric  acid  in  the  highest  degree  of 
oxygenation,  it  will  be  merely  necessary 
to  pour  barytes  water  into  oxygenated 
sulphuric  acid,  so  as  to  precipitate  only  a 
part  of  the  acid. 

All  these  operations,  with  a  little  prac- 
tice, may  be  performed  without  the  least 
difficulty.  By  combining  the  two  methods 
just  described,  M.  Thenard  found  that  lie 
could  obtain  oxygenized  muriatic  acid, 
containing  nearly  16  times  as  many  vo- 
lumes of  oxygen  as  of  muriatic  acid,  which 
represents  about  64  equivalent  primes  of 
the  former  to  one  of  the  latter.  This 
oxygenized  acid  leaves  no  residuum  when 
evaporated.  It  is  a  very  acid,  colourless 
liquid,  almost  destitute  of  smell,  and  pow- 
erfully reddens  turnsole.  When  boiled 
for  some  time,  its  oxygen  is  expelled.  It 
dissolves  zinc  without  effervescence.  Its 
action  on  the  oxide  of  silver  is  curious. 
These  two  bodies  occasion  as  lively  an  ef- 
fervescence as  if  an  acid  were  poured 
upon  a  carbonate.  Water  and  a  chloride 
are  formed,  while  the  oxygen  is  evolved. 
This  oxide  enables  us  to  determine  the 
quantity  of  oxygen  present  in  the  oxygen- 
ized acid.  Pour  mercury  into  a  graduated 
glass  tube,  leaving  a  small  determinate 
space,  which  must  be  filled  with  the  above 
acid,  invert  the  tube  in  mercury,  let  up 
oxide  of  silver  diffused  in  water ;  instantly 
the  oxygen  is  separated. 

We  ought,  however,  to  regard  this  ap- 
parent oxygenation  of  the  acid,  merely 
as  the  conversion  of  a  portion  of  its  com- 


ACI 


ACI 


Mined  water  into  deutoxide  of  hydrogen. 
The  same  explanation  maybe  extended  to 
the  other  oxygenized  acids  of  M.  Thenard. 
See  WATER.* 

*  ACID  (CHLORIC).  We  place  this  acid 
after  the  muriatic  acid,  because  it  has 
chlorine  also  for  its  base.  It  was  first  eli- 
minated from  the  salts  containing  it  by  M. 
Gay-Lussac,  and  described  by  him  in  his 
admirable  memoir  on  iodine,  published  in 
the  91st  volume  of  the  Jttmales  de  Chimie. 
When  a  current  of  chlorine  is  passed  for 
some  time  through  a  solution  of  barytic 


ber  is  however  too  great,  in  consequence 
of  estimating  the  specific  gravity  of  oxy- 
gen 1.1111,  while  M.  Gay-Lussac  makes  it 
1.10359.  Chloric  acid  is  at  any  rate  a  com- 
pound of  5  primes  of  oxygen  +  1  of  chlo- 
rine =  5.  -f-  4.43  by  Bcrzelius,  or  5.  -f 
4.45  by  Dr.  Ure's  estimate  of  the  atom  of 
chlorine. 

M.  Vauquelin,  in  making  phosphate  of 
silver  act  on  the  mixed  saline  solution 
above  described,  tried  to  accelerate  its 
action  by  dissolving  it  previously  in  acetic 
acid.  But  on  evaporating  the  chlorate  of 

earth  in  warm  water,  a  substance  called  barytes  so  obtained  to  dryness,  and  ex- 
hyperoxymuriate  of  barytes  by  its  first  posing  about  30  grains  to  a  decomposing 
discoverer,  M.  Chenevix,  is  formed,  as  heat,  a  tremendous  explosion  took  place, 
well  as  some  common  muriate.  The  lat-  which  broke  the  furnace,  rent  a  thick 
ter  is  separated,  by  boiling  phosphate  of  platina  crucible,  and  drove  its  lid  into  the 
silver  in  the  compound  solution.  The  for-  chimney,  where  it  stuck.  It  was  the  em- 
mer  may  then  be  obtained  by  evaporation,  ployment  of  acetic  acid  which  occasioned 
in  fine  rhomboidal  prisms.  Into  a  dilute  this  accident,  and  therefore  it  ought  never 
solution  of  this  salt,  M.  Gay-Lussac  poured 


weak  sulphuric  acid.  Though  he  added 
only  a  few  drops  of  acid,  not  nearly  enough 
to  saturate  the  barytes,  the  liquid  became 
sensibly  acid,  and  not  a  bubble  of  oxygen 
escaped.  By  continuing  to  add  sulphuric 
acid  with  caution,  he  succeeded  in  obtain- 
ing an  acid  liquid  entirely  free  from  sul- 
phuric acid  and  barytes,  and  not  precipi- 
tating nitrate  of  silver.  It  was  chloric  acid 
dissolved  in  water.  Its  characters  are  the 
following. 

This  acid  has  no  sensible  smell.     Its  so- 
lution in  water  is  perfectly  colourless.    Its 
taste  is  very  acid,  and  it  reddens  litmus 
without  destroying  the  colour.  It  produces 
no  alteration  on  solution  of  indigo  in  sul- 
phuric acid.    Light  does  not  decompose  it. 
It  may  be  concentrated  by  a  gentle  heat, 
without    undergoing    decomposition,    or 
without  evaporating.     It  was  kept  a  long 
time  exposed  to  the  air  without  sensible 
diminution  of  its  quantity.     When  con- 
centrated, it  has  something  of  an  oily  con- 
sistency.    When  exposed  to  heat,  it  is 
partly  decomposed  into  oxygen  and  chlo- 
rine, and  partly  volatilized  without  altera- 
tion.    Muriatic  acid  decomposes  it  in  the 
same  way,  at  the  common  temperature. 
Sulphurous  acid,  and  sulphuretted  hydro- 
gen, have  the  same  property;  but  nitric 
acid  produces  no  change  upon  it.     Com- 
bined with  ammonia,  it  forms  a  fulminating 
salt,  formerly  described  by  M.  Chenevix. 
It  does  not  precipitate  any  metallic  solu- 
tion. It  readily  dissolves  zinc,  disengaging 
hydrogen ;  but  it  acts  slowly  on  mercury. 
It  cannot  be  obtained  in  the  gaseous  state. 
It  is  composed  of  1  volume  chlorine  -{- 
2.5  oxygen,  or,  by  weight,  of  100  chlorine 
-f-  111.70  oxygen,  if  we  consider  the  spe- 


to  be  used  in  this  way. 

To  the  preceding  account  of  the  pro- 
perties of  chloric  acid,  M,  Vauquelin  has 
added  the  following  :  Its  taste  is  not  only 
acid,  but  astringent,  and  its  odour,  when 
concentrated,  is  somewhat  pungent.  It 
differs  from  chlorine,  in  not  precipitating 
gelatin.  When  paper  stained  with  litmus 
is  left  for  rfome  time  in  contact  with  it,  the 
colour  is  destroyed.  Mixed  with  muriatic 
acid,  water  is  formed,  and  both  acids  are 
converted  into  chlorine.  Sulphurous  acid 
is  converted  into  sulphuric,  by  taking  oxy- 
gen from  the  chloric  acid,  which  is  con- 
sequently converted  into  chlorine. 

Chloric  acid  combines  with  the  bases, 
and  forms  the  chlorates,  a  set  of  salts  for- 
merly known  by  the  name  of  the  hyperoxy- 
genized  muriates.  They  may  be  formed 
either  directly  by  saturating  the  alkali  or 
earth  with  the  chloric  acid,  or  by  the  old 
process  of  transmitting  chlorine  through 
the  solutions  of  the  bases,  in  Woulfe's 
bottles.  In  this  case  the  water  is  decom- 
posed. Its  oxygen  unites  to  one  portion  of 
the  chlorine,  forming  chloric  acid,  while 
its  hydrogen  unites  to  another  portion  of 
chlorine,  forming  muriatic  acid ;  and 
hence,  chlorates  and  muriates  must  be 
contemporaneously  generated,  and  must 
be  afterwards  separated  by  crystalliza- 
tion, or  peculiar  methods. 

The  chlorate  of  potash,  or  hyperoxymu- 
riate, has  been  long  known.  When  ex- 
posed to  a  red  heat,  100  grains  of  this  salt 
yield  38.88  of  oxygen,  and  are  converted 
into  the  chloride  of  potassium,  or  the  dry 
muriate.  This  remainder  of  61.12  grains 
consists  of  32.19  potassium  and  28.93  chlo- 
rine. But  32.19  potassium  require  6.50 


cific  gravity  of  chlorine  to  be  2.4866.  But  oxygen,  to  form  the  potash  which  existed 
if  it  be  called  2.420,  as  M.  Gay-Lussac  does  in  the  original  chlorate.  Therefore,  sub- 
in  his  memoir,  it  will  then  come  out  100  tracting  this  quantity  from  38. 88,  we  have 
Chlorine  -f-  114.7  oxygen.  This  last  num-  32.38  for  the  oxygen  combined  with  the 


ACI 


AC1 


chlorine,  constituting  61.31  of  chloric  acid, 
to  38.69  of  potash.* 

To  its  compounds  we  shall  proceed, 
premising1,  that  we  are  indebted  to  M. 
Chenevix  for  the  first  accurate  descrip- 
tion of  the  chlorates,  orhyperoxymuriates. 

Chlorate,  or  hyperoxy  muriate  of  potash, 
may  be  procured  by  receiving  chlorine,  as 
it  is  formed,  into  a  solution  of  potash. 
When  the  solution  is  saturated,  it  may  be 
evaporated  gently,  and  the  first  crystals 
produced  will  be  the  salt  desired,  this 
crystallizing  before  the  simple  muriate, 
which  is  produced  at  the  same  time  with 
it.  Its  crystals  are  in  shining  hexaedral 
laminae,  or  rhomboidal  plates.  It  is  solu- 
ble in  17  parts  of  cold  water ;  and,  but 
very  sparingly,  in  alcohol.  *  Its  taste  is 
cooling,  and  rather  unpleasant.  Its  speci- 
fic gravity  is  2.0.  16  parts  of  water,  at  60°, 
dissolve  one  of  it,  and  2£  of  boiling  water. 
The  purest  oxygen  is  extracted  from  this 
salt,  by  exposing  it  to  a  gentle  red  heat. 
One  hundred  grains  yield  about  115  cubic 
inches  of  gas.  It  consists  of  9.45  chloric 
acid  -|-  5.95  potash  =  15.4,  which  is  the 
prime  equivalent  of  the  salt.*  It  is  not  de- 
composed by  the  direct  rays  of  the  sun. 
Subjected  to  distillation  in  a  coated  retort, 
it  first  fuses,  and  on  increasing  the  heat, 
gives  out  oxygen  gas.  It  is  incapable  of 
discharging  vegetable  colours;  but  the 
addition  of  a  little  sulphuric  acid  developes 
this  property.  So  likewise  a  few  grains  of 
it,  added  to  an  ounce  of  muriatic  acid,  give 
it  this  property.  It  is  decomposed  by  the 
sulphuric  and  nitric  acids.  If  a  few  grains  be 
dropped  into  strong  sulphuric  acid,  an  of- 
fensive smell  is  produced,  resembling  that 
of  a  brick-kiln,  mixed  with  that  of  nitrous 
gas  ;  and  if  the  quantity  be  large  enough, 
an  explosion  will  encue.  If  the  vessel  be 
deep,  it  will  be  filled  with  a  thick,  heavy 
vapour,  of  a  greenish  yellow  colour,  but 
not  producing  the  symptoms  of  catarrh, 
at  least  in  so  violent  a  degree  as  the  fumes 
of  chlorine.  Underneath  this  vapour  is  a 
bright  orange-coloured  fluid.  This  vapour 
inflames  alcohol,  oil  of  turpentine,  cam- 
phor, resin,  tallow,  elastic  gum,  and  some 
other  inflammable  substances,  if  thrown 
into  it.  If  the  sulphuric  acid  be  poured 
upon  the  salt,  a  violent  decrepitation  takes 
place,  sometimes,  though  rarely,  accom- 
panied by  a  flash.  M.  Chenevix  attempted 
to  disengage  the  chloric  acid  from  this 
salt,  by  adding  sulphuric  acid  to  it  in  a  re- 
tort ;  but  almost  as  soon  as  the  fire  was 
kindled,  an  explosion  took  place,  by  which 
a  French  gentleman  present  was  severely 
wounded,  and  narrowly  escaped  the  loss 
of  an  eye. 

The  effects  of  this  salt  on  inflammable 
bodies  are  very  powerful.  Rub  two  grains 
into  powder  in  a  mortar,  add  a  grain  of  sul- 
phur, mix  them  well  by  gentle  trituration, 


then  collect  the  powder  into  a  heap,  and 
press  upon  it  suddenly  and  forcibly  with 
the  pestle,  a  loud  detonation  will  ensue. 
If  the  mixture  be  wrapped  in  strong  pa- 
per, and  struck  with  a  hammer,  the  report 
will  be  still  louder.  Five  grains  of  the  salt, 
mixed  in  the  same  manner  with  two  and  a 
half  of  charcoal,  will  be  inflamed  by  strong 
trituration,  especially  if  a  grain  or  two  of 
sulphur  be  added,  but  without  much  noise. 
If  a  little  sugar  be  mixed  with  half  its 
weight  of  the  chlorate,  and  a  little  strong 
sulphuric  acid  poured  on  it,  a  sudden  and 
vehement  inflammation  will  ensue  ;  but 
this  experiment  requires  caution,  as  well 
as  the  following.  To  one  grain  of  the  pow- 
dered salt  in  a  mortar,  add  half  a  gram  of 
phosphorus,  it  will  detonal  e,  with  a  loud 
report,  on  the  gentlest  trituration.  In  this 
experiment  the  hand  should  be  defended 
by  a  glove,  and  great  care  should  be  taken 
that  none  of  the  phosphorus  get  into  the 
eyes.  Phosphorus  may  be  inflamed  by  it 
under  water,  by  putting  into  a  wine  glass 
one  part  of  phosphorus  and  two  of  the  chlo- 
rate, nearly  filling  the  glass  with  water, 
and  then  pouring  in  through  a  glass  tube 
reaching  to  the  bottom,  three  or  four 
parts  of  sulphuric  acid.  This  experiment, 
too,  is  very  hazardous  to  the  eyes.  If 
olive  or  linseed  oil  be  taken  instead  of 
phosphorus,  it  maybe  inflamed  by  similar 
means  on  the  surface  of  the  water.  This 
salt  should  not  be  kept  mixed  with  sul- 
phur, or  perhaps  any  inflammable  sub- 
stance, as  in  this  state  it  has  been  known 
to  detonate  spontaneously.  As  it  is  the 
common  effect  of  mixtures  of  this  salt  with 
inflammable  substances  of  every  kind,  to 
take  fire  on  being  projected  into  the  stron- 
ger acids,  M.  Chenevix  tried  the  experi- 
ment with  it  mixed  with  diamond  powder 
in  various  proportions,  but  without  success. 

Chlorate  of  soda  may  be  prepared  in 
the  same  manner  as  the  preceding,  by  sub- 
stituting soda  for  potash  ;  but  it  is  not  easy 
to  obtain  it  separate,  as  it  is  nearly  as  so- 
luble as  the  muriate  of  soda,  requiring  on- 
ly 3  parts  of  cold  water.  *  Vauquelin 
formed  it,  by  saturating  chloric  acid  with 
soda ;  500  parts  of  the  dry  carbonate  yield- 
ing 1  !00  parts  of  crystallized  chlorate.  It 
consists  of  3.95  soda  -\-  9.45  acid  =  13.4, 
which  is  its  prime  equivalent.*  It  crystal- 
lizes in  square  plates,  produces  a  sensation 
of  cold  in  the  mouth,  and  a  saline  taste  ; 
is  slightly  deliquescent,  and  in  its  other 
properties  resembling  the  chlorate  of  pot- 
ash. 

Barytes  appears  to  be  the  next  base  in 
order  of  affinity  for  this  acid.  The  best 
method  of  forming  it  is  to  pour  hot  water 
on  a  large  quantity  of  this  earth,  and  to 
pass  a  current  of  chlorine  through  the 
liquid  kept  warm,  so  that  a  fresh  portion 
of  barytes  may  be  taken  up  as  the  former 


ACI 


ACI 


is  saturated.  This  salt  is  soluble  in  about 
four  parts  of  cold  water,  and  less  of  warm, 
and  crystallizes  like  the  simple  muriate. 
It  may  be  obtained,  however,  by  the  agen- 
cy of  double  affinity  ;  for  phosphate  of 
silver  boiled  in  the  solution  will  decom- 
pose the  simple  muriate,  and  the  muriate 
of  silver  and  phosphate  of  barytes  being- 
insoluble,  will  both  fall  down  and  leave 
the  chlorate  in  solution  alone.  The  phos- 
phate of  silver  employed  in  this  process 
must  be  perfectly  pure,  and  not  the  least 
contaminated  with  copper. 

The  chlorate  of  strontites  may  be  obtain- 
ed in  the  same  manner.  It  is  deliquescent, 
melts  immediately  in  the  mouth  and  pro- 
duces cold ;  is  more  soluble  in  alcohol 
than  the  simple  muriate,  and  crystallizes 
in  needles. 

The  chlorate  of  lime,  obtained  in  a  si- 
milar way,  is  extremely  deliquescent,  li- 
quefies at  a  low  heat  is  very  soluble  in 
alcohol,  produces  much  cold  in  solution, 
and  has  a  sharp  bitter  taste. 

Chlorace  of  ammonia  is  formed  by  dou- 
ble affinity,  the  carbonate  of  ammonia  de- 
composing1 the  earthy  salts  of  this  genus, 
giv.ig  up  its  carbonic  acid  to  their  base, 
and  combining  with  their  acid  into  chlo- 
rate of  ammonia,  which  may  be  obtained 
by  evaporation.  It  is  very  soluble  both  in 
water  and  alcohol,  and  decomposed  by  a 
moderate  heat. 

The  chlorate  of  magnesia  much  resem- 
bles that  of  lime. 

To  obtain  chlorate  of  alumina,  M.  Chene- 
vix  put  some  alumina,  precipitated  from 
the  muriate,  and  well  washed,  but  still 
moist,  into  a  Woulfe's  apparatus,  and  treat- 
ed it  as  the  other  earths.  The  alumina 
shortly  disappeared  ;  and  on  pouring  sul- 
phuric acid  into  the  liquor,  a  strong  smell 
i  of  chloric  acid  was  perceivable  ;  but  on  at- 
tempting to  obtain  the  salt  pure  by  means 
of  phosphate  of  silver,  the  whole  was  de- 
composed, and  nothing  but  chlorate  of 
silver  was  found  in  the  solution.  M.  Chene- 
!  vix  adds,  however,  that  the  aluminous  salt 
appears  to  be  very  deliquescent,  and  so- 
luble in  alcohol. 

*  Acin  (PERCHLORIC).  If  about  3  parts  of 
sulphuric  acid  be  poured  on  one  of  chlo- 
rate of  potash  in  a  retort,  and  after  the 
first  violent  action  is  over,  heat  be  gradu- 
ally applied,  to  separate  the  deutoxide  of 
chlorine,  a  saline  mass  will  remain,  con- 
sisting of  bisulphate  of  potash  and  per- 
chlorate  of  potash.  By  one  or  two  crystal- 
lizations, the  latter  salt  may  be  separated 
from  the  former.  It  is  a  neutral  salt,  with 
a  taste  somewhat  similar  to  the  common 
muriate  of  potash.  It  is  very  sparingly  so- 
luble in  cold  water,  since  at  60°,  only  j-^ 
is  dissolved;  but  in  boiling  water  it  is  more 
soluble.  Its  crystals  are  elongated  octahe- 
drons. It  detonates  feebly  when  triturated 


with  sulphur  in  a  mortar.  At  the  heat  of 
412°,  it  is  resolved  into  oxygen  and  muri- 
ate of  potash,  in  the  proportion  of  46  of 
the  former  to  54  of  the  latter.  Sulphuric 
acid,  at  280°,  disengages  the  perchloric 
ucid.  For  these  facts  science  is  indebted 
to  Count  Von  Stadion.  It  seems  to  consist 
of  7  primes  of  oxygen,  combined  with  1  of 
chlorine,  or  7.0  -|-  4.45.  These  curious 
discoveries  has  been  lately  verified  by  Sir 
H  Davy.  The  other  perchlorates  are  not 
known. 

Before  leaving  the  acids  of  chlorine,  we 
shall  describe  the  ingenious  method  em- 
ployed by  Mr.  Wheeler  to  procure  chloric 
acid  from  the  chlorate  of  petash.  He  mix- 
ed a  warm  solution  of  this  salt  with  one  of 
fluosilicic  acid.  He  kept  the  mixture  mo- 
derately hot  for  a  few  minutes,  and  to  en- 
sure the  perfect  decomposition  of  the  salt, 
added  a  slight  excess  of  the  acid..  Aque- 
ous solution  of  ammonia  will  show,  by  the 
separation  of  silica,  whether  any  of  the 
fluosilicic  acid  be  left  after  the  decompo- 
sition of  the  chlorate.  Thus  we  can  effect 
its  complete  decomposition.  The  mixture 
becomes  turbid,  and  fluosilicate  of  potash 
is  precipitated  abundantly  in  the  form  of  a 
gelatinous  mass.  The  supernatant  liquid 
will  then  contain  nothing  but  chloric  acid, 
contaminated  with  a  small  quantity  of  fluo- 
silicic. This  may  be  removed  by  the  cau- 
tious addition  of  a  small  quantity  of  solu- 
tion of  chlorate.  Or  after  filtration,  the 
whole  acid  may  be  neutralized  by  carbo- 
nate of  barytes,  and  the  chlorate  of  that 
earth  being  obtained  in  crystals,  is  employ- 
ed to  procure  the  acid,  as  directed  by  M. 
Gay-Lussac.* 

ACID  (NiTiuc.)  The  two  principal  con- 
stituent parts  of  our  atmosphere,  when  in 
certain  proportions,  are  capable,  under 
particular  circumstances,  of  combining 
chemically  into  one  of  the  most  powerful 
acids,  the  nitric.  If  these  gases  be  mixed 
in  a  proper  proportion  in  a  glass  tube  about 
a  line  in  diameter,  over  mercury,  and  a  se- 
ries of  electric  shocks  be  passed  through 
them  for  some  hours,  they  will  form  nitric 
acid;  or,  if  a  solution  of  potash  be  present 
with  them,  nitrate  of  potash  will  be  obtain- 
ed. The  constitution  of  this  acid  may  be 
further  proved,  analytically,  by  driving  it 
through  a  red  hot  porcelain  tube,  as  thus 
it  will  be  decomposed  into  oxygen  and  ni- 
trogen gases.  For  all  practical  purposes, 
however,  the  nitric  acid  is  obtained  from 
nitrate  of  potash,  from  which  it  is  expelled 
by  sulphuric  acid. 

Three  parts  of  pure  nitrate  of  potash,f 
coarsely  powdered,  are  to  be  put  into  a 
glass  retort,  with  two  of  strong  sulphu- 

f  Deprived  of  its  water  of  crystalliza- 
tion by  heating  it  nearly  red  hot  in  an  iron 
pan. 


ACI 


ACI 


ric  acid.  This  must  be  cautiously  added, 
taking1  care  to  avoid  the  fumes  that  arise. 
Join  to  the  retort  a  tubulated  receiver  of 
large  capacity,  with  an  adopter  interposed, 
and  lute  the  junctures  with  glazier's  put- 
ty. In  the  tubulure  fix  a  glass  tube,  ter- 
minating in  another  large  receiver,  in 
which  is  a  small  quantity  of  water;  and,  if 
you  wish  to  collect  the  gaseous  products, 
let  a  bent  glass  tube  from  this  receiver 
communicate  with  a  pneumatic  trough. 
Apply  heat  to  the  retort  by  means  of  a 
sand  bath.  The  first  product  that  passes 
into  the  receiver  is  generally  red  acd  fu- 
ming; but  the  appearances  gradually  di- 
minish, till  the  acid  comes  over  pale,  and 
even  colourless,  if  the  materials  used  were 
clean.  After  this  it  again  becomes  more 
and  more  red  and  fuming,  till  the  end  of 
the  operation ;  and  the  whole  mingled  to- 
gether will  be  of  a  yellow  or  orange  colour. 
*  Empty  the  receiver,  and  again  replace 
it.  Then  introduce  by  a  small  funnel,  ve- 
ry cautiously,  one  part  of  boiling  water  in 
a  slender  stream,  and  continue  the  distilla- 
tion. A  small  quantity  of  a  weaker  acid 
will  thus  be  obtained,  which  can  be  kept 
apart.  The  first  will  have  a  specific  gra- 
vity of  about  1.500,  if  the  heat  have  been 
properly  regulated,  and  if  the  receiver  was 
refrigerated  by  cold  water  or  ice.  Acid 
of  that  density,  amounting  to  two-thirds  of 
the  weight  of  the  nitre,  may  thus  be  pro- 
cured. But  commonly  the  heat  is  pushed 
too  high,  whence  more  or  less  of  the  acid 
is  decomposed,  and  its  proportion  of  water 
uniting  to  the  remainder,  reduces  its 
strength.  It  is  not  profitable  to  use  a 
smaller  proportion  of  sulphuric  acid,  when 
a  concentrated  nitric  is  required.  But 
when  only  a  dilute  acid,  called  in  com- 
merce aquafortis,  is  required,  then  less 
sulphuric  acid  will  suffice,  provided  a  por- 
tion of  water  be  added.  One  hundred 
parts  of  good  nitre,  sixty  of  strong  sulphu- 
ric acid,  and  twenty  of  water,  form  econo- 
mical proportions.* 

In  the  large  way,  and  for  the  purposes 
of  the  arts,  extremely  thick  cast  iron  or 
earthen  retorts  are  employed,  to  which  an 
earthen  head  is  adapted,  and  connected 
with  a  range  of  proper  condensers.  The 
strength  of  the  acid  too  is  varied,  by  put- 
ting more  or  less  water  in  the  receivers. 
The  nitric  acid  thus  made  generally  con- 
tains sulphuric  acid,  and  also  muriatic, 
from  the  impurity  of  the  nitrate  employed. 
If  the  former,  a  solution  of  nitrate  of  bary- 
tes  will  occasion  a  white  precipitate ;  if 
the  latter,  nitrate  of  silver  will  render  it 
milky.  The  sulphuric  acid  may  be  sepa- 
rated by  a  second  distillation  from  very 
pure  nitre,  equal  in  weight  to  an  eighth 
of  that  originally  employed;  or  by  preci- 
pitating with  nitrate  of  barytes,  decanting 
the  clear  liquid,  and  distilling  it.  The  mu- 


riatic acid  may  be  separated  by  proceed- 
ing in  the  same  way  with  nitrate  of  silver, 
or  with  litharge,  decanting  the  clear  li- 
quor, and  re -distilling  it,  leaving  an  eighth 
or  tenth  part  in  the  retort.  The  acid  for 
the  last  process  should  be  condensed  as 
much  as  possible,  and  the  re-distillation 
conducted  very  slowly;  and  if  it  be  s\op- 
ped  when  half  is  come  over,  beautiful  crys- 
tals of  muriate  of  lead  will  be  obtained  on 
cooling  the  remainder,  if  litharge  be  used, 
as  M.  Steinacher  informs  us;  who  also 
adds,  that  the  vessels  should  be  made  to 
fit  tight  by  grinding,  as  any  lute  is  liable 
to  contaminate  the  product. 

As  this  acid  still  holds  in  solution  more 
or  less  nitrous  gas,  it  is  not  in  fact  nitric 
acid,  but  a  kind  of  nitrous :  it  is  therefore 
necessary  to  put  it  into  a  retort,  to  which 
a  receiver  is  added,  the  two  vessels  not 
being  luted,  and  to  apply  a  very  gentle 
heat  for  several  hours,  changing  the  re- 
ceiver as  soon  as  it  is  filled  with  red  va- 
pours. The  nitrous  gas  will  thus  be  ex- 
pelled, and  the  nitric  acid  will  remain  in 
the  retort  as  limpid  and  colourless  as  wa- 
ter. It  should  be  kept  in  a  bottle  secluded 
from  the  light,  otherwise  it  will  lose  part 
of  its  oxygen. 

"What  remains  in  the  retort  is  a  bisul- 
phate  of  potash,  from  which  the  superflu- 
ous acid  may  be  expelled  by  a  pretty  strong 
heat,  and  the  residuum,  being  dissolved 
and  crystallized,  will  be  sulphate  of  potash. 
As  nitric  acid  in  a  fluid  state  is  always 
mixed  with  water,  different  attempts  have 
been  made  to  ascertain  its  strength,  or  the 
quantity  of  real  acid  contained  in  it.  Mr. 
Kirwan  supposed,  that  the  nitrate  of  soda 
contained  the  pure  arid  undiluted  with  wa- 
ter, and  thus  calculated  its  strength  from 
the  quantity  requisite  to  saturate  a  given 
portion  of  soda.  Sir  LI.  Davy  more  recent- 
ly took  the  acid  in  the  form  of  gas  as  the 
standard,  and  found  how  much  of  this  is 
contained  in  an  acid  of  a  given  specific 
gravity  in  the  liquid  state. 

*  Mr.  Kirwan  gave  68  as  the  quantity  of 
real  acid  in  100  of  the  liquid  acid  of  speci- 
fic gravity  1.500;  Sir  H.  Davy's  determi- 
nation was  91 ;  Dr.  Wollaston's,  as  infer- 
red from  the  experiments  of  Mr.  R.  Philips, 
75  ;  and  Mr.  Dalton's  corrected  result  from 
Kirwan's  table,  was  68.  In  this  state  of 
discordance  Dr.  Ure  performed  a  series  of 
experiments,  with  the  view  of  determining 
the  constitution  of  liquid  nitric  acid,  and 
published  an  account  of  them,  with  some 
new  tables,  in  the  fourth  and  sixth  vo- 
lumes of  the  Journal  of  Science  and  the 
Arts. 

From  regular  prisms  of  nitre,  he  procur- 
ed by  slow  distillation,  with  concentrated 
oil  of  vitriol,  nitric  acid;  which  by  the  tests 
of  nitrates  of  silver  and  of  barytes,  was 
found  to  be  pure.  Only  the  first  portion 


ACI 


ACI 


that  came  over  was  employed  for  the  ex- 
periments. It  was  nearly  colourless,  and 
had  a  specific  gravity  of  1.500.  A  re-dis- 
tilled and  colourless  nitric  acid,  prepared 
in  London,  was  also  used  for  experiments 
of  verification,  in  estimating1  the  quantity 
ef  dry  acid  in  liquid  acid  of  a  known  den- 
sity. 

The  above  acid  of  1.500  being  mixed  in 
numbered  phials,  with  pure  water,  in  the 
different  proportions  of  95  -f-  5,  90  -{-  10, 
80  -f-  20,  &c.  he  obtained,  after  due  agita- 
tion, and  an  interval  of  24  hours,  liquids 
whose  specific  gravities,  at  60°  Fahren- 
heit, were  determined  by  means  of  an  ac- 
curate balance,  with  a  narrow-necked  glass 
globe  of  known  capacity.  By  considering 
the  series  of  numbers  thus  obtained,  he 
discovered  the  geometrical  law  which  re- 
gulates them.  The  specific  gravity  of  di- 
lute acid,  containing  10  parts  in  the  100  of 
that  whose  density  is  1.500,  is  1.054.  Ta- 
king this  number  as  the  root,  its  successive 
powers  will  give  us  the  successive  densi- 
ties, at  the  terms  of  20,  30,  40,  &c.  per 
cent.  Thus  1.0542  ^  l.m  is  the  speci- 
fic gravity  corresponding  to  20  of  the  strong 
liquid  acid  -f  80  water;  1.0543  _  1.171 
is  that  for  30  per  cent,  of  strong  acid ; 
1.0544  =  1.^34  is  the  specific  gravity  at 
40  per  cent.  The  specific  gravities  are 
therefore  a  series  of  numbers  in  geometri- 
cal prog'ression,  corresponding  to  the  terms 
of  dilution,  another  series  in  arithmetical 
progression,  exactly  as  he  had  shown  in  the 
7th  number  of  the  Journal  of  Science  with 
regard  to  sulphuric  acid.  Hence  if  one 
term  be  given,  the  whole  series  may  be 
found.  On  uniting  the  strong  acid  with 
water,  a  considerable  condensation  of  vo- 
lume takes  place.  The  maximum  conden- 
sation occurs,  when  58  of  acid  are  mixed 
with  42  of  water.  Above  this  point,  the 
curve  of  condensation  has  a  contrary  flex- 
ure ;  and  therefore  a  small  modification 
must  be  made  on  the  root  1.054,  in  order 
to  obtain  with  final  accuracy,  in  the  higher 
part  of  the  range,  the  numerical  powers 
which  represent  the  specific  gravities. 
The  modification  is  however  very  simple. 
To  obtain  the  number  for  50  per  cent,  the 
root  is  1.053 ;  and  for  each  decade  up  to 
70,  the  root  must  be  diminished  by  0,002. 
Thus  for  60,  it  will  become  1.051,  and  for 
70,  1.049.  Above  this  we  shall  obtain  a 
precise  correspondence  with  experiment, 
up  to  1.500  sp.  gravity,  if  for  each  succes- 
sive decade  we  subtract  0.0025  from  the 
last  diminished  root,  before  raising  it  to  the 
desired  power,  which  represents  the  per 
centage  of  liquid  acid. 

It  is  established  by  the  concurring  ex- 
periments of  Sir  II.  Davy  and  M.  Gay-Lus- 
sac,  that  dry  nitric  acid  is  a  compound  of 
2£  volumes  of  oxygen  combined  with  1 
of  nitrogen ;  of  which  the  weights  are 
2.5  X  1.1U  =  2.777  for  the  proportion  of 


oxygen,  and  0.9722  for  that  of  nitrogen ; 
and  in  100  parts,  of  73^  of  the  former -f- 
263  of  the  latter.  But  nitrogen  combines 
with  several  inferior  proportions  o-:  oxy- 
gen, which  are  all  multiples  of  its  prime 
equivalent  1.0;  and  the  present  compound 
is  exactly  represented  by  making  1  prime 
of  nitrogen  =  1.75,  and  5  of  oxygen  = 
5.0 ;  whence  the  acid  prime  is  the  sum  of 
these  two  numbers,  or  6.75.  Now  this  re- 
sult deduced  from  its  constituents,  coin- 
cides perfectly  with  that  derived  from  the 
quantity  in  which  this  acid  saturates  defi- 
nite quantities  of  the  salifiable  bases,  pot- 
ash, soda,  lime,  &c.  There  can  be  no 
doubt,  therefore,  that  the  prime  equiva- 
lent of  the  acid  is  6.75 ;  and  as  little  that 
it  consists  of  5  parts  of  oxygen  and  1.75  of 
nitrogen.  Possessed  of  these  data,  we  may 
perhaps  see  some  reason  why  the  greatest 
condensation  of  volume,  in  diluting  strong 
liquid  acid,  should  take  place  with  58  of 
it,  and  42  of  water.  Since  100  parts  of 
acid  of  1.500  contain,  by  Dr.  Ure's  expe- 
riments, 79.7  of  dry  acid,  therefore  acid  of, 
the  above  dilution  will  contain  46  dry  acid, 
and  54  water ;  or  reducing  the  numbers  to 
prime  proportions,  we  have  the  ratio  of 
6.75  to  7.875,  being  that  of  one  prime  of 
real  acid  to  7  primes  of  water.  But  we 
have  seen  that  the  real  acid  prime,  is  made 
up  of  1  of  nitrogen  associated  by  chemical 
affinity  with  5  of  oxygen.  Now  imagine 
a  figure,  in  which  the  central  prime  of  ni- 
trogen is  surrounded  by  5  of  oxygen.  To 
the  upper  and  under  surface  of  the  nitro- 
gen let  a  prime  of  water  be  attached ;  and 
one  also  to  each  of  the  primes  of  oxygen. 
We  have  thus  the  7  primes  distributed  in 
the  most  compact  and  symmetrical  man- 
ner. By  this  hypothesis,  wre  can  understand 
how  the  elements  of  acid  and  water  may 
have  such  a  collocation  and  proportion,  as 
to  give  the  utmost  efficacy  to  their  reci- 
procal attractions,  whence  the  maximum 
condensation  will  result.  A  striking  analo- 
gy will  be  found  in  the  dilution  of  sulphu- 
ric acid. 

If  on  58  parts  by  weight  of  acid  of 
1.500,  we  pour  cautiously  42  of  water  in  a 
graduated  measure,  of  which  the  whole 
occupies  100  divisions,  and  then  mix  them 
intimately,  the  temperature  will  rise  from 
60°  to  140°,  and  after  cooling  to  60°  again, 
the  volume  will  be  found  only  92.65.  No 
other  proportion  of  water  and  acid  causes 
the  evolution  of  so  much  heat.  When  90 
parts  of  the  strong  acid  are  united  with  10 
of  water,  100  in  volume  become  97;  and 
Aviien  10  parts  of  the  same  acid  are  com- 
bined with  90  of  water,  the  resulting  vo- 
lume is  98.  It  deserves  notice,  that  80  of 
acid  -f-  20  water,  and  30  of  acid  -4-  70  wa- 
ter, each  gives  a  dilute  acid,  whose  degree 
of  condensation  is  the  same,  namely,  100 
measures  become  94.8, 


ACI 


ACI 


TABLE  of  Nitric  Acid,  by  Dr. 


Sp.Gr. 

Jjiq. 
Add 
in  100 

Dry 

Acid 
in  100. 

Sp.Gr. 

Liq. 

Jlcid 
in  100 

Dry 
Acid 
in  100. 

Sp.Gr. 

Liq.   Dry 
Acid  Acid 
•n  100  'in  100. 

Sp.Gr. 

Liq. 
Acid 
in  100 

Dry 

Acid 
in  100. 

1.5000 

100 

79.700 

1.4189 

75 

59.775 

1.2947 

5>J 

39.850 

1.1403 

25 

19.925 

1.4980 

99 

78.903 

1.4147 

74 

58.978 

1.2887 

49 

39.053 

.1345 

24 

19.128 

1.4960 

98 

78.106 

1.4107 

73 

58.181 

i.2826 

48 

38.256 

1.1286 

23 

18.331 

1.4940 

97 

77.309 

1.4065 

72 

57.384 

1.2765 

47 

37.459 

1.1227 

22 

17.534 

1.4910 

96 

76.512 

1.4023 

71 

56.587 

1.2705 

46 

35.662 

1.1168 

21 

16.737 

1.4830 

95 

75.715 

1.3978 

70 

55.790 

1.2644 

45 

35.865 

1.1109 

20 

15.940 

1.4850 

94 

74.918 

1.3945 

69 

54.993 

1.2583 

44 

35.068 

1.1051 

19 

15.143 

1.4820 

93 

74.121 

1.3882 

68 

54.196 

1.252.) 

43 

34.271 

1.0993 

la 

14.346 

1.4790 

92 

73.324 

1.3833 

67 

53.399 

1.2462 

42 

33.474  1 

1.0935 

17 

13.549 

1.4760 

91 

72.527 

1.3783 

66 

52.602 

1.2402 

41 

32.677 

1.0878 

16 

12.752 

1.4730 

90 

71.730 

1.3732 

65 

51.805 

1.2341 

40 

31.880 

1.0821 

15 

11.955 

1.4700 

89 

70.933 

1.3681 

64 

51.068 

1.2277 

39 

31.083 

1.0764 

14  ill.  158 

1.4670 

88 

70.136 

1.3630 

63 

50.211 

1.2212 

38 

30.286 

1.0708 

13 

10.361 

1.4640 

87 

69.339 

1.3579 

62 

49.414 

1.2148 

37 

29.489 

1.0651 

12 

9.564 

1.4600 

86 

68.542 

1.3529'  61 

48.617 

1.2084 

36 

28.692 

1.0595 

11 

8.767 

1.4570 

85 

67.745 

1.3477  j  60 

47.820 

1.2019 

35  (27.895 

1.0540 

10 

7.970 

1.4530 

84 

66.948 

1.34271  59 

47.023 

1.1958 

34 

27.098 

'  1.0485 

9 

7.173 

1.4500 

83 

66.155 

1.33761  58 

46.226 

1.1895 

33 

26.301 

1.0430 

8 

6.376 

1.4460 

82 

65.354 

1.3323 

57 

45.429 

1.1833 

32 

25.504 

1.0375 

7 

5.579 

1.4424 

81 

64.557 

1.3270 

56 

44.632 

1.1770 

31 

24.707 

1.0320 

6 

4.782 

1.4385 

80 

63.76 

1.3216 

55 

43.835 

1.1709 

30 

23.910 

1.0267 

5 

3.985 

1.4346 

79 

62.963 

1.3163 

54 

43.038 

1.1648 

29 

23.113 

1.0212 

4 

3.188 

1.4306 

78 

62.166 

1.3110 

53 

42.241 

1.1587 

28 

22.316 

1.0159 

3 

2.391 

1.4269 

77 

61.369 

1.3056 

52 

41.444 

1.1526 

27 

21.519 

1.0106 

2 

1.594 

1.4228 

76 

60.572  j  1.3001 

51 

40.647  i  1.1465 

26 

20.722 

1.0053 

1 

0.797 

The  column  of  dry  acid  shows  the  weight 
which  any  salifiable  base  would  gain,  by 
uniting  with  100  parts  of  the  liquid  acid 
of  the  corresponding  specific  gravity. 
But  it  may  be  proper  here  to  observe,  that 
Sir  H.  Davy,  in  extending  his  views  rela- 
tive to  the  constitution  of  the  dry  muriates, 
to  the  nitrates,  has  suggested,  that  the 
latter  when  dry  may  be  considered  us 
consisting,  not  of  a  dry  nitric  acid  com- 
bined with  the  salinable  oxide,  but  of 
the  oxygen  and  nitrogen  of  the  nitric 
acid  with  the  metal  itself  in  triple  union. 
A  view  of  his  reasoning  will  be  found 
under  the  article  SALT.  He  regards  liquid 
nitric  acid  at  its  utmost  density  as  a  com- 
pound of  1  prime  of  hydrogen,  1  of  nitro- 
gen, and  6  of  oxygen.* 

The  strongest  acid  that  Mr.  Kirwan 
could  procure  at  60°  was  1.5543 ;  but 
Rouelle  professes  to  have  obtained  it  of 
1.583. 

Nitric  acid  should  be  of  the  specific 
gravity  of  1.5,  or  a  little  more,  and  colour- 
less. 

*  That  of  Mr.  Kirwan  seems  to  have 
consisted  of  one  prime  of  real  acid  and 
one  of  water,  when  the  suitable  correc- 
tions are  made  ;  but  no  common  chemical 
use  requires  it  of  such  a  strength.  The 
following  table  of  boiling  points  has  been 
given  by  Mr.  Dalton. 


Acidofsp.gr.  1.50  boils  at  210° 
1.45  240 

1.42  248 

1.40  247 

1.35  242 

1.30  236 

1.20  226 

1.15  219 

At  1.42  specific  gravity  it  distils  unalter- 
ed. Stronger  acid  than  that  becomes 
weaker,  and  weaker  acid  stronger,  by 
boiling.  When  the  strong  acid  is  cooled 
down  to — 60Q,  it  concretes,  by  slight 
agitation,  into  a  mass  of  the  consistence  of 
butter. 

This  acid  is  eminently  corrosive,  and 
hence  its  old  name  of  aquafortis.  Its  taste 
is  sour  and  acrid  It  is  a  deadly  poison 
when  introduced  into  the  stoniach  in  a 
concentrated  state  ;  but  when  greatly- 
diluted,  it  may  be  swallowed  without 
inconvenience.  It  is  often  contaminated, 
through  negligence  or  fraud  in  the  manu- 
facturer, with  sulphuric  and  muriatic  acids. 
Nitrate  of  lead  detects  both,  or  nitrate  of 
barytes  may  be  employed  to  determine 
the  quantity  of  sulphuric  acid,  and  nitrate 
of  silver  that  of  the  muriatic.  The  latter 
proceeds  from  the  crude  nitre  usually 
containing  a  quantity  of  common  salt.* 

When  it  is  passed  through  a  red  hot 
porcelain  tube,  it  is  resolved  into  oxygen 


AC1 


ACI 


and  nitrogen,  in  the  proportion  above 
stated.  It  retains  its  oxygen  with  little 
force,  so  that  it  is  decomposed  by  all 
combustible  bodies.  Brought  into  contact 
with  hydrogen  gas  at  a  high  temperature, 
a  violent  detonation  ensues,  so  that  this 
must  not  be  done  without  great  caution. 
It  inflames  essential  oils,  as  those  of  tur- 
pentine and  cloves,  when  suddenly  poured 
on  them  ;  but,  to  perform  this  experiment 
with  safety,  the  acid  must  be  poured  out 
of  a  bottle  tied  to  the  end  of  a  long  stick, 
otherwise  the  operator's  face  and  eyes 
will  be  greatly  endangered.  If  it  be 
poured  on  perfectly  dry  charcoal  powder, 
it  excites  combustion,  with  the  emission 
of  copious  fumes.  By  boiling  it  with 
sulphur  it  is  decomposed,  and  its  oxygen, 
uniting  with  the  sulphur,  forms  sulphuric 
acid.  ^  Chemists  in  general  agree,  that  it 
acts  very  powerfully  on  almost  all  the 
metals ;  but  Baume  has  asserted,  that  it 
will  not  dissolve  tin,  and  Dr.  Woodhouse 
of  Pennsylvania  affirms,  that  in  a  highly 
concentrated  and  pure  state  it  acts  not  at 
all  on  silver,  copper,  or  tin.  though,  with 
the  addition  of  a  little  water,  its  action  on 
them  is  very  powerful. 

*  Proust  has  ascertained,  that  acid  having 
the  specific  gravity  1.48,  has  no  more  ac- 
tion on  tin  than  on  sand,  while  acid  some- 
what stronger  or  weaker  acts  furiously  on 
the  metal.  Now,  acid  of  1.485,  by  Dr. 
Ure's  table,  consists  of  one  prime  of  real 
acid  united  with  two  of  water,  constituting, 


COLOUR. 
Pale  yellow 
Bright  yellow 
Dark  orange 
Light  olive 
Dark  olive 
Bright  green 
Blue  green 

REAL  ACID. 
90.5 
88.94 
8C.84 
86.0 
85.4 
84.8 
84.6 

it  would  thus  appear,  a  peculiarly  power- 
ful combination. 

Acid  which  takes  up  TVQ8o  tns  of  'ts 
weight  of  marble,  freezes,  according  to 
Mr.  Cavendish,  at  —  2°.  When  it  can  dis- 
solve T5oVs»  **  requires  to  be  cooled  to  — 
41°.6  before  congelation;  and  when  so 
much  diluted  as  to  take  up  only  YBiys*  it 
congeals  at—  40°.o.  The  first  has  a 
specific  gravity  of  1.330  nearly,  and  con- 
sists of  1  prime  of  dry  acid  -j-  7  of  water  ; 
the  second  has  a  specific  gravity  of  1.420, 
and  contains  exactly  one  prime  of  dry 
acid  4-  four  of  water  ;  while  the  third  has 
a  specific  gravity  of  1.215,  consisting  of 
one  prime  of  acid  -f-  14  of  water.  We 
perceive,  that  the  liquid  acid  of  1.420, 
composed  of  4  primes  of  water  -f-  one  of 
dry  acid,  possesses  the  greatest  power  of 
resisting  the  influence  of  temperature  to 
change  its  slate.  It  requires  the  maximum 
heat  to  boil  it,  when  it  distils  unchanged; 
and  the  maximum  cold  to  effect  its  con- 
gelation.* 

It  has  already  been  observed,  that  the 
nitric  acid,  when  first  distilled  over,  holds 
in  solution  a  portion  of  nitric  oxide,  which 
is  greater  in  proportion  as  the  heat  has 
been  urged  toward  the  end,  and  much 
increased  by  even  a  small  portion  of  in- 
flammable matter,  should  any  have  been 
present.  The  colour  of  the  acid,  too,  is 
affected  by  the  quantity  of  nitric  oxide  it 
holds,  and  Sir  H.  Davy  has  given  us  the 
following  table  of  proportions  answering 
to  its  different  hues. 


But  these  colours  are  not  exact  indica- 
tions of  the  state  of  the  acid,  for  an  addition 
of  water  will  change  the  colour  into  one 
lower  in  the  scale,  so  that  a  considerable 
portion  of  water  will  change  the  dark 
orange  to  a  blue  green. 

The  nitric  acid  is  of  considerable  use  in 
the  arts.  It  is  employed  for  etching  on 
copper ;  as  a  solvent  of  tin  to  form  with 
that  metal  a  mordant  for  some  of  the  finest 
dyes ;  in  metallurgy  and  assaying ;  in  va- 
rious chemical  processes,  on  account  of 
the  facility  with  which  it  parts  with  oxy- 
gen and  dissolves  metals ;  in  medicine  as 
a  tonic,  and  as  a  substitute  for  mercurial 
preparations  in  syphilis  and  affections  of 
the  liver;  as  alse  in  form  of  vapour  to  de- 
stroy contagion.  For  the  purposes  of  the 
arts  it  is  commonly  used  in  a  diluted  state, 
and  contaminated  with  the  sulphuric  and 
muriatic  acids,  by  the  name  of  aquafortis. 
This  is  erenerahy  prepared  by 
Voi.  i.  [  10  ] 


NITRIC  OXIDE, 
1.2 

2.96 
5.56 
6.45 
7.1 

7.76 
8. 


WATER. 
8.3 
8.10 
7.6 
7.55 
7.5 
7.44 
7.4 


common  nitre  with  an  equal  weight  o*f 
sulphate  of  iron,  and  half  its  weight  of  the 
same  sulphate  calcined,  and  distilling  the 
mixture  ;  or  by  mixing  nitre  with  twice 
its  weight  of  dry  powdered  clay,  and  dis- 
tilling in  a  reverberatory  furnace.  Two 
kinds  are  found  in  the  shops,  one  called 
double  aquafortis^  which  is  about  half  the 
strength  of  nitric  acid  ;  the  other  simply 
aquafortis,  which  is  half  the  strength  of 
the  double. 

A  compound  made  by  mixing  two  parts 
of  the  nitric  acid  with  one  of  muriatic, 
known  formerly  by  the  name  of  aqua 
regia,  and  now  by  that  of  nitro  -muriatic 
acid,  has  the  property  of  dissolving  gold 
and  platina.  On  mixing  the  two  acids, 
heat  is  given  out,  an  effervescence  takes 
place,  and  the  mixture  acquires  an  orange 
colour.  This  is  likewise  made  by  adding 
gradually  to  an  ounce  of  powdered  muriate 
of  ammonia,  four  ounces  of  double  aqua- 


ACI 


ACI 


fbrtis,  and  keeping  the  mixture  in  a  sand- 
heat  till  the  salt  is  dissolved ;  taking  care 
to  avoid  the  fames  as  the  vessel  must  be 
left  open  ;  or  by  distilling  nitric  acid  with 
an  equal  weight,  or  rather  more,  of  com- 
mon  salt. 

*  On  this  subject  we  are  indebted  to 
Sir  H.  Davy  for  some  excellent  observa- 
tions, published  by  him  in  the  first  volume 
of  the  Journal  of  Science.  If  strong  nitrous 
acid,  saturated  with  nitrous  gas,  be  mixed 
with  a  saturated  solution  of  muriatic  acid 
gas,  no  other  effect  is  produced  than  might 
be  expected  from  the  action  of  nitrous 
acid  of  the  same  strength  on  an*  equal 
quantity  of  water ;  and  the  mixed  acid  so 
formed  has  no  power  of  action  on  gold  or 
platina.  Again,  if  muriatic  acid  gas,  and 
nitrous  gas  in  equal  volumes,  be  mixed 
together  over  mercury,  and  half  a  volume 
of  oxygen  be  added,  the  immediate  con- 
densation will  be  more  than  might  be  ex- 
pected from  the  formation  of  nitrous  acid 
gas.  And  when  this  is  decomposed,  or 
absorbed  by  the  mercury,  the  muriatic 
acid  gas  is  found  unaltered,  mixed  with  a 
certain  portion  of  nitrous  gas. 

It  appears  then  that  nitrous  acid,  and 
fnuriatic  acid  gas,  have  no  chemical  action 
on  each  other.  If  colourless  nitric  acid,  and 
muriatic  acid  of  commerce,  be  mixed  to- 
gether, the  mixture  immediately  becomes 
yellow,  and  gains  the  power  of  dissolving 
gold  and  platinum.  If  it  be  gently  heated, 
ptire  chlorine  arises  from  it,  and  the  co- 
lour becomes  deeper.  If  the  heat  be  lon- 
ger continued,  chlorine  still  rises,  but  mix- 
ed with  nitrous  acid  gas'  When  the  pro- 
cess has  been  very  long  continued  till  the 
colour  becomes  very  deep,  no  more  chlo- 
rine can  be  procured,  and  it  loses  its  power 
of  acting  upon  platinum  and  gold.  It  is 
now  nitrous  and  muriatic  acid.  It  appears 
then  from  these  observations,  which  have 
been  very  often  repeated,  that  nitro-mu- 
riatic  acid  owes  its  peculiar  properties  to 
a  mutual  decomposition  of  the  nitric  and 
muriatic  acids;  and  that  water,  chlorine, 
and  nitrous  acid  gas,  are  the  results. 
Though  nitrous  gas  and  chlorine  have  no 
action  on  each  other  when  perfectly  dry, 
yet  if  water  be  present  there  is  an  imme- 
diate decomposition,  and  nitrous  acid  and 
muriatic  acid  are  formed.  118  parts  of 
strong  liquid  nitric  acid  being  decompos- 
ed in  this  case,  yield  67  of  chlorine.  Aqua 
regia  does  not  oxidize  gold  and  platina. 
It  merely  causes  their  combination  with 
chlorine. 

A  bath  made  of  nitro-muriatic  acid,  di- 
luted so  much  as  to  taste  no  sourer  than 
vinegar,  or  of  such  a  strength  as  to  prick 
the  skin  a  little,  after  being  exposed  to  it 
for  twenty  minutes  or  half  an  hour,  has 
been  introduced  by  Dr.  Scott  of  Bombay 
as  a  remedy  in  chronic  syphilis,  a  variety 


of  ulcers,  and  diseases  of  the  skin,  chronic 
hepatitis,  bilious  dispositions,  general  de- 
bility, and  languor.  He  considers  every 
trial  as  quite  inconclusive,  where  a  ptyalism, 
some  affection  of  the  gums,  or  some  very 
evident  constitutional  effect,  has  not  arisen 
from  it.  The  internal  use  of  the  same  acid 
has  been  recommended  to  be  conjoined 
with  that  of  the  partial  or  general  bath.* 

With  the  different  bases  the  nitric  acid 
forms  nitrates. 

The  nitrate  of  barytes,  when  perfectly 
pure,  is  in  regular  octaedral  crystals, 
though  it  is  sometimes  obtained  in  small 
shining  scales.  It  may  be  prepared  by 
uniting  barytes  directly  with  nitric  acid, 
or  by  decomposing  the  carbonate  or  sul- 
phuret  of  barytes  with  this  acid  Exposed 
to  heat  it  decrepitates,  and  at  length  gives 
out  its  acid,  which  is  decomposed ;  but  if 
the  heat  be  urged  too  far,  the  barytes  is 
apt  to  vitrify  with  the  earth  of  the  cruci- 
ble. It  is  soluble  in  12  parts  of  coid,  and 
3  or  4  of  boiling  water.  It  is  said  to  exist 
in  some  mineral  waters.  *  It  consists  of 
6.75  acid  -f  9.75,  or  9.7  base.* 

The  nitrate  of  potash  is  the  salt  well 
known  by  the  name  of  nitre  or  saltpetre. 
It  is  found  ready  formed  ;in  the  East  In- 
dies, in  Spain,  in  the  kingdom  of  Naples, 
and  elsewhere,  in  considerable  quantities  ; 
but  nitrate  of  lime  is  still  more  abundant. 
Far  the  greater  part  of  the  nitrate  made 
use  of  is  produced  by  a  combination  of 
circumstances  which  tend  to  compose  and 
condense  nitric  acid.  This  acid  appears 
to  be  produced  in  all  situations,  where 
animal  matters  are  completely  decompos- 
ed, with  access  of  air  and  of  proper  sub- 
stances with  which  it  can  readily  combine. 
Grounds  frequently  trodden  by  cattle  and 
impregnated  with  their  excrements,  or 
the  walls  of  inhabited  places  where  putrid 
animal  vapours  abound,  such  as  slaughter- 
houses, drains,  or  the  like,  afford  nitre  by 
long  exposure  to  the  air.  Artificial  nitre 
beds  are  made  by  an  attention  to  the  cir- 
cumstances in  which  this  salt  is  produced 
by  nature.  Dry  ditches  are  dug,  and  co- 
vered with  sheds,  open  at  the  sides,  to 
keep  off  the  rain :  these  are  filled  with 
animal  substances — such  as  dung,  or  other 
excrements,  with  the  remains  of  vegeta- 
bles, and  old  mortar,  or  other  loose  calca- 
reous earth ;  this  substance  being  found 
to  be  the  best  and  most  convenient  recep- 
tacle for  the  acid  to  combine  with.  Occa- 
sional watering,  and  turning  up  from  time 
to  time,  are  necessary,  to  accelerate  the 
process,  and  increase  the  surfaces  to  which 
the  air  may  apply ;  but  too  much  moisture 
is  hurtful.  WThen  a  certain  portion  of  ni- 
trate is  formed,  the  process  appears  to  go 
on  more  quickly ;  but  a  certain  quantity 
stops  it  altogether,  and  after  this  cessation 
the  materials  will  go  on  to  furnish 


ACI 


ACI 


if  what  is  formed  be  extracted  by  lixivia- 
tion.  After  a  succession  of  many  months, 
more  or  less,  according  to  the  manage- 
ment of  the  operation,  in  which  the  action 
of  a  regular  current  of  fresh  air  is  of  the 
greatest  importance,  nitre  is  found  in  the 
mass.  If  the  beds  contained  much  vege- 
table matter,  a  considerable  portion  of  the 
nitrous  salt  will  be  common  saltpetre, 
but,  if  otherwise,  the  acid  will,  for  the 
most  part,  be  combined  with  the  calca- 
reous earth.  *  It  consists  of  6.75  acid  -f- 
5.95  potash.* 

To  extract  the  saltpetre  from  the  mass 
of  earthy  matter,  a  number  of  large  casks 
are  prepared,  with  a  cock  at  the  bottom 
of  each,  and  a  quantity  of  straw  within,  to 
prevent  its  being  stopped  up.  Into  these 
the  matter  is  put,  together  with  wood- 
ashes,  either  strewed  at  top,  or  added 
during  the  filling.  Boiling  water  is  then 
poured  on,  and  suffered  to  stand  for  some 
time;  after  which  it  is  drawn  off,  and 
other  water  added  in  the  same  manner, 
as  long  as  any  saline  matter  can  be  thus 
extracted.  The  weak  brine  is  heated,  and 
passed  through  other  tubs,  until  it  be- 
comes of  considerable  strength.  It  is  then 
carried  to  the  boiler,  and  contains  nitre 
and  other  salts ;  the  chief  of  which  is  com- 
mon culinary  salt,  and  sometimes  muriate 
of  magnesia.  It  is  the  property  of  nitre 
to  be  much  more  soluble  in  hot  than  cold 
water ;  but  common  salt  is  very  nearly  as 
soluble  in  cold  as  in  hot  water.  When- 
ever, therefore,  the  evaporation  is  carried 
by  boiling  to  a  certain  point,  much  of  the 
common  salt  will  fall  to  the  bottom,  for 
want  of  water  to  hold  it  in  solution,  though 
the  nitre  will  remain  suspended  by  virtue 
of  the  heat.  The  common  salt  thus  sepa- 
rated is  taken  out  with  a  perforated  ladle, 
and  a  small  quantity  of  the  fluid  is  cooled, 
from  time  to  time,  that  its  concentration 
may  be  known  by  the  nitre  which  crystal- 
lizes in  it.  When  the  fluid  is  sufficiently 
evaporated,  it  is  taken  out  and  cooled,  and 
great  part  of  the  nitre  separates  in  crys- 
tals ;  while  the  remaining  common  salt  con- 
tinues dissolved,  because  equally  soluble  in 
cold  and  in  hot  water.  Subsequent  evapora- 
tion of  the  residue  will  separate  more  nitre 
in  the  same  manner.  *  By  the  suggestion 
of  Lavoisier,  a  much  simpler  plan  was 
adopted ;  reducing  the  crude  nitre  to 
powder,  and  washing  it  twice  with  water.* 

This  nitre,  which  is  called  nitre  of  the 
first  boiling,  contains  some  common  salt ; 
from  which  it  may  be  purified  by  solution 
in  a  small  quantity  of  water,  and  subse- 
quent evaporation;  for  the  crystals  thus 
obtained  are  much  less  contaminated  with 
common  salt  than  before ;  because  the 
proportion  of  water  is  so  much  larger, 
with  respect  to  the  small  quantity  con- 
tained by  the  nitre,  that  very  little  of  it 


will  crystallize.  For  nice  purposes,  the 
solution  and  crystallization  of  nitre  are 
repeated  four  times.  The  crystals  of  nitre 
are  usually  of  the  form  of  six-sided  flatten- 
ed prisms,  with  diedral  summits.  Its  ;aste 
is  penetrating ;  but  the  cold  produced  by 
placing  the  salt  to  dissolve  in  the  mouth 
is  such  as  to  predominate  over  the  real 
taste  at  first.  Seven  parts  of  water  dis- 
solve two  of  nitre,  at  the  temperature  of 
sixty  degrees ;  but  boiling  water  dissolves 
its  own  weight.  100  parts  of  alcohol,  at  a 
heat  of  176°,  dissolve  only  2.9. 

On  being  exposed  to  a  gentle  heat,  nitre 
fuses;  and  in  this  state  being  poured  into 
moulds,  so  as  to  form  little  round  cakes, 
for  balls,  it  is  called  sal  prunella,  or  crystal 
mineral.  This  at  least  is  the  way  in  which 
this  salt  is  now  usually  prepared,  conforma- 
bly to  the  directions  of  Boerha  »ve ;  though 
in  most  dispensatories  a  twenty-fourth 
part  of  sulphur  was  directed  to  be  defla- 
grated on  the  nitre  before  it  was  poured 
out.  This  salt  should  not  be  left  on  the 
fire  after  it  has  entered  into  fusion,  other- 
wise it  will  be  converted  into  a  nitrite  of 
potash.  If  the  heat  be  increased  to  red- 
ness, the  acid  itself  is  decomposed,  and  a 
considerable  quantity  of  tolerably  pure 
oxygen  gas  is  evolved,  succeeded  by  ni- 
trogen. 

This  salt  powerfully  promotes  the  com- 
bustion of  inflammable  substances.  Two 
or  three  parts  mixed  with  one  of  charcoal, 
and  set  on  fire,  burn  rapidly ;  azote  and 
carbonic  acid  gas  are  given  out,  and  a 
small  portion  of  the  latter  is  retained  by 
the  alkaline  residuum,  which  was  formerly 
called  clyssus  of  nitre.  Three  parts  of  nitre, 
two  of  subcarbonate  of  potash,  and  one  of 
sulphur,  mixed  together  in  a  warm  mor- 
tar, form  the  fulminating  powder  /  a  small 
quantity  of  which,  laid  on  a  fire-shovel, 
and  held  over  the  fire  till  it  begins  to 
melt,  explodes  with  a  loud  sharp  noise. 
Mixed  with  sulphur  and  charcoal,  it  forms 
gunpowder.  See  GUNPOWDER. 

Three  parts  of  nitre,  one  of  sulphur, 
and  one  of  fine  saw-dust,  well  mixed,  con- 
stitute what  is  called  the  powder  of  fusion. 
If  a  bit  of  base  copper  be  folded  up  and 
covered  with  this  powder  in  a  walnut- 
shell,  and  the  powder  be  set  on  fire  with  a 
lighted  paper,  it  will  detonate  rapidly, 
and  fuse  the  metal  into  a  globule  of  sul- 
phuret,  without  burning  the  shell. 

If  nitrate  of  potash  be  heated  in  a  retort 
with  half  its  weight  of  solid  phosphoric  or 
boracic  acid,  as  soon  as  this  acid  begins  to 
enter  into  fusion,  it  combines  with  the  pot- 
ash, and  the  nitric  acid  is  expelled,  ac- 
companied with  a  small  portion  of  oxygen 
gas  and  nitric  oxide. 

Silex,  alumina,  and  barytes,  decompose 
this  salt  in  a  high  temperature  by  uniting 
with  its  base.  The  alumina  will  effect 


ACI 


ACI 


this  even  after  it  has  been  made  into 
pottery. 

The  uses  of  nitre  are  various.  Beside 
those  already  indicated,  it  enters  into  the 
composition  of  fluxes,  and  is  extensively 
employed  in  metallurgy  ;  it  serves  to  pro- 
mote the  combustion  of  sulphur  in  fabri- 
cating its  acid ;  it  is  used  in  the  art  of 
dyeing- ;  it  is  added  to  common  salt  for 
preserving  meat,  to  which  it  gives  a  red 
hue  ;  it  is  an  ingredient  in  some  frigorific 
mixtures;  and  it  is  prescribed  in  medi- 
cine, as  cooling,  febrifuge,  and  diuretic  ; 
and  some  have  recommended  it  ^nixed 
with  vinegar  as  a  very  powerful  remedy 
for  the  sea  scurvy. 

Nitrate  of  soda,  formerly  called  cubic  or 
quadrangular  nitre,  approaches  in  its  pro- 
perties to  the  nitrate  of  potash ;  but  dif- 
fers from  it  in  being  somewhat  more  solu- 
ble in  cold  water,  though  less  in  hot,  which 
takes  up  little  more  than  its  own  weight ; 
in  being  inclined  to  attract  moisture  from 
the  atmosphere;  and  in  crystallizing  in 
rhombs,  or  rhomboidal  prisms.  It  maybe 
prepared  by  saturating  soda  with  the  ni- 
tric acid ;  by  precipitating  nitric  solutions 
of  the  metals,  or  of  the  earths,  except 
barytes,  by  soda ;  by  lixiviating  and  crys- 
tallizing the  residuum  of  common  salt  dis- 
tilled with  three-fourths  its  weight  of  ni- 
tric acid ;  or  by  saturating  the  mother 
waters  of  nitre  with  soda  instead  of  potash. 

This  salt  has  been  considered  as  use- 
less ;  but  professor  Proust  says,  that  live 
parts  of  it,  with  one  of  charcoal  and  one  of 
sulphur,  will  burn  three  times  as  long  as 
common  powder,  so  as  to  form  an  econo- 
mical composition  for  fire-works.  *lt  con- 
sists of  6.75  acid-f-  3.95  soda.* 

Nitrate  of  strontian  maybe  obtained  in 
the  same  manner  as  that  of  barytes,  with 
which  it  agrees  in  the  shape  of  its  crystals, 
and  most  of  its  properties.  It  is  much 
more  soluble,  however,  requiring  but  four 
or  five  parts  of  water  according  to  Van- 
quelin,  and  only  an  equal  weight  accord- 
ing to  Mr.  Henry.  Boiling  water  dissolves 
nearly  twice  as  much  as  cold.  Applied  to 
the  wick  of  a  candle,  or  added  to  burning 
alcohol,  it  gives  a  deep  red  colour  to  the 
flame.  On  this  account  it  may  be  useful, 
perhaps,  in  the  art  of  pyrotechny.  *lt  con- 
sists of  6.75  acid  -f-  6.5  strontian.* 

Nitrate  of  lime,  the  calcareous  nitre  of 
older  writers,  abounds  in  the  mortar  of 
old  buildings,  particularly  those  that  have 
been  much  exposed  to  animal  effluvia,  or 
processes  in  which  azote  is  set  free. 
Hence  it  abounds  in  nitre  beds,  as  was  ob- 
served when  treating  of  the  nitrate  of  pot- 
ash. It  may  also  be  prepared  artificially, 
by  pouring  dilute  nitric  acid  on  carbonate 
of  lime.  11  the  solution  be  boiled  down  to 
•\  sirupy  consistence,  and  exposed  in  a 
cool  place,  it  crystallizes  in  long  prisms, 


resembling  bundles  of  needles  diverging 
from  a  centre.  These  are  soluble,  accord- 
ing to  Henry,  in  an  equal  weight  of  boil- 
ing water,  and  twice  their  weight  of  cold  ; 
soon  deliquesce  on  exposure  to  the  air, 
and  are  decomposed  to  a  red  heat.  Four- 
croy  says,  that  cold  water  dissolves  four 
times  its  weight,  and  that  its  own  water  of 
crystallization  is  sufficient  to  dissolve  it  at 
a  boiling  heat.  It  is  likewise  soluble  in  less 
than  its  weight  of  alcohol.  By  evaporat- 
ing the  aqueous  solution  to  dryness,  con- 
tinuing the  heat  till  the  nitrate  fuses,  keep- 
ing it  'in  this  state  five  or  ten  minutes,  and 
then  pouring  it  into  an  iron  pot  previous- 
ly heated,  we  obtain  Saldivin's  phvsphonis. 
This,  which  is  perhaps  more  properly  ni- 
trite of  lime,  being  broken  to  pieces,  and 
kept  in  a  phial  closely  stopped,  will  emit 
a  beautiful  white  light  in  the  dark,  after 
having  been  exposed  some  time  to  the 
rays  of  the  sun.  At  present  no  use  is  made 
of  this  salt,  except  lor  drying  some  of  tho 
gases  by  attracting  their  moisture  ;  but  it 
might  be  employed  instead  of  the  nitrate 
of  potash  for  manufacturing  aquafortis. 

The  nitrate  of  ammonia  possesses  the 
property  of  exploding,  and  being  totally 
decomposed,  at  the  temperature  of  600°  ; 
whence  it  acquired  the  name  of  Jiilrwn 
fammans.  The  readiest  mode  of  preparing 
it  is  by  adding  carbonate  of  ammonia  to 
dilutef  nitric  acid  till  saturation  takes 
place.  If  this  solution  be  evaporated  in  a 
heat  between  70°  and  100°,  and  the  evapo- 
ration not  carried  too  far,  it  crystallizes  in 
hexaedral  prisms  terminating  in  very  acute 
pyramids:  if  the  heat  rise  to  212°,  it  will 
afford,  on  cooling,  long  fibrous  silky  crys- 
tals :  if  the  evaporation  be  earned  so  far 
as  for  the  salt  to  concrete  immediately  on 
a  glass  rod  by  cooling,  it  will  form  a  com- 
pact mass.  According  to  Sir  H.  Davy, 
these  differ  but  little  from  each  other,  ex- 
cept in  the  water  they  contain,  their  com- 
ponent parts  being  as  follows: 

Prismatic-     con-  rG9. 


ter 


12.1 

8.2 
5.7 


Fibrous     >  tains-5  72.5         •  •<  19.3 
Compact  3  acid  *74.5  monla  Cl9.8 


All  these  are  completely  deliquescent, 
but  they  differ  a  little  in  solubility.  Alco- 
hol at  176°  dissolves  nearly  90.9  of  its  own 
weight. 

*  When  dried  as  much  as  possible  with- 
out decomposition,  it  consists  of  6.75  acid 
4-  2.13  ammonia-]-  1.125  water.* 

The  chief  use  of  this  salt  is  for  affording 
nitrous   oxide   on   being  decomposed  by 
heat.  See  NITROGEN,  (OXIDE  of). 
Nitrate  of  magnesia,  magnesian  nilre,  crys- 

f  [  have  ascertained,  that  very  strong 
nitric  acid,  saturated  by  carbonate  of  am- 
monia, yields  the  compact  nitrate  extem- 
poraneously. 


ACI 


AC1 


•tallizes  in  four-sided  rhomboidal  prisms, 
with  oblique  or  truncated  summits,  and 
sometimes  in  bundles  of  small  needles.  Its 
taste  is  bitter,  and  very  similar  to  that  of 
nitrate  of  lime,  but  less  pungent.  It  is  fu- 
sible, and  decomposable  by  heat,  giving 
out  first  a  little  oxygen  gas,  then  nitrous 
oxide,  and  lastly  nitric  acid.  It  deliquesces 
slowly.  It  is  soluble  in  an  equal  weight  of 
cold  water,  and  in  but  little  more  hot,  so 
that  it  is  scarcely  crystallizable  but  by 
spontaneous  evaporation. 

The  two  preceding  species  are  capable 
of  combining  into  a  triple  salt,  an  ammo- 
niaco-magnesian  nitrate,  either  by  uniting 
the  two  in  solution,  or  by  a  partial  decom- 
position of  either  by  means  of  the  base  of 
the  other.  This  is  slightly  inflammable 
when  suddenly  heated ;  and  by  a  lower 
heat  is  decomposed,  giving  out  oxygen, 
azote,  more  water  than  it  contained,  ni- 
trous oxide,  and  nitric  acid.  The  residuum 
is  pure  magnesia.  It  is  disposed  to  attract 
moisture  from  the  air,  but  is  much  less  de- 
liquescent than  either  of  the  salts  that 
compose  it,  and  requires  eleven  parts  of 
water  at  60°  to  dissolve  it.  Boiling  water 
takes  up  more,  so  that  it  will  crystallize 
by  cooling1.  It  consists  of  78  parts  of  ni- 
traie  of  magnesia,  and  22  of  nitrate  of  am- 
monia. 

From  the  activity  of  the  nitric  acid  as  a 
solvent  of  earths  in  analyzation,  the  nitrate 
of  glucine  is  better  known  than  any  other 
of  the  salts  of  this  new  earth.  Its  form  is 
either  pulverulent,  or  a  tenacious  or  duc- 
tile mass.  Its  taste  is  at  first  saccharine, 
and  afterwards  astringent.  It  grows  soft 
by  exposure  to  heat,  soon  melts,  its  acid 
is  decomposed  into  oxygen  and  azote,  and 
its  base  alone  is  left  behind.  It  is  very  so- 
luble and  very  deliquescent. 

Nitra'e,  or  rather  supernitrate,  of  alu- 
mina crystallizes,  though  with  difficulty, 
in  thin,  soft,  pliable  flakes.  It  is  of  an  aus- 
tere and  acid  taste,  and  reddens  blue  veg- 
etable colours.  It  may  be  formed  by  dis- 
solving in  diluted  nitric  acid,  with  the  as- 
sistance of  heat,  fresh  precipitated  alumi- 
na, well  washed  but  not  dried.  It  is  deli- 
quescent, and  soluble  in  a  very  small  por- 
tion of  water.  Alcohol  dissolves  its  own 
weight.  It  is  easily  decomposed  by  heat. 

Nitrate  of  zircone  was  first  discovered 
by  Klaproth,  and  has  since  been  examined 
by  Guyton-Morveau  and  Vauquelin.  Its 
crystals  are  small,  capillary,  silky  needles. 
Its  taste  is  astringent.  It  is  easily  decom- 
posed by  fire,  very  soluble  in  water,  and 
deliquescent.  It  may  be  prepared  by  dis- 
solving zircone  in  strong  nitric  acid ;  but, 
like  the  preceding  species,  the  acid  is  al- 
ways in  excess. 

Nitrate  of  yttria  may  be  prepared  in  a 
similar  manner.  Its  taste  is  sweetish  and 
astringent.  It  is  scarcely  to  be  obtained  in 


crystals ;  and  if  it  be  evaporated  by  too 
strong  a  heat,  the  salt  becomes  soft  like 
honey,  and  on  cooling  concretes  into  a 
stony  mass. 

ACID  (NiTuors).  It  was  formerly  called 
fuming  nitrous  acid.  It  appears  to  form  a 
distinct  genus  of  salts,  that  may  be  termed 
nitrites.  But  these  cannot  be  made  by  a 
direct  union  of  their  component  parts,  be- 
ing obtainable  only  by  exposing  a  nitrate 
to  a  high  temperature,  which  expels  a  por- 
tion of  its  oxygen  in  the  state  of  gas,  and 
leaves  the  remainder  in  the  state  of  a  ni- 
trite, if  the  heat  be  not  urged  so  far,  or 
continued  so  long,  as  to  effect  a  complete 
decomposition  of  the  salt.  In  this  way  the 
nitrites  of  potash  and  soda  may  be  obtain- 
ed, and  perhaps  those  of  barytes,  strontian, 
lime,  and  magnesia.  The  nitrites  are  par- 
ticularly characterized,  by  being  decom- 
posable by  all  the  acids  except  the  car- 
bonic, even  by  the  nitric  acid  itself,  all  of 
which  expel  from  them  nitrous  acid.  We  are 
little  acquainted  with  any  one  except  that 
of  potash,  which  attracts  moisture  from  the 
air,  changes  blue  vegetable  colours  to 
green,  is  somewhat  acrid  to  the  taste,  and 
when  powdered,  emits  a  smell  of  nitric 
oxide. 

*  The  acid  itself  is  best  obtained  by  ex- 
posing nitrate  of  lead  to  heat  in  a  glass  re- 
tort.   Pure  nitrous  acid  comes  over  in  the 
form  of  an  orange  coloured  liquid.  It  is  so 
volatile,  as  to  boil  at  the  temperature  of 
82°.    Its  specific  gravity  is  1.450.  When 
mixed  with  water  it  is  decomposed,  and 
nitrous  gas  is  disengaged,  occasioning  ef- 
fervescence. It  is  composed  of  one  volume 
of  oxygen  united  with  two  of  nitrous  gas. 
It  therefore  consists  by  weight  of  1.75  ni- 
trogen -f-  4  oxygen  ;  by  measure  of  1| 
oxygen  -f-  1   nitrogen.     The  various  co- 
loured acids  of  nitre  are  not  nitrous  acids, 
but  nitric  acid  impregnated  with  nitrous 
gas,  the  deutoxide  of  nitrogen,  or  azote. 
(See  the  preceding  table  of  Sir  H.  Davy, 
concerning  the  coloured  acid.)* 

*  ACID  (NITRIC  OXYGENIZED).     In  out- 
general remarks  on  acidity,  we  have  de- 
scribed  Mr.  Thenard's  newly  discovered 
method   of  oxygenizing  the  liquid  acids. 
The  first  that  he  examined  was  the  com- 
bination of  nitric  acid  and  oxygen.    When 
the  peroxide  of  barium,  prepared  by  satu- 
rating barytes  with  oxygen,  is  moistened, 
it  falls  to  powder,  without  much  increase 
of  temperature.  If  in  this  state  it  be  mixed 
with  seven  or  eight  times  its  weight  of 
water,  and  dilute  nitric  acid  be  gradually 
poured  upon  it,  it  dissolves  gradually  by 
agitation,  without  the  evolution  of  any  gas. 
The  solution  is  neutral,  or  has  no  action 
on  turnsole  or  turmeric.     When  we  add 
to  this   solution  the   requisite  quantity  of 
sulphuric  acid,  a  copious  precipitate  of 
sulphate  of  barytes  falls,  and  the  filtered 


ACI 


AC1 


liquor  is  merely  water,  holding  in  solution 
oxygenized  nitric  acid.  This  acid  is  liquid 
and  colourless ;  it  strongly  reddens  turn- 
sole, and  resembles  in  all  its  properties 
nitric  acid. 

When  heated  it  immediately  begins  to 
discharge  oxygen ;  but  its  decomposition 
is  never  complete  unless  it  be  kept  boiling 
for  some  time.  The  only  method  which 
M.  Thenard  found  successful  for  concen- 
trating it,  was  to  place  it  in  a  capsule, 
under  the  receiver  of  an  air  pump,  along 
with  another  capsule  full  of  lime,  and  to 
exhaust  the  receiver.  By  this  means  he 
obtained  an  acid  sufficiently  concentrated 
to  give  out  11  times  its  bulk  of  oxygen 
gas. 

This  acid  combines  very  well  with  ba- 
rytes,  potash,  soda,  ammonia,  and  neu- 
tralizes them.  When  crystallization  com- 
mences in  the  liquid,  by  even  a  sponta- 
neous evaporation,  these  salts  are  instant- 
ly decomposed.  The  exhausted  receiver 
also  decomposes  them.  The  oxygenized 
nitrates,  when  changed  into  common 
nitrates,  do  not  change  the  state  of  their 
neutralization.  Strong  solution  of  potash 
poured  into  their  solutions  decomposes 
them. 

Oxygenized  nitric  acid  does  not  act  on 
gold ;  but  it  dissolves  all  the  metals  which 
the  common  acid  acts  on,  and  when  it  is 
not  too  concentrated,  it  dissolves  them 
without  effervescence.  Deutoxide,  or 
peroxide  of  barium,  contains  just  double 
the  proportion  of  oxygen  that  its  protoxide 
does.  But  M.  Thenard  says,  that  the 
barytes  obtained  from  the  nitrate  by 
ignition  contains  always  a  little  of  the 
peroxide.  When  oxygenized  nitric  acid 
is  poured  upon  oxide  of  silver,  a  strong 
effervescence  takes  place,  owing  to  the 
disengagement  of  oxygen.  One  portion 
of  the  oxide  of  silver  is  dissolved,  the 
other  is  reduced  at  first,  and  then  dissolves 
likewise,  provided  the  quantity  of  acid  be 
sufficient.  The  solution  being  Completed, 
if  we  add  potash  to  it,  by  little  and  little, 
a  new  effervescence  takes  place,  and  a 
dark  violet  precipitate  falls;  at  least  this 
is  always  the  colour  of  the  first  deposite. 
It  is  insoluble  in  ammonia,  and  accord- 
ing to  all  appearance,  is  a  protoxide  of 
silver. 

As  soon  as  we  plunge  a  tube  containing 
oxide  of  silver  into  a  solution  of  oxygen- 
ized nitrate  of  potash,  a  violent  efferves- 
cence takes  place,  the  oxide  is  reduced, 
the  silver  precipitates,  the  whole  oxygen 
of  the  oxygenized  nitrate  is  disengaged 
at  the  same  time  with  that  of  the  oxide  ; 
and  the  solution,  which  contains  merely 
common  nitrate  of  potash,  remains  neutral, 
if  it  was  so  at  first.  But  the  most  unac- 
countable phenomenon  is  the  following  : 
If  silver,  in  a  state  of  extreme  division 


(fine  filings),  be  put  into  the  oxygenized 
nitrate,  or  oxygenized  muriate  of  potash, 
the  whole  oxygen  is  immediately  disen- 
gaged. The  silver  itself  is  not  attacked, 
and  the  salt  remains  neutral  as  before. 
Iron,  zinc,  copper,  bismuth,  lead,  and 
platinum,  likewise  possess  this  property 
of  separating  the  oxygen  of  the  oxygen- 
ized nitrate.  Iron  and  zinc  are  oxidized, 
and  at  the  same  time  occasion  the  evolution 
of  oxygen.  The  other  metals  are  not 
sensibly  oxidized.  They  were  all  employ- 
ed in  the  state  of  filings.  Gold  scarcely 
acts.  The  peroxides  of  manganese  and 
of  lead  decompose  the  oxynitrates.  A 
very  small  quantity  of  these  oxides,  in 
powder,  is  sufficient  to  drive  off  the  whole 
oxygen  from  the  saline  solution.  The 
effervescence  is  lively.  The  peroxide  of 
manganese  undergoes  no  alteration. 

Though  nitric  acid  itself  has  no  action 
on  the  peroxides  of  lead  and  manganese, 
the  oxygenized  acid  dissolves  both  of 
them  with  the  greatest  facility.  The  so- 
lution is  accompanied  by  a  great  disen- 
gagement of  oxygen  gas.  The  effect  of 
silver,  he  thinks,  may  probably  be  ascri- 
bed to  voltaic  electricity. 

The  remarks  appended  to  our  account 
of  M.  Thenard's  oxygenized  muriatic 
acid,  are  equally  applicable  to  the  nitric  ; 
but  the  phenomena  are  too  curious  to  be 
omitted  in  a  work  of  the  present  kind.* 

*  Acin  (OtEic).  When  potash  and 
hog's  lard  are  saponified,  the  margarate  of 
the  alkali  separates  in  the  form  of  a  pearly 
looking  solid,  while  the  fluid  fat  remains 
in  solution,  combined  with  the  potash. 
When  the  alkali  is  separated  by  tartaric 
acid,  the  oily  principle  of  fat  is  obtained, 
which  M.  Chevreul  purifies  by  saponify- 
ing it  again  and  again,  recovering  it  two 
or  three  times,  by  which  means  the  whole 
of  the  margarine  is  separated.  As  this 
oil  has  the  property  of  saturating  bases 
and  forming  neutral  compounds,  he  has 
called  it  oleic  acid.  In  his  sixth  memoir, 
he  gives  the  following  table  of  results. 

100  Oleic  acid  of  human  fat 
Saturate  Barytes        Strontian        Lead 
26.00  19.41  82.48 

100  Oleic  acid  of  sheep  fat 
26.77  19.38  81.81 

100  Oleic  acid  of  ox  fat 
28.93  19.41  81.81 

100  Oleic  acid  of  goose  fat 
26.77  19.38  81.34 

100  Oleic  acid  of  hog  fat 
27.00  29.38  81.80 

Oleic  acid  is  an  oily  fluid  without  taste 
and  smell.  Its  specific  gravity  is  0.914.  It 
is  generally  soluble  in  its  own  weight  of 
boiling  alcohol,  of  the  specific  gravity  of 
0.7952;  but  some  of  the  varieties  are  still 
more  soluble.  100  of  the  oleic  acid  satu* 


AM 


ACI 


rate  16.58  of  potash,  10.11  of  soda,  7.52  of 
magnesia,  14.83  of  zinc,  and  13.93  perox- 
ide of  copper.  M.  Chevreul's  experi- 
ments have  finally  induced  him  to  adopt 
the  quantities  of  100  acid  to  27  barytes,  as 
the  most  correct ;  whence  calling  barytes 
9-75,  we  have  the  equivalent  prime  of 
oleic  acid  =  36.0.* 

ACID  (OXALIC).  This  acid,  which  a- 
bounds  in  wood  sorrel,  and  which,  com- 
bined with  a  small  portion  of  potash,  as 
it  exists  in  that  plant,  has  been  sold  under 
the  name  of  salt  of  lemons,  to  be  used  as  a 
substitute  for  the  juice  of  that  fruit,  par- 
ticularly for  discharging  ink  spots  and 
iron-moulds,  was  long  supposed  to  be 
analogous  in  that  of  tartar.  In  the  year 
1776,  however,  Bergmann  discovered,  that 
a  powerful  acid  might  be  extracted  from 
sugar  by  means  of  the  nitric ;  and  a  few 
years  afterwards  Scheele  found  this  to  be 
identical  with  the  acid  existing  naturally 
in  sorrel.  Hence  the  acid  began  to  be 
distinguished  by  the  name  of  saccharine, 
but  has  since  been  known  in  the  new 
nomenclature  by  that  of  oxalic. 

Scheele  extracted  this  acid  from  the 
salt  of  sorrel,  or  acidulous  oxalate  of  pot- 
ash, as  it  exists  in  the  juice  of  that  plant, 
by  saturating  it  with  ammonia,  when  it 
becomes  a  very  soluble  triple  salt,  and 
adding  to  the  solution  nitrate  of  barytes 
dissolved  in  water.  Having  well  washed 
the  oxalate  of  barytes,  which  is  precipita- 
ted, he  dissolved  it  in  boiling  water,  and 
precipitated  its  base  by  sulphuric  acid. 
To  ascertain  that  no  sulphuric  acid  re- 
mained in  the  supernatant  liquor,  he  added 
a  little  of  a  boiling  solution  of  oxalate  of 
barytes  till  no  precipitate  took  place,  and 
then  filtered  the  liquor,  which  contained 
nothing  but  pure  oxalic  acid,  which  he 
crystallized  by  evaporation  and  cooling. 

It  may  be  obtained,  however,  much 
more  readily  and  economically  from  sugar 
in  the  following  way :  To  six  ounces  of 
nitric  acid  in  a  stoppered  retort,  to  which 
a  large  receiver  is  luted,  add,  by  degrees, 
one  ounce  of  lump  sugar  coarsely  pow- 
dered. A  gentle  heat  may  be  applied 
during  the  solution,  and  nitric  oxide  will 
be  evolved  in  abundance.  When  the 
whole  of  the  sugar  is  dissolved,  distil  off 
a  part  of  the  acid,  till  what  remains  in  the 
retort  has  a  sirupy  consistence,  and  this 
will  form  regular  crystals,  amounting  to 
58  parts  from  100  of  sugar.  These  crys- 
tals must  be  dissolved  in  water,  re-crystal- 
lized, and  dried  on  blotting  paper. 

A  variety  of  other  substances  afford 
the  oxalic  acid  when  treated  by  distillation 
with  the  nitric.  Bergmann  procured  it 
from  honey,  gum  arabic,  alcohol,  and  the 
calculous  concretions  in  the  kidneys  and 
bladders  of  animals.  Scheele  and  Hermb- 
stadt  from  sugar  of  milk.  Scheele  from 


a  sweet  matter  contained  in  fat  oils,  and 
also  from  the  uncrystallizable  part  of  the 
juice  of  lemons.  Hermbstadt  from  the 
acid  of  cherries,  and  the  acid  of  tartar, 
Goetling  from  beech  wood.  Kohl  from 
the  residuum  in  the  distillation  of  ar- 
dent spirits.  Westrumb  not  only  from  the 
crystallized  acids  of  currants,  cherries,  ci- 
trons, raspberries,  but  also  from  the  sac- 
charine matter  of  these  fruits,  and  from 
the  uncrvstallizable  parts  of  the  acid  jui- 
ces. Hoffmann  from  the  juice  of  the  bar- 
berry ;  and  Berthollet  from  silk,  hair,  ten- 
dons, wool ;  also  from  other  animal  sub- 
stances, especially  from  the  coagulum  of 
blood,  whites  of  eggs,  and  likewise  from 
the  amylaceous  and  glutinous  parts  of 
flour.  M.  Berthollet  observes,  that  the 
quantity  of  the  oxalic  acid  obtained  by 
treating  wool  with  nitric  acid  was  veiy 
considerable,  being  aV  ove  half  the  weight 
of  the  wool  employed.  He  mentions  a 
difference  which  he  observed  between 
animal  and  vegetable  substances  thus  treat- 
ed with  nitric  acid,  namely,  that  the  for- 
mer yielded,  beside  ammonia,  a  large  quan- 
tity of  an  oil  which  the  nitric  acid  could 
not  decompose ;  whereas  the  oily  parts  of 
vegetables  were  totally  destroyed  by  the 
action  of  this  acid  r  and  he  remarks,  that 
in  this  instance  the  glutinous  part  of  flour 
resembled  animal  substances,  whereas  the 
amylaceous  part  of  the  flour  retained  its 
vegetable  properties.  He  further  remarks, 
that  the  quantity  of  oxalic  acid  furnished 
by  vegetable  matters  thus  treated  is  pro- 
portionable to  their  nutritive  quality,  and 
particularly  that,  from  cotton,  he  could  not 
obtain  any  sensible  quantity.  Deyeux, 
having  cut  with  scissars  the  hairs  of  the 
chick  pea,  found  they  gave  out  an  acid  li- 
quor, which,  on  examination,  proved  to 
be  an  aqueous  solution  of  pure  oxalic  acid. 
Proust  and  other  chemists  had  before  ob- 
served, that  the  shoes  of  persons  walking 
through  a  field  of  chick  pease  were  corro- 
ded. 

Oxalic  acid  crystallizes  in  quadrilateral 
prisms,  the  sides  of  which  are  alternately 
broad  and  narrow,  and  summits  diedral ; 
or,  if  crystallized  rapidly,  in  small  irregu- 
lar needles.  They  are  efflorescent  in  dry 
air,  but  attract  a  little  humidity  if  it  be 
damp ;  are  soluble  in  one  part  of  hot  and 
two  of  cold  water;  and  are  decomposable 
by  a  red  heat,  leaving  a  small  quantity  of 
coaly  residuum. — 100  parts  of  alcohol  take 
up  near  56  at  a  boiling  heat,  but  not  above 
40  cold.  Their  acidity  is  so  great,  that 
when  dissolved  in  3600  times  their  weight 
of  water,  the  solution  reddens  litmus  pa- 
per, and  is  perceptibly  acid  to  the  taste. 

The  oxalic  acid  is  a  good  test  for  de- 
tecting lime,  which  it  separates  from  all 
the  other  acids,  unless  they  are  present  in 
excess.  It  has  likewise  a  greater  affinity 


ACI 


ACI 


for  lime  than  for  any  other  of  the  bases, 
and  forms  with  it  a  pulverulent  insoluble 
salt,  not  decomposable  except  by  fire,  and 
turning  sirup  of  violets  green. 

*  From  the  oxalate  of  lead,  Berzelius 
infers  its  prime  equivalent  to  be  4.552,  and 
by  igneous  decomposition  he  finds  it  re- 
solved into  66.534  oxygen,  33.222  carbon, 
and  0.244  hydrogen.  The  quantity  of  the 
latter,  when  reduced  to  primitive  ratios, 
gives  only,  as  Dr.  Thomson  admits,  l-12th 
of  an  atom  of  hydrogen,  which  makes  this 
analysis  of  Berzelius  and  the  Atomic 
theory  incompatible.  Since  Berzeljjis  pub- 
lished his  analysis,  oxalic  acid  has  been 
made  the  subject  of  some  ingenious  re- 
marks by  Dobereiner,  in  the  16th  vol.  of 
Schvveigger's  Journal.  We  see  that  the 
carbon  and  oxygen  are  to  each  other  in 
the  simple  ratio  of  1  to  2 ;  or  referred  to 
their  prime  equivalent,  as  2  of  carbon  = 
1.5,  to  3  of  oxygen  =  3.  This  propor- 
tion is  what  would  result  from  a  prime  of 
carbonic  acid  =  C  -\-  2.  O,  combined  with 
one  of  carbonic  oxide  =  C  -f-  O.  C  being 
carbon,  and  O  oxygen.  The  sum  of  the 
above  weights  gives  4.5  for  the  prime 
equivalent  of  oxalic  acid,  disregarding  hy- 
drogen, which  constitutes  but  l-37th  of 
the  whole,  and  may  possibly  be  referred 
to  the  imperfect  desiccation  of  the  oxala'e 
of  lead  subjected  to  analysis.  Oxalic  acid 
acts  as  a  violent  poison  when  swallowed 
in  the  quantity  of  2  or  3  drachms;  and 
several  fatal  accidents  have  lately  occur- 
red in  London,  in  consequence  of  its  being 
improperly  sold  instead  of  Epsom  salts. 
Its  vulgar  name  of  salts,  under  which  the 
acid  is  bought  for  the  purpose  of  whiten- 
ing boot-tops,  occasions  these  lamentable 
mistakes.  But  the  powerfully  acid  taste  of 
the  latter  substance,  joined  to  its  prismatic 
or  needle-formed  crystallization,  are  suffi- 
cient to  distinguish  it  from  every  thing 
else.  The  immediate  rejection  from  the 
stomach  of  this  acid,  by  an  emetic,  aided 
by  copious  draughts  of  warm  water  con- 
taining bicarbonate  of  potash,  or  soda, 
chalk,  or  carbonate  of  magnesia,  are  the 
proper  remedies.* 

With  barytes  it  forms  an  insoluble  salt; 
but  this  salt  will  dissolve  in  water  acidu- 
lated with  oxalic  acid,  and  afford  angular 
crystals.  If,  however,  we  attempt  to  dis- 
solve these  crystals  in  boiling  water,  the 
excess  of  acid  will  unite  with  the  water, 
and  leave  the  oxalate,  which  will  be  pre- 
cipitated. 

The  oxalate  of  strontian  too  is  a  nearly 
insoluble  compound. 

Oxalate  of  magnesia  too  is  insoluble,  un- 
less the  acid  be  in  excess. 

The  oxalate  of  potash  exists  in  two 
states,  that  of  a  neutral  salt,  and  that  of  an 
acidule.  The  latter  is  generally  obtained 
ii;om  the  juice  of  the  leaves  of  the  oxutis 


acetosella,  wood  sorrel,  or  nnncx  acetosa^, 
common  sorrel.  The  expressed  juice,  be- 
ing diluted  with  water,  should  be  set  by 
for  a  few  days,  till  the  feculent  parts  havt 
subsided,  and  the  supernatant  fluid  is  be- 
come clear;  or  it  may  be  clarified,  when 
expressed,  with  the  whites  of  eggs.  It  is 
then  to  be  strained  off,  evaporated  to  a 
pellicle,  and  set  in  a  cool  place  to  crystal- 
lize. The  first  product  of  crystals  being 
taken  out,  the  liquor  may  be  further  evap- 
orated, and  crystallized ;  and  the  same, 
process  repeated  till  no  more  can  be  ob- 
tained. In  this  way  Schlereth  informs  us 
about  nine  drachms  of  crystals  may  be  ob- 
tained from  two  pounds  of  juice,  which 
are  generally  afforded  by  ten  pounds  of 
wood  sorrel.  Savary,  however,  says,  that 
ten  parts  of  wood  sorrel  in  full  vegetation 
yield  five  parts  of  juice,  which  give  little 
more  than  a  two-hundredth  of  tolerably 
pure  salt.  He  boiled  down  the  juice,  how- 
ever, in  the  first  instance,  without  clari- 
fying it;  and  was  obliged  repeatedly  to 
dissolve  and  re-crystallize  the  salt  to  ob- 
tain it  white. 

This  salt  is  in  small,  white,  neeclly,  or 
lamellar  crystals,  not  alterable  in  the  air. 
It  unites  with  barytes,  magnesia,  soda,  am- 
monia, and  most  of  the  metallic  oxides,  in- 
to triple  salts.  Yet  its  solution  precipitates 
the.  nitric  solutions  of  mercury  and  silver 
in  the  state  of  insoluble  oxalate  of  these 
metals,  the  nitric  acid  in  this  case  com- 
bining with  the  potash.  It  attacks  iron, 
lead,  tin,  zinc,  and  antimony. 

This  salt,  besides  its  use  in  taking  out 
ink  spots,  and  as  a  test  of  lime,  forms  with 
sugar  and  water  a  pleasant  cooling  bever- 
age ;  and  according  to  Berthollet,  it  pos- 
sesses considerable  powers  as  an  antisep- 
tic. 

The  neutral  oxalate  of  potash  is  very 
soluble,  and  assumes  a  gelatinous  form, 
but  may  be  brought  to  crystallize  in  hex- 
aedral  prisms  with  diedral  summits,  by  ad- 
ding more  potash  to  the  liquor  than  is  suf- 
ficient to  saturate  the  acid. 

Oxalate  of  soda  likewise  exists  in  two 
different  states,  those  of  an  acidulous  and 
a  neutral  salt,  which  in  their  properties 
are  analogous  to  those  of  potash. 

The  acidulous  oxalate  of  ammonia  is 
crystallizable,  not  very  soluble,  and  capa- 
ble, like  the  preceding  acidules,  of  com- 
bining with  other  bases,  so  as  to  form 
triple  salts.  But  if  the  acid  be  saturated 
with  ammonia,  we  obtain  a  neutral  oxalate, 
which  on  evaporation  yields  very  fine 
crystal*  in  tetraedral  prisms  with  diedral 
summits,  one  of  the  planes  of  which  cuts 
of!' three  sides  of  the  prism.  This  salt  is 
decomposable  by  fire,  which  raises  frr.m 
it  carbonate  of  ammonia,  and  leaves  only 
some  light  traces  of  a  coaly  residuum. 
Lime,  barytes,  and  strontiun  unite  \vilh 


ACI 


ACI 


Its  acid,  and  the  ammonia  flies  off'  in  the 
form  of  gas. 

The  oxalic  acid  readily  dissolves  alumi- 
na, and  the  solution  gives  on  evaporation 
a  yellowish  transparent  mass,  sweet  and  a 
little  astringent  to  the  taste,  deliquescent, 
and  reddening  tincture  of  litmus,  but  not 
sirup  of  violets.  This  salt  swells  up  in  the 
fire,  loses  its  acid,  and  leaves  the  alumina 
a  little  coloured. 

*  The  composition  of  the  different  oxa- 
lates  may  be  ascertained  by  considering 
the  neutral  salts  as  consisting  of  one  prime 
of  acid  =  4.552  to  1  of  base,  and  the  bin- 
oxalate  of  potash  of  2  of  acid  to  1  of  base, 
as  was  first  proved  by  Ur.  Wollaston. 
But  this  eminent  philosopher  has  further 
shown,  that  oxalic  acid  is  capable  of  com- 
bining in  four  proportions  with  the  oxides, 
whence  result  neutral  oxalates,  suboxa- 
lates,  acidulous  oxalates,  and  acid  oxalates. 
The  neutral  contain  twice  as  much  acid  as 
the  suboxalates;  one-half  of  the  quantity 
of  acid  in  the  acidulous  oxalates ;  and  one- 
quarter  of  that  in  the  acid  oxalates.* 

Acin  (PERLATE).  This  name  was  given 
by  Bergmann  to  the  acidulous  phosphate  of 
soda,  Haupt  having  called  the  phosphate 
of  soda  sal  mirabile  perlatum. 

Acin  (PHOSPHORIC.)  The  base  of  this 
acid,  or  the  acid  itself,  abounds  in  the  mi- 
neral, vegetable,  and  animal  kingdoms.  In 
the  mineral  kingdom  it  is  found  in  combi- 
nation with  lead,  in  the  green  lead  ore ; 
with  iron,  in  the  bog  ores  which  afford 
oold  short  iron ;  and  more  especially  with 
calcareous  earth  in  several  kinds  of  stone. 
Whole  mountains  in  the  province  of  Es- 
tremadura  in  Spain  are  composed  of  this 
combination  of  phosphoric  acid  and  lime. 
Mr.  Howies  affirms,  that  the  stone  is  whi- 
tish and  tasteless,  and  affords  a  blue  flame 
without  smell  when  thrown  upon  burning 
coals.  Mr.  Proust  describes  it  as  a  dense 
stone,  not  hard  enough  to  strike  fire  with 
steel ;  and  says  that  it  is  found  in  strata, 
which  always  lie  horizontally  upon  quartz, 
and  which 'are  intersected  with  veins  of 
quartz.  When  this  stone  is  scattered  up- 
on burning  coals,  it  does  not  decrepitate, 
but  burns  with  a  beautiful  green  light, 
which  lasts  a  considerable  time.  It  melts 
into  a  white  enamel  by  the  blow-pipe ;  is 
soluble  with  heat,  and  some  effervescence 
in  the  nitric  acid,  and  forms  sulphate  of 
lime  with  the  sulphuric  acid,  while  the 
phosphoric  acid  is  set  at  liberty  in  the  fluid. 

The  vegetable  kingdom  abounds  with 
phosphorus,  or  its  acid.  It  is  principally 
found  in  plants  that  grow  in  marshy  places, 
in  turf,  and  several  species  of  the  white 
woods.  Various  seeds,  potatoes,  agaric, 
soot,  and  charcoal  afford  phosphoric  acid,§ 

§  To  this  Prof.  Bartholdi  ascribes  two 
accidents  at  the  powder-mills  at  Essone, 
where  spontaneous  combustion  appeured 
Vat,  i  [11]. 


by  abstracting  the  nitric  acid  from  thetfi> 
and  lixiviating  the  residue.  The  lixivium 
contains  the  phosphoric  acid,  which  may 
either  be  saturated  with  lime  by  the  addi- 
tion of  lime-water,  in  which  case  it  forms 
a  solid  compound;  or  it  may  be  tried  by 
examination  of  its  leading  properties  by 
other  chemical  methods. 

In  the  animal  kingdom  it  is  found  in  al- 
most every  part  of  the  bodies  of  animals 
which  are  not  considerably  volatile.  There 
is  not,  in  all  probability,  any  part  of  these 
organized  beings  which  is  free  from  it.  It 
has  been  obtained  from  blood,  flesh,  both 
of  land  and  water  animals ;  from  cheese ; 
and  it  exists  in  large  quantities  in  bones, 
combined  with  calcareous  earth.  Urine 
contains  it,  not  only  in  a  disengaged  state, 
but  also  combined  with  ammonia,  soda, 
and  lime.  It  was  by  the  evaporation,  and 
distillation  of  this  excrementitious  fluid 
with  charcoal  that  phosphorus  was  first 
made ;  the  charcoal  decomposing  the  dis- 
engaged acid  and  the  ammoniacal  salt.  (See 
PHOSPHORUS.)  But  it  is  more  cheaply  ob- 
tained by  the  process  of  Scheele,  from 
bones,  by  the  application  of  an  acid  t® 
their  earthy  residue  after  calcination. 

In  this  process  the  sulphuric  acid  ap- 
pears to  be  the  most  convenient,  because 
it  forms  a  nearly  insoluble  compound  with 
the  lime  of  the  bones.  Bones  of  beef, 
mutton,  or  veal,  being-  calcined  to  white- 
ness in  an  open  fire,  lose  almost  half  of 
their  weight.  This  must  be  pounded,  and 
sifted,  or  the  trouble  may  be  spared  by 
buying  the  powder  that  is  sold  to  make 
cupels  for  the  assayers,  and  is,  in  fact,  the 
powder  of  burned  bones  ready  sifted.  To 
three  pounds  of  the  powder  there  may  be 
added  about  two  pounds  of  concentrated 
sulphuric  acid.  Four  or  five  pounds  of 
water  must  be  afterward  added  to  assist 
the  action  of  the  acid ;  and  during  the 
whole  process  the  operator  must  remem- 
ber to  place  himself  and  his  vessels  so  that 
the  fumes  may  be  blown  from  him.  The 
whole  may  then  be  left  on  a  gentle  sand 
bath  for  twelve  hours  or  more,  taking  care 
to  supply  the  loss  of  water  which  happens 
by  evaporation.  The  next  day  a  large 
quantity  of  water  must  be  added,  the 
whole  strained  through  a  sieve,  and  the 
residual  matter,  which  is  sulphate  of  lime, 
must  be  edulcorated  by  repeated  affusion* 
of  hot  water,  till  it  passes  tasteless.  The 
waters  contain  phosphoric  acid  nearly  free 
from  lime,  and  by  evaporation,  first  in 
glazed  earthen,  and  then  in  glass  vessels, 

to  have  taken  place  in  one  instance  in  the 
charcoal  store-room,  in  the  other  in  the 
box  into  which  the  charcoal  was  sifted; 
as  well  as  three  successive  explosions  at 
the  powder-mills  of  Vosges.  This  cer* 
tainly  merits  the  attention  of  gunpowder 
manufacturers, 


ACI 


ACI 


or  rather  in  vessels  of  platina  or  silver,  for 
the  hot  acid  acts  upon  glass,  afford  the 
acid  in  a  concentrated  state,  which,  by  the 
force  of  a  strong  heat  in  a  crucible,  may 
be  made  to  acquire  the  form  of  a  transpa- 
rent consistent  glass,  though  indeed  it  is 
usually  of  a  milky,  opaque  appearance. 

For  making  phosphorus,  it  is  not  neces- 
sary to  evaporate  the  water  further  than 
to  bring  it  to  the  consistence  of  sirup ; 
and  the  small  portion  of  lime  it  contains  is 
not  an  impediment  worth  the  trouble  of 
removing,  as  it  affects  the  produce  very 
little.  But  when  the  acid  is  required  in  a 
purer  state,  it  is  proper  to  add  a  quantity 
of  carbonate  of  ammonia,  which,  by  dou- 
ble elective  attraction,  precipitates  the 
lime  that  was  held  in  solution  by  the  phos- 
phoric acid.  The  fluid  being  then  evapo- 
rated, affords  a  crystallized  ammoniacal 
salt,  which  may  be  melted  in  a  silver  ves- 
sel, as  the  acid  acts  upon  glass  or  earthen 
vessels.  The  ammonia  is  driven  off  by 
the  heat,  and  the  acid  acquires  the  form 
of  a  compact  glass  as  transparent  as  rock 
crystal,  acid  to  the  taste,  soluble  in  water, 
and  deliquescent  in  the  air. 

This  acid  is  commonly  pure,  but  never- 
theless may  contain  a  small  quantity  of  so- 
da, originally  existing  in  the  bones,  and 
not  capable  of  being  taken  away  by  this 
process,  ingenious  as  it  is.  The  only  une- 
quivocal method  of  obtaining  a  pure  acid 
appears  to  consist  in  first  converting  it  in- 
to phosphorus  by  distillation  of  the  mate- 
rials with  charcoal,  and  then  converting  it 
again  into  acid  by  rapid  combustion,  at  a 
high  temperature,  either  in  oxygen  or  at- 
mospheric air,  or  some  other  equivalent 
process. 

Phosphorus  may  also  be  converted  into 
the  acid  state  by  treating  it  with  nitric 
acid.  In  this  operation,  a  tubulated  retort 
with  a  ground  stopper,  must  be  half  filled 
with  nitric  acid,  and  a  gentle  heat  applied. 
A  small  piece  of  phosphorus  being  then 
introduced  through  the  tube  will  be  dis- 
solved with  effervescence,  produced  by 
the  escape  of  a  large  quantity  of  nitric  ox- 
ide. The  addition  of  phosphorus  must 
be  continued  until  the  last  piece  remains 
undissolved.  The  fire  being  then  raised 
to  drive  over  the  remainder  of  the  nitric 
acid,  the  phosphoric  acid  will  be  found  in 
the  retort,  partly  in  the  concrete  and  part- 
ly in  the  liquid  form. 

Sulphuric  acid  produces  nearly  the  same 
effect  as  the  nitric;  a  large  quantity  of 
sulphurous  acid  flying  off.  But  as  it  re- 
quires a  stronger  heat  to  drive  off  the  last 
portions  of  this  acid,  it  is  not  so  well  adapt- 
ed to  the  purpose.  The  liquid  chlorine 
likewise  acidifies  it. 

When  phosphorus  is  burned  by  a  strong 
heat,  sufficient  to  cause  it  to  flame  rapid- 
ly,' it  is  almost  perfectly  converted  into 


dry  acid,  some  of  which  is  thrown  up  by 
the  force  of  the  combustion,  and  the  rest 
remains  upon  the  supporter. 

This  substance  has  also  been  acidified 
by  the  direct  application  of  oxygen  gas 
passed  through  hot  water,  in  which  the 
phosphorus  was  liquefied  or  fused. 

The  general  characters  of  phosphoric 
acid  are :  1.  It  is  soluble  in  water  in  all 
proportions,  producing  a  specific  gravity, 
which  increases  as  the  quantity  of  acid  is 
greater,  but  does  not  exceed  2.687,  which 
is  that  of  the  glacial  acid.  2.  It  produces 
heat  when  mixed  with  water,  though  not 
very  considerable.  3.  It  has  no  smell 
when  pure,  and  its  taste  is  sour,  but  not 
corrosive.  4.  When  perfectly  dry,  it  sub- 
limes in  close  vessels;  but  loses  this  pro- 
perty by  the  addition  of  water ;  in  which 
circumstance  it  greatly  differs  from  the 
boracic  acid,  which  is  fixed  when  dry,  but 
rises  by  the  help  of  water.  5.  When  con- 
siderably diluted  with  water,  and  evapo- 
rated, the  aqueous  vapour  carries  up  a 
small  portion  of  the  acid.  6.  With  char- 
coal or  inflammable  matter,  in  a  strong 
heat,  it  loses  its  oxygen,  and  becomes  con- 
verted into  phosphorus. 

Phosphoric  acid  is  difficult  of  crystalli- 
zing. 

Though  the  phosphoric  acid  is  scarcely 
corrosive,  yet,  when  concentrated,  it  acts 
upon  oils,  which  it  discolours,  and  at  length 
blackens,  producing  heat,  and  a  strong 
smell  like  that  of  ether  and  oil  of  turpen- 
tine ;  but  does  not  form  a  true  acid  soap. 
It  has  most  effect  on  essential  oils,  less  on 
drying  oils,  and  least  of  all  on  fat  oils. 
Spirit  of  wine  and  phosphoric  acid  have  a 
weak  action  on  each  other.  Some  heat  is 
excited  by  this  mixture,  and  the  product 
which  comes  over  in  distillation  of  the  mix- 
ture is  strongly  acid,  of  a  pungent  arsenical 
smell,  inflammable  with  smoke,  miscibie 
in  all  proportions  with  water,  precipitating 
silver  and  mercury  from  their  solutions, 
but  not  gold;  and  although  not  an  ether, 
yet  it  seems  to  be  an  approximation  to  that 
kind  of  combination. 

*  From  the  syntheses  of  the  phosphates 
of  soda,  barytes,  and  lead,  Berzelius  de- 
duces the  prime  equivalent  of  phosphoric 
acid  to  be  4.5.  But  the  experiments  of 
Berzelius  on  the  synthesis  of  the  acid  it- 
self, show  it  to  be  a  compound  of  about 
100  phosphorus  -f-  133  oxygen  ;  or  of  2 
oxygen  -f-  1.5  phosphorus  ==»  3.5  for  the 
prime  equivalent  of  the  acid.  Lavoisier's 
synthesis  gave-2  oxygen  -j-  1.33  phospho- 
rus. So  did  that  of  Sir  H.  Davy  by  rapid 
combustion  in  oxygen  gas,  as  published  in 
the  Phil.  Trans,  for  1812.  Dr.  Thomson, 
in  his  account  of  the  improvements  in  Phy- 
sical Science,  published  in  his  Annals  for 
January  1817,  says,  "it  is  quite  clear  from 
these  analyses  (of  Berzelius)  that  the 


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ACI 


equivalent  number  for  phosphoric  acid  is 
4.5."  M.  Dulong1,  in  an  elaborate  paper 
published  in  the  third  volume  of  the  Me- 
moires  d'Arcneil,  gives  as  the  result  of  di- 
versified experiments,  the  proportions  of 
100  phosphorus  to  123  oxygen ;  or  of  2 
oxygen  -f-  1.627  phosphorus  =  3.627  for 
the  acid  equivalent. 

In  the  Annals  of  Philosophy  for  April 
1816,  page  305,  Dr.  Thomson  gives  the 
following  statement :  "  From  this  result  it 
follows  that  the  acid  is  composed  of 
Phosphorus,      100 
Oxygen,  123,46. 

"  To  verify  this  result,  the  author  (Dr. 
Thomson)  had  recourse  to  the  phosphate 
of  lead,  which  is  a  compound  of  2  atoms 
phosphoric  acid-f  1  atom  yellow  oxide  of 
lead."  He  gives  three  analyses  of  this 
sal* ;  one  by  Dr  Wollaston  ;  one  by  Pro- 
fessor Berzelius;  and  one  by  himself. 
These  analyses  are  as  follow  : — 

Acid.      Base. 

By  Wollaston,  100  -f  370.72 
Berzelius,  100  -f-  380.56 
Thomson,  100  -f-  398.49 


Mean,  100  +  383.26. 

This  mean,  which  corresponds  nearly 
with  the  analysis  of  Berzelius,  is  consid- 
ered by  him  as  exhibiting  the  true  com- 
position of  phosphate  of  lead  From  this 
the  weight  of  an  atom  of  phosphoric  acid 
is  shown  to  be  3.649.  But  after  a  com- 
parison of  results  by  different  methods,  he 
says,  "  This  gives  us  1.634  for  the  weight 
of  an  atom  of  phosphorus  ;  2.634  for  the 
weight  of  an  atom  of  phosphorous  acid  ; 
and  3.634  for  the  weight  of  an  atom  of 
phosphoric  acid."  Page  306. 

In  the  subsequent  January,  when  he^ 
gives  an  Account  of  Physical  Science  for 
the  same  year  1816,  however,  he  says,  "It 
is  quite  clear  from  these  analyses,"  (of 
Berzelius,  whom  he  there  properly  styles 
one  of  the  most  accurate  chemists  of  the 
present  day),  "  that  the  equivalent  num- 
ber for  phosphoric  acid  is  4.5."  And  far- 
ther, in  the  fifth  edition  of  his  System  of 
Chemistry,  published  in  1817,  from  an  ex- 
tremely large  collection  of  experiments, 
he  determines  the  equivalent  of  phospho- 
rus to  be  1.5;  and  that  of  phosphoric  acid 
to  be  4.5.  Finally,  in  March  1820,  without 
hinting  in  the  least  at  his  abandonment  of 
the  number  3.634,  and  adoption  of  4.5,  he 
merely  says,  "  that  a  set  of  experiments 
lie  published  some  years  ago  seem  to  me 
to  demonstrate  the  constitution  of  these 
two  acids  in  a  satisfactory  manner."  And 
he  immediately  fixes  on  3.5  for  phosphoric 
acid. 

Amid  all  these  perplexities,  it  is  com- 
fortable to  resort  to  Sir  H.  Davy's  clear 
and  decisive  paper,  read  before  the  Royal 
Society  on  the  9th  April  1818.  With  his 


well  known  sagacity,  he  invented  a  new 
method  of  research,  to  elude  the  former 
sources  of  error.  He  burned  the  vapour 
of  phosphorus  as  it  issues  from  a  small 
tube,  contained  in  a  reton  filled  with  oxy- 
gen gas.  By  adopting  this  proces,  he  de- 
termined the  composition  of  phosphoric 
acid  to  be  100  phosphorus -f-  134.5  oxy- 
gen ;  whence  its  equivalent  comes  out 
3.500.  Phosphorous  acid  he  then  shows 
to  consist  of  1  oxygen  -f  '  -500  phosphorus 
=  2.500.  We  shall  therefore  fix  on  Sir 
H.  Davy's  number  3.500  for  the  prime 
equivalent  of  phosphoric  acid. 

We  see,  indeed,  in  the  Annals  of  Philos, 
for  1816,  in  a  paper  on  phosphuretted  hy- 
drogen by  Dr.  Thomson,  that  this  chemist 
had  determined  the  atom  of  phosphorus 
to  be  1.5,  and  that  of  phosphoric  acid  3.5, 
but  he  subsequently  renounced  them.  It 
will  be  instructive  to  place  his  fluctuations 
of  opinion  in  one  view. 

In  the  Annals  for  April  1816,  the  report 
of  Dr.  Thomson's  paper,  read  at  the  Royal 
Society,  on  phosphoric  acid  and  the  phos* 
phates,  makes  the  acid  equivalent  3.634; 
in  the  Annals  for  August  181 6,  the  phos- 
phuretted hydrogen  experiments  make  it 
3.5:  the  history  of  1816  improvements, 
inserted  in  January  1817,  gives  us  4.5  as 
the  equivalent,  and  an  explicit  renuncia- 
tion of  3.5 ;  the  System  of  Chemistry  in 
October  1817,  confirms  this  number  4.5 
by  multiplied  facts  and  reasonings ;  and, 
finally,  after  Sir  H.  Davy's  experiments 
appeared  in  1818,  which  demonstrated 
3.500  to  be  the  real  number,  Dr.  Thomson 
resumes  3.5;  and  to  show  his  claim  to  pri- 
ority, refers  simply  to  his  former  paper  on 
phosphuretted  hydrogen.  From  this  ex- 
ample,  beginners  in  the  study  of  chemistry 
will  learn  the  danger  of  dogmatizing  has- 
tily on  experimental  subjects.* 

*  ACID  (PHOSPHOROUS)  was  discovered 
in  1812  by  Sir  H.  Davy.    When  phospho- 
rus and  corrosive  sublimate  act  on  each 
other  at  an  elevated  temperature,  a  liquid 
called  protochloride  of  phosphorus  is  form- 
ed.    Water  added  to  this,  resolves  it  into 
muriatic  and  phosphorous  acids.    A  mo- 
derate heat  suffices  to  expel  the  former, 
and  the  latter  remains,  associated  with 
water.     It  has  a  very  sour  taste,  reddens 
vegetable  blues,  and  neutralizes   bases. 
When  heated  strongly  in  open  vessels,  it 
inflames.     Phosphuretted  hydrogen  flies 
off,  and  phosphoric  acid  remains.     Ten 
parts  of  it  heated  in  close  vessels  give 
off  1^   of  bihydroguret   of  phosphorus, 
and  leave  8£  of  phosphoric  acid.    Hence 
the  liquid  acid  consists  of  80.7  acid  -f-  19.3 
water.    Its  prime  equivalent  is  2.5.* 

*  ACID  (HYPOPHOSPHOHOUS),  lately  dis- 
covered by  M.  Dulong.     Pour  water  on 
the  phosphuret  of  barytes,  and  wait  till  all 
the  phosphuretted  hydrogen  be  disengag. 


AOI 


ACI 


ed.  Add  cautiously  to  the  filtered  liquid 
dilute  sulphuric  acid,  till  the  barytes  be  all 
precipitated  in  the  state  of  sulphate.  The 
supernatant  liquid  is  hypophosphorous 
acid,  which  should  be  passed  through  a 
iilter.  This  liquid  may  be  concentrated 
by  evaporation,  till  it  become  viscid.  It 
has  a  very  sour  taste,  reddens  vegetable 
blues,  and  does  not  crystallize.  It  is  pro- 
bably composed  of  2  primes  of  phospho- 
rus =  3.  -f-  1  of  oxygen.  Dulong's  analy- 
sis approaches  to  this  proportion.  He 
assigns,  but  from  rather  precarious  data, 
100  phosphorus  to  37.44  oxygen.*  The 
hypophosphites  have  the  remarkable  pro- 
perty of  being  all  soluble  in  water;  while 
many  of  the  phosphates  and  phosphites  are 
insoluble. 

M.  Thenard  succeeded  in  oxygenizing 
phosphoric  acid  by  the  method  described 
under  nitric  and  muriatic  acids. 

With  regard  to  the  phosphates  and 
phosphites,  we  have  so  many  discrepan- 
cies in  our  latest  publications,  that  we 
must  suspend  our  judgment  as  to  their 
composition.  Sir  H.  Davy  says  most  ap- 
propriately in  his  last  memoir  on  some  of 
the  combinations  of  phosphorus,  that  "new 
researches  are  required  to  explain  the 
anomalies  presented  by  the  phosphates." 
We  may  add,  that  after  he  has  so  effectu- 
ally cleared  up  the  mysteries  of  the  acids 
themselves,  the  scientific  world  look  to 
him  to  throw  the  same  light  on  their  saline 
combinations.* 

Phosphoric  acid,  united  with  barytes, 
produces  an  insoluble  salt,  in  the  form  of 
a  heavy  white  powder,  fusible  at  a  high 
temperature  into  a  gray  enamel.  The  best 
mode  of  preparing  it  is  by  adding  an  alka- 
line phosphate  to  the  nitrate  or  muriate 
ofbarytes. 

The  phosphate  of  strontian  differs  from 
the  preceding  in  being  soluble  in  an  ex- 
cess of  its  acid. 

Phosphate  of  lime  is  very  abundant  in 
the  native  state.  At  Marmarosch  in  Hun- 
gary, it  is  found  in  a  pulverulent  form, 
mixed  with  fluate  of  lime  :  in  the  province 
of  Estremadura  in  Spain,  it  is  in  such  large 
masses,  that  walls  of  enclosures,  and  even 
houses,  are  built  with  it;  and  it  is  frequent- 
ly crystallized,  as  in  the  apatite  of  Werner, 
when  it  assumes  different  tints  of  gray, 
brown,  purple,  blue,  olive,  and  green.  In 
the  latter  state,  it  has  been  confounded 
with  the  crysolite,  and  sometimes  with  the 
beryl  and  aqua  marine,  as  in  the  stone 
called  the  Saxon  beryl.  It  likewise  con- 
stitutes the  chief  part  of  the  bones  of  all 
animals. 

The  phosphate  of  lime  is  very  difficult 
to  fuse,  but  in  a  glasshouse  furnace  it  soft- 
ens, and  acquires  the  semitransparency 
and  grain  of  porcelain.  It  is  insoluble  in 
,  but  when  well  calcined,  forms  a 


kind  of  paste  with  it,  as  in  making  cupels, 
Besides  this  use  of  it,  it  is  employed  for 
polishing  gems  and  metals,  for  absorbing 
grease  from  cloth,  linen,  or  paper,  and  for 
preparing  phosphorus.  In  medicine  it  has 
been  strongly  recommended  against  the 
rickets  by  Dr.  Bonhomme  of  Avignon, 
either  alone  or  combined  with  phosphate 
of  soda.  The  burnt  hartshorn  of  the  shops 
is  a  phosphate  of  lime. 

An  acidulous  phosphate  of  lime  is  found 
in  human  urine,  and  may  be  crystallized  in 
small  silky  filaments,  or  shining  scales, 
which  unite  together  into  something  like 
the  consistence  of  honey,  and  have  a  per- 
ceptibly acid  taste.  It  may  be  prepared  by 
partially  decomposing  the  calcareous  phos- 
phate of  bones  by  the  sulphuric,  nitric,  or 
muriatic  acid,  or  by  dissolving  that  phos- 
phate in  phosphoric  acid.  It  is  soluble  ia 
water,  and  crystallizable.  Exposed  to  the 
action  of  heat,  it  softens,  liquefies,  swells 
up,  becomes  dry,  and  may  be  fused  into  a 
transparent  glass,  which  is  insipid,  insolu- 
ble, and  unalterable  in  the  air.  In  these 
characters  it  differs  from  the  glacial  acid 
of  phosphorus.  It  is  partly  decomposable 
by  charcoal,  so  as  to  afford  phosphorus. 

The  phosphate  of  potash  is  very  deli- 
quescent, and  not  crystallizable,  but  con- 
densing into  a  kind  of  jelly.  Like  the  pre- 
cediivg  species,  it  first  undergoes  the  aque- 
ous fusion,  swells,  dries,  and  may  be  fused 
into  a  glass ;  but  this  glass  deliquesces. 
It  has  a  sweetish  saline  taste. 

The  phosphate  of  soda  was  first  disco- 
vered combined  with  ammonia  in  urine,  by 
Schockwitz,  and  was  called  fusible  or  micro- 
cosmic  salt.  Margraff  obtained  it  alone  by 
lixiviating  the  residuum  left  after  prepar- 
ing phosphorus  from  this  triple  salt  and 
charcoal.  Haupt,  who  first  discriminated 
the  two,  gave  the  phosphate  of  soda  the 
name  of  sal  mirabileperlatwn.  Ron  elle  very 
properly  announced  it  to  be  a  compound 
of  soda  and  phosphoric  acid.  Bergman 
considered  it,  or  rather  the  acidulous  phos- 
phate, as  a  peculiar  acid,  and  gave  it  the 
name  ofperlate  acid.  Guyton-Morveau  did 
the  same,  but  distinguished  it  by  the  name 
ofouretic:  at  length  Klaproth  ascertained 
its  real  nature  to  be  as  Rouelle  had  affirmed. 

This  phosphate  is  now  commonly  pre- 
pared by  adding  to  the  acidulous  phos- 
phate of  lime  as  much  carbonate  of  soda 
in  solution  as  will  fully  saturate  the  acid. 
The  carbonate  of  lime,  which  precipitates, 
being  separated  by  filtration,  the  liquid  is 
duly  evaporated  so  as  to  crystallize  the 
phosphate  of  soda;  but  if  there  be  not  a 
slight  excess  of  alkali,  the  crystals  will  not 
be  large  and  regular.  M.  Funcke,  of  Linz, 
recommends,  as  a  more  economical  and 
expeditious  mode,  to  saturate  the  excess 
of  lime  in  calcined  bones  by  dilute  sulphu- 
ric acid,  and  dissolve  the  phosphate  of 


ACI 


ACI 


lime  tli.it  remains  in  nitric  acid.    To  this 
solution  he  adds  an  equal  quantity  of  sul- 

Shate  of  soda,  and  recovers  the  nitric  acid 
y  distillation.  He  then  separates  the 
phosphate  of  soda  from  the  sulphate  of 
lime  by  elutriation  and  crystallization,  as 
usual.  The  crystals  are  rhomhoidal  prisms 
of  different  shapes;  efflorescent;  soluble 
in  3  parts  of  cold  and  14  of  hot  water. 
They  are  capable  of  being-  fused  into  an 
opaque  white  glass,  which  may  be  again 
dissolved  and  crystallized.  It  may  be  con- 
verted into  an  acidulous  phosphate  by  an 
addition  of  acid,  or  by  either  of  the  strong- 
acids,  which  partially,  but  not  wholly,  de- 
compose it.  As  its  taste  is  simply  saline, 
without  any  thing-  disagreeable,  it  is  much 
used  as  a  purg-ative,  chiefly  in  broth,  in 
which  it  is  not  distinguishable  from  com- 
mon salt.  For  this  elegant  addition  to  our 
pharmaceutical  preparations,  we  are  in- 
debted to  Dr.  Pearson.  In  assays  with  the 
blow-pipe  it  is  of  great  utility ;  and  it  has 
been  used  instead  of  borax  for  soldering. 
The  phosphate  of  ammonia  crystallizes 
in  prisms  with  four  regular  sides,  termi- 
nating in  pyramids,  and  sometimes  in  bun- 
dles of  small  needles.  Its  taste  is  cool,  sa- 
line, pungent,  and  urinous.  On  the  fire  it 
comports  itself  like  the  preceding  species, 
except  that  the  whole  of  its  base  may  be 
driven  off  by  a  continuance  of  the  heat, 
leaving  only  the  acid  behind.  It  is  but  lit- 
tle more  soluble  in  hot  water  than  in  cold, 
\vhich  takes  up  a  fourth  of  its  weight.  It 
is  pretty  abundant  in  human  urine,  par- 
ticularly after  it  is  become  putrid.  It  is  an 
excellent  flux  both  for  assay  sand  the  blow- 
pipe, and  in  the  fabrication  of  coloured 
glass  and  artificial  gems. 

Phosphate  of  magnesia  crystallizes  in  ir- 
regular hexaedral  prisms,  obliquely  trun- 
cated ;  but  is  commonly  pulverulent,  as  it 
effloresces  very  quickly.  It  requires  fifty 
parts  of  water  to  dissolve  it.  Its  taste  is 
cool  and  sweetish.  This  salt  too  is  found 
in  urine.  Fourcroy  and  Vauquelin  have 
discovered  it  likewise  in  small  quantity  in 
the  bones  of  various  animals,  though  not 
in  those  of  man.  The  best  way  of  prepar- 
ing it  is  by  mixing  equal  parts  of  the  solu- 
tions of  phosphate  of  soda  and  sulphate  of 
magnesia,  and  leaving  them  some  time  at 
rest,  when  the  phosphate  of  magnesia  will 
crystallize,  and  leave  the  sulphate  of  soda 
dissolved. 

An  ammoniaco-magnesian  phosphate  has 
been  discovered  in  an  intestinal  calculus 
of  a  horse  by  Fourcroy,  and  since  by  Bar- 
tholdi,  and  likewise  by  the  former  in  some 
human  urinary  calculi.  Notwithstanding 
the  solubility  of  the  phosphate  of  ammo- 
nia, this  triple  salt  is  far  less  soluble  than 
the  phosphate  of  magnesia.  It  is  partially 
decomposable  into  phosphorus  by  char- 
coal, in  consequence  of  its  ammonia. 


The  phosphate  of  g-lucine  has  been  ex» 
amined  by  Vauquelin,  who  informs  us,  that 
it  is  a  white  powder,  or  mucilaginous  mass, 
without  any  perceptible  taste ;  fusible, 
but  not  decomposable  by  heat ;  unaltera- 
ble in  the  air;  and  insoluble  unless  in  an 
excess  of  its  acid. 

It  has  been  observed,  that  the  phospho- 
ric acid,  aided  by  heat,  acts  upon  silex; 
and  we  may  add,  that  it  enters  into  many 
artificial  gems  in  the  state  of  a  siliceous 
phosphate. 

ACID  (Purssrc).  The  combination  of 
this  acid  with  iron  was  long-  known  and 
used  as  a  pigment  by  the  name  of  prussian 
blue,  before  its  nature  was  understood. 
Macquer  first  found,  that  alkalis  would  de- 
compose prussian  blue,  by  separating-  the 
iron  from  the  principle,  with  which  it  was 
combined  in  it,  and  which  he  supposed  to 
be  phlogiston.  In  consequence,  the  prus- 
siate  of  potash  was  long  qalled  phlogisti- 
cated  alkali.  Bergmann,  however,  from  a 
more  scientific  consideration  of  its  proper- 
ties, ranked  it  among  the  acids  ;  and  as 
early  as  1772,  Sage  announced,  that  this 
animal  acid,  as  he  called  it,  formed  with 
the  alkalis  neutral  salts,  that  with  potash 
forming  octa'';dral  crystals,  and  that  with 
soda,  rhomboids  or  hexagonal  laminae. 
About  ttie  same  time  Scheele  instituted  a 
series  of  sagacious  experiments,  not  only 
to  obtain  the  acid  separate,  which  he  ef- 
fected, but  also  to  ascertain  its  constituent 
principles.  These,  according  to  him,  are 
ammonia  and  carbon ;  and  Berthollet  there- 
after added,  that  its  triple  base  consists  of 
hydrogen  and  azote,  nearly,  if  not  precise- 
ly,  in  the  proportions  that  form  ammonia, 
and  carbon.  Berthollet  could  find  no  oxy- 
gen in  any  of  his  experiments  for  decom- 
posing this  acid. 

Scheele's  method  is  this :  Mix  four  oun- 
ces of  prussian  blue  with  two  of  red  oxide 
of  mercury  prepared  by  nitric  acid,  and 
boil  them  in  twelve  ounces  by  weight  of 
water,  till  the  whole  becomes  colourless ; 
filter  the  liquor,  and  add  to  it  one  ounce 
of  clean  iron  filings,  and  six  or  seven  drams 
of  sulphuric  acid.  Draw  off' by  distillation 
about  a  fourth  of  the  liquor,  which  will  be 
prussic  acid  ;  though,  as  it  is  liable  to  be 
contaminated  with  a  portion  of  sulphuric, 
to  render  it  pure,  it  may  be  rectified  by 
redistilling  it  from  carbonate  of  lime. 

This  prussic  acid  has  a  strong  smell  of 
peach  blossoms,  or  bitter  almonds ;  its 
taste  is  at  first  sweetish,  then  acrid,  hot, 
and  virulent,  and  excites  coughing  ;  it  has 
a  strong  tendency  to  assume  the  form  of 
gas ;  it  has  been  decomposed  in  a  high 
temperature,  and  by  the  contact  of  light, 
into  carbonic  acid,  ammonia,  and  carbu- 
retted  hydrogen.  It  does  not  completely 
neutralize  alkalis,  and  is  displaced  even  by 
the  carbonic  acid ;  it  has  no  action  upon 


ACI 


ACI 


metals,  but  unites  with  their  oxides,  and 
forms  salts  for  the  most  part  insoluble;  it 
likewise  unites  into  triple  salts  with  these 
oxides  and  alkalis ;  the  oxygenated  muri- 
atic acid  decomposes  it. 

The  peculiar  smell  of  the  prussic  acid 
could  scarcely  fail  to  suggest  its  affinity 
with  the  deleterious  principle  that  rises  in 
the  distillation  of  the  leaves  of  the  lauro- 
cerasus,  bitter  kernels  of  fruits,  and  some 
other  vegetable  productions;  and  M. 
Schrader  of  Berlin  has  ascertained  the  fact, 
that  these  vegetable  substances  do  con- 
tain a  principle  capable  of  formingpa  blue 
precipitate  with  iron;  and  that  with  lime 
they  afford  a  test  of  the  presence  of  iron, 
equal  to  the  prussiate  of  that  earth.  Dr. 
Bucholz  of  Weimar,  and  Mr.  Roloff  of 
Magdeburg,  confirm  this  fact.  The  prussic 
acid  appears  to  come  over  in  the  distilled 
oil. 

*  Prussic  acid  and  its  combinations  have 
been  lately  investigated  by  M,  Gay-Lussac 
and  Vauquelin  in  France,  and  Mr.  Porrett 
in  England,  who  have  happily  succeeded 
in  removing  in  some  measure  the  veil 
which  continued  to  hang  over  this  depart- 
ment of  chemistry. 

To  a  quantity  of  powdered  prussian 
blue  diffused  in  boiling  water,  let  red  oxide 
of  mercury  be  added  in  successive  portions 
till  the  colour  is  destroyed.  Filter  the 
liquid,  and  concentrate  by  evaporation  till 
a  pellicle  appears.  On  cooling,  crystals 
of  prussiate  or  cyanide  of  mercury  will  be 
formed.  Dry  these,  and  put  them  into  a 
tubulated  glass  retort,  to  the  beak  of 
which  is  adapted  a  horizontal  tube  about 
two  feet  long,  and  fully  half  an  inch  wide 
at  its  middle  part.  The  first  third  part  of 
the  tube  next  the  retort  is  filled  with 
small  pieces  of  white  marble,  the  two  other 
thirds  with  fused  muriate  of  lime.  To 
the  end  of  this  tube  is  adapted  a  small 
receiver,  which  should  be  artificially 
refrigerated.  Pour  on  the  crystals,  muri- 
atic acid,  in  rather  less  quantity  than  is 
sufficient  to  saturate  the  oxide  of  mercurv, 
which  formed  them.  Apply  a  very  gentle 
heat  to  the  retort.  Prussic  acid,  named 
hydrocyanic  by  M.  Gay-Lussac,  will  be 
evolved  in  vapour,  and  will  condense  in 
the  tube.  Whatever  muriatic  acid  may 
pass  over  with  it,  will  be  abstracted  by  the 
marble,  while  the  water  will  be  absorbed 
tythe  muriate  of  lime.  By  means  of  a 
rnoderate  heat  applied  to  the  tube,  the 
prussic  acid  may  be  made  to  pass  succes- 
sively along;  and  after  being  left  some 
time  in  contract  with  the  muriate  of  lime, 
it  may  be  finally  driven  into  the  receiver. 
As  the  carbonic  acid  evolved  from  marble 
by  the  muriatic  is  apt  to  carry  off  some  of 
the  prussic  acid,  care  should  be  taken  to 
conduct  the  heat  so  as  to  prevent  the 
distillation  of  this  mineral  acid. 


Prussic  acid  thus  obtained  has  the 
following  properties.  It  is  a  colourless 
liquid,  possessing  a  strong  odour ;  "and  the 
exhalation,  if  incautiously  snuffed  up  the 
nostrils,  may  produce  sickness  or  tainting. 
Its  taste  is  cooling  at  first,  then  hot,  as- 
thenicin  a  high  degree,  and  a  true  poison. 
Its  specific  gravity  at  44£°,  is  0.7058 ;  at 
64°  it  is  0.6969.  It  boils  at  8l£°,  and  con- 
geals  at,  about  3°.  It  then  crystallizes 
regularly,  and  affects  sometimes  the 
fibrous  form  of  nitrate  of  ammonia.  The 
cold  which  it  produces,  when  reduced 
into  vapour,  even  at  the  temperature  of 
68°,  is  sufficient  to  congeal  it.  This 
phenomenon  is  easily  produced  by  putting 
a  small  drop  at  the  end  of  a  slip  of  paper 
or  a  glass  tube.  Though  repeatedly  recti- 
fied on  pounded  marble,  it  retains  the 
property  of  feebly  reddening  paper  tinged 
blue  with  litmus.  The  red  colour  disap- 
pears as  the  acid  evaporates. 

The  specific  gravity  of  its  vapour,  ex- 
perimentally compared  to  thac  of  air,  is 
0.9476.  By  calculation  from  its  constitu- 
ents, its  true  specific  gravity  comes  out 
0.9360,  which  differs  from  the  preceding 
number  by  only  one-hundredth  part. 
This  small  density  of  prussic  acid,  com- 
pared with  its  great  volatility,  furnishes  a 
new  proof  that  the  density  of  vapours 
does  not  depend  upon  the  boiling  point 
of  the  liquids  that  furnish  them,  but  upon 
their  peculiar  constitution. 

M.  Gay-Lussac  analyzed  this  acid  by  in- 
troducing its  vapour  at  the  temperature 
of86y  into  ajar,  two-thirds  filled  with 
oxygen,  over  warm  mercury.  When  the 
temperature  of  the  mercury  was  reduced 
to  that  of  the  ambient  air,  a  determinate 
volume  of  the  gaseous  mixture  was  taken 
and  washed  in  a  solution  of  potash,  which 
abstracts  the  prussic  acid,  and  leaves  the 
oxygen.  This  gaseous  mixture  may  after 
this  inspection,  be  employed  without  any 
chance  that  the  prussic  acid  will  condense, 
provided  the  temperature  be  not  too  low  ; 
but  during  M.  Gay-Lussac's  experiments 
it  was  never  under  7l2Q.  A  known  vol- 
ume was  introduced  into  a  Volta's  eudi- 
ometer, with  platina  wires,  and  an  elec- 
tric spark  was  passed  across  the  gaseous 
mixture.  The  combustion  is  lively,  and 
of  a  bluish  white  colour.  A  white  prussic 
vapour  is  seen,  and  a  diminution  of  volume 
takes  place,  which  is  ascertained  by 
measuring  the  residue  in  a  graduated 
tube.  This  being  washed  with  a  solution 
of  potash  or  barytes,  suffers  a  new  di- 
minution from  the  absorption  of  the  car- 
bonic acid  gas  formed.  Lastly,  the  gas, 
which  the  alkali  has  left,  is  analyzed  over 
water  by  hydrogen,  and  it  is  ascertained 
to  be  a  mixture  of  nitrogen  and  oxygen, 
because  this  last  gas  was  employed  in 


ACI 


AC! 


The  following  are  the  results,  referred 
to  prussic  acid  vapour. 

Vapour,  -  -  -  f  -  100 
Diminution  after  combustion,  -  78.5 
Carbonic  acid  gas  produced,  101.0 
Nitrogen,  -  ...  46.0 
Hydrogen,  ....  55.0 

During  the  combustion  a  quantity  of 
oxygen  disappears,  equal  to  about  1£  of 
the  vapour  employed.  The  carbonic  acid 
produced  represents  one  volume  ;  and  the 
other  fourth  is  supposed  to  be  employed 
in  forming  vvat  er ;  for  it  is  impossible  to 
doubt  that  hydrogen  enters  into  the  com- 
position of  prussic  acid.  From  the  laws  of 
chemical  proportions,  M.  Gay-Lussac  con- 
cludes that  prussic  acid  vapour  contains 
just  as  much  carbon  as  will  form  its  own 
bulk  of  carbonic  acid,  half  a  volume  of 
nitrogen,  and  half  a  volume  of  hydro- 
gen. This  result  is  evident  for  the  car- 
bon ;  and  though,  instead  of  50  of  nitro- 
gen and  hydrogen,  which  ought  to  be  the 
numbers  according  to  the  supposition,  he 
obtained  46  for  the  first,  and  55  for  the  se- 
cond, he  ascribes  the  discrepancy  to  a  por- 
tion of  the  nitrogen  having  combined  with 
the  oxygen  to  form  nitric  acid. 

The  density  of  carbonic  acid  gas  being, 
according  to  M.  Gay-Lussac,  1.5196,  and 
that  of  oxygen  1.1036,  the  density  of  the 
vapour  of  carbon  is  1.5196  —  1.1036  «= 
0.4160.  Hence  1  volume  carbon,=  0.4160 

Half  a  volume  of  hydrogen,  =•=  0.0366 

Half  a  volume  of  nitrogen,     =  0.4845 

Sum,  =  0.9371 

Thus,  according  to  the  analytical  state- 
ment, the  density  of  prussic  vapour  is 
0.9371,  and  by  direct  experiment  it  was 
found  to  be  0.9476.  It  may  therefore  be 
inferred  from  this  near  coincidence,  that 
prussic  acid  vapour  contains  one  volume 
of  the  vapour  of  carbon,  half  a  volume  of 
nitrogen,  and  half  a  volume  of  hydrogen, 
condensed  into  one  volume,  and  that  no 
other  substance  enters  into  its  composition. 

M.  Gay-Lussac  confirmed  the  above  de- 
termination, analyzing  prussic  acid  by 
passing  its  vapour  through  an  ignited  por- 
celain tube  containing  a  coil  of  fine  iron 
wire,  which  facilitates  the  decomposition 
of  this  vapour,  as  does  it  with  ammonia. 
No  trace  of  oxygen  could  be  found  in 
prussic  acid.  And  again,  by  transmitting 
the  acid  in  vapour  over  ignited  peroxide 
of  copper  in  a  porcelain  tube,  he  came  to 
the  same  conclusion  with  regard  to  its  con- 
constituents.  They  are, — 

One  volume  of  the  vapour  of  carbon, 

Half  a  volume  of  hydrogen, 

Haifa  volume  of  nitrogen, 
condensed  into  one  volume;  OT  in  weight, 


Carbon, 44.39 

Nitrogen, 51.71 


Hydrogen, 


3.90 

luo.oo 


This  acid,  when  compared  with  the  oth- 
er animal  products,  is  distinguished  by  the 
great  quantity  of  nitrogen  it  contains,  by 
its  small  quantity  of  hydrogen,  and  espe- 
cially by  the  absence  of  oxygen. 

When  this  acid  is  kept  in  well-closed 
vessels,  even  though  no  air  be  present,  it 
is  sometimes  decomposed  in  less  than  an 
hour.  It  has  been  occasionally  kept  15 
days  without  alteration ;  but  it  is  seldom 
that  it  can  be  kept  longer,  without  ex- 
hibiting signs  of  decomposition.  It  begins 
by  assuming  a  reddish  brown  colour, 
which  becomes  deeper  and  deeper,  and  it 
gradually  deposites  a  considerable  carbo- 
naceous matter,  which  gives  a  deep  colour 
to  both  water  and  acids,  and  emits  a  strong 
smell  of  ammonia.  If  the  bottle  containing 
the  prussic  acid  be  not  hermetically  sealed, 
nothing  remains  but  a  dry  charry  mass, 
which  gives  no  colour  to  water.  Thus  a 
prussiate  of  ammonia  is  formed  at  the  ex- 
pense of  a  part  of  the  acid,  and  an  azoturet 
of  carbon.  When  potassium  is  heated  in 
prussic  acid  vapour  mixed  with  hydrogen 
or  nitrogen,  there  is  absorption  without  in- 
flammation, and  the  m4tal  is  converted 
into  a  gray  spongy  substance,  which  melts:, 
and  assumes  a  yellow  colour. 

Supposing  the  quantity  of  potassium 
employed  capable  of  disengaging  from 
water  a  volume  of  hydrogen  equal  to  50 
parts,  we  find  after  the  action  of  the  po- 
tassium,— 

1.  That  the  gaseous  mixture  has  experi- 
enced a  diminution  of  volume  amounting 
to  50  parts :  2.  On  treating  this  mixture 
with  potash,  and  analyzing  the  residue  by 
oxygen,  that  50  parts  of  hydrogen  have 
been  produced :  3.  And  consequently 
that  the  potassium  has  absorbed  100  parts 
of  prussie  vapour;  for  there  is  a  diminu- 
tion of  50  parts,  which  would  obviously 
have  been  twice  as  great  had  not  50  part* 
of  hydrogen  been  disengaged.  The  yel- 
low matter  is  prussiate  of  potash  ;  proper- 
ly a  prusside  of  potassium,  analogous  in  its 
formation  to  the  chloride  and  iodide,  when 
muriatic  and  hydriodic  gases  are  made  to 
act  on  potassium. 

The  base  of  prussic  acid  thus  divested 
of  its  acidifying  hydrogen,  should  be  call- 
ed, agreeably  to  the  same  chemical  ana- 
logy, prussine.  M.  Gay-Lussac  styles  it 
cyanogen,  because  it  is  the  principle  which 
generates  blue ;  or  literally,  the  blue- 
maker. 

Like  muriatic  and  hydriodic  acids  also^ 
it  contains  half  its  volume  of  hydrogen. 


AC1 


AC1 


The  only  difference  is,  that  the  former 
have  in  the  present  state  of  our  knowledge 
simple  radicals,  chlorine  and  iodine,  while 
that  of  the  latter  is  a  compound  of  one 
volume  vapour  of  carbon,  and  half  a  vol- 
time  of  nitrogen.  This  radical  forms  true 
prussides  wivii  metals. 

If  the  term  cyanogen  be  objectionable 
as  allying1  it  to  oxygen,  instead  of  chlorine 
and  iodine,  the  term  hydrocyanic  acid 
must  be  equally  so,  as  implying  that  it 
contains  water.  Thus  we  say  hydronitric, 
hydromuriatic,  and  hydro  phosphoric,  to 
denote  the  aqueous  compounds  of  4he  ni- 
tric, muriatic,  and  phosphoric  acids.  As 
the  singular  merit  of  M.  Gay-Lussac,  how- 
ever, has  commanded  a  very  general  com- 
pliance among  chemists  with  his  nomen- 
clature, we  shall  use  the  term  prussic  acid 
and  hydrocyanic  indifferently,  as  has  long 
been  done  with  the  words  nitrogen  and 
azote. 

The  prusside  or  cyanide  of  potassium 
gives  a  very  alkaline  solution  in  water, 
even  when  a  great  excess  of  hydrocyanic 
vapour  has  been  present  at  its' formation. 
In  this  respect  it  differs  from  the  chlorides 
and  iodides  of  that  metal,  which  are  per- 
fectly neutral.  Knowing  the  composition 
t*f  prussic  acid,  and  that  potassium  sepa- 
rates from  it  as  much  hydrogen  as  from 
water,  it  is  easy  to  find  its  proportional 
number  or  equivalent  to  oxygen.  We 
must  take  such  a  quantity  of  prussic  acid 
that  its  hydrogen  may  saturate  10  of  oxy- 
gen. Thus  we  find  the  prime  equivalent 
of  this  acid  to  be  33.846  ;  and  subtracting 
the  weight  of  hydrogen,  there  remains 
3,2.52  for  the  equivalent  of  cyanogen  or 
prussine.  But  if  we  reduce  the  numbers 
representing  the  volumes  to  the  prime 
equivalents  adopted  in  this  Dictionory, 
vi/.  0.75  for  carbon,  0.125  for  hydrogen, 
and  1.75  for  nitrogen,  we  shall  have"  the 
relation  of  volumes  slightly  modified.  Since 
the  fundamental  combining  ratio  of  ox\  gen 
to  hydrogen  in  bulk  is  £  to  1,  we  must 
multiply  the  prime  equivalent  by  half  the 
specific  gravity  of  oxygen,  and  we  obtain 
the  following  numbers: 

1  volume  car.  =0  75  X  0.5555  =  0.41663 


52  primes  carbon,  - 
1  prime  hydrogen, 
1  prime  nitrogen, 


0.125 
1.750 


volume  hd.= 


0.125X0.5555 


volume  nitr.-    '-^XO.iM5 


0.03471 
0.48610 


Sum  =  0.93744 

Or,  as  is  obvious  by  the  above  calcula- 
tion, we  may  take  2  primes  of  carbon,  1  of 
hydrogen,  and  1  of  nitrogen,  which  direct- 
ly added  together  will  g'ive  the  same  re- 
sults, since  by  so  doing  we  merely  take 
away  the  common  multiplier  0.5555.  Thus 
•we  have-. 


3.375 

Which  reduced  to  proportions  per  cent, 
give  of 

Carbon, 44.444 

Hydrogen, 3.704 

Nitrogen,        ---...    51.852 

100.000 

Barytes,  potash,  and  soda  combine  with 
prussine,  forming  true  prussides  of  these 
alkaline  oxides ;  analogous  to  what  are 
vulgarly  called  oxy  muriates  of  lime,  potash, 
and  soda.  The  red  oxide  of  mercury  acts 
so  powerfully  on  prussic  acid  vapour,  when 
assisted  by  heat,  that  the  compound  which 
ought  to  result  is  destroyed  by  the  heat 
disengaged.  The  same  thing  happens 
when  a  little  of  the  concentrated  acid  is 
poured  upon  the  oxide.  A  grer.t elevation 
of  temperature  takes  place,  which  would 
occasion  a  dangerous  explosion  if  the  ex- 
periment were  made  upon  considerable 
quantities.  When  the  acid  is  diluted,  the 
oxide  dissolves  rapidly,  with  a  considera- 
ble heat,  and  without  the  disengagement 
of  any  gas.  The  substance  formerly  called 
prussiate  of  mercury  is  generated,  which 
when  moist  may,  like  the  muriates,  still 
retain  that  name  ;  but  when  dry  is  a  prus- 
side of  the  metal. 

When  the  cold  oxide  is  placed  in  con- 
tact with  the  acid,  dilated  into  a  gaseous 
form  by  hydrogen,  its  vapour  is  absorbed 
in  a  few  minutes.  The  hydrogen  is  un- 
changed. When  a  considerable  quantity  of 
vapour  has  thus  been  absorbed,  the  oxide 
adheres  to  the  side  of  the  tube,  and  on  ap- 
plying heat,  water  is  obtained.  The  hy- 
drogen of  the  acid  has  here  united  with 
the  oxygen  of  the  oxide  to  form  the  water, 
while  their  two  radicals  combine.  Red 
oxide  of  mercury  becomes  an  excellent 
reagent  for  detecting  prussic  acid. 

By  exposing  the  dry  prusside  of  mer- 
cury to  heat  in  a  retort,  the  radical  cyano- 
gen or  prussine  is  obtained.  See  PRUSSINE. 

On  subjecting  hydrocyanic,  or  prussic 
acid,  to  the  action  of  a  battery  of  20  pairs 
of  plates,  much  hydrogen  is  disengaged  at 
the  negative  pole ;  and  cyanogen  or  prus- 
sine at  the  positive,  which  remains  dis- 
solved in  the  acid.  This  compound  should 
be  regarded  as  a  hypoprussic  or  prussous 
acid.  Since  potash  by  heat  separates  the 
hydrogen  of  the  prussic  acid,  we  see  that 
in  exposing  a  mixture  of  potash  and  ani- 
mal matters  to  a  high  temperature,  a  true 
prusside  or  cyanide  of  potash  is  obtained, 
formerly  called  the  prussian  or  phlogisti- 
cated  alkali.  When  cyanide  of  potassium 
is  dissolved  in  water,  hydrocyanate  of  pot- 
-Jlsh  is  produced,  which  is  decomposed  by 


ACI 


ACI 


the  acids  without  generating1  ammonia  or 
carbonic  acid  ;  but  when  cyanide  of  pot- 
ash dissolves  in  water  no  change  takes 
place ;  and  neither  ammonia,  carbonic 
acid,  nor  hydrocyanic  vapour,  is  given  out, 
unless  an  acid  be  added.  These  are  the 
characters  which  distinguish  a  metallic 
cyanide  from  the  cyanide  of  an  oxide. 

From  the  experiments  of  M.  Magendie 
it  appears,  that  the  pure  hydrocyanic  acid 
is  the  most  violent  of  all  poisons.  When  a 
rod  dipped  into  it  is  brought  in  contact 
with  the  tongue  of  an  animal,  death  en- 
sues before  the  rod  can  be  withdrawn.  If 
a  bird  be  held  a  moment  over  the  mouth 
of  a  phial  containing  this  acid,  it  dies.  In 
the  Annales  de  Chimie  for  1814  we  find 
this  notice  :  M.  B.  Professor  of  Chemis- 
try, left  by  accident  on  a  table  a  flask  con- 
taining alcohol  impregnated  with  prussic 
acid  ;  the  servant,  enticed  by  the  agreea- 
ble flavour  of  the  liquid  swallowed  a  small 
flass  of  it.  In  two  minutes  she  dropped 
own  dead,  as  if  struck  with  apoplexy. 
The  body  was  not  examined. 

"  Scharinger,  a  professor  at  Vienna," 
says  Orfila,  "  prepared  six  or  seven  months 
ago  a  pure  and  concentrated  prussic  acid; 
he  spread  a  certain  quantity  of  it  on  his 
naked  arm,  and  died  a  little  time  thereaf- 
ter." 

Dr.  Magendie  has,  however,  ventured 
to  introduce  its  employment  into  medi- 
cine. He  found  it  beneficial  against  phthi- 
sis and  chronic  catarrhs.  His  formula  is 
the  following: — 

Mix  one  part  of  the  pure  prussic  or  hy- 
drocyanic acid  of  M.  Gay-Lussac  with  8£ 
of  water  by  weight.  To  this  mixture  he 
gives  the  name  of  medicinal  prussic  acid. 
Of  this  he  takes  1  gros.  or  59  gr.  Troy. 
Distilled  water,  1  Ib.  or  7560  grs. 
Pure  sugar,  1£  oz.  or  708|  grs. 
And  mixing  the  ingredients  well  together, 
he  administers  a  table  spoonful  every 
morning  and  evening.  A  well  written  re- 
port of  the  use  of  the  prussic  acid  in  cer- 
tain diseases,  by  Dr.  Magendie,  was  com- 
municated by  Dr.  Granville  to  Mr.  Brande, 
and  is  inserted  in  the  fourth  volume  of  the 
Journal  of  Science. 

For  the  following  ingenious  and  accu- 
rate process  for  preparing  prussic  acid  for 
medicinal  uses,  I  am  indebted  to  Dr.  Nim- 
mo  of  Glasgow  : 

"  Take  of  the  ferroprussiate  of  potash 
100  grains,  of  the  protosulphate  of  iron 
84^  grains ;  dissolve  them  separately  in 
four  ounces  of  water,  and  mingle  them. 
After  allowing  the  precipitate  of  the  pro- 
toprussiate  of  iron  to  settle,  pour  off  the 
clear  part,  and  add  water  to  wash  the  sul- 
phate of  potash  completely  away.  To  the 
protoprussiate  of  iron,  mixed  with  four 
ounces  of  pure  water,  add  135  grains  of 
the  peroxide  of  mercury,  and  boil  the 
VOL.  T.  [  12  ] 


whole  till  the  oxide  is  dissolved.  With 
the  above  proportions  of  peroxide  of  mer- 
cury, the  protoprussiate  of  iron  is  com- 
pletely decomposed.  The  vessel  being 
kept  warm,  the  oxide  of  iron  will  fall  to 
the  bottom,  the  clear  part  may  be  poured 
off  to  be  filtered  through  paper,  taking 
care  to  keep  the  funnel  covered,  so  that 
crystals  may  not  form  in  it  by  refrigeration. 
The  residuum  may  be  treated  with  more 
water,  and  thrown  upon  the  filter,  upon 
which  warm  water  ought  to  be  poured, 
until  all  the  soluble  part  is  washed  away. 
By  evaporation,  and  subsequent  rest  in  a 
cool  place,  145  grains  of  crystals  of  the 
prusside  or  cyanide  of  mercury  will  be 
procured  in  quadrangular  prisms. 

"  The  following  process  for  eliminating 
the  hydrocyanic  acid  I  believe  to  be  new. 
Take  of  the  cyanide  of  mercury  in  fine 
powder  one  ounce,  diffuse  it  in  two  oun- 
ces of  water,  and  to  it,  by  slow  degrees, 
add  a  solution  of  hydrosulphuret  of  bary- 
tes,  made  by  decomposing  sulphate  of  ba- 
rytes  with  charcoal  in  the  common  way. 
Of  the  sulphuret  of  barytes  take  an  ounce, 
boil  it  with  six  ounces  of  water,  and  filter 
it  as  hot  as  possible.  Add  this  in  small  por- 
tions to  the  cyanide  of  mercury,  agitating 
the  whole  very  well,  and  allowing  suffi- 
cient time  for  the  cyanide  to  dissolve, 
while  the  decomposition  is  going  on  be- 
tween it  and  the  hydrosulphuret  as  it  is 
added.  Continue  the  addition  of  the  hy. 
drosulphuret  so  long  as  a  dark  precipitate 
of  sulphuret  of  mercury  falls  down,  and 
even  allowing  a  small  excess.  Let  the 
whole  be  thrown  upon  a  filter,  and  kept 
warm  till  the  fluid  drops  through;  add 
more  water  to  wash  the  sulphuret  of  mer- 
cury, until  eight  ounces  of  fluid  have  pass- 
ed through  the  filter,  and  it  has  become 
tasteless.  To  this  fluid,  which  contains  the 

Srussiate  of  barytes,  with  a  small  excess  of 
ydrosulphuret  of  barytes,  add  sulphuric 
acid,  diluted  with  an  equal  weight  of  wa- 
ter, and  allowed  to  become  cold,  so  long 
as  sulphate  of  barytes  falls  down.  The  ex- 
cess of  sulphuretted  hydrogen  will  be  re- 
moved by  adding  a  sufficient  portion  of 
carbonate  of  lead,  and  agitating  very  well. 
The  whole  ma^  now  be  put  upon  a  filter, 
which  must  be  closely  covered ;  the  fluid 
which  passes  is  the  hydrocyanic  acid, 
of  what  is  called  the  medical  standard 
strength. " 

Dr.  Nimmo  finds,  that  cyanide  of  mer- 
cury is  capable  of  dissolving  the  mercuri- 
al peroxide.  Hence,  the  above  proportions 
must  be  strictly  observed,  if  we  wish  to 
obtain  this  powerful  medicine  of  uniform 
strength.  He  conceives,  therefore,  that 
the  ferroprussiate  of  potash  should  be  ta- 
ken for  the  basis  of  the  calculation. 

Scheele  found  that  prussic  acid  occa- 
sioned precipitates  with  only  the  following 


AC! 


AC1 


three  metallic  Solutions,  nitrates  of  silver, 
and  mercury,  and  carbonate  of  silver.  The 
first  is  white,  the  second  black,  the  third 
green  becoming1  blue.  In  the  Annals  of 
Phil,  for  May  1820,  Dr.  Thomson  gives  an 
account  of  some  metallic  precipitates  by  a 
substance  of  a  crystalline  nature,  which  he 
obtained  in  the  sublimation  of  Prussian 
blue  at  a  red  heat,  and  which  he  reckons 
hydrocyanatc  of  ammonia.  But  the  nature 
of  the  substance  is  by  no  means  demon- 
strated; and  the  precipitates  differ  so 
much  from  those  of  Scheele  as  to  justify 
scepticism.  Free  prussic  acid,  for  exiimple, 
gives  with  nitrate  of  mercury  a  black  pre- 
cipitate; while  Dr.  Thomson's  crystals 
give  a  white.  Vauquelin  found  the  crys- 
tals that  sublime  from  prussian  blue  to  be 
ammoniacal  carbonate,  and  not  hydrocy- 
anate. 

The  hydrocyanatesare  all  alkaline,  even 
when  a  great  excess  of  acid  is  employed 
in  their  formation  ;  and  they  are  decom- 
posed by  the  weakest  acids. 

The  hydrocyanate  of  ammonia  crystal- 
lizes in  cubes,  in  small  prisms  crossing 
each  other,  or  in  feathery  crystals,  like 
the  leaves  of  a  fern.  Its  volatility  is  such, 
that  at  the  temperature  of  7l£°,  it  is  capa- 
ble of  bearing  a  pressure  of  17.72  inches 
of  mercury  ;  and  at  97°  its  elasticity  is 
equal  to  that  of  the  atmosphere.  Unfor- 
tunately this  salt  is  charred  and  decom- 
posed with  extreme  facility.  Its  great  vo- 
latility prevented  M.  Gay-Lussac  from  de- 
termining the  proportion  of  its  constitu- 
ents. What  is  known  of  the  cyanides  or 
prussides  will  be  found  under  prussinc,  or 
their  bases.  M.  Gay-Lussac  considers  prus- 
sian blue  as  a  hydrated  cyanide  of  iron,  or  a 
cyanide  having  water  in  combination ;  and 
M.  Vauquelin,  in  a  memoir  lately  read  be- 
fore the  Academy  of  Sciences,  regards 
prussian  blue  as  a  simple  hydrocyanate  of 
iron.  He  finds  that  water  impregnated 
with  cyanogen  can  dissolve  iron  without 
changing  it  into  prussian  blue,  and  without 
the  disengagement  of  any  hydrogen  gas, 
while  prussiun  blue  was  left  in  the  undis- 
solved  portion.  But  hydrocyanic  acid  con- 
Verts  iron  or  its  oxide  into  prussian  blue 
without  the  help  either  of  alkalis  or  acids. 
He  conceives  that  cyanogen  acts  on  iron 
and  water  as  iodine  does  on  water  and  a 
base  ;  and  that  a  CYANIC  acid  is  formed 
which  dissolves  a  part  of  the  iron,  but  al- 
so and  at  the  same  time  hydrocyanic  acid, 
which  changes  another  part  of  the  iron  in- 
to prussian  blue.  He  farther  lays  it  down 
as  a  general  rule,  that  those  metals  which, 
like  iron,  decompose  water  at  the  ordina- 
ry temperature  of  the  atmosphere,  form 
liydrocyanates ;  and  that  those  metals 
which  do  not  possess  this  power,  as  silver 
and  quicksilver,  form  only  cyanides.  Are 
we  to  regard  the  cyanic  acid  of  M.  Yau- 


quelin  as  a  compound  of  one  prime  of  oxy     . 
gen,  and  one  of  cyanogen,  or  in  other 
words,  one  of  oxygen,  two  of  carbon,  and 
and  one  of  nitrogen  ? 

According  to  M.  Vauquelin,  very  com- 
plex changes  take  place  when  gaseous 
cyanogen  is  combined  with  water,  which 
leave  the  nature  of  cyanic  acid  involved  iu 
great  obscurity.  The  water  is  decompos- 
ed ;  part  of  its  hydrogen  combines  with 
one  part  of  the  cyanogen,  and  forms  hy- 
drocyanic acid;  another  part  unites  with 
the  nitrogen  of  the  cyanogen,  and  forms 
ammonia ;  and  the  oxygen  of  the  water 
forms  carbonic  acid,  with  one  part  of  the 
carbon  of  the  cyanogen.  Hydrocyanate, 
cai-bonate,  and  cyanate  of  ammonia,  are 
also  found  in  the  liquid ;  and  there  still 
remain  some  carbon  and  nitrogen,  which 
produce  a  brown  deposite.  Four  and  a  half 
parts  of  water  absorb  one  of  gaseous  cyano- 
gen, which  communicates  to  it  a  sharp 
taste  and  smell,  but  no  colour.  The  solu- 
tion in  the  course  of  some  days,  however, 
becomes  yellow,  and  afterwards  brown,  in 
consequence  of  the  intestine  changes  re~ 
lated  above. 

Hydrocyanic  acid  is  separated  from  pot- 
ash by  carbonic  acid  ;  but  when  oxide  of 
iron  is  added  to  the  potash,  M.  Gay-Lussac 
conceives  that  a  triple  compound,  united 
by  a  much  more  energetic  affinity,  results, 
constituting  what  is  usually  called  prus- 
siate  of  potash,  or  prussiate  of  potash  and 
iron.  In  illustration  of  this  view,  he  pre- 
pared a  hydrocyanate  of  potash  and  silver, 
which  was  quite  neutral,  and  which  crys- 
tallized in  hexagonal  plates.  The  solution 
of  these  crystals  precipitates  salts  of  iron 
and  copper,  white.  Muriate  of  ammonia 
does  not  render  it  turpid ;  but  muriatic 
acid,  by  disengaging  hydrocyanic  acid, 
precipitates  chloride  of  silver.  Sulphu- 
retted hydrogen  produces  in  it  an  analo- 
gous change.  This  compound,  says  M. 
Gay-Lussac,  is  evidently  the  triple  hydro- 
cyanate of  potash  and  silver ;  and  its  for- 
mation ought  to  be  analogous  to  that  of 
the  other  triple  liydrocyanates.  "  And  as 
we  cannot  doubt/'  adds  he,  "  that  hydro- 
cyanate of  potash  and  silver  is  in  reality, 
from  the  mode  of  its  formation,  a  compound 
of  cyanide  of  silver  and  hydrocyanate  of 
potash,  I  conceive  that  the  hydrocyanate 
of  potash  and  iron  is  likewise  a  compound 
of  neutral  hydrocyanate  of  potash,  and 
subcyanide  of  iron,  which  I  believe  to  be 
combined  with  hydrocyanic  acid  in  the 
white  precipitate.  We  may  obtain  it  per- 
fectly neutral,  and  then  it  does  not  decom- 
pose alum  ;  but  the  hydrocyanate  of  pot- 
ash, which  is  always  alkaline,  produces  in 
it  a  light  and  flocculent  precipitate  of  alu- 
mina. To  the  same  excess  of  alkali  we 
must  ascribe  the  ochry  colour  of  the  pre 
cipitates  which  hydrocyanate  of  potash 


ACI 


AC1 


forms  with  the  persalts  of  iron.  Thus  the 
remarkable  fact,  which  ought  to  fix  the  at- 
tention of  chemists,  and  which  appears  to 
me  to  overturn  the  theory  of  Mr.  Porrett, 
is,  that  hydroc^anate  of  potash  cannot  be- 
come neutral  except  when  combined  with 
the  cyanides."* 

*  ACID  (CHLOHOCYATSTIC,  orCHLOHornus- 
sic).  M.  Berthollet  discovered,  that  when 
hydrocyanic  acid  is  mixed  with  chlorine,  it 
acquires  new  properties.  Its  odour  is 
much  increased.  It  no  longer  forms  Prus- 
sian blue  with  solutions  of  iron,  but  a  green 
precipitate,  which  becomes  blue  by  the 
addition  of  sulphurous  acid.  Hydrocyanic 
acid  thus  altered  had  acquired  the  name 
of  oxyprnssic,  because  it  was  supposed  to 
have  acquired  oxygen.  M.  Gay-Lussac 
subjected  it  to  a  minute  examination,  and 
found  that  it  was  a  compound  of  equal  vo- 
lumes of  chlorine  and  cyanogen,  whence 
he  proposed  to  distinguish  it  by  the  name 
of  chlorocyanic  acid.  To  prep  are  this  com- 
pound he  passed  a  current  of  chlorine  into 
solution  of  hydrocyanic  acid,  till  it  destroy- 
ed the  colour  of  sulphate  of  indigo ;  and 
by  agitating  the  liquid  with  mercury,  he 
deprived  it  of  the  excess  of  chlorine.  By 
distillation,  afterwards,  in  a  moderate  heat, 
an  elastic  fluid  is  disengaged,  which  pos- 
sesses the  properties  formerly  assigned  to 
oxyprussic  acid.  This,  however,  is  not 
pure  chlorocyanic  acid,  but  a  mixture  of  it 
with  carbonic  acid,  in  proportions  which 
vary  so  much,  as  to  make  it  difficult  to  de- 
termine them. 

When  hydrocyanic  acid  is  supersaturat- 
ed with  chlorine,  and  the  excess  of  this 
last  is  removed  by  mercury,  the  liquid  con- 
tains chlorocyanic  and  muriatic  acids.  Hav- 
ing put  mercury  into  a  glass  jar  till  it  was 
o-4thsfull,  he  filled  it  completely  with  that 
acid  liquid,  and  inverted  the  jar  in  a  vessel 
of  mercury.  On  exhausting  the  receiver 
of  an  air  pump  containing  this  vessel,  the 
mercury  sunk  in  the  jar,  in  consequence 
of  the  elastic  fluid  disengaged.  By  de- 
grees the  liquid  itself  was  entirely  expel- 
led, and  swam  on  the  mercury  on  the  out- 
side. On  admitting  the  air  the  liquid  could 
not  enter  the  tube,  but  only  the  mercury, 
and  the  whole  elastic  fluid  condensed,  ex- 
cept a  small  bubble.  Hence  it  was  con- 
cluded that  chlorocyanic  acid  was  not  a 
permanent  gas,  and  that,  in  order  to  remain 
gaseous  under  the  pressure  of  the  air,  it 
must  be  mixed  with  another  gaseous  sub- 
stance. 

The  mixture  of  chlorocyanic  and  carbo- 
nic acids,  has  the  following  properties.  It 
is  colourless,  its  smell  is  very  strong.  A 
very  small  quantity  of  it  irritates  the  pitui- 
tary membrane,  and  occasions  tears.  It 
reddens  litmus,  is  not  inflammable,  and 
does  not  detonate  when  mixed  with  twice 
its  bulk  of  oxygen  or  hydrogen.  Its  den- 


sity, determined  by  calculation,  is  2.1 1U 
Its  aqueous  solution  does  not  precipitate 
nitrate  of  silver,  nor  barytes  water.  The 
alkalis  absorb  it  rapidly,  but  an  excess  of 
them  is  necessary  to  destroy  its  odour.  If 
we  then  add  an  acid,  a  strong  efferves- 
cence of  carbonic  acid  is  produced,  and 
the  odour  of  chlorocyanic  acid  is  no  longer 
perceived.  If  we  add  an  excess  of  lime 
to  the  acid  solution,  ammonia  is  disengag- 
ed in  abundance.  To  obtain  the  green 
precipitate  from  solution  of  iron,  we  must 
begin  by  mixing  chlorocyanic  acid  with 
that,  solution.  We  then  add  a  little  potash, 
and  at  last  a  little  acid.  If  we  add  the  al- 
kali before  the  iron,  we  obtain  no  green 
precipitate. 

M.  Gay-Lussac  deduces  for  the  compo- 
sition of  chlorocyanic  acid  1  volume  of  car- 
bon -4-  ^  a  volume  of  azote -f-  i  a  volume 
of  chlorine ;  and  when  decomposed  by  the 
successive  action  of  an  alkali  and  an  acid, 
it  produces  1  volume  of  muriatic  acid  gas 
-f-  1  volume  of  carbonic  acid  -\-  1  volume 
of  ammonia.  The  above  three  elements 
separately  constituting  two  volumes,  are 
condensed,  by  forming  chlorocarbonic  acid, 
into  one  volume.  And  since  one  volume 
of  chlorine,  and  one  volume  of  cyanogen, 
produce  two  volumes  of  chlorocyanic  acid, 
the  density  of  this  last  ought  to  be  the  halt' 
of  the  sum  of  the  densities  of  its  two  con- 
stituents.  Density  of  chlorine  is  2.421, 
density  of  cyanogen  1.801,  half  sum  — 
2.111,  as  stated  above  :  Or  the  proportions 
by  weight  will  be  3.375  =  a  prime  equiv- 
alent of  cyanogen  -|-  4.45  =  a  prime  of 
chlorine,  giving  the  equivalent  of  chloro- 
cyanic acid  =•=  7.825. 
"  Chlorocyanic  acid  exhibits  with  potas.- 
sium  almost  the  same  phenomena  as  cyan- 
ogen. The  inflammation  is  equally  slow, 
and  the  gas  diminishes  as  much  in  volume. 
The  directions  given  by  Dr.  Thomson 
for  forming  chlorocyanic  acid  in  the  second 
volume  of  his  System,  5th  edition,  p.  276, 
are  apparently  erroneous.  He  seems  to 
have  mistaken  M.  Gay-Lussac's  ingenious 
plan  for  proving  that  this  new  acid  is  not 
naturally  gaseous,  for  the  process  of  ob- 
taining the  acid  itself,  as  prescribed  both 
by  him  and  M.  Thenard.  The  chlorocy- 
anic and  carbonic  acids  which  come  over 
in  distillation,  are  to  be  condensed  in 
water,  or  received  over  mercury.  But  the 
requisite  process  of  distillation  is  not  even 
hinted  at  by  Dr.  Thomson,  whose  chloro- 
cyanic acid  must  be  a  mixture  of  chloro- 
cyanic and  muriatic  acids.* 
*  *  ACID  (FKUUOPHUSSIC).  Into  a  solu- 
tion of  the  amber-coloured  crystals,  usual- 
ly called  prussiate  of  potash,  pour  hydro- 
sulphuret  of  barytes,  as  long  as  any  pre- 
cipitate falls.  Throw  the  whole  on  a  iii- 
ter,  and  wash  the  precipitate  with  cold 
water,  Dry  it ;  and  having-  dissolved  100 


ACI 


AC1 


parts  in  cold  water,  add  gradually  SO  of 
concentrated  sulphuric  acid;  agitate  the 
mixture,  and  set  it  aside  to  repose.  The 
supernatant  liquid  is  ferroprussic  acid,  cal- 
led by  Mr.  Porrett,  who  had  the  merit  of 
discovering  it,  ferruretted  chyazic  acid. 

It  has  a  pale  lemon  yellow  colour,  but 
no  smell.  Heat  and  light  decompose  it. 
Hydrocyanic  acid  is  then  formed,  and  white 
ferroprussiate  of  iron,  which  soon  becomes 
blue.  Its  affinity  for  the  bases  enables  it 
to  displace  acetic  acid,  without  heat,  from 
the  acetates,  and  to  form  ferroprussiates. 

When  a  saline  solution  containsba  base 
with  which  the  ferroprussic  acid  forms  an 
insoluble  compound,  then,  agreeably  to 
Berthollet's  principle,  it  is  capable  of  sup- 
planting it^  acid.  When  ferroprussiate  of 
soda  is  exposed  to  voltaic  electricity,  the 
acid  is  evolved  at  the  positive  pole,  with 
its  constituent  iron.  Mr.  Porrett  consid- 
ers this  acid  "  as  a  compound  of 

4  atoms  carbon  =  30.00 
1  atom  azote  =  17.50 
1  atom  iron  =  17  50 

1  atom  hydrogen  =    1.25 

66.25" 

This  sum  represents  the  weight  of  its 
prime  equivalent.  Ferroprussiate  of  pot- 
ash, and  of  barytes,  will  each,  therefore, 
according  to  him,  consist,  of  an  atom  of 
acid  -f*  an  atom  of  base  -{-  two  atoms  of 
water. 

Dr.  Thomson  says,  in  his  System,  "  From 
the  analysis  of  Mr.  Porrett  it  appears,  that 
this  acid  is  composed  of 

Cyanogen,        8.904 
Iron,  3.500 

"  This  approaches  to  three  atoms  of 
cyanogen  and  one  atom  of  iron,  If  we 
suppose  this  to  be  the  real  constitution  of 
the  acid,  its  constituents  will  be 

Cyanogen,  9.75 

Iron,  3.50 

"  But  such  a  composition  is  quite 
irreconcileable  to  the  equivalent  number 
for  ferrocyanic  acid,  derived  from  the 
anaiysis  of  the  ferrocyanate  of  barytes. 
This  salt,  according  to  the  experiments 
of  Mr.  Porrett,  is  composed  of 

Ferrocyanic  acid,    34.31  6.813 

Barytes,  49.10  9.750 

Water,  16.59 

100.00 

"  We  see  that  by  this  analysis  the  equiva- 
lent number  for  ferrocyanic  acid  is  6.813. 
Now  this  agrees  very  nearly  with  the 
supposition  that  the  acid  is  a  compound 
of  one  atom  cyanogen  -f-  one  atom  iron. 
For  the  weights  of  an  atom  of  these 
bodies  are  as  follows : 

Cyanogen,  3.25 

Iron,  3.5 


"•The  difference  between  6.75  and 
6.813  does  not  exceed  one  per  cent.  I 
am  disposed,  therefore,  to  consider  this 
as  the  true  constitution  of  ferrocyanic 
acid." 

It  is  a  real  misfortune  to  chemical  stu- 
dents, when  so  elaborate  a  systematist  as 
Dr.  Thomson  so  readily  scatters  around 
him  precipitate  and  dogmatical  judgments, 
on  discussions  of  such  importance  and 
delicacy  as  the  present.  There  were  no 
reasonable  grounds  whatever  for  peremp- 
torily deciding-,  as  he  did,  that  the  ferruret- 
ted chyazic  acid  of  Mr.  Porrett  was  a 
simple  cyanide  of  iron,  or  a  compound  of 
cyanogen  and  iron.  The  mere  similarity 
of  two  numbers,  viz.  the  sum  of  the  atoms 
of  cyanogen  and  iron,  and  the  equivalent 
of  Mr.  Porrett's  acid,  were  apparently  the 
chief,  and  surely  very  frivolous  motives, 
for  that  erroneous  determination. 

Mr  Porrett  expresses  himself  thus,  in 
the  Ann.  of  Phil,  for  September  1818. 
"  It  is  a  great  satisfaction  to  nie  to  find 
that  Dr.  Thomson  has  abandoned  the 
opinion  which  he  entertained,  that  the 
ferruretted  chyazic  acid  contained  no  hy- 
drogen, and  was  a  compound  of  cyanogen 
and  iron  only ;  an  opinion  which  induced 
him  to  name  it,  in  his  System  of  Chemis- 
try, the  ferrocyanic  acid  and  its  salts 
ferrocyanates.  I  was  perfectly  convinced, 
from  many  circumstances  that  occurred 
during  my  first  experiments,  that  this 
opinion  was  erroneous,  and  should  have 
combated  it  when  it  appeared  in  his  Sys- 
tem, had  I  been  fond  of  controversy,  or 
been  able  to  find  time  for  carrying  on 
such  a  course  of  experiments,  as  would 
perhaps  have  been  requisite  to  produce 
conviction  in  others.  As  it  was,  I  con- 
tented myself  with  expressing  to  my 
chemical  friends,  my  dissent  from  Dr. 
Thomson's  opinion  on  this  subject;  and  I 
can  venture  to  assure  him,  that  whenever 
he  makes  experiments  with  the  sulphuret- 
ted chyazic  acid,  he  will  be  convinced 
that  it  also  contains  hydrogen,  and  that 
the  names  sulphocyanic,  and  sulphocyan- 
ates,  are  quite  inappropriate  ;  equally  so 
are  the  names  proposed  by  Dr.  Henry  of 
ferroprussic,  and  sulphuretted  prussic 
acids,  as  these  names  imply,  that  the 
prussic  acid  is  contained  in  these  com- 
pounds, instead  of  being  merely  the  re- 
sult of  a  new  play  of  affinities  when  they 
are  decomposed." 

How  little  room  there  is  for  arbitrary 
decrees  on  every  thing  regarding  the 
prussic  combinations,  we  may  readily 
judge,  when  we  consider  that  M.  Gay- 
Lussac,  and  M.  Vauquelin,  two  of  the  first 
chemists  of  the  age,  have  been  led,  after 
a  series  of  admirable  researches,  to  form 
views  totally  inconsistent  with  those  re- 
sulting from  Mr.  Porrett's  very  ingenious 


ACI 


ACI 


experiments.  On  the  relations  of  prussic 
acid  and  iron,  the  following  observations 
by  M.  Vauquelin  are  important.  Hydro- 
cyanic acid  diluted  with  water,  when  pla- 
ced in  contact  with  iron  in  a  glass  vessel 
standing  over  mercury,  quickly  produces 
Prussian  blue,  while,  at  the  same  time,  hy- 
drogen gas  is  given  out.  The  greatest 
part  of  the  prussian  blue  formed  in  that 
operation,  remains  in  solution  in  the  liquid. 
It  appears  only  when  the  liquid  comes  in 
contact  with  the  air.  This  shows  us  that 
prussian  blue,  at  a  minimum  of  oxidize- 
ment,  is  soluble  in  hydrocyanic  acid.  Dry 
hydrocyanic  acid,  placed  in  contact  with 
iron  filings,  undergoes  no  change  in  its 
colour  nor  smell;  but  the  iron,  which  be- 
comes agglutinated  together  at  the  bottom 
of  the  vessel,  assumes  a  brown  colour.  Af- 
ter some  days,  the  hydrocyanic  acid  being 
separated  from  the  iron,  and  put  in  a  small 
capsule  under  a  glass  jar,  evaporated  with- 
out leaving  any  residue.  Therefore  it  had 
dissolved  no  iron.  Hydrocyanic  acid  dis- 
solved in  water,  placed  in  contact  with 
hydrate  of  iron,  obtained  by  means  of  pot- 
ash, and  washed  with  boiling  water,  fur- 
nished prussian  blue  immediately  without 
the  addition  of  any  acid.  Scheele  has 
made  mention  of  this  fact.  When  hydro- 
cyanic acid  is  in  excess  on  the  oxide  of 
iron,  the  liquor  which  floats  over  the  prus- 
sian blue  assumes,  after  some  time,  a  beau- 
tiful purple  colour.  The  liquor,  when 
evaporated,  leaves  upon  the  edge  of  the 
dish  circles  of  blue,  and  others  of  a  pur- 
ple colour,  and  likewise  crystals  of  this 
last  colour.  When  water  is  poured  upon 
these  substances,  the  purple-coloured  bo- 
dy alone  dissolves,  and  gives  the  liquid  a 
fine  purple  colour.  The  substance  which 
remains  undissolved  is  prussian  blue,  which 
has  been  held  in  solution  in  the  hydrocy- 
anic acid.  Some  drops  of  chlorine  let  fall 
into  this  liquid  change  it  to  blue,  and  a 
greater  quantity  destroys  its  colour  entire- 
ly. It  is  remarkable  that  potash  poured 
into  the  liquid  thus  deprived  of  its  colour, 
occasions  no  precipitate  whatever. 

Chemists  will  not  fail  to  remark,  from 
these  experiments,  that  hydrocyanic  acid 
does  not  form  prussian  blue  directly  with 
iron ;  but  that,  on  the  addition  of  water, 
(circumstances  remaining  the  same)  prus- 
sian blue  is  produced.  They  will  remark, 
likewise,  that  cyanogen  united  to  water 
dissolves  iron.  This  is  confirmed  by  the 
inky  taste  which  it  acquires,  by  the  disap- 
pearance of  its  colour,  and  by  the  residue 
which  it  leaves  when  evaporated;  yet 
prussian  blue  is  not  formed.  These  first 
experiments  seem  already  to  show  that 
prussian  blue  is  a  hydrocyanate,  and  not  a 
cyanide. 

The  ammonia,  and  hydrocyanic  acid, 
disengaged  during  the  whole  duration  of 


the  combustion  of  prussian  blue,  give  a 
new  support  to  the  opinion,  that  this  sub- 
stance is  a  hydrocyanate  of  iron ;  and  like- 
wise the  results  which  are  furnished  by 
the  decomposition  of  prussian  blue  by 
heat  in  a  retort,  show  clearly  that  it  con- 
tains  both  oxygen  and  hydrogen,  which 
are  most  abundant  towards  the  end,  long 
after  any  particles  of  adhering  water  must 
have  been  dissipated. 

We  shall  conclude  this  subject  with  a 
comparison  of  Dr.  Thomson's  and  Mr. 
Porrett's  latest  results.  In  the  Anna's  of 
Phil,  for  August  1818,  we  have  a  pupei1  by 
Dr.  Thomson,  detailing  numerous  experi- 
ments which  he  had  performed  to  ascer- 
tain the  constitution  of  prussiate  of  potash 
and  iron.  "  From  this  analysis,"  says  he, 
"  it  follows  that  the  acid  in  the  triple  salt 
(not  reckoning  the  iron)  is  composed  of 
Carbon,  0.6579  42.51 

Azote,          0.7175  46.37 

Hydrogen,   0.1722  11.12 

1.5476          100.00 

"From  the  preceding  analysis,  we  see, 
that  the  triple  prussiate  of  potash  is  com- 
posed as  follows: 


^r^WSoiH'90 

-        -        -         41.64 
13.00 


Potash, 
Water, 


100.54 


"We  see,  from  the  preceding  analysis, 
that  one-third  part  of  the  acid  consists  of 
iron,  while  two-thirds  of  its  weight  con- 
sists of  carbon,  azote,  and  hydrogen.  The 
smallest  number  of  atoms,  which  agrees 
nearly  with  the  preceding  proportions  of 
the  ingredients,  is  the  following  : 

2  atoms  carbon      =  1.50          41.379 
1  atom  azote         =  1.75          48.277 

3  atoms  hydrogen  =  0.375        10.344 

3.625      100.000" 

Mr.  Porrett,  besides  his  communica- 
tions to  the  Royal  Society  in  1814  and 
1815,  which  Dr.  Thomson  justly  describes 
"  as  very  ingenious  and  important  experi- 
ments, and  conclusions  respecting  this 
acid,"  published  two  or  three  papers  in 
the  Annals  of  Philosophy,  one  of  them  in 
September  1818,  already  quoted,  and  an- 
other in  October  1819.  The  latter  pre- 
sents us  with  experiments  of  the  same  na- 
ture as  Dr.  Thomson's,  from  which  the 
following  inferences  are  drawn. 

"  Collecting  now  from  the  preceding 
experiments  the  proportions  of  all  the 
constituents  of  100  gr.  of  ferrochyazate  of 
potash,  they  appear  as  follows  : 


ACI 


ACI 


Potash, 
Ferrochyazic  acid 


Water, 


41.68  gr. 

riron,          12.60 

j  Carbon      22.64 

"S  Azote,        13.32 

l.Hydrogeii,  0.80 

13.00 

104.04 


Being  a  surplus  of  four  grains,  arising1  from 
the  unavoidable  inaccuracies  in  determin- 
ing experimentally,  on  small  portions  of 
the  salt,  the  proportions  of  so  many  con- 
stituents. • 

"  These  inaccuracies  are  easily  removed 
by  the  application  of  the  atomic  theory  ; 
for,  by  taking  as  our  guide  the  weights  of 
the  atoms  of  each  of  the  elements,  we 
obtain  the  following  numbers  : 

1  atom  potash,  60.      40.34 

latomferro-rif"1™'     Jnn     on^r 

chyazicacidJ  4  do.  carbon,  30.0    20.17 

fifi  95          1   1  do.  azote,     17.5     11.76 

Li  do.  hydrogen  1.250   0.84 

2  atoms  water,        -        -        22.50   15.13 


1  at.  ferrochyazate  of  potash,  148.75  100.00 

Which  doubtless  gives  the  true  propor- 

tions of  the  several  elements  of  this  salt." 

"  We  are  now  entitled  to  consider  the 

atom  of  ferrochyazic  acid  as  composed  of 

4  atoms  of  carbon       =  30.00      45.3  • 

1  atom  of  azote          =  17.5        26.4 

1  atom  of  hydrogen    =    1.25        1.89 

1  atom  of  iron  =  17.5        26.4 

66.25      99.99" 

The  discordances  of  these  two  sets  of 
results,  are  such  as  to  destroy  all  confi- 
dence in  them.  Thus,  Dr.  Thomson, 
finds  15  per  cent  of  iron;  and  Mr.  Porett's 
corrected  quantity  of  that  metal,  per  cent, 
is  only  11£,  a  difference  quite  absurd  in 
the  present  state  of  chemical  analysis. 
Here  follows  a  tabular  comparison,  of  the 
acid  constituents,  exclusive  of  the  iron: 
Dr.  Thomson.  Mr.  Porrett. 
€arbon,  42.51  61.54 

Azote,  46.37  35.90 

Hydrogen,       11.12  2.56 

100.00          100.00 

It  has  been  supposed  that  Mr.  Porrett's 
new  acid  is  nothing  but  a  hydrocyanate 
or  prussiate  of  iron,  which,  from  the  muta- 
bility of  its  constituents,  is  easily  decom- 
posed by  heat  and  light  ;  and  that  the 
only  permanent  compound  which  that 
acid  forms  is  in  triple  salts.  This  is  the 
old  opinion,  and  also  the  present  opinion, 
of  several  eminent  chemists.  These  com- 
pounds we  shall  call  ferroprussiates.  M. 
Vauquelin  and  M.  Thenard  style  them 
ferruginous  prussiates. 

Ferroprusxate  of  potash.    Into  an  egg- 


Chapped  iron  pot,  brought  to  moderate 
ignition,  project  a  mixture  of  good  pearl- 
ash  and  dry  animal  matters,  of  which 
hoofs  and  horns  are  best,  it  the  proportion 
of  two  parts  of  the  former  to  five  of  the 
latter.  Stir  them  well  with  a  fiat  iron 
paddle.  The  mixture,  as  it  calcines,  will 
gradually  assume  a  pasty  form,  during 
which  transition  it  must  be  tossed  about 
with  much  manual  labour  and  dexterity. 
When  the  conversion  into  a  chemical 
compound  is  seen  to  be  completed  by 
the  cessation  of  the  fetid  animal  vapours, 
remove  the  pasty  mass  with  an  iron 
ladle. 

If  this  be  thrown,  while  hot,  into  water, 
some  of  the  prussic  acid  will  be  converted 
into  ammonia,  and  of  course  the  usual  pro- 
duct diminished.  Allow  it  to  cool,  dis- 
solve it  in  water,  clarify  the  solution  by 
filtration  or  subsidence,  evaporate,  and, 
on  cooling,  yellow  crystals  of  the  ferro- 
prussiate  of  potash  will  form.  Separate 
these,  redissolve  them  in  hot  \vateiv  and 
by  allowing  the  solution  to  cool  very 
slowly,  larger  and  very  regular  crystals 
n»ay  be  had.  This  salt  is  n»w  manufac- 
tured in  several  parts  of  Great  Britain,  on 
the  large  scale ;  and  therefore  the  ex- 
perimental chemist  need  not  incur  the 
trouble  and  nuisance  of  its  preparation. 
Nothing  can  exceed  in  beauty,  purity,  and 
perfection,  the  crystals  of  it  prepared  at 
Campsie,  by  Messrs  Mackintosh  and 
Wilson. 

An  extemporaneous  ferroprussiate  of 
potash  may  at  any  time  be  made,  by  acting 
on  prussian  blue,  with  pure  carbonate  of 
potash,  prepared  from  the  ignited  bicar- 
bonate or  bitartrate.  The  blue  should  be 
previously  digested,  at  a  moderate  heat, 
for  an  hour  or  two  in  its  own  weight  of 
sulphuric  acid  diluted  with  five  times  its 
weight  of  water;  then  filtered,  and 
thoroughly  edulcorated  by  hot  water, 
from  the  sulphuric  acid.  Of  this  purified 
prussian  blue,  add  successive  portions  to 
the  alkaline  solution,  as  long  as  its  colour 
is  destroyed,  or  while  it  continues  to 
change  from  blue  to  brown.  Filter  the 
liquid,  saturate  the  slight  alkaline  excess 
with  acetic  acid,  concentrate  by  evapor- 
ation, and  allow  it  slowly  to  cool.  Qua- 
drangular bevelled  crystals  of  the  ferro- 
prussiate of  potash  will  form. 

This  salt  is  transparent,  and  of  a  beau- 
tiful lemon  or  topaz  yellow.  Its  specific 
gravity  is  1.830.  It  has  a  saline,  cooling, 
but  not  unpleasant  taste.  In  large  crystals 
it  possesses  a  certain  kind  of  toughness, 
and,  in  thin  scales,  of  elasticity.  The 
inclination  of  the  bevelled  side  to  the 
plane  of  the  crystal  is  about  135°.  It  loses 
about  13  per  cent  of  water,  when  moder- 
ately heated;  and  then  appears  of  a  white 
colour,  as  happens  to  the  green  copperas; 


ACI 


ACI 


but  it  does  not  melt  like  this  salt.  The 
crystals  retain  their  figure  till  the  heat 
verges  on  ignition.  At  a  red  heat  it 
blackens,  but,  from  the  mode  of  its  for- 
mation, we  see  that  even  that  temperature 
is  compatible  with  the  existence  of  the 
acid,  provided  it  be  not  too  long  contin- 
ued. Water  at  60°  dissolves  nearly  one- 
third  of  its  weight  of  the  crystals  ;  and  at 
the  boiling  point,  almost  its  own  weight. 
It  is  not  soluble  in  alcohol ;  and  hence, 
chemical  compilers,  with  needless  scru- 
pulosity have  assigned  to  that  liquid  the 
hereditary  sinecure  of  screening  the  salt 
from  the  imaginary  danger  of  atmospheri- 
cal action.  It  is  not  altered  by  the  air. 
Exposed  in  a  retort  to  a  strong  red  heat, 
it  yields  prussic  acid,  ammonia,  carbonic 
acid,  and  a  coaly  residue  consisting  of 
charcoal,  metallic  iron,  and  potash.  When 
dilute  sulphuric  or  muriatic  acid  is  boiled 
on  it,  prussic  acid  is  evolved,  and  a  very 
abundant  white  precipitate  of  proto- 
prussiate  of  iron  and  potash  falls,  which 
afterwards,  treated  with  liquid  chlorine, 
yields  a  prussian  blue,  equivalent  to  fully 
one-third  of  the  salt  employed.  Neither 
sulphuretted  hydrogen,  the  hydrosul- 
phurets,  nor  infusion  of  galls,  produce  any 
change  on  this  salt.  Red  oxide  of  mer- 
cury acts  powerfully  on  its  solution  at  a 
moderate  heat.  Prussiate  of  mercury  is 
formed,  which  remains  in  solution ;  while 
peroxide  of  iron  and  metallic  mercury 
precipitate.  Thus  we  see  that  a  portion 
of  the  mercurial  oxide  is  reduced,  to  carry 
the  iron  to  the  maximum  of  oxidizement. 

The  solution  of  ferroprussiate  of  potash 
is  not  affected  by  alkalis;  but  it  is  decom- 
posed by  almost  all  the  salts  of  the  perma- 
nent metals.  The  following  table  presents 
a  view  of  the  colours  of  the  metallic  pre- 
cipitates thus  obtained. 

Solutions  of  Give  a 

Manganese,  "White  precipitate. 

Protoxide  of  iron,      Copious  white. 
Deutoxide  of  iron,     Copious  clear  blue. 
Tritoxide  of  iron,       Copious  dark  blue. 
Tin,  White. 

Zinc,  White. 

Antimony,  White. 

Uranium,  Blood  coloured. 

Cerium,  White. 

Cobalt,  Grass  green. 

Titanium,  Green. 

Bismuth,  White. 

Protoxide  of  copper,  White. 
Deutoxide  of  copper,  Crimson  brown-. 
Nickel,  Apple  green. 

Lead,  White. 

Deutoxide  of  mercury,  White. 
Silver,  White,    passing    to 

blue,  in  the  air. 
Palladium,  Olive. 

Rhodium,  Platinum, 

and  Gold,- 


If  some  of  these  precipitates,  for  exam- 
ple those  of  manganese  or  copper,  be  di- 
gested in  a  solution  of  potash,  we  obtain  a 
ferroprussiate  of  potash  and  iron  exactly 
similar  to  what  is  formed  by  the  action  of 
the  alkaline  solution  on  prussian  blue. 
Those  precipitates,  therefore,  contain  a 
quantity  of  iron.  I  think  this  fact  is  very 
favourable  to  the  theory  of  Mr.  Porrett; 
and  scarcely  explicable  on  any  other  sup- 
position. This  salt  is  composed  of  the 
following  constituents,  by  the  latest  ana- 
lyses. 

Mr.  Porrett.  Dr.  Thomson. 
Potash,  40.34  41.64 

Ferrochyazic  acid,   44.53  45.90 

Water,  15.13  13.00 

100.00  100.54 

The  small  excess  in  the  latter  sum,  Dr. 
Thomson  thinks,  may  be  equally  divided 
among  all  the  ingredients.  We  shall  then 
have  for  his  analysis : 

Potash,  41.41 

Acid,  45.67 

Water,  12.92 

100.00 

We  have  seen  the  enormous  discrepant 
cies  with  regard  to  the  estimates  of  the  ul- 
timate acid  constituents  by  these  two  ex- 
perimentalists ;  and  if  we  consider  the  di- 
rectness and  simplicity  of  the  methods  by 
which  the  primary  constituents  of  the  salt 
may  be  ascertained,  the  above  differences 
also  seem  too  great.  By  a  well  regulated 
desiccation,  the  water  of  crystallization 
may  be  pretty  nearly  determined;  and  the 
concurring  results  of  experiment  give  for 
its  quantity  13  per  cent.  Now  the  action 
of  nitric  acid  properly  conjoined  with  that 
of  heat,  should  decompose  and  dissipate 
the  gaseous  part  of  the  acid,  and  convert 
the  iron  into  an  insoluble  peroxide ;  the 
weight  of  potash  may  then  be  exactly  de- 
termined, first  by  saturation  with  acid,  and 
secondly,  by  the  weight  of  resulting  salt. 
In  fact  had  Mr.  Porrett  adhered  to  his  ex- 
perimental numbers,  and  not  modified 
them  by  his  atomical  notions,  we  should 
have  had  the  following  results,  which  are 
probably  correct. 

Potash,  41.68 

Water,  13.00 

Ferrochyazic  acid,    45.32 

100.00 

And  from  this  real  analysis,  we  deduce 
directly  from  the  proportion  of  potash  "= 
41.68,  the  apparent  prime  equivalent  of 
this  neutral  salt  to  be  =  14.29 ;  or  rather 
its  double,  28.58. 

If  we  make  it  28.275,  then  we  would 
have  the  following  hypothetical  arrange- 
ment of  proportions, 


ACI 


ACI 


2  primes  of  potash,  =  11.900  42.04 

2  do.  of  ferrochyazic  acid,  =  13.000  45  96 

3  do.  of  water,  =   3.375   12.00 

28.275  100.00 

We  have  treated  the  subject  of  the  fer- 
roprussiate of  potash  at  considerable  de- 
tail, since  it  is  one  of  the  most  valuable 
re -agents,  which  the  chemist  possesses,  in 
metallic  analysis. 

Ferroprussiate  of  soda  may  be  prepared 
from  prussian  blue,  and  pure  soda,  by  a 
similar  process  to  that  prescribed  for  the 
preceding  salt.  It  crystallizes  in^bur-si- 
ded  prisms,  terminated  by  dihedral  sum- 
mits. They  are  yellow,  transparent,  have 
a  bitter  taste,  and  effloresce,  losing  in  a 
warm  atmosphere  37£  per  cent.  At  55° 
they  are  soluble  in  4£  parts  of  water,  and 
in  a  much  less  quantity  of  boiling  water. 
As  the  solution  cools,  crystals  separate. 
Their  specific  gravity  is  1.458.  They  are 
said  by  Dr.  John  to  be  soluble  in  alcohol. 

Ferroprussiate  of  lime  may  be  easily  form- 
ed from  prussian  blue  and  lime-water.  Its 
solution  yields  crystalline  grains  by  evapo- 
ration. 

Ferroprussiate  of  barytes  may  be  formed 
in  the  same  way  as  the  preceding  species ; 
or  much  more  elegantly  by  Mr.  Porrett's 
process,  described  already  in  treating  of 
the  ferroprussic  acid.  Its  crystals  are 
rhomboidal  prisms,  of  a  yellow  colour,  and 
soluble  in  2000  parts  of  cold  water,  and 
100  of  boiling  water.  By  Mr.  Porrett's 
second  account  of  this  salt,  it  is  composed 
of 

Expert.      Theory. 

Acid,      41.5  41.49    1  atom    84.84 

Barytes,  47.5  47.44    1  atom    97.00 

Water,    11.0  11.07    2  atoms  22.64 


100.0 


100.00 


204.48 


These  results  were  given  in  the  Annals 
of  Philosophy  for  September  1818.  In  Dr. 
Thomson's  System,  published  in  October 
181?,  we  have  the  following  statement: — 
"  Mr.  Porrett  has  analyzed  this  salt  with 
much  precision.  According  to  his  expe- 
riments, it  is  composed  of 


Ferrocyanic  acid, 

Barytes, 

Water, 


34.31 
49.10 
16.59 


100.00" 

In  the  Annals  for  October  1819,  Mr. 
Porrett  gives  as  its  true  proportions, 
1  atom  ferrochyazic  ucid,    66.25        35.66 

1  atom  barytes,  97.  52.22 

2  atoms  water,  22.5          12.12 

185.75      100.00 
The  discrepancies  are  singular,  with  a 


substance  so  unalterable  and  so  easily  as- 
certained as  barytes ;  for  Dr.  Thomson's 
quotation  gives  of  this  substance  49.1  per 
cent. ;  the  second  account  makes  it  47.5  ; 
and  the  last  52. 22.  The  quantity  of  bary- 
tes may  be  determined  absolutely,  without 
being  deduced  from,  or  entangled  with, 
the  estimate  of  water  or  acid. 

Ferroprussiate  of  strontian  and  magnesia 
have  also  been  made. 

Ferroprussiate  of  iron.  With  the  pro- 
toxide of  iron  and  this  acid  we  have  a  white 
powder,  which,  on  exposure  to  air,  be- 
comes blue,  passing  into  deutoferroprussiate 
of  iron,  or  prussian  blue.  We  have  already 
described  the  method  of  making  the  fer- 
roprussiate  of  potash,  which  isthe  first  step 
in  the  manufacture  of  this  beautiful  pig- 
ment. This  is  usually  made  by  mixing  to- 
gether one  part  of  the  ferroprussiate  of 
potash,  one  part  of  copperas,  and  four 
parts  or  more  of  alum,  each  previously  dis- 
solved in  water.  Prussian  blue,  consist- 
ing of  the  deutoferroprussiate  cf  iron,  mix- 
ed with  more  or  less  alumina,  precipitates. 
It  is  afterwards  dried  on  chalk  stones,  in  a 
stove. 

Pure  prussian  blue  is  a  mass  of  an  ex- 
tremely deep  blue  colour,  insipid,  inodo- 
rous, and  considerably  denser  than  water. 
Neither  water  nor  alcohol  has  an}'  action 
on  it.  Boiling  solutions  of  potash,  soda, 
lime,  barytes,  and  strontites  decompose  it ; 
forming  on  one  hand  soluble  ferroprus- 
siates  with  these  bases,  and  on  the  other 
a  residue  of  brown  deutoxide  of  iron,  and 
a  yellowish  brown  subferroprussiate  of 
iron.  This  last,  by  means  of  sulphuric,  ni- 
tric, or  muriatic  acid,  is  brought  back  to 
the  state  of  a  ferroprussiate,  by  abstracting 
the  excess  of  iron  oxide.  Aqueous  chlo- 
rine changes  the  blue  to  a  green  in  a  few 
minutes,  if  the  blue  be  recently  precipitat- 
ed. Aqueous  sulphuretted  hydrogen,  re- 
duces the  blue  ferroprussiate  to  the  white 
protoferroprussiate. 

Its  igneous  decomposition  in  a  retort  has 
lately  been  executed  by  M.  Vauquelin  with 
minute  attention.  He  regards  it  as  a  hy- 
drocyanate  or  mere  prussiate  of  iron ;  but 
the  changes  he  describes  are  very  com- 
plex, nor  do  they  invalidate  Mr.  Porrett's 
opinion,  that  it  is  a  combination  of  red  ox- 
ide of  iron,  with  a  ferruretted  acid.  The 
general  results  of  M.  Vauquelin's  analysis, 
were  hydrocyanic  acid,  hydrocyanate  of 
ammonia,  an  oil  soluble  in  potash,  crystal- 
line needles,  which  contained  no  hydrocy- 
anic acid,  but  were  merely  carbonate  of 
ammonia;  and  finally,  a  ferreous  residue 
slightly  attracted  by  the  magnet,  and  con- 
taining a  little  undecomposed  prussian 
blue.  If  we  are  to  regard  prussian  blue 
as  a  deutoferroprussiate  of  iron,  then  by 
Mr.  Porrett's  latest  considerations,  it  would 
be  composed  of 


ACI 


ACI 


1  atom  acid,  =    6.625  35.1 

1  atom  red  oxide,    =  10.000  53.0 

2  atoms  water,         =    2.250  11.9 

18.875  100.0 

Dr.  Thomson,  after  reporting1  it  from  Mr. 
Porrettto  consist  of 

Acid,  53.38        6.75 

Peroxide  of  iron,    34.23        4.328 
Water,  12.o9 

100.00 

thinks  it  likely  that  the  true  composition  is, 
Ferrocyanic  acid,  6.75 
Peroxide  of  iron,  5.00 
Proust,  in  the  Annales  de  Chimie,  voL 
Ix.  states,  that  100  parts  of  prussian  blue, 
without  alum,  yield  0.55  of  red  oxide  of 
iron  by  combustion;  and  by  nitric  acid, 
0.54.  100  of  prussiate  of  potash  and  iron, 
lie  further  says,  afford,  after  digestion  with 
sulphuric  or  nitric  acid,  35  parts  of  prus- 
sian blue.  If  we  compare  with  this,  Mr. 
Forrett's  earliest  estimate  of  34.23  per 
«ent  of  ferreous  peroxide,  besides  the  third 
of  the  weight  of  the  acid,  =  17.79,  which 
being  metallic  iron,  is  equivalent  to  25.4  of 
peroxide,  we  shall  have  the  sum  59.63,  as 
the  quantity  of  peroxide  in  100  of  prussian 
blue,  calling  the  atom  of  iron  3.5,  and  of 
peroxide  5.0.  Or  if  we  take  Dr.  Thom- 
son's correction,  we  have  the  following 
numbers,  supposing  it  to  consist  of 
1  atom  acid,  6.75  48.2 

1  peroxide,  5.00        35.7 

2  water,        2.25        16.1 

14.00  100.0 
or  perhaps 

1  atom  acid,          6.75  52.3 

1           peroxide,  5.00  39.0 

1           water,       1.125  8.7 

12.875     100.0 

To  the  35.7  of  peroxide  base  in  the  first, 
if  we  add  23  for  the  equivalent  of  peroxide 
in  its  acid,  we  have  58.7  for  the  whole  per- 
oxide in  100  gr. ;  and  to  the  39  of  peroxide 
in  the  second,  it  we  add  25  for  the  equiva- 
lent peroxide  in  the  acid,  we  have  the  sum 
of  64 ;  both,  quantities  considerably  greater 
than  Mr.  Proust's.* 

*  Sci.pHuuepiiussTC  ACID  ;  the  sulphu- 
retted chyazic  acid  of  Mr.  Porrett. 

Dissolve  in  water  one  part  of  sulphuret 
of  potash,  and  boil  it  for  a  considerable 
time  with  three  or  four  parts  of  powdered 
prussian  blue  added  at  intervals.  Sulphu- 
ret of  iron  is  formed,  and  a  colourless  liquid 
containing  the  new  acid  combined  with 
potash,  mixed  with  hyposulphite  and  sul- 
phate of  potash.  Render  this  liquid  sen- 
sibly sour,  by  the  addition  of  sulplmric 
acid.  Continue  the  boiling  for  a  little,  and 
when  it  cools,  add  a  little  peroxide  of 
manganese  in  fine  powder,  which  will  give 
Vox*  r«  [13] 


the  Kquid  a  fine  crimson  colour.  To  the 
filtered  liquid  add  a  solution  containing 
persulphate  of  copper,  and  protosulphate 
of  iron,  in  the  proportion  of  two  of  the  for- 
mer salt  to  three  of  the  latter,  until  the 
crimson  colour  disappears.  Sulphuro- 
prussiate  of  copper  falls.  Boil  this  with  a 
solution  of  potash,  which  will  separate  the 
copper.  'Distil  the  liquid  mixed  with  sul- 
phuric acid  in  a  glass  retort,  and  the  pecu- 
liar acid  will  con.e  over.  By  saturation 
with  carbonate  of  barvtes,  and  then  throw- 
ing down  this  by  the  equivalent  quantity 
of  sulphuric  acid,  the  sulphuroprussic  acid 
is  obtained  pure. 

It  is  a  transparent  and  colourless  liquki, 
possessing  a  strong1  odour,  somewhat  re- 
sembling acetic  acid.  Its  specific  gravity 
is  only  1.022.  It  dissolves  a  little  sulphur 
at  a  boiling  heat.  It  then  blackens  nitrate 
of  silver ;  but  the  pure  acid  throws  down 
the  silver  white.  By  repeated  distillations, 
sulphur  is  separated  and  the  acid  is  de- 
composed. Mr.  Porrett,  in  the  Annals  of 
Phil,  for  May  1819,  states  the  composition 
of  this  acid,  as  it  exists  in  the  sulphuretted 
chyazate  of  copper,  to  be 

2  atoms  sulphur,      «=  4.*'00 
2  carbon,        =  1.508 

1  azote,  =  1.754 

I  hydrogen,  =.  0.132 

7.394 

This  is  evidently  an  atom  of  the  hydro* 
cyanic  acid  of  M.  Gay-Lussac,  combined 
with  2  of  sulphur.  If  to  the  above  we  add 
9.  for  an  atom  of  protoxide  of  copper,  we 
have  16.394  for  the  prime  equivalent  of  the 
metallic  salt.  When  cyanogen  and  sul- 

Ehuretted  hydrogen  were  mixed  together 
y  M.  Gay  Lussac  in  his  researches  on  the 
prussic  principle,  he  found  them  to  con- 
dense into  yellow  acicular  crystals.  Mr. 
Porrett  has  since  remarked,  that  these 
crystals  are  not  formed  when  the  two  gases 
are  quite  diy,  but  that  they  are  quickly 
produced  if  a  drop  of  water  is  passed  up 
into  the  mixture.  He  does  not  think  their 
solution  in  water  corresponds  to  liquid 
sulphuretted  chyazic  acid ;  it  does  not 
change  the  colour  of  litmus  ;  it  has  no  ef- 
fect on  solutions  of  iron ;  it  contains  nei- 
ther prussic  nor  sulphuretted  chyazic  acid, 
yet  this  acid  is  formed  in  it  when  it  is  mix- 
ed first  with  an  alkali  and  then  with  an  acid. 
The  same  treatment  does  not  form  any 
prussic  acid. 

The  facility  with  which  the  atomic  hy- 
pothesis may  be  twisted  to  any  theoretical 
perversion,  is  well  exemplified  in  the  fol- 
lowing passage  :  — "  The  weight  of  an  atom 
of  hydrocyanic  acid  is  3.375,  and  that  of 
an  atom  of  sulphur  2.  But  6.328"  (Mr. 
Porrett's  first  proportion  of  sulphur)  "  not 
being  a  multiple  of  two,  this  statement 
does  not  actjord  we.ll  with  tbjs  atqrnic  tliet^ 


ACI 


ACI 


sy.  It  agrees  much  better  with  that  theo- 
ry, if  we  suppose  the  acid  to  be  a  com- 
pound  of  sulphur  and  cyanogen.  Its  con- 
stitution will  then  be, 

Sulphur,          1.20          100          6.09 
Cyanogen,      0.64  53.3        3.25 

Thus  we  see  that  it  is  a  compound  of  1 
atom  of  cyanogen  and  3  atoms  of  sulphur." 
Thomson's  System,  Vol.  ii.  p.  292. 

This  procedure  looks  more  like  leger- 
demain than  philosophical  research.  Had 
Dr.  Thomson  contented  himself  with  say- 
ing that  the  statement  of  Mr.  Porrett  did 
not  accord  with  the  atomic  theory,  he 
would  have  said  right ;  and  there  he  should 
have  left  the  matter,  or  have  insfituted 
experiments  to  settle  the  point.  But  to 
create  a  new  genus  of  compounds,  sulphur 
and  cyanogen,  and  erect  it  into  a  new  acid, 
on  such  a  frivolous  conceit,  throws  an  air 
of  ridicule  on  the  science.  Nay  further, 
the  Doctor  describing  M.  Gay-Lussac's 
crystalline  compound  of  sulphuretted  hy- 
drogen and  cyanogen,  says,  that  "  as  far  as 
its  description  goes,  this  substance  agrees 
exactly  with  the  sulphuretted  chyazic 
acid  of  Mr.  Porrett.  Tf  we  abstract  the  hy- 
drogen of  the  sulphuretted  hydrogen, 
which  probably  did  not  enter  into  the  com- 
position of  the  compound,  it  will  be  a  com- 
pound of  1  atom  cyanogen,  and  1£  atom 
sulphur,  or  in  whole  numbers  of  2  atoms 
cyanogen  and  3  atoms  sulphur.  So  that  it 
will  contain  just  half  the  quantity  of  sul- 
phur which  Mr.  Porrett  found."  M.  Gay- 
Lussac  expressly  states  that  the  yellow 
needles  obtained  from  the  joint  action  of 
cyanogen  and  sulphuretted  hydrogen  are 
*'  composed  of  one  volume  of  cyanogen, 
and  1^  volume  of  sulphuretted  hydrogen." 
So  that  instead  of  containing  no  hydrogen, 
this  substance  contains  half  a  volume  more 
than  hydrocyanic  acid. 

The  sulphuroprussiates  have  been  ex- 
amined only  by  Mr.  Porrett.  That  of  the 
red  oxide  of  iron  is  a  deliquescent  salt,  of 
a  beautiful  crimson  colour.  It  may  be  ob- 
tained in  a  solid  form  by  an  atmosphere 
artificially  dried.  A  concise  account  of 
these  sJls  is  given  in  the  5th  Vol.  of  the 
Annals  of  Philos.* 

*  ACID  (PURPURIC).  The  excrements  of 
the  serpent  Boa  Constrictor,  consist  of  pure 
lithic  acid.  Dr.  Prout  found  that  on  digest- 
ing this  substance  thus  obtained,  or  from 
urinary  calculi,  in  dilute  nitric  acid,  an  ef- 
fervescence takes  place,  and  the  lithic 
acid  is  dissolved,  forming  a  beautiful  pur- 
ple liquid.  The  excess  of  nitric  acid  being 
neutralized  with  ammonia,  and  the  whole 
concentrated  by  slow  evaporation,  the  co- 
lour of  the  solution  becomes  of  a  deeper 
purple,  and  dark  red  granular  crystals, 
sometimes  of  a  greenish  hue  externally, 
soon  begin  to  separate  in  abundance. 
These  crystals  are  a  compound  of  ammo 


ma  with  the  acid  principle  in  question, 
The  ammonia  was  displaced  by  digesting 
the  salt  in  a  solution  of  caustic  potash,  till 
the  red  colour  entirely  disappeared.  This 
alkaline  solution  was  then  gradually  drop- 
ped into  dilute  sulphuric  acid,  "which, 
uniting  with  the  potash,  left  the  acid  prin- 
ciple in  a  state  of  purity. 

This  acid  principle  is  likewise  produced 
from  lithic  acid  by  chlorine,  and  also,  but 
with  more  difficulty,  by  iodine.  Dr.  Prout, 
the  discoverer  of  this  new  acid  has,  at  the 
suggestion  of  Dr.  Wollaston,  called  it  pur- 
puric  acid,  because  its  saline  compounds 
have  for  the  most  part  a  red  or  purple  co- 
lour. 

This  acid,  as  obtained  by  the  preceding 
process,  usually  exists  in  the  form  of  a  very 
fine  powder,  of  a  slightly  yellowish  or 
cream  colour ;  and  when  examined  with  a 
magnifier,  especially  under  water,  appears 
to  possess  a  pearly  lustre.  It  has  no  smell, 
nor  taste.  Its  spec.  grav.  is  considerably 
above  water.  It  is  scarcely  soluble  in  wa- 
ter. One-tenth  of  a  grain,  boiled  for  a  con- 
siderable time  in  1000  grains  of  water,  was 
not  entirely  dissolved.  The  water,  how- 
ever, assumed  a  purple  tint,  probably,  Dr. 
Prout  thinks,  from  the  formation  of  a  lit- 
tle purpurate  of  ammonia.  Purpuric  acid 
is  insoluble  in  alcohol  and  ether.  The 
mineral  acids  dissolve  it  only  when  they 
are  concentrated.  It  does  not  affect  litmus 
paper.  By  igniting  it  in  contact  with  oxide 
of  copper,  he  determined  its  composition 
to  be, 

2  atoms  hydrogen,    0.250    -    -      4.54 
2  carbon,          1.500    -    -     27.27 

2  oxygen,        2.000    -    -    36.36 

1  azote,  1.750    -    -    31.81 

5.50  99.98 

Purpuric  acid  combines  with  the  alkalis, 
alkaline  earths,  and  metallic  oxides.  It  is 
capable  of  expelling  carbonic  acid  from 
the  alkaline  carbonates  by  the  assistance 
of  heat,  and  does  not  combine  with  any 
other  acid.  These  are  circumstances  suffi- 
cient, as  Dr.  Wollaston  observed,  to  dis- 
tinguish it  from  an  oxide,  and  to  establish 
its  character  as  an  acid. 

Purpurate  of  ammonia  crystallizes  in 
quadrangular  prisms,  of  a  deep  garnet-red 
colour.  It  is  soluble  in  1500  parts  of  water 
at  60°,  and  in  much  less  at  the  boiling 
temperature.  The  solution  is  of  a  beauti- 
ful deep  carmine,  or  rose-red  colour.  It 
has  a  slightly  sweetish  taste,  but  no  smell, 
Purpurate  of  potash  is  much  more  soluble ; 
of  soda  is  less;  that  of  lime  is  nearly  in- 
soluble ;  those  of  strontian  and  lime  are 
slightly  soluble.  All  the  solutions  have 
the  characteristic  colour.  Purpurate  of 
magnesia  is  very  soluble  ;  and  in  solution, 
of  a  very  beautiful  colour.  A  solution  of 
acetate  of  zinc  produces  with  purpurate 


ACT 


ACI 


of  ammonia,  a  solution  and  precipitate  of  a 
beautiful  gold-yellow  colour ;  and  a  most 
brilliant  iridescent  pellicle,  in  which  green 
and  yellow  predominate,  forms  on  the  sur- 
face of  the  solution.  Dr.  Prout  conceives 
the  salts  to  be  anhydrous,  or  void  of  wa- 
ter, and  composed  of  two  atoms  of  acid 
and  one  of  base.  The  purpuric  acid  and 
its  compounds  probably  constitute  the  ba- 
ses of  many  animal  and  vegetable  colours. 
The  well  known  pink  sediment  which 
generally  appears  in  the  urine  of  those 
labouring  under  febrile  affections,  appears 
to  owe  its  colour  chiefly  to  the  purpurate 
of  ammonia,  and  perhaps  occasionally  to 
the  purpurate  of  soda. 

The  solution  of  lithic  acid  in  nitric  acid 
-stains  the  skin  of  a  permanent  colour, 
which  becomes  of  a  deep  purple  on  ex- 
posure to  the  sun.  These  apparently  sound 
experimental  deductions  of  Dr.  Prout, 
kave  been  called  in  question  by  M.  Vau- 
<quelin ;  but  Dr.  Prout  ascribes  M.  Vau- 
qu  elm's  failure,  in  attempting  to  procure 
purpuric  acid,  to  his  having  operated  on  an 
impure  lithic  acid.  We  think  entire  confi- 
dence may  be  put  in  Dr.  Prout's  experi- 
ments. He  says  that  it  is  difficult  to  obtain 
purpuric  acid  from  the  lithic  acid  of  urina- 
ry concretions. — Phil.  Trans,  for  1818. 
•and  Annals  of  Phil.  vol.  14.* 

ACID  (PYHOLIONOUS).  In  the  destruc- 
tive distillation  of  any  kind  of  wood,  an 
acid  is  obtained,  which  was  formerly  cal- 
ied  acid  spirit  (if  wood,  and  since  pyrolig- 
nous  acid.  *  Fourcroy  and  Vauquelin 
showed  that  this  acid  was  merely  the  ace- 
tic, contaminated  with  empyreumatic  oil 
and  bitumen.  See  ACETIC  ACID. 

Under  acetic  acid  will  be  found  a  full 
account  of  the  production  and  purification 
of  pyrolignous  acid.  We  shall  add  here, 
that  M.  Monge  discovered,  about  two 
years  ago,  that  this  acid  has  the  property 
of  preventing  the  decomposition  of  animal 
substances.  It  is  sufficient  to  plunge  meat 
for  a  few  moments  into  this  acid,  even 
slightly  empyreumatic,  to  preserve  it  as 
long  as  you  please.  "  Putrefaction,"  it  is 
said,  "  not  only  stops,  but  retrogrades." 
To  the  empyreumatic  oil  a  part  of  this  ef- 
fect has  been  ascribed ;  and  hence  has 
been  accounted  for,  the  agency  of  smoke 
in  the  preservation  of  tongues,  hams,  her- 
rings, &.c.  Dr.  Jorg  of  Leipsichas  entirely 
recovered  several  anatomical  preparations 
from  incipient  corruption  by  pouring  this 
acid  over  them.  With  the  empyreumatic 
oil  or  tar  he  has  smeared  pieces  of  flesh 
already  advanced  in  decay,  and  notwith- 
standing that  the  weather  was  hot,  they 
soon  became  dry  and  sound.  To  the  above 
statements  Mr.  Ramsay  of  Glasgow,  an 
eminent  manufacturer  of  pyrolignous  acid, 
and  well  known  for  the  purity  of  his  vine- 
gar from  wood,  has  recently  added  the  fol- 


lowing facts  in  the  5th  number  of  rthe  Ed- 
inburgh Philosophical  Journal.    If  fish  be 
simply  dipped  in  redistilled  pyrolignous 
acid,  of  the  specific  gravity  1.012,  and  af- 
terwards dried  in  the  shade,  they  preserve 
perfectly  well.   On  boiling  herrings  treat- 
ed in  this  manner,  they  were  very  agreea- 
ble to  the  taste,  and  had  nothing  of  the 
disagreeable  empyreuma  which  those  of 
his  earlier  experiments  had,  which  were 
steeped  for  three  hours  in  the  acid.    A 
number  of  very  fine  haddocks  were  clean- 
ed, split,  and  sjightly  sprinkled  with  salt 
for  six  hours.     After  being  drained,  they 
were  dipped  for  about  three  seconds  in 
pyrolignous  acid,  then  hung  up  in  the 
shade  for  six  days.    On  being  broiled,  the 
fish  were  of  an  uncommonly  fine  flavour, 
and  delicately  white.    Beef  treated  in  the 
same  way,  had  the  same  flavour  as  Ham- 
burgh beef,  and  kept  as  well.  Mr.  Ramsay 
has  since  found,  that  his  perfectly  purifi- 
ed vinegar,  specific  gravity  1.034  being 
applied  by  a  cloth  or  sponge  to  the  sur- 
face of  fresh  meat,  makes  it  keep  sweet 
and  sound  for  several  days  longer  in  sum- 
mer than  it  otherwise  would.    Immersion 
for  a  minute  in  his  purified  common  vine- 
gar, specific  gravity  1.009,  protects  beef 
and  fish  from  all  taint  in  summer,  provided 
they  be  hung  up  and  dried  in  the  shade. 
When,  by  frequent  use,  the  pyrolignous 
acid  has  become  impure,  it  may  be  clari- 
fied by  beating  up  twenty  gallons  of  it 
with  a  dozen  of  eggs  in  the  usual  manner, 
and  heating  the  mixture  in  an  iron  boiler. 
Before   boiling,  the  eggs  coagulate,  and 
bring  the  impurities  to  the  surface  of  the 
boiler,  which  are  of  course  to  be  carefully 
skimmed  off.  The  acid  must  immediately  be 
withdrawn  from  theboiler,as  it  acts  oniron.* 
*AciD  (PYROLJTHIC).  When  uric  acid 
concretions  are  distilled  in  a  retort,  silvery 
white  plates  sublime.  These  are  pyrolith- 
ate  of  ammonia.     When  their  solution  is 
poured  into  that  of  sub  acetate  of  lead,  a 
pyrolithate  of  lead  falls,  which,  after  pro- 
per washing,  is  to  be  shaken  with  water, 
and  decomposed  by  sulphuretted  hydro- 
gen gas.  The  supernatant  liquid  is  now  a 
solution  of  pyrolithic  acid,  which  yields 
small  acicular  crystals  by  evaporation.  By 
heat  these  melt  and  sublime  in    white 
needles.  They  are  soluble  in  four  parts  of 
cold  water,  and  the  solution  reddens  veg- 
etable blues.  Boiling  alcohol  dissolves  the 
acid,  but  on  cooling  it  deposites  it,  in  small 
white  grains.  Nitric  acid  dissolves  without 
changing  it.    Hence,  pyrolithic  is  a  differ- 
ent acid  from  the  lithic,  which,  by  nitric 
acid,  is  convertible  into  purpurate  of  am- 
monia. The  pyrolithate  of  lime  crystallizes 
in   stalactites,   which   have    a   bitter  and 
slightly  acrid  taste.  It  consists  of'91.4 acid 
-{-  8.6  lime.     Pyrolithate  of  barytes  is  a 
nearly  insoluble  powder.  The  salts  ofpo> 


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AC1 


ash,  soda,  and  ammonia,  are  soluble,  and 
the  former  two  crystallizable.  At  a  red 
heat,  and  by  passing  it  over  ignited  oxide 
of  copper,  it  is  decomposed,  into  oxygen 
44.32,  carbon  28.29,  azote  16.84,  hydro- 
gen 10.* 

*  Aciu   (PrROttALic).     When  malic  or 
sorbic  acid,  for  they  are  the  same,  is  dis- 
tilled in   a  retort,  an  acid  sublimate,   in 
white  needles,  appears  in  the  neck  of  the 
retort,  and  an  acid  liquid  distils  into  the 
receiver.     This   liquid,    by    evaporation, 
affords   crystals,    constituting  a  peculiar 
acid,  to  which  the  above  name  has  been 
given. 

They  are  permanent  in  the  air,  ifielt  at 
118°  Fahr.,  and  on  cooling,  form  a  pearl 
coloured  mass  of  diverging  needles.  When 
thrown  on  red  hot  coals,  they  completely 
evaporate  in  an  acrid,  cough-exciting 
smoke.  Exposed  to  a  strong  heat  in  a  re- 
tort, they  are  partly  sublimed  in  needles, 
and  are  partly  decomposed.  They  are 
very  soluble  in  strong  alcohol,  and  in  dou- 
ble their  weight  of  water,  at  the  ordinary 
temperature.  The  solution  reddens  vege- 
table blues,  and  yields  white  flocculent 
precipitates  with  acetate  of  lead  and  ni- 
trate of  mercury ;  but  produces  no  pre- 
cipitate with  lime-water.  By  mixing  it 
with  barytes-water,  a  white  powder  falls, 
which  is  redissolved  by  dilution  with  wa- 
ter, after  which,  by  gentle  evaporation, 
the  pyromalate  of  barytes  may  be  obtain- 
ed in  silvery  plates.  These  consist  of  100 
acid,  and  185.142  barytes,  or  in  prime 
equivalents,  of  5.24+  9.70. 

Pyromalate  of  potash  may  be  obtained 
in  feather  formed  crystals,  which  deli- 
quesce. Pyromalate  of  lead  forms  first  a 
white  flocculent  precipitate,  soon  passing 
into  a  semi-transparent  jelly,  which  by  di- 
lution and  filtration  from  the  water,  yields 
brilliant  pearly  looking  needles.  The 
white  crystals  that  sublime  in  the  original 
distillation,  are  considered  by  M.  Las- 
saigne  as  a  peculiar  acid.* 

*  ACID  (PTHOTARTA.RIC).     Into  a  coated 
glass  retort  introduce  tartar,  or  rather  tar- 
taric  acid,  till  it  is  half  full,  and  fit  to  it  a 
tubulated  receiver.     Apply  heat,  which  is 
to  be  gradually  raised  to  redness.     Pyro- 
tartaric  acid  of  a  brown  colour,  from  im- 
purity,   is  found  in  the  liquid  products. 
We  must  filter  these  through  paper  pre- 
viously wetted,  to  separate  the  oily  mat- 
ter.    Saturate  the  liquid  with  carbonate 
of  potash ;   evaporate  to  dryness;  reclis- 
solve,  and  filter  through  clean  moistened 
.paper.     By  repeating  this  process  of  eva- 
poi-ation,  solution,   and  filtration,  several 
times,  we  succeed  in  separating  all  the 
oil.     The  dry  salt  is  then  to  be  treated  in 
a  glass  retort,  at  a  moderate  heat,  with 
dilute  sulphuric  acid.    There  passes  over 
into  the  receiver,  first  of  all  a  liquor  con- 


taining  evidently  acetic  acid;  but  towards 
the  end  of  the  distillation,  there  is  con- 
densed in  the  vault  of  the  retort,  a  white 
and  foliated  sublimate,  which  is  the  pyro- 
tartaric  acid,  perfectly  pure. 

It  has  a  very  sour  taste,  and  reddens 
powerfully  the  tincture  of  turnsole.  Heat- 
ed in  an  open  vessel,  the  acid  rises  in  a, 
white  smoke,  without  leaving  the  char- 
coaly  residuum,  which  is  left  in  a  retort. 
It  is  very  soluble  in  water,  from  which  it 
is  separated  in  crystals  by  spontaneous 
evaporation.  The  bases  combine  with  it, 
forming  pyrotartrates,  of  which  those  of 
potash,  soda,  ammonia,  barytes,  strontites, 
and  lime,  are  very  soluble.  That  of  pot- 
ash is  deliquescent,  soluble  in  alcohol,  ca- 
pable of  crystallizing  in  plates,  like  the 
acetate  of  potash.  This  pyrotartrate  pre- 
cipitates both  acetate  of  lead  and  nitrate 
of  mercury,  whilst  the  acid  itself  precipi- 
tates only  the  latter.  Rose  is  the  discover- 
er of  this  acid,  which  was  formerly  con- 
founded with  the  acetic.  * 

*  Acn>  (ROSASIC).     There  is  deposited 
from  the  urine  of  persons  labouring  under 
intermittent  and  nervous  fevers,  a  sedi- 
ment of  a  rose  colour,  occasionally  in  red- 
dish  crystals.     This  was  first  discovered 
to  be   a  peculiar  acid  by  M.  Proust,  and 
afterwards    examined  by   M.  Vauquelin. 
This  acid  is  solid,  of  a  lively  cinnabar  hue, 
without  smell,  with  a  faint  taste,  but  red- 
dening litmus  very  sensibly.     On  burning 
coal  it  is  decomposed  into  a  pungent  va- 
pour, which  has  not  the  odour  of  burning 
animal  matter.  It  is  very  soluble  in  water, 
and  it  even  softens  in  the  air.     It  is  solu- 
ble in  alcohol.      It   forms  soluble    salts 
with  potash,    soda,    ammonia,    barytes, 
strontites,   and  lime.      It  gives  a  slight 
rose-coloured  precipitate  with  acetate  of 
lead.     It  also  combines  with   lithic  acid, 
forming  so  intimate  a  union,  that  the  lithic 
acid  in  precipitating  from  urine  carries  the 
other,  though  a  deliquescent  substance, 
down  along  with  it.     It  is  obtained  pure 
by  acting  on  the  sediment  of  urine  with 
alcohol.     See  ACID  (PuRpcRifc).* 

*  ACID  (SACLACTIC).  See  Aciu  (Mucic).* 

*  ACID(SEBACIC).     Subject,  to   a  con- 
siderable heat,  7  or  8  pounds  of  hog's  lard, 
in  a  stoneware  retort  capable  of  holding 
double  the  quantity,  and  connect  its  beak 
by  an   adopter  with  a  cooled  receiver. 
The  condensible  products  are  chiefly  fat, 
altered  by  the  fire,  mixed  with  a  little 
acetic  and  sebacic  acids.     Treat  this  pro- 
duct with  boiling  water  several  times,  agi- 
tating the  liquor,  allowing  it  to  cool  and 
decanting  each  time.  Pour  at  last,  into  the 
watery  liquid,  solution  of  acetate  of  lead  in. 
excess.      A  white  flocculent  precipitate 
of  sebate  of  lead  will  instantly  fall,  which 
must  be  collected  on  a  filter,  washed,  and 
dried,  Put  the  sebate  of  lead  into  a  phial, 


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sttid  pour  upon  it  its  own  weight  of  sulphu- 
ric acid,  diluted  with  five  or  six  times  its 
weight  of  water.  Expose  this  phial  to  a 
heat  of  about  212°.  The  sulphuric  acid 
combines  with  the  oxide  of  lead,  and  sets 
the  sebacic  acid  at  liberty.  Filter  the 
whole  while  hot.  As  the  liquid  cools,  the 
sebacic  acid  crystallizes,  which  must  be 
washed,  to  free  it  completely  from  the 
adhering  sulphuric  acid.  Let  it  be  then 
dried  at  a  gentle  heat. 

The  sebacic  acid  is  inodorous ;  its  taste 
is  slight,  but  it  perceptibly  reddens  lit- 
mus paper;  its  specific  gravity  is  above 
that  of  water  and  its  crystals  are  small 
white  needles  of  little  coherence.  Ex- 
posed to  heat,  it  melts  like  fat,  is  decom- 
posed, and  partially  evaporated.  The 
air  has  no  effect  upon  it.  It  is  mxich  more 
soluble  in  hot  than  in  cold  water;  hence, 
boiling  water  saturated  with  it,  assumes 
a  nearly  solid  consistence  on  coohng.  Al- 
cohol dissolves  it  abundantly  at  ordinary 
temperature. 

With  the  alkalis  it  forms  soluble  neutral 
salts  ;  but  if  we  pour  into  their  concentra- 
ted solutions,  sulphuric,  nitric,  or  muriatic 
acids,  the  sebacic  is  immediately  deposited 
in  large  quantity.  It  affords  precipitates 
with  the  acetates  and  nitrates  of  lead, 
mercury,  and  silver. 

Such  is  theaccount  given  by  M.  Thenard 
ef  this  acid,  in  the  3d  volume  of  his  Traite 
de  Chimie,  published  in  1815.  Berzelius, 
inl 806,  published  an  elaborate  dissertation, 
to  prove  that  M.  Thenard's  new  sebacic 
acid  was  only  the  benzoic,  contaminated 
by  the  fat,  from  which,  however,  it  may 
be  freed,  and  brought  to  the  state  of  com- 
mon benzoic  acid.  M.  Thenard  takes  no 
notice  of  M.  Berzelius  whatever,  but  con- 
cludes his  account  by  stating,  that  it  has 
been  known  only  for  twelve  or  thirteen 
years,  and  that  it  must  not  be  confounded 
with  the  acid  formerly  called  sebacic, 
which  possesses  a  strong  disgusting  odour, 
and  was  merely  acetic  or  muriatic  acid, 
or  fat,  which  had  been  changed  in  some 
way  or  other,  according  to  the  process 
used  in  the  preparation.* 

*  ACID  (SOKBIC).  The  acid  of  apples, 
called  malic,  may  be  obtained  most  conve- 
niently and  in  greatest  purity  from  the 
berries  of  the  mountain  ash,  called  sorbiis, 
or  pyrus  aiicuparia,  and  hence  the  present 
name,  sorbic  acid.  This  was  supposed  to 
be  anew  and  peculiar  acid  by  Mr.  Don- 
ovan and  M.  Vauquelin,  who  wrote  good 
dissertations  upon  it.  But  it  now  appears 
that  the  sorbic  and  pure  malic  acids  are 
identical. 

Bruise  the  ripe  berries  in  a  mortar,  and 
then  squeeze  them  in  a  linen  bag.  They 
yield  nearly  .half  their  weight  of  juice,  of 
the  specific  gravity  of  1.077.  This  viscid 
juice,  by  remaining  for  about  a  fortnight 


in  a  warm  temperature,  experiences  the 
vinous  fermentation,  and  would  yield  a 
portion  of  alcohol.  By  this  change,  it  has 
become  bright,  clear,  and  passes  easily- 
through  the  filter,  while  the  sorbic  acid 
itself  is  not  altered.  Mix  the  clear  juice 
with  filtered  solution  of  acetate  of  lead. 
Separate  the  precipitate  on  a  filter,  and 
wash  it  with  cold  water.  A  large  quan- 
tity of  boiling  water  is  then  to  be  poured 
upon  the  filter,  and  allowed  to  drain  into 
glass  jars.  At  the  end  of  some  hours,  the 
solution  deposites  crystals  of  great  lustre 
and  beauty.  Wash  these  with  cold  water, 
dissolve  them  in  boiling  water,  filter,  and 
crystallize.  Collect  the  new  crystals,  and 
boil  them  for  half  an  hour  in  2.3  times 
their  weight  of  sulphuric  acid,  specific 
gravity  1.090,  supplying  water  as  fast  as 
it  evaporates,  and  stirring  the  mixture 
diligently  with  a  glass  rod.  The  clear 
liquor  is  to  be  decanted  into  a  tall  narrow 
glass  jar,  and  while  still  hot,  a  stream  of 
sulphuretted  hydrogen  is  to  be  passed 
through  it.  When  the  lead  has  been  all 
thrown  down  in  a  sulphuret,  the  liquid  is 
to  be  filtered,  and  then  boiled  in  an  open 
vessel  to  dissipate  the  adhering  sulphu- 
retted hydrogen.  It  is  now  a  solution  of 
sorbic  scid. 

When  it  is  evaporated  to  the  consistence 
of  a  sirup,  it  forms  mammelated  masses  of 
a  crystalline  structure.  It  still  contains  a 
considerable  quantity  of  water,  and  delU 
quesces  when  exposed  to  the  air.  Its  so- 
lution is  transparent,  colourless,  void  of 
smell,  but  powerfully  acid  to  the  taste. 
Lime  and  barytes  waters  are  not  precipi- 
tated by  solution  of  the  sorbic  acid,although 
the  sorbate  of  lime  is  nearly  insoluble. 
One  of  the  most  characteristic  properties 
of  this  acid,  is  the  precipitate  which  it  gives 
with  the  acetate  of  lead,  which  is  at  first 
white  and  flocculent,  but  afterwards  as- 
sumes a  brilliant  crystalline  appearance. 
With  potash,  soda,  and  ammonia,  it  forms 
crystallizable  salts  containing  an  excess  of 
acid.  That  of  potash  is  deliquescent.  Sor- 
bate of  barytes  consists,  according  to  M. 
Vauquelin,  of  47  sorbic  acid,  and  53  bary- 
tes in  100.  Sorbate  of  lime  well  dried,  ap- 
peared to  be  composed  of  67  acid  -f-  33 
lime  =  100.  Sorbate  of  lead,  which  in 
solution,  like  most  of  the  other  sorbates, 
retains  an  acidulous  taste,  consists  in  the 
dried  state  of  33  acid  -f-  67  oxide  of  lead 
in  100.  The  ordinary  sorbate  contains 
12.5  per  cent  of  water.  M.  Vauquelin. 
says  that  Mr.  Donovan  was  mistaken  in 
supposing  that  he  had  obtained  super  and 
subsorbates  of  lead.  There  is  only  one 
salt  with  this  base,  according  to  M.  Vau- 
quelin. It  is  nearly  insoluble  in  cold  water ; 
but  a  little  moie  so  in  boiling  water :  as  it 
cools  it  crystallizes  in  the  beautiful  white, 
brilliant,  and  shining  needles,  of  which  we 


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iave  already'  spoken.  A  remarkable  phe- 
nomenon occurs,  when  sorbate  of  lead  is 
boiled  in  water.  Whilst  one  part  of  the 
salt  saturates  the  water,  the  other  part, 
for  want  of  a  sufficient  quantity  of  fluid  to 
dissolve  it,  is  partially  melted,  and  is  at  first 
-kept  on  the  surface  by  the  force  of  ebulli- 
tion, but  after  some  time  falls  to  the  bot- 
tom, and  as  it  cools  becomes  strongly  fix- 
ed to  the  vessel. 

To  procure  sorbic  acid,  M.  Bracennot 
saturates  with  chalk  the  juice  of  the  scarce- 
ly ripe  berries,  evaporates  to  the  consis- 
tence of  a  sirup,  removing  the  froth ;  and 
a  granular  sorbate  falls,  which  he  decom- 
poses by  carbonate  of  soda.  The  sorbate 
of  soda  is  freed  from  colouring  matter  by 
a  little  lime,  strained,  freed  from  lime  by 
carbonic  acid  gas,  and  decomposed  by 
subacetate  of  lead,  and  treated  as  above. 

M.  Vauquelin  analyzed  the  acid,  in  the 
dry  sorbates  of  copper  and  lead. 

The  following  are  its  constituents : 
Hydrogen,    16.8 
Carbon,         28.3 
Oxygen,       54.9 

100.0 

M.  Vauquelin's  analysis  of  the  sorbate  of 
lead  gives  7.0  for  the  prime  equivalent  of 
this  acid  ;  the  sorbate  of  lime  gives  7.230; 
and  the  sorbate  of  barytes  8.6.  If  we  take 
that  of  lime  for  the  standard,  as  it  was  the 
«nly  one  quite  neutral,  we  shall  have  the 
following  relation  of  prime  equivalents : 
Theory.  Exp. 

4  of  oxygen     «=  4.00        53.3        54.9 

3  of  carbon      =2.25        30.0        28.3 

10  of  hydrogen  =  1.25        16.7        16.8 

7.50       100.0      100.0 
The  approximation  of  these  sets  of  pro- 
portions, illustrates  and  confirms  the  accu- 
racy of  M.  VauquelhVs  researches. 

The  calcareous  salt  having  been  pro- 
cured in  a  neutral  state,  by  the  addition  of 
carbonate  of  potash  to  its  acidulous  solu- 
tion, it  might  readily  be  mixed  with  as 
much  carbonate  of  lime  as  would  diminish 
the  apparent  equivalent  of  acid  from  7.50 
to  7.230 ;  especially  as  the  barytic  com- 
pound gives  no  less  than  8.6.  Had  the 
composition  of  the  sorbate  of  lime  been 
67.7  and  32.3,  instead  of  67  and  33,  the 
prime  equivalent  of  the  acid  would  come 
cut  7.5,  as  its  ultimate  analysis  indicates. 

As  the  pure  sorbic  acid  appears  to  be 
without  odour,  without  colour,  and  of  an 
agreeable  taste,  it  might  be  substituted  for 
the  tartaric  and  citric,  in  medicine  and  the 
arts. 

The  same  acid  may  be  got  from  apples, 
in  a  similar  way.* 

ACID  (  S  t  B  ERI  c) .  This  acid  was  obtain- 
ed by  Brugnatelli  from  cork,  and  after- 
wards more  fully  examined  by  Bouillon  la 


Grange.    To  procure  it,  pour  on  cork, 
grated  to  powder,  six  times  its  weight  of 
nitric  acid,  of  the  specific  gravity  of  1.26, 
in  a  tubulated  retort,  and  distil  the  mix- 
ture with  a  gentle  heat,  as  long  as  any  red 
fumes  arise.     As  the  distillation  advances,    . 
a  yellow  matter,  like  wax,  appears  on  the 
surface  of  the  liquid  in  the  retort.   While    j 
its  contents  continue  hot,  pour  them  into    j 
a  glass  vessel,  placed  on  a  sand-heat,  and    j 
keep  them  continually  stirring  with  a  glass 
rod;  by  which  means  the  liquid  will  gra- 
dually grow  thicker.     As  soon  as  white 
penetrating  vapours  appear,  let  it  be  re- 
moved from  the  sand-heat,  and  kept  stir- 
ring till  cold.    Thus  an  orange-coloured 
mass  will  be  obtained,  of  the  consistence 
of  honey,  of  a  strong  sharp  smell  while 
hot,  and  a  peculiar  aromatic  smell  when 
cold.     On  this,  pour  twice  its  weight  of 
boiling  water,  apply  heat  till  it  liquefies, 
and  filter.     As  the  filtered  liquor  cools,  it 
deposites  a  powdery  sediment, and  acquires 
a  thin  pellicle.     Separate  the  sediment  by 
filtration,  and  evaporate  the  fluid  nearly 
lo  dryness.    The  mass  thus  obtained  is  the 
suberic  acid,  which  may  be  purified  by 
saturating  with  an  alkali,  and  precipitating 
by  an  acid,  or  by  boiling  it  with  charcoal 
powder. 

*  M.  Chevreul  obtained  the  suberic  acid 
by  mere  digestion  of  the  nitric  acid  on 
grated  cork,  without  distillation,  and  pu- 
rified it  by  washing  with  cold  water.  12 
parts  of  cork  may  be  made  to  yield  1  of 
acid.  'When  pure,  it  is  white  and  pulve- 
rulent, having  a  feeble  taste,  and  little  ac- 
tion on  litmus.  It  is  soluble  in  80  parts  of 
water  at  55^°  F.  and  in  38  parts  at  140°. 
It  is  much  more  soluble  in  alcohol,  from 
which  water  throws  down  a  portion  of  the 
suberic  acid.  It  occasions  a  white  preci- 
pitate when  poured  into  acetate  of  lead, 
nitrates  of  lead,  mercury,  and  silver,  mu- 
riate of  tin,  and  protosulphate  of  iron.  It 
affords  no  precipitate  with  solutions  of 
copper  or  zinc.  The  suberates  of  potash, 
soda,  and  ammonia,  are  very  soluble.  The 
two  latter  may  be  readily  crystallized. 
Those  of  barytes,  lime,  magnesia,  and  alu- 
mina, are  of  sparing  solubility.* 

ACID  (SucciNic.)  It  has  long  been 
known  that  amber,  when  exposed  to  dis- 
tillation, affords  a  crystallized  substance, 
which  sublimes  into  the  upper  part  of  the 
vessel.  Before  its  nature  was  understood 
it  was  called  salt  of  amber  ,•  but  it  is  now 
known  to  be  a  peculiar  acid,  as  Boyle  first 
discovered.  The  crystals  are  at  first  con- 
taminated with  a  little  oil,  which  gives 
them  a  brownish  colour;  but  they  maybe 
purified  by  solution  and  crystallization, 
repeated  as  often  as  necessary,  when  they 
will  become  transparent  and  shining.  Pott 
recommends  to  put  on  the  filter,  through 
\vhich  the  solution  is  passed,  a  little  ootion 


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previously  wetted  with  oil  of  amber.  Their 
figure  is  that  of  a  triangular  prism.  Their 
taste  is  acid,  and  they  redden  the  blue  co- 
lour of  litmus,  but  not  that  of  violets.  They 
are  soluble  in  less  than  two  parts  of  boil- 
ing alcohol,  in  two  parts  of  boiling  water, 
and  in  twenty -five  of  cold  water. 

M.  Planche  of  Paris  observes,  that  a 
considerable  quantity  might  be  collected 
in  making  amber  varnish,  as  it  sublimes 
while  the  amber  is  melting  for  this  pur- 
pose, and  is  wasted. 

*  Several  processes  have  been  proposed 
for  purifying  this  acid :  that  of  Richter  ap- 
pears to  be  the  best.     The  acid  being  dis- 
colved  in  hot  water,  and  filtered,  is  to  be 
saturated  with  potash  or  soda,  and  boiled 
with  charcoal,  which  absorbs  the  oily  mat- 
ter.  The  solution  being  filtered,  nitrate  of 
lead  is  added ;  whence  results  an  insoluble 
succinate  of  lead,  from  which,  by  digestion 
in  the  equivalent  quantity  of  sulphuric  acid, 
pure  succinic  acid  is  separated.  Nitrate  or 
muriate  of  barytes,  will  show  whether  any 
sulphuric  acid  remains  mixed  with  the  suc- 
cinic solution ;  and  if  so,  it  may  be  with- 
drawn by  digesting  the  liquid  with  a  little 
more  succinate  of  lead.     Pure    succinic 
acid  may  be  obtained  by  evaporation,  in 
white  transparent  prismatic  crystals  Their 
taste  is  somewhat  sharp,  and  they  redden 
powerfully  tincture    of  turnsole.      Heat 
melts  and  partially  decomposes  succinic 
acid.     Air  has  no  effect  upon  it.    It  is  so- 
luble in  both  water  and  alcohol,  and  much 
more  so  when  they  are  heated.    Its  prime 
equivalent,  by  Berzelius,  is  6.26 ;  and  it  is 
composed  of  4.51  hydrogen,  47.6  carbon, 
47.888  oxygen  in  100,  or  2  -f  4  +  3 
primes.* 

With  barytes  and  lime  the  succinic  acid 
forms  salts  but  little  soluble ;  and  with 
magnesia  it  unites  into  a  thick  gummy 
substance.  The  succinates  of  potash  and 
ammonia  are  crystallizable  and  deliques- 
cent ;  that  of  soda  does  not  attract  mois- 
ture. The  succinate  of  ammonia  is  useful 
in  analysis  to  separate  oxide  of  iron. 

*  ACID  (SULPHOVINIC.)   The  name  given 
by  Vogel  to  an  acid,  or  class  of  acids, 
which  may  be  obtained  by  digesting  alco- 
hol and  sulphuric  acid  together  with  heat. 
It  seems  probable,  that  this  acid  is  merely 
the  hypo-sulphuric,  combined  with  a  pe- 
culiar oily  matter.* 

ACID  (SULPHURIC.)  When  sulphur  is 
heated  to  180°  or  190°  in  an  open  vessel, 
it  melts,  and  soon  afterward  emits  a  blu- 
ish flame,  visible  in  the  dark,  but  which, 
in  open  day -light,  has  the  appearance 'of  a 
white  fume.  This  flame  has  a  suffocating 
smell,  and  has  so  little  heat  that  it  will  not 
set  fire  to  flax,  or  even  gunpowder,  so  that 
in  this  way  the  sulphur  may  be  entirely 
consumed  out  of  it.  If  the  heat  be  still 
augmented,  the  sulphur  boils,  arid  sudden- 


ly bursts  into  a  much  more  luminous  flatnfc, 
the  same  suffocating  vapour  still  continu- 
ing to  be  emitted. 

The  suffocating  vapour  of  sulphur  is 
imbibed  by  water,  with  which  it  forms  the 
fluid  formerly  called  volatile  vitriolic,  now 
sulphurous  acid.  If  this  fluid  be  expose* 
for  a  time  to  the  air,  it  loses  the  sulphure- 
ous smell  it  had  at  first,  and  the  acid  be- 
comes more  fixed.  It  is  then  the  fluid 
which  was  formerly  called  the  spirit  of  -vi- 
triol. Much  of  the  water  may  be  driven 
off  by  heat,  and  the  dense  acid  which  re- 
mains is  the  sulphuric  acid,  commonly 
called  oil  of  vitriol;  a  name  which  was  pro- 
bably given  to  it  from  the  little  noise  it 
makes  when  poured  out,  and  the  unctuous 
feel  it  has  when  rubbed  between  the  fin- 
gers, produced  by  its  corroding  and  de- 
stroying the  skin,  with  which  it  forms  a 
soapy  compound. 

The  stone  or  mineral  called  martial  py- 
rites, which  consists  for  the  most  part  of 
sulphur  and  iron,  is  found  to  be  converted 
into  the  salt  vulgarly  called  green  vitriol, 
but  more  properly  sulphate  of  iron,  by  ex- 
posure to  air  and  moisture.  In  this  natu- 
ral process  the  pyrites  breaks  and  falls  in 
pieces;  and  if  the  change  take  place  ra- 
pidly, a  considerable  increase  of  tempera- 
ture follows,  which  is  sometimes  sufficient 
to  set  the  mass  on  fire.  By  conducting  this 
operation  in  an  accurate  way,  it  is  found 
that  oxygen  is  absorbed.  The  sulphate  is 
obtained  by  solution  in  water,  and  subse- 
quent evaporation ;  by  which  the  crystals 
of  the  salt  are  separated  from  the  earthy 
impurities,  which  were  not  suspended  in 
the  water. 

The  sulphuric  acid  was  formerly  obtain- 
ed in  this  country  by  distillation  from  sul- 
phate of  iron,  as  it  still  is  in  many  parts 
abroad:  the  common  green  vitriol  is  made 
use  of  for  this  purpose,  as  it  is  to  be  met 
with  at  a  low  price,  and  the  acid  is  most 
easily  to  be  extracted  from  it.  With  re- 
spect to  the  operation  itself,  the  following; 
particulars  should  be  attended  to:  First, 
the  vitriol  must  be  calcined  in  an  iron  or 
earthen  vessel,  till  it  appears  of  a  yellow* 
ish  red  colour:  by  this  operation  it  will 
lose  half  its  weight.  This  is  done  in  order 
to  deprive  it  of  the  greater  part  of  the  wa- 
ter which  it  has  attracted  into  its  crystals 
during  the  crystallization,  and  which  would 
otherwise,  in  the  ensuing  distillation,  great- 
ly weaken  the  acid.  As  soon  as  the  calci- 
nation is  finished,  the  vitriol  is  to  be  put 
immediately,  while  it  is  warm,  into  a  coat- 
ed earthen  retort,  which  is  to  be  filled 
two-thirds  with  it,  so  that  the  ingredients 
may  have  sufficient  room  upon  being  dis- 
tended by  the  heat,  and  thus  the  bursting 
of  the  retort  be  prevented.  It  will  be 
most  advisable  to  have  the  retort  immedi- 
ately enclosed  \jn  brick-work  in  a  reverbc- 


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•feitory  furnace,  and  to  stop  up  the  neck  of 
it  till  the  distillation  begins,  in  order  to 
prevent  the  materials  from  attracting1  fresh 
humidity  from  the  air.  At  the  beginning1 
of  the  distillation  the  retort  must  be  open- 
ed, and  a  moderate  fire  is  to  be  applied  to 
it,  in  order  to  expel  from  the  vitriol  all 
that  part  of  the  phlegm  which  does  not 
taste  strongly  of  the  acid,  and  which  may 
be  received  in  an  open  vessel  placed  un- 
der the  retort.  But  as  soon  as  there  ap- 
pear any  acid  drops,  a  receiver  is  to  be 
added,  into  which  has  been  previously 
poured  a  quantity  of  the  acidulous  fluid 
which  has  come  over,  in  the  proportion  of 
half  a  pound  of  it  to  twelve  pounds  of  the 
calcined  vitriol;  when  the  receiver  is  to 
be  secured  with  a  proper  luting.  The  fire 
is  now  to  be  raised  by  little  and  little  to 
the  most  intense  degree  of  heat,  and  the 
receiver  carefully  covered  with  wet  cloths, 
and,  in  winter  time,  with  snow  or  ice,  as 
the  acid  rises  in  the  form  of  a  thick  white 
vapour,  which  toward  the  end  of  the  ope- 
ration becomes  hot,  and  heats  the  receiv- 
er to  a  great  degree.  The  fire  must  be 
continued  at  this  high  pitch  for  several 
days,  till  no  vapour  issues  from  the  retort, 
nor  any  drops  are  seen  trickling  down  its 
sides.  In  the  case  of  a  great  quantity  of 
vitriol  being  distilled,  M.  Bcrnhardt.  has 
observed  it  to  continue  emitting  vapours 
in  this  manner  for  the  space  often  days. 
"When  the  vessels  are  quite  cold,  the  re- 
ceiver must  be  opened  carefully,  so  that 
none  of  the  luting  may  fall  into  it;  after 
which  the  fluid  contained  in  it  is  to  be 
poured  into  a  bottle,  and  the  air  carefully 
excluded.  The  fluid  that  is  thus  obtained 
is  the  German  sulphuric  acid,  of  which 
Bernhardt  got  sixty -four  pounds  from  six 
hundred  weight  of  vitriol;  and  on  the 
«ther  hand,  when  no  water  had  been  pre- 
viously poured  into  the  receiver,  fifty-two 
pounds  only  of  a  dry  concrete  acid.  This 
acid  was  formerly  called  glacial  oil  of  vitriol, 
and  its  consistence  is  owing  to  a  mixture 
of  sulphurous  acid,  which  occasions  it  to 
become  solid  at  a  moderate  temperature. 
*  It  has  been  lately  stated  by  A^ogel, 
that  when  this  fuming  acid  is  put  into  a 
glass  retort,  and  distilled  by  a  moderate 
heat  into  a  receiver  cooled  with  ice,  the 
fuming  portion  comes  over  first,  and  may 
be  obtained  in  a  solid  state  by  stopping 
the  distillation  in  time.  This  has  been 
supposed  to  constitute  absolute  sulphuric 
acid,  or  acid  entirely  void  of  water.  It  is 
in  silky  filaments,  tough,  difficult  to  cut, 
and  somewhat  like  asbestos.  Exposed  to 
the  air,  it  fumes  strongly,  and  gradually 
evaporates.  It  does  not  act  on  the  skin 
so  rapidly  as  concentrated  oil  of  vitriol. 
Up  to  66°  jt  continues  solid,  but  at  tempe- 
ratures above  this  it  becomes  a  colourless 
vapour,  which  whit-en?  rw  front-act  with 


air.  Dropped  into  water  in  small  quanti- 
ties, it  excites  a  hissing  noise,  as  if  it  were 
red  hot  iron ;  in  larger  quantities  it  pro- 
duces a  species  of  explosion.  It  is  said  to 
be  convertible  into  ordinary  sulphuric 
acid,  by  the  addition  of  a  fifth  of  water. 
It  dissolves  sulphur,  and  assumes  a  blue, 
green,  or  brown  colour,  according  to  the 
proportion  of  sulphur  dissolved.  The  spe- 
cific gravity  of  the  black  fuming  sulphuric 
acid,  prepared  in  large  quantities  from 
copperas,  at  Nordhausen,  is  1.896.  Its 
constitution  is  not  well  ascertained.* 

The  sulphuric  acid  made  in  Great  Bri- 
tain is  produced  by  the  combustion  of  sul- 
phur. There  are  three  conditions  requi- 
site in  this  operation.  Oxygen  must  be 
present  to  maintain  the  combustion ;  the 
vessel  must  be  so  close  as  to  prevent  the 
escape  of  the  volatile  matter  which  rises, 
and  water  must  be  present  to  imbibe  it. 
For  these  purposes,  a  mixture  of  eight 
parts  of  sulphur  with  one  of  nitre  is  placed 
in  a  proper  vessel,  enclosed  within  a  cham- 
ber of  considerable  size,  lined  on  all  sides 
with  lead,  and  covered  at  bottom  with  a 
shallow  stratum  of  water.  The  mixture- 
being  set  on  fire,  will  burn  for  a  conside- 
rable time  by  virtue  of  the  supply  of  oxy- 
gen which  nitre  gives  out  when  heated, 
and  the  water  imbibing  the  sulphurous 
vapours,  becomes  gradually  more  and 
more  acid  after  repeated  combustions,  and 
the  acid  is  afterward  concentrated  by  dis- 
tillation. 

*  Such  was  the  account  usually  given  of 
this  operation,  till  MM.  Clement  and  Des- 
ormes  showed,  in  a  very  interesting  me- 
moir, its  total  inadequacy  to  account  for 
the  result.  100  parts  of  nitre,  judiciously 
managed,  will  produce,  with  the  requisite 
quantity  of  sulphur,  2000  parts  of  concen- 
trated sulphuric  acid.  Now  these  contain 
1200  parts  of  oxygen,  while  the  hundred 
parts  of  nitre  contain  only  39^  of  oxygen ; 
being  not  gVh  part  of  what  is  afterwards 
found  in  the  resulting  sulphuric  acid.  But 
af'er  the  combustion  of  the  sulphur,  the 
nitre  is  converted  into  sulphate  and  bisul- 
phate  of  potash,  which  mingled  residuary 
salts  contain  nearly  as  much  oxygen  as  the 
nitre  originally  did.  Hence,  the  origin  of 
the  1200  parts  of  the  oxygen  in  the  sulphu- 
ric acid  is  still  to  be  sought  for.  The  fol- 
lowing ingenious  theory  was  first  given  by 
MM.  Clement  and  Desormes.  The  burn- 
ing sulphur,  or  sulphurous  acid,  taking 
from  the  nitre  a  portion  of  its  oxygen, 
forms  sulphuric  acid,  which  unites  with  the 
potash,  and  displaces  a  little  nitrous  and 
nitric  acids  in  vapour.  These  vapours  are 
decomposed,  by  the  sulphurous  acid,  into 
nitrous  gas,  or  deutoxide  of  azote.  This 
gas,  naturally  little  denser  than  air,  and 
now  expanded  by  the  heat,  suddenly  rises 


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t'o  the  roof  of  the  chamber ;  and  might  be 
expected  to  escape  at  the  aperture  there, 
which  manufacturers  were  always  obliged 
to  leave  open,  otherwise  they  found  the 
acidification  would  not  proceed.  But  the 
instant  that  nitrous  gas  comes  in  contact 
with  atmospherical  oxygen,  nitrous  acid 
vapour  is  formed,  which  being  a  very 
heavy  aeriform  body,  immediately  precipi- 
^ates  on  the  sulphurous  flame,  and  con- 
vferts  it  into  sulphuric  acid  ;  while  itself  re- 
suming the  state  of  nitrous  gas,  reascends 
for  a  new  charge  of  oxygen,  again  to  rede- 
scend,  and  transfer  it,  to  the  flaming  sul- 
phur. Thus  we  see,  that  a  small  volume 
of  nitrous  vapour,  by  its  alternate  meta- 
morphoses into  the  states  of  oxide  and 
acid,  and  its  consequent  interchanges,  may 
be  capable  of  acidifying  a  great  quantity 
of  sulphur. 

This  beautiful  theory  received  a  modifi- 
cation  from  Sir  H.  Davy.  He  found  that 
nitrous  gas  had  no  action  on  sulphurous 
gas,  to  convert  it  into  sulphuric  acid,  un- 
less water  be  present.  With  a  small  pro- 
portion of  water,  4  volumes  of  sulphurous 
acid  gas,  and  3  of  nitrous  gas,  are  conden- 
sed into  a  crystalline  solid,  which  is  instant- 
ly decomposed  by  abundance  of  water ;  oil 
of  vitriol  is  formed,  and  nitrous  gas  given 
off,  which  with  contact  of  air  becomes  ni- 
trous acid  gas,  as  above  described.  The 
process  continues,  according  to  the  same 
principle  of  combination  and  decomposi- 
tion, till  the  water  at  the  bottom  of  the 
chamber  is  become  strongly  acid.  It  is 
first  concentrated  in  large  leaden  pans,  and 
afterwards  in  glass  retorts  heated  in  a  sand- 
bath.  Platinum  alembics,  placed  within 
pots  of  cast-iron  of  a  corresponding  shape 
and  capacity,  have  been  lately  substituted 
in  many  manufactories  for  glass,  and  have 
been  found  to  save  fuel,  and  quicken  the 
process  of  concentration. 

The  proper  mode  of  burning  the  sul- 
phur with  the  nitre,  so  as  to  produce  the 
greatest  quantity  of  oil  of  vitriol,  is  a  prob- 
lem, concerning  which  chemists  hold  a  va- 
riety of  opinions.  M.  Thenard  describes 
the  following  as  the  best.  Near  one  of 
the  sides  of  the  leaden  chamber,  and  about 
a  foot  above  its  bottom,  an  iron  plate,  fur- 
nished with  an  upright  border,  is  placed 
horizontally  over  a  furnace,  whose  chim- 
ney passes  across,  under  the  botton  of  the 
chamber,  without  having  any  connexion 
with  it.  On  this  plate,  which  is  enclosed 
in  a  little  chamber,  the  mixture  of  sulphur 
and  nitre  is  laid.  The  whole  being  shut 
up,  and  the  bottom  of  the  large  chamber 
covered  with  water,  a  gentle  fire  is  kindled 
in  the  furnace.  The  sulphur  soon  takes 
fire,  and  gives  birth  to  the  products  de- 
scribed. When  the  combustion  is  finish- 
ed, which  is  seen  through  a  little  pane 
adapted  to  the  trap -door  of  the  chamber, 
Vo*.  i.  [14] 


this  is  opened,  the  sulphate  of  potash  ik 
withdrawn,  and  is  replaced  by  a  mixture 
of  sulphur  and  nitre.  The  air  in  the^great 
chamber  is  meanwhile  renewed,  by  open- 
ing its  lateral  door,  and  a  valve  in  its  oppo- 
site side.  Then,  after  closing  these  open- 
ings, the  furnace  is  lighted  anew.  Succes- 
sive mixtures  are  thus  burned  till  the  acid 
acquires  a  specific  gravity  of  about  1.390, 
taking  care  never  to  put  at  once  on  the 
plate  more  sulphur  than  the  air  of  the 
chamber  can  acidify.  The  acid  is  then 
withdrawn  by  stopcocks,  and  concentrated. 

The  following  details  are  extracted  from 
a  paper  on  sulphuric  acid  by  Dr.  Ure, 
which  was  published  in  the  4th  volume  of 
the  Journal  of  Science  and  the  Arts. 

The  best  commercial  sulphuric  acid  that 
I  have  been  able  to  meet  with,  contains 
from  one-half  to  three  quarters  of  a  part  in 
the  hundred,  of  solid  saline  matter,  foreign 
to  its  nature.  These  fractional  parts  con- 
sist of  sulphate  of  potash  and  lead,  in  the 
proportion  of  four  of  the  former  to  one  of 
the  latter.  It  is,  I  believe,  difficult  to  manu- 
facture it  directly,  by  the  usual  methods, 
of  a  purer  quality*.  The  ordinary  acid  sold 
in  the  shops  contains  often  3  or  4  per  cent* 
of  saline  matter.  Even  more  is  occasion- 
ally introduced,  by  the  employment  of  ni- 
tre, to  remove  the  brown  colour  given  to 
the  acid  by  carbonaceous  matter.  The 
amount  of  these  adulterations,  whether 
accidental  or  fraudulent,  may  be  readily 
determined  by  evaporating,  in  a  small  cap- 
sule of  porcelain,  or  rather  platinum,  a  de- 
finite weight  of  the  acid.  The  platinum 
cup,  placed  on  the  red  cinders  of  a  com- 
mon fire,  will  give  an  exact  result  in  five 
minutes  If  more  than  five  grains  of  mat- 
ter remain  from  five  hundred  of  acid,  we 
may  pronounce  it  sophisticated. 

Distillation  is  the  mode  by  which  pure 
oil  of  vitriol  is  obtained.  This  process  is 
described  in  chemical  treatises  as  both  dif- 
ficult and  hazardous  ;  but  since  adopting 
the  following  plan,  I  have  found  it  perfect- 
ly safe  and  convenient.  I  take  a  plain 
glass  retort,  capable  of  holding  from  two 
to  four  quarts  of  water,  and  put  into  it 
about  a  pint  measure  of  the  sulphuric  acid, 
(and  a  few  fragments  of  glass,)  connecti  ng- 
the  retort  with  a  large  globular  receiver, 
by  means  of  a  glass  tube  four  feet  long, 
and  from  one  to  two  inches  in  diameter. 
The  tube  fits  very  loosely  at  both  ends. 
The  retort  is  placed  over  a  charcoal  fire, 
and  the  flame  is  made  to  play  gently  on 
its  bottom.  When  the  acid  begins  to  boil 
smartly,  sudden  explosions  of  dense  va- 
pour, rush  forth  from  time  to  time,  which 
would  infallibly  break  small  vessels.  Here, 
however,  these  expansions  are  safely  per- 
mitted, by  the  large  capacity  of  the  retort 
and  receiver,  as  well  as  by  the  easy  com- 
munication with  the  air  at  both  ends  of  the 


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adopter  tube.  Should  the  retort,  indeed, 
be  exposed  to  a  great  intensity  of  flame, 
the  vapour  will  no  doubt  be  generated 
with  incoereible  rapidity,  and  break  the 
apparatus.  But  this  accident  can  proceed 
only  from  gross  imprudence.  It  resem- 
bles, in  suddenness,  the  explosion  of  gun- 
powder, and  illustrates  admirably  Dr. 
Black's  observation,  that,  but  for  the  great 
latent  heat  of  steam,  a  mass  of  water, 
powerfully  heated,  would  explode  on 
reaching  the  boiling  temperature,  1  have 
ascertained  that  the  specific  caloric  of  the 
vapour  of  sulphuric  acid  is  very  small,  and 
hence  the  danger  to  which  rash  operators 
may  be  exposed  during  its  distillation. 
Hence,  also,  it  is  unnecessary  to  surround 
the  receiver  with  cold  water,  as  when  alco- 
hol and  most  other  liquids  are  distilled. 
Indeed  the  application  of  cold  to  the  bot- 
tom of  the  receiver  generally  causes  it,  in 
the  present  operation  to  crack.  By  the 
above  method,  I  have  made  the  concen- 
trated oil  of  vitriol  flow  over  in  a  continu- 
ous slender  stream,  without  the  globe  be- 
coming sensibly  hot. 

I  have  frequently  boiled  the  distilled  acid 
till  only  one-half  remained  in  the  retort ; 
yet  at  the  temperature  of  60°  Fahrenheit, 
I  have  never  found  the  specific  gravity  of 
acid  so  concentrated,  to  exceed  1.8455. 
It  is,  I  believe,  more  exactly  1.8452.  The 
number  1.850,  which  it  has  been  the  fash- 
ion to  assign  for  the  density  of  pure  oil  of 
vitriol,  is  undoubtedly  very  erroneous,  and 
ought  to  be  corrected.  Genuine  commer- 
cial acid  should  never  surpass  1.8485; 
when  it  is  denser,  we  may  infer  sophistica- 
tion, or  negligence,  in  the  manufacture. 

The  progressive  increase  of  its  density, 
with  saline  contamination,  will  be  shown 
by  the  following  experiments.  To  4100 
grains  of  genuine  commercial  acid  (but 
concentrated  to  only  1 .8350)  40  grains  of 
dry  sulphate  of  potash  were  added.  When 
the  solution  was  completed,  the  specific 
gravity  at  60^  had  become  1.8417.  We 
see  that  at  these  densities  the  addition  of 
0.01  of  salt  increases  the  specific  gravity 
by  about  0.0067.  To  the  above  4140 
grains  other  80  grains  of  sulphate  were 
added,  and  the  specific  gravity,  after  so- 
lution, was  found  to  be  1.8526.  Wre  per- 
ceive that  somewhat  more  salt  is  now  re- 
quired to  produce  a  proportional  increase 
of  density ;  0.01  of  the  former  changing 
the  latter  by  only  0.0055.  Five  hundred 
grains  of  this  acid  being  evaporated  in  a 
platinum  capsule  left  16^  grains,  whence 
the  composition  was 

Sulphate  of  potash,  with  a  little  sulphate 
of  lead,  -  ...  3.30 

Water  of  dilution,        -         -         5.3 

Oil  of  vitriol  of  1.8485,         -      91.4 

100.0 


Thus,  acid  of  1.8526,  which  in  commerce 
would  have  been  accounted  very  strong, 
contained  little  more  than  91  per  cent  of 
genuine  acid. 

Into  the  last  acid  more  sulphate  of  pot- 
ash was  introduced,  and  solution  being  fa- 
voured by  digestion  in  a  moderate  heat, 
the  specific  gravity  became,  at  60°,  1.9120. 
Of  this  compound,  300  grains,  evaporated 
in  the  platinum  capsule,  left  41  grains  of 
gently  ignited  saline  matter.  We  have, 
therefore,  nearly  14  per  cent.  On  the 
specific  gravity  in  this  interval,  an  increase 
of  0.0054  was  effected  by  0.01  of  sulphate, 
This  liquid  was  composed  of 

Saline  matter,      ...        14. 

Water  of  dilution,        -        -          4.7 

Oil  of  vitriol  of  1 .8485,         -        81.3 

100.0 

The  general  proportion  between  the  den- 
sity and  impurity  may  be  stated  at  0.0055 
of  the  former,  to  0.01  of  the  latter. 

If  from  genuine  oil  of  vitriol,  containing 
%  of  a  per  cent  of  saline  matter,  a  consider- 
able quantity  of  acid  be  distilled  off,  what 
remains  in  the  retort  will  be  found  very 
dense.  At  the  specific  gravity  1.865,  such 
acid  contains  3£  of  solid  salt  in  the  100 
parts.  The  rest  is  pure  concentrated  acid. 
From  such  heavy  acid,  at  the  end  of  a  few 
days,  some  minute  crystals  will  be  deposi- 
ted, after  which  its  specific  gravity  be- 
comes 1.860,  and  its  transparency  is  per- 
fect. It  contains  about  2£  per  cent  of  sa- 
line matter.  Hence  if  the  chemist  em- 
ploy for  nis  researches  an  acid,  which, 
though  originally  pretty  genuine,  has  been 
exposed  to  long  ebullition,  he  will  fall  into 
great  errors.  From  the  last  experiments 
it  appears,  that  concentrated  oil  of  vitriol 
can  take  up  only  a  little  saline  matter  in 
comparison  with  that  which  is  somewhat 
dilute.  It  is  also  evident,  that  those  who 
trust  to  specific  gravity  alone,  for  ascer- 
taining the  value  of  oil  of  vitriol,  are  liable 
to  great  impositions. 

The  saline  impregnation  exercises  an 
important  influence,  on  all  the  densities  at 
subsequent  degrees  of  dilution.  Thus, 
the  heavy  impure  concentrated  acid,, 
specific  gravity  1.8650,  being  added  to 
water  in  the  proportion  of  one  part  to  ten, 
by  weight,  gave,  after  twenty-four  hours, 
a  compound  whose  specific  gravity  was 
1.064.  But  the  most  concentrated  genu- 
ine acid,  as  well  as  distilled  acid,  by  the 
same  degree  of  dilution,  namely  1-f-  10, 
acquires  the  specific  gravity  of  only  1.0602, 
while  that  of  1.852,  containing,  as  stated 
above,  3%  per  cent  of  sulphate  of  potash 
combined  with  acid  of  1.835,  gives,  on  a 
similar  dilution,  1.058.  This  difference, 
though  very  obvious  to  good  instruments, 
is  inappreciable  by  ordinary  commercial 
apparatus,  Hence  this  mode  ofascertain» 


ACI 


ACI 


ing  the  value  of  an  acid,  recommended  by 
Mr.  Dalton,  is  inadequate  to  detect  a 
deterioration  of  even  8  or  9  per  cent.  Had 
a  little  more  salt  been  present  in  the 
acid,  the  specific  gravity  of  the  dilute,  in 
this  case,  would  have  equalled  that  of  the 
genuine.  On  my  acidimeter  one  per 
cent  of  deterioration  could  not  fail  to  be 
detected,  even  by  those  ignorant  of 
science. 

The  quantity  of  oxide,  or  rather  sul- 
phate of  lead,  which  sulphuric  acid  can 
take  up,  is  much  more  limited  than  is 
commonly  imagined.  To  the  concentra- 
ted oil  of  vitriol  I  added  much  carbonate 
of  lead,  and  after  digestion  by  a  gentle 
heat,  in  a  close  vessel,  for  twenty-four 
hours,  with  occasional  agitation,  its  specific 
gravity,  when  taken  at  60°,  was  scarcely 
greater  than  before  the  experiment.  It 
contained  about  0.005  of  sulphate  of 
lead. 

The  quantity  of  water  present  in  100 
parts  of  concentrated  and  pure  oil  of 
vitriol,  seems  to  be  pretty  exactly  18  46. 

In  the  experiments  executed,  to  de- 
termine the  relation  between  the  density 
of  diluted  oil  of  vitriol,  and  its  acid 
strength,  1  employed  a  series  of  phials, 
numbered  with  a  diamond.  Into  each 
phial,  recently  boiled  acid,  and  pure 
water,  were  mixed  in  the  successive  pro- 
portions of  99  -f  1;  98  +  2;  97  +  3; 
&c.  through  the  whole  range  of  digits 
down  to  1  acid  -f-  "  water.  The  phials 
were  occasionally  agitated  during  24 
hours,  after  which  the  specific  gravity  was 
taken.  The  acid  was  genuine  and  well 
concentrated.  Its  specific  gravity  was 
1.8485,  Some  of  the  phials  were  kept 
with  their  acid  contents  for  a  week  or 
two,  but  no  further  change  in  the  density 
took  place.  The  strongest  possible  dis- 
tilled acid  was  employed  for  a  few  points, 
and  gave  the  same  results  as  the  other. 

Of  the  three  well  known  modes  of  as- 
certaining the  specific  gravity  of  a  liquid, 
namely,  that,  by  Fahrenheit's  hydrometer ; 
by  weighing  a  vessel  of  known  capacity 
filled  with  it ;  and  by  poising  a  glass  ball, 
suspended  by  a  fine  platina  wire  from  the 


ana  of  a  delicate  balance ;  I  decidedly 
prefer  the  last.  The  corrosiveness,  vis- 
cidity, and  weight  of  oil  of  vitriol,  render 
the  first  two  methods  ineligible ;  whereas, 
by  a  ball  floating  in  a  liquid,  of  which  the 
specific  gravity  does  not  differ  much 
from  its  own,  the  balance,  little  loaded, 
retains  its  whole  sensibility,  and  will  give 
the  most  accurate  consistency  of  results. 

In  taking  the  specific  gravity  of  con- 
centrated or  slightly  diluted  acid,  the 
temperature  must  be  minutely  regulated, 
because,  from  the  small  specific  heat  of 
the  acid,  it  is  easily  afiected,  and  because 
it  greatly  influences  the  density.  On 
removing  the  thermometer,  it  will  speedily 
rise  in  the  air  to  75°  or  80°,  though  the 
temperature  of  the  apartment  be  only  60°. 
Afterwards  it  will  slowly  fall  to  perhaps 
60°  or  62°.  If  this  thermometer,  having 
its  bulb  covered  with  a  film  of  dilute  acid 
(from  absorption  of  atmospheric  moisture), 
be  plunged  into  a  strong  acid,  it  will  in- 
stantly rise  10°,  or  more,  above  the  real 
temperature  of  the  liquid.  This  source  of 
embarrassment  and  occasional  error  is 
obviated  by  wiping  the  bulb  after  every 
immersion.  An  elevation  of  temperature, 
equal  to  10°  Fahr.  diminishes  the  density 
of  oil  of  vitriol  by  0.005  -,  1000  parts  being 
heated  from  60°  to  212°,  become  1.043  in 
volume,  as  I  ascertained  by  very  careful 
experiments.  The  specific  gravity,  which 
was  1.848  becomes  only  1.772,  being  the 
number  corresponding  to  a  dilution  of  14 
per  cent  of  water.  The  viscidity  of  oil  of 
vitriol,  which  below  50°  is  such  as  to 
render  it  difficult  to  determine  the  specific 
gravity  by  a  floating  ball,  diminishes  very 
rapidly  as  the  temperature  rises,  evincing* 
that  it  is  a  modification  of  cohesive  at- 
traction. 

The  following  table  of  densities,  corres- 
ponding to  degrees  of  dilution,  was  the  re- 
sult, in  each  point,  of  a  particular  experi- 
ment, and  was,  moreover,  verified  in  a 
number  of  its  terms,  by  the  further  dilu- 
tion of  an  acid,  having  previously  com- 
bined with  it  a  known  proportion  of 
water.  The  balance  was  accurate  anil 
sensible. 


ACI 


ACI 


TABLE  of  the  quantity  of  Oil  of  Vitriol  and  dry  Sulphuric  Acid  in  100  parts  of  dilute, 
at  different  Densities,  by  Dr.  UIIK. 


Liq. 

bp.  Gr. 

Dry. 

Liq. 

3p.  Gr. 

Dry 

Uq. 

Sp.Gr. 

Dry. 

Liq. 

*p.  Gr. 

Dry. 

100 

1.8485 

81.54 

75 

1.6520 

61.15 

50 

.3884 

40.77 

25 

1.1792 

20.38 

99 

1.8475 

80.72 

74 

1.6415 

60.34 

49 

.3788 

39.95 

24 

1.1706 

19.57 

98 

1.8460 

79.90 

73 

1.6321 

59.52 

48 

.3697 

39.14 

23 

1.1626 

18.75 

97 

1.8439 

79.09 

72 

1.6204 

58.71 

47 

.3612 

38.32 

22 

1.1549 

17.94 

96 

1.8410 

78.28 

71 

1.6090 

57.89 

46 

.3530 

37.51 

21 

.1480 

17.12 

95 

1.8376 

77.46 

70 

1.5975 

57.08 

45 

.3440 

36.69 

20 

.1410 

16.31 

94 

1.8336 

76.65 

69 

1.5868 

56.26 

44 

.3345 

35.88 

19 

.1330 

15.49 

93 

1.8290 

75.83 

68 

1.5760 

55.45 

43 

.3255 

35.06 

IS 

.1246 

14.68 

92 

1.8-33 

75.02 

67 

1.5648 

*54.63 

42 

1.3165 

34.^5 

17 

.1165 

13.86 

91 

1,8179 

74.20 

66 

1.5503 

53.82 

41 

1.3080 

33.43 

16 

.1090 

13.05 

90 

1.8115 

73.39 

65 

1.5390 

5:.00 

i  40 

1.2999 

32.61 

15 

.1019 

12.23 

89 

1.8043 

72.57 

64 

1.5280 

52.18 

39 

1.291., 

31.80 

14 

.U953 

11.41 

88 

1.7962 

71.75 

63 

1.5170 

51.37 

38 

1.2826 

30.98 

13 

10.60 

87 

1.7870 

7'<.94 

62 

1.5066 

50.55 

37 

1.2740 

30.17 

13 

.0809 

9.78 

86 

1.7774 

70.12 

61 

1.4960 

49.74 

36 

1.2654 

29.35 

11 

.0743 

8.97 

85 

1.7673 

69.31 

60 

1.4860 

48.92 

35 

1.2572 

28.54 

10 

.0682 

8.15 

84 

1.7570 

68.49 

59 

.4760 

48.11 

34 

1.2490 

27.72 

9 

.0614 

7.34 

83 

1.7465 

67.68 

58 

4660 

47.29 

33 

1.2409 

26.91 

8 

.0544 

6.52 

82 

1.7360 

66.86 

57 

.4560 

46.48 

3J 

1.2334 

26.09 

7 

1.0477 

5.71 

81 

1.7  ,'45 

66.05 

56 

.4460 

45.66 

31 

1.2-260 

25.28 

6 

1.0405 

4.89 

80 

1.7120 

65.23 

55 

.4360 

44.85 

30 

1.2184 

24.46 

5 

1.0336 

4.08 

79 

1.6993 

64.42 

54 

.4265 

44.03 

29 

1.2108 

23.65 

4 

1.0268 

3.26 

78 

1.6870 

63.60 

53 

.4170 

43.22 

28 

1.2032 

22.83 

3 

1.0206 

2.446 

77 

1.6750 

62.78 

52 

1.4073 

42.40 

27 

1.1956 

22.01 

2 

1.0140 

1.63 

76 

1.6630 

61.97 

51 

1.3977 

41.58 

26 

1.1876 

21.20 

1 

1.0074 

0.8154 

In  order  to  compare  the  densities  of  the 
preceding1  dilute  acid,  with  those  of  dis- 
tilled and  again  concentrated  acid,  I  mix- 
ed one  part  of  the  latter  with  nine  of  pure 
water,  and  after  agitation,  and  a  proper 
interval,  to  ensure  thorough  combination, 
I  found  its  specific  gravity  as  above  1.0682 ; 
greater  density  indicates  saline  contamin- 
ation. 

Dilute  acid  having  a  specific  gravity  = 
1.6321,  has  suffered  the  greatest  con- 
densation ;  100  parts  in  bulk  have  become 
92.14.  If  either  more  or  less  acid  exist 
in  the  compound,  the  volume  will  be  in- 
creased. What  reason  can  be  assigned 
for  the  maximum  condensation  occuring 
at  this  particular  term  of  dilution  ?  The 
above  dilute  acid  consists  of  73  per  cent 
of  oil  of  vitriol,  and  27  of  water.  But  73 
of  the  former  contains,  by  this  Table, 
59.52  of  dry  acid,  and  13.48  of  water. 
Hence  100  of  the  dilute  acid  consist  of 
59.52  of  dry  acid,  -f-  13.48  x  3  =  40.44 
of  water  =  99.96 ;  or  it  is  a  compound  of 
owe  atom  of  dry  acid,  with  three  atoms  of 
water.  Dry  sulphuric  acid  consists  of  three 
atoms  of  oxygen,  united  to  one  of  sulphur. 
Here  each  atom  of  oxygen  is  associated 
with  one  of  water,  forming  a  symmetrical 
arrangement.  We  may  therefore  infer, 
that  the  least  deviation  from  the  above 
definite  proportions,  must  impair  the 
balance  of  the  attractive  forces,  whence 


they  will  act  less  efficaciously,  and  there- 
fore produce  less  condensation. 

The  very  minute  and  patient  examin- 
ation which  1  was  induced  to  bestow  on 
the  table  of  specific  gravities,  disclosed  to 
me  the  general  law  pervading  the  whole, 
and  consequently  the  means  of  inferring 
at  once  the  density  from  the  degree  of 
dilution,  as  also  of  solving  the  inverse 
proposition. 

If  we  take  the  specific  gravity,  corres- 
ponding to  ten  per  cent  of  oil  of  vitriol, 
or  1.0682  as  the  root;  then  the  specific 
gravities  at  the  successive  terms  of  20, 
30,  40,  &c.  will  be  the  successive  powers 
of  that  root.  The  terms  of  dilution  are 
like  logarithms,  a  series  of  numbers  in 
in  arithmetical  progression,  corresponding 
to  another  series,  namely,  the  specific 
gravities  in  geometrical  progression. 

The  simplest  logarithmic  formula  which 
1  have  been  able  to  contrive  is  the  follow- 
ing. 

2a 

Log.  S  *= ,  where  S  is  the  specific 

700 
gravity,  and  a  the  per  centage  of  acid. 

And  a  =  Log.   S  X  350. 

In  common  language  the  two  rules  may 
be  stated  thus. 

Problem  1st,  To  find  the  proportion  of 
oil  of  vitriol  in  dilute  acid  of  a  given  spe- 
cific gravity.  Multiply  the  logarithm  of 


ACI 


ACI 


the  specific  gravity  by  350,  the  product 
is  directly  the  per  centage  of  acid. 

If  the  dry  acid  be  sought,  we  must  mul- 
tiply the  logarithm  of  the  specific  gravity 
by  285,  and  the  product  will  be  the  an- 
swer. 

Problem  2d,  To  find  the  specific  gravity 
corresponding  to  a  given  proportion  of 
acid.  Multiply  the  quantity  of  acid  by  "2, 
and  divide  by  700  ;  the  quotient  is  the  lo- 
garithm of  the  specific  gravity. 

Table  of  distilled  sulphuric  acid,  for  the 
higher  points,  below  which  it  agrees  with 
the  former  table. 


Liquid  Acid  in  100. 
100 
95 
90 
85 
80 
75 

Sp.  Gr. 

1.846 
1.834 
1.807 
1.764 
1.708 
1.650 

Dry  Acid. 
81.63 
77.55 
73.47 
69.39 
65.30 
61.22* 

The  sulphuric  acid  strongly  attracts  wa- 
ter, which  it  takes  from  the  atmosphere 
very  rapidly,  and  in  larger  quantities,  if 
suffered  to  remain  in  an  open  vessel,  im- 
bibing one-thi'-d  of  its  weight  in  twenty- 
four  hours,  and  more  than  six  times  its 
weight  in  a  twelvemonth.  If  four  parts  by 
weight  be  mixed  with  one  of  water  at  50°, 
they  produce  an  instantaneous  heat  of 
300°  F. ;  and  four  parts  raise  one  of  ice  to 
212° ;  on  the  contrary,  four  parts  of  ice, 
mixed  with  one  of  acid,  sink  the  ther- 
mometer to  4°  below  0.  When  pure  it  is 
colourless,  and  emits  no  fumes.  It  re- 
quires a  great  degree  of  cold  to  freeze  it ; 
and  if  diluted  with  half  a  part  or  more  of 
water,  unless  the  dilution  be  carried  very 
far,  it  becomes  more  and  more  difficult  to 
congeal ;  yet  at  the  specific  gravity  of 
1.78,  or  a  few  hundredths  above  or  below 
this,  it  may  be  frozen  by  surrounding  it 
with  melting  snow.  Its  congelation  forms 
regular  prismatic  crystals  Math  six  sides. 
Its  boiling  point,  according  to  Bergmann, 
is  540° ;  according  to  Dalton,  590°. 

*  Sulphuric  acid  consists  of  three  prime 
equivalents  of  oxygen,  one  of  sulphur,  and 
one  of  water;  and  by  weight,  therefore, 
of  3.0  oxygen  -f-  2.0  sulphur  -j-  1.125  wa- 
ter =  6.125,  which  represents  the  prime 
equivalent  of  the  concentrated  liquid 
acid ;  while  3  +  2  «=  5,  will  be  that  of 
the  dry  acid. 

Pure  sulphuric  acid  is  without  smell  and 
colour,  and  of  an  oily  consistence.  Its  ac- 
tion on  litmus  is  so  strong,  that  a  single 
drop  of  acid  will  redden  an  immense  quan- 
tity. It  is  a  most  violent  caustic ;  and  has 
sometimes  been  administered  with  the 
most  criminal  purposes.  The  person  who 
unfortunately  swallows  it,  speedily  dies  in 
dreadful  agonies  and  convulsions.  Chalk, 
or  common  carbonate  of  magnesia,  is  the 
best  antidote  for  this,  as  well  as  for  the 
strong  nitric  and  muriatic  acids'. 


When  transmitted  through  an  ignited 
porcelain  tube  of  one-fith  of  an  inch  dia- 
meter, it  is  resolved  into  two  parts  of  sul- 
phurous acid  gas,  and  one  of  oxygen  gas, 
with  water.  Voltaic  electricity  causes  an 
evolution  of  sulphur  at  the  negative  pole  ; 
whilst  a  sulphate  of  the  metallic  wire  is 
formed  at  the  positive.  Sulphuric  acid 
has  no  action  on  oxygen  gas  or  air.  It 
merely  abstracts  their  aqueous  vapour. 

If  the  oxygenized  muriatic  acid  of  M. 
Thenard  be  put  in  contact  with  the  sul- 
phate of  silver,  there  is  immediately  form- 
ed insoluble  chloride  of  silver,  and  oxy- 
genized sulphuric  acid.  To  obtain  sul- 
phuric acid  in  the  highest  degree  of  oxy- 
genation,  it  is  merely  necessary  to  pour 
barytes-water  into  the  above  oxygenized 
acid,  so  as  to  precipitate  only  a  part  of  it, 
leaving  the  rest  in  union  with  the  whole 
of  the  oxygen.  Oxygenized  sulphuric 
acid  partially  reduces  the  oxide  of  silver, 
occasioning  a  strong  effervescence. 

All  the  simple  combustibles  decompose 
sulphuric  acid,  with  the  assistance  of  heat. 
About  400°  Fahr.  sulphur,  converts  sul- 
phuric into  sulphurous  acid.  Several  me- 
tals at  an  elevated  temperature  decompose 
this  acid,  with  evolution  of  sulphurous 
acid  gas,  oxidizement  of  the  metal,  and 
combination  of  the  oxide,  with  the  unde- 
composed  portion  of  the  acid.* 

The  sulphuric  acid  is  of  very  extensive 
use  in  the  art  of  chemistry,  as  well  as  in 
metallurgy,  bleaching,  and  some  of  the 
processes  for  dyeing;  in  medicine  it  is 
given  as  atonic,  stimulant,  and  lithontrip- 
tic,  and  sometimes  used  externally  as  a 
caustic. 

The  combinations  of  this  acid  with  the 
various  bases  are  called  sulphates,  and 
most  of  them  have  long  been  known  by 
various  names.  With  barytes  it  is  found 
native  and  nearly  pure  in  various  forms, 
in  coarse  powder,  rounded  masses,  sta- 
lactites, and  regular  crystallizations,  which 
are  in  some  lamellar,  in  others  needly,  in 
others  prismatic  or  pyramidal.  The  cawks 
of  our  country  and  the  Bologiiian  stone  are 
merely  native  sulphates  of  barytes.  Their 
colour  varies  considerably  as  well  as  their 
figure,  but  their  specific  gravity  is  great, 
that  of  a  very  impure  kind  being  3.89, 
and  the  pure  sorts  varying  from  4  to 
4.865 ;  hence  it  has  been  distinguished  by 
the  names  of  marmor  metallicum  and  pon- 
derous spar. 

*  It  consists,  according  to  Dr.  Wollas- 
ton,  of  5  parts  of  dry  acid,  and  9.75  of 
barytes ;  and  by  Professor  Berzelius's  last 
estimate,  of  5  of  acid  and  9.573  barytes.* 

This  salt,  though  deleterious,  is  less  so 
than  the  carbonate  of  barytes,  and  is  more 
economical  for  preparing  the  muriate  for 
medicinal  purposes.  It  requires  43.000 
parts  of  water  to  dissolve  it  at  60°. 

Sulphate  of  strontian  has  a  considerable 


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resemblance  to  that  of  barytes  in  its  pro- 
perties. It  is  found  native  in  considerable 
quantities  at  Aust  Passage  and  other 
places  in  the  neighbourhood  of  Bristol. 
It  requires  3840  parts  of  boiling  water  to 
dissolve  it. 

*  Its  composition  is  5  acid  -j-  6.5  base.* 
The  sulphate  of  potash,  vitriolated  kali 
of  the  London  college,  formerly  vitriolated 
tartar,  sal  de  duobns,  and  arcanum  duplica- 
turn,    crystallizes    in    hexaedral    prisms, 
terminated  by  hexagonal  pyramids,  but 
susceptible  of  variations.     Its  crystalliza- 
tion by  quick  cooling  is  confused.    Its 
taste  is  bitter,  acrid,  and  a  little  saline. 
It  is  soluble  in  5  parts  of  boiling  water, 
and  16  parts  at  60°.    In  the  fire  it  decrepi- 
tates, and  is  fusible  by  a  strong  heat.     It 
is  decomposable  by  charcoal  at  a  high 
temperature.    It  may  be  prepared  by  di- 
rect mixture  of  its  component  parts ;  but 
the  usual  and  cheapest  mode  is  to  neutral- 
ize the  acidulous  sulphate  left  after  distill- 
ing nitric  acid,  the  sal  enixum  of  the  old  che- 
mists, by  the  addition  of  carbonate  of  pot- 
ash. The  sal  poly  chrest  of  old  dispensatories, 
made  by  deflagrating  sulphur  and  nitre  in 
a  crucible,  was  a  compound  of  the  sulphate 
and  sulphite  of  potash.  The  acidulous  sul- 
phate is  sometimes  employed  as  a  flux, 
and  likewise  in  the  manufacture  of  alum. 
In  medicine  the  neutral  salt  is  sometimes 
used  as  a  deobstruent,  and  in  large  doses 
as  a  mild  cathartic ;  dissolves  in  a  consid- 
erable portion  of  water,  and  taken  daily  in 
such  quantity  as  to  be  gently  aperient,  it 
has  been  found  serviceable  in  cutaneous 
affections,  and  is  sold  in  London  for  this 
purpose  as  a  nostrum ;  and  certainly  it  de- 
serves to  be  distinguished  from  the  gene- 
rality of  quack  medicines,  very  few  indeed 
of  which  can  be  taken  without  imminent 
hazard. 

*  It  consists  of  5  acid+  5.95  base;  but 
there  is  a  .compound  of  the  same  constitu- 
ents, in  the  proportion  of  10  acid  -j-  5.95 
•potash,  called  the  bisulphate.* 

The  sulphate  of  soda  is  the  -vitriolated 
natron  of  the  col'ege,  the  well  known 
Glauber's  salt,  or  sal  mirabile.  It  is  com- 
monly prepared  from  the  residuum  left 
after  distilling  muriatic  acid,  the  superflu- 
ous acid  of  which  may  be  saturated  by  the 
addition  of  soda,  or  precipitated  by  lime  ; 
and  is  likewise  obtained  in  the  manufac- 
ture of  the  muriate  of  ammonia.  (See  AM- 
MONIA). Scherer  mentions  another  mode 
by  Mr.  Funcke,  which  is,  making  8  parts 
of  calcined  sulphate  of  lime,  5  of  clay,  and 
5  of  common  salt,  into  a  paste  with  water ; 
burning  this  in  a  kiln;  and  then  powder- 
ing, lixiviating,  and  crystallizing.  It  exists 
in  large  quantities  under  the  sin-face  of  the 
earth  in  some  countries,  as  Persia,  Bohe- 
mia, and  Switzerland ;  is  found  mixed 
with  other  substances  in  mineral  springs 


and  sea  water ;  and  sometimes  effloresces 
on  walls.  Sulphate  of  soda  is  bitter  and 
saline  to  the  taste.  It  is  soluble  in  2.85 
parts  of  cold  water,  and  0.8  at  a  boiling 
heat ;  it  crystallizes  in  hexagonal  prisms 
bevelled  at  the  extremities,  sometimes 
grooved  longitudinally,  and  of  very  large 
size,  when  the  quantity  is  great :  these 
effloresce  completely  into  a  white  pow- 
der if  exposed  to  a  dry  air,  or  even  if  kept 
wrapped  up  in  paper  in  a  dry  place ;  yet 
they  retain  sufficient  water  of  crystalliza- 
tion to  undergo  the  aqueous  fusion  on  ex- 
posure to  heat,  but  by  urging  the  fire, 
melt.  Barytes  and  strontian  take  its  acid 
from  it  entirely,  and  potash  partially ;  the 
nitric  and  muriatic  acids,  though  they  have 
a  weaker  affinity  for  its  base,  combine 
with  a  part  of  it  when  digested  on  it. 
Heated  with  charcoal  its  acid  is  decompo- 
sed. As  a  purgative  its  use  is  very  gene- 
ral ;  and  it  has  been  employed  to  furnish 
soda.  Pajot  des  Charmes  has  made  some 
experiments  on  it  in  fabricating  glass: 
with  sand  alone  it  would  not  succeed,  but 
equal  parts  of  carbonate  of  lime,  sand,  and 
dried  sulphate  of  soda,  produced  a  clear, 
solid,  pale,  yellow  glass. 

*  It  is  composed  of  5  acid  -f  3.95  base 
-f-  11.25  water  in  crystals ;  when  dry,  the 
former  two  primes  are  its  constituents.* 

Sulphate  of  soda  and  sulphate  of  am- 
monia form  together  a  triple  salt. 

Sulphate  of  lime,  selenite,  gypsum,  plas- 
ter of  Paris,  or  sometimes  alabaster,  forms 
extensive  strata  in  various  mountains.  The 
specular  gypsum,  GY glades  Marine,  is  a  spe- 
cies of  this   salt,  and  affirmed  by  some 
French  travellers  to  be  employed  in  Rus- 
sia>  where  it  abounds,  as  a  substitute  for 
glass  in  windows.     Its  specific  gravity  is 
from  1.872  to  2.311.  It  requires  500  parts 
of  cold  water,  and  450  of  hot,  to  dissolve 
it.  When  calcined  it  decrepitates,  becomes 
very  friable  and  white,  and  heats  a  little 
with  water,  with  which  it  forms  a  solid 
mass.    In  this  process  it  loses  its  water  of 
crystallization.  In  this  state  it  is  found  na- 
tive in  Tyrol,  crystallized  in  rectangular 
parallelepipeds,  or  octaedral  or  hexaedral 
prisms,  and  is  called  anhydrous  sulphate  of 
lime.  Both  the  natural  and  artificial  anhy- 
drous sulphate  consists  of  56.3  lime  and 
43.6  acid,  according    to   Mr.    Chenevix. 
The  calcined  sulphate  is  much  employed 
for  making  casts  of  anatomical  and  orna- 
mental figures;    as  one  of  the  bases  of 
stucco  ;  as  a  fine  cement  for  making  close 
and  strong  joints  between  stone,  and  join- 
ing rims  or  tops  of  metal  to  glass ;  for 
making  moulds  for  the  Staffordshire  pot- 
teries ;  for  cornices,  mouldings,  and  other 
ornaments  in  building.    For  these  purpo- 
ses, and  for  being  wrought  into  columns, 
chimney-pieces,   and   various  ornaments, 
about  eight  hundred  tons  are  raised  annu- 


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ally  in  Derbyshire,  where  it  i&  called  ala- 
baster. In  America  it  is  laid  on  grass  land 
as  a  manure. 

*  Ordinary  crystallized  gypsum  consists 
of  5  sulphuric  acid  -\-  3.6  lime  -f-  2.25  wa- 
ter ;  the  anhydrous  variety  wants  of  course 
the  last  ingredient.* 

Sulphate  of  magnesia,  the  vitriolated 
magnesia  of  the  late,  and  sal  catharticus 
umarus  of  former  London  Pharmacopoeias, 
is  commonly  known  by  the  name  of  Epsom 
aaltt  as  it  was  furnished  in  considerable 
quantity  by  the  mineral  water  at  that  place, 
mixed  however  with  a  considerable  por- 
tion of  sulphate  of  soda.  It  is  afforded, 
however,  in  great  abundance  and  more 
pure  from  the  bittern  left  after  the  extrac- 
tion of  salt  from  sea  water.  It  has  likewise 
been  found  efflorescing  on  brick  walls, 
both  old  and  recently  erected,  and  in  small 
quantity  in  the  ashes  ot  coals.  The  capil- 
lary salt  of  Idria,  found  in  silvery  crystals 
mixed  with  the  aluminous  schist  in  the 
mines  of  that  place,  and  hitherto  consider- 
ed as  a  feathery  alum,  has  been  ascertain- 
ed by  Klaproth  to  consist  of  sulphate  of 
magnesia,  mixed  with  a  small  portion  of 
sulphate  of  iron  When  pure  it  crystallizes 
in  small  quadrangular  prisms,  terminated 
by  quadrangular  pyramids  or  diiidral  sum- 
mits. Its  taste  is  cool  and  bitter.  It  is  very 
soluble,  requiring  only  an  equal  weight  of 
cold  water,  and  three-fourths  its  weight  of 
hot.  It  effloresces  in  the  air,  though  but 
slowly.  If  it  attract  moisture,  it  contains 
muriate  of  magnesia  or  of  lime.  Exposed 
to  heat,  it  dissolves  in  its  own  water  of 
crystallization,  and  dries,  but  is  not  de- 
composed, nor  fused,  but  with  extreme 
difficulty.  It  consists,  according  to  Berg- 
mann,  of  33  acid,  19  magnesia,  48  water. 
A  very  pure  sulphate  is  said  to  be  prepar- 
ed in  the  neighbourhood  of  Genoa  by 
roasting  a  pyrites  found  there ;  exposing 
it  to  the  air  in  a  covered  place  for  six 
months,  watering  it  occasionally,  and  then 
lixiviating. 

Sulphate  of  magnesia  is  one  of  our  most 
valuable  purgatives ;  for  which  purpose 
only  it  is  used,  and  for  furnishing  the  car- 
bonate of  magnesia. 

*  It  is  composed  of  5  acid  -j-  2. 5  magne- 
sia +  7-875  water,  in  the  state  of  crystals.* 

Sulphate  of  ammonia  crystallizes  in  slen- 
der, flattened,  hexaedral  prisms,  termi- 
nated by  hexagonal  pyramids  ;  it  attracts 
a  little  moisture  from  very  damp  air,  par- 
ticularly if  the  acid  be  in  excess ;  it  dis- 
solves in  two  parts  of  cold  and  one  of  boil- 
ing water,  [t  is  not  used,  though  Glauber, 
who  called  it  his  secret  ammoniacal  salt, 
vaunted  its  excellence  in  assaying. 

*  It  consists  of  5  acid  +  2.17  ammonia 
-f-  1.125  water  in  its  most  desiccated  state ; 
and  in  its  crystalline  state  of  5  acid  -f-  2.13 
ammonia -|-  3.375  water.* 


If  sulphate  of  ammonia  and  sulphate  of 
magnesia  be  added  together  in  solution, 
they  combine  into  a  triple  salt  of  an  octae- 
dral  figure,  but  varying  much ;  less  solu- 
ble than  either  of  its  component  parts  ; 
unalterable  in  the  air ;  undergoing  on  the 
fire  the  watery  fusion ;  after  which  it  is 
decomposed,  part  of  the  ammonia  flying 
off,  and  the  remainder  subliming  with  an 
excess  of  acid.  It  contains,  according  to 
Fourcroy,  68  sulphate  of  magnesia,  and 
32  sulphate  of  ammonia. 

Sulphate  of  glucina  crystallizes  with 
difficulty,  its  solution  readily  acquiring 
and  retaining  a  sirupy  consistence ;  its 
taste  is  sweet,  and  slightly  astringent ;  it 
is  not  alterable  in  the  air ;  a  strong  heat 
expels  its  acid,  and  leaves  the  earth  pure ; 
heated  with  charcoal  it  forms  a  sulphuret ; 
infusion  of  galls  forms  a  yellowish  white 
precipitate  with  its  solution. 

Yttria  is  readily  dissolved  by  sulphuric 
acid ;  and  as  the  solution  goes  on,  the  sul- 
phate crystallizes  in  small  brilliant  grains, 
which  have  a  sweetish  taste,  but  less  so 
than  sulphate  of  glucina,  and  are  of  alight 
amethyst  red  colour.  They  require  30 
parts  of  cold  water  to  dissolve  them,  and 
give  up  their  acid  when  exposed  to  a  high 
temperature.  They  are  decomposed  by 
oxalic  acid,  prussiate  of  potash,  infusion 
of  galls,  and  phosphate  of  soda. 

Sulphate  of  alumina  in  its  pure  state  is 
but  recently  known,  and  it  was  first  atten- 
tively examined  by  Vauquelin.  It  may  be 
made  by  dissolving  pure  alumina  in  pure 
sulphuric  acid,  heating  them  for  some  time, 
evaporating  the  solution  to  dryness,  dry- 
ing the  residuum  with  a  pretty  strong  heat^ 
redissolving  it,  and  crystallizing.  Its  crys- 
tals are  soft,  foliaceous,  shining,  and  pear- 
ly ;  but  these  are  not  easily  obtained  with- 
out cautious  evaporation  and  refrigeration. 
They  have  an  astringent  taste  ;  are  little 
alterable  in  the  air ;  are  pretty  soluble> 
particularly  in  hot  water ;  give  out  their 
acid  on  exposure  to  a  high  temperature ; 
are  decomposable  by  combustible  substan- 
ces, though  not  readily  ;  and  do  not  form 
a  pyrophorus  like  alum. 

If  the  evaporation  and  desiccation  di- 
rected above  be  omitted,  the  alumina  will 
remain  supersaturated  with  acid,  as  may- 
be known  by  its  taste,  and  by  its  redden- 
ing vegetable  blue.  This  is  still  more  dif- 
ficult to  crystallize  than  the  neutral  salt, 
and  frequently  thickens  into  a  gelatinous 
mass. 

A  compound  of  acidulous  sulphate  of 
alumina  with  potash  or  ammonia  has  long 
been  known  by  the  name  of  ALUM.  See 
ALUMINA. 

If  this  acidulous  sulphate  or  alum  be  dis- 
solved in  water,  and  boiled  with  pure  alu- 
mina, the  alumina  will  become  saturated 
with  its  base,  and  fall  down  an  insipid 


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white  powder.  This  salt  is  completely  in- 
soluble, and  is  not  deprived  of  its  acid  by 
heat  but  at  a  very  high  temperature.  It 
may  be  decomposed  by  long  boiling  with 
the  alkaline  or  earth  bases;  and  several 
acids  convert  it  into  common  alum,  but 
slow!}'. 

Sulphate  of  zircon  may  be  prepared  by 
adding  sulphuric  acid  to  the  earth  recent- 
ly precipitated,  and  not  yet  dry.  It  is 
sometimes  in  small  needles,  but  common- 
ly pulverulent ;  very  friable;  insipid;  in- 
soluble in  \vater,  unless  it  contain  some 
acid;  and  easily  decomposed  by  heat. 

ACID  (StJLPHtrnors.)  It  has  already  h,een 
observed,  that  sulphur  burned  at  a  low 
temperature  absorbs  less  oxygen  than  it 
does  when  exposed  to  greater  heat,  and  is 
consequently  acidified  in  a  slighter  de- 
gree, so  as  to  form  sulphurous  acid.  This 
in  the  ordinary  state  of  the  atmosphere  is 
a  gas ;  but  on  reducing  its  temperature 
very  low  by  artificial  cold,  and  exposing 
it  to  strong  compression,  it  becomes  a  li- 
quid. To  obtain  it  in  the  liquid  state, 
however,  for  practical  purposes,  it  is  re- 
ceived into  water,  by  which  it  is  absorbed. 
As  the  acid  obtained  by  burning  sulphur 
in  this  way  is  commonly  mixed  with  more 
cr  less  sulphuric  acid,  when  sulphurous 
acid  is  wanted,  it  is  commonly  made  by  ab- 
stracting part  of  the  oxygen  from  sulphu- 
ric acicl  by  means  of  some  combustible 
substance.  Mercury  or  tin  is  usually  pre- 
ferred. For  the  purposes  of  manufactures, 
however,  chopped  straw  or  saw-dust  may 
be  employed.  If  one  part  of  mercury  and 
two  of  concentrated  sulphuric  acid  be  put 
into  a  glass  retort  with  a  long  neck,  and 
heat  applied  till  an  effervescence  is  pro- 
duced, the  sulphurous  acid  will  arise  in  the 
form  of  gas,  and  may  be  collected  over 
quicksilver,  or  received  into  water,  which 
at  the  temperature  of  61°  will  absorb  33 
times  its  bulk,  or  nearly  an  eleventh  of  its 
weight. 

Water  thus  saturated  is  intensely  acid 
to  the  taste,  and  has  the  smell  of  sulphur 
burning  slowly.  It  destroys  most  vegcta- 
fcle  colours,  but  the  blues  are  reddened 
by  it  previous  to  their  being  discharged. 
A  pleasing  instance  of  its  effect  on  colours 
may  be  exhibited  by  holding  a  red  rose 
ever  the  blue  flame  of  a  common  match, 
by  which  the  colour  will  be  discha)-ged 
wherever  the  sulphurous  acid  comes  into 
contact  with  it,  so  as  to  render  it  beautiful- 
ly variegated,  or  entirely  white.  If  it  be 
then  dipped  into  water,  the  redness  after 
a  time  will  be  restored. 

*  The  specific  gravity  of  sulphurous  acid 
gas,  as  given  by' MM.  Thenard  and  Gay- 
Lussac,  is  2.2553,  but  by  Sir  H.  Davy  "is 
2.2295,  and  hence  100  cubic  inches  weigh 
68  grains ;  but  its  sp.  gr.  most  probably 
should  be  estimated  at  2-.222,  and  the 


weight  of  100  cubic  inches  will  become 
67.777.  Its  constituents  by  volume  are 
one  of  oxygen,  and  one  of  vapour  of  sul- 
phur; each  having  a  sp.  gr.  of  1.111,  con- 
densed so  that  both  volumes  occupy  onl> 
one.  Or  in  popular  language,  sulphurous 
acid  may  be  said  to  be  a  solution  of  sul- 
phur in  oxygen,  which  doubles  the  weight 
of  this  gas,  without  augmenting  its  bulk. 
It  obviously,  therefore,  consists  by  weight 
of  equal  quantities  of  the  two  constituents. 
Its  equivalent  will  either  be  2  oxygen  -{- 
2  sulphur  =«  4 ;  or  1  oxygen  -f-  1  sulphur 
=  2.  Now  the  analysis  of  sulphite  of  ba- 
rytes  by  Berzelius  gives  209.22  base  to 
86.53  acid;  which  being  reduced,  presents 
for  the  prime  equivalent  of  sulphurous 
acid,  the  number  4.  Hydrogen  and  car- 
bon readily  decompose  sulphurous  acid  at 
a  red  heat,  and  even  under  it.  Mr.  Hig- 
gins  discovered,  that  liquid  sulphurous 
acid  dissolves  iron,  without  the  evolution 
of  any  gas  The  peroxides  of  lead  and 
manganese  furnish  oxygen  to  convert  it 
into  sulphuric  acid,  which  forms  a  sul- 
phate, with  the  resulting  metallic  protox- 
ide.* 

Sulphurous  acid  is  used  in  bleaching, 
particularly  for  silks.  It  likewise  dischar- 
ges vegetable  stains,  and  iron-moulds  from 
linen. 

In  combination  with  the  salifiable  bases, 
it  forms  sulphites,  which  differ  from  the 
sulphates  in  their  properties  The  alka- 
line sulphites  are  more  soluble  than  the 
sulphates,  the  earthy  less.  They  are  con- 
verted into  sulphates  by  an  addition  of 
oxygen,  which  they  acquire  even  by  ex- 
posure to  the  air.  The  sulphite  of  lime  is 
the  slowest  to  undergo  this  change.  A 
strong  heat  either  expels  their  acid  entire- 
ly, or  converts  them  into  sulphates.  They 
have  all  a  sharp,  disagreeable,  sulphurous 
taste.  The  best  mode  of  obtaining  them 
is  by  receiving  the  sulphurous  acid  gas  in- 
to water,  holding  the  base,  or  its  carbo- 
nate, in  solution,  or  diffused  in  it  in  fine 
powder.  None  of  them  has  yet  been  ap- 
plied to  any  use. 

*  ACID  (Hvposui.nirnovs.)  In  the  85th 
volume  of  the  Annales  de  Chimie,  M.  Gay- 
Lussac  describes  permanent  crystalhzable 
salts  having  lime  and  strontites  for  their 
base,  combined  with  an  acid  of  sulphur,  in 
which  the  proportion  of  oxygen  is  less 
than  in  sulphurous  acid  ;  but  this  acid  he 
does  not  seem  to  have  examined  in  a  se- 
parate state.  Those  salts  were  procured 
by  exposing  solutions  of  the  sulphurets  of 
the  earths  to  the  air,  when  sulphur  and 
carbonate  of  lime  precipitated.  When  the 
filtered  liquid  is  then  evaporated,  and  cool- 
ed, colourless  crystals  form.  The  calca- 
reous are  prismatic  needles,  and  those 
with  strontites  are  rhomboidal.  He  called 
tliese  new  compounds  sulphuretted  sui- 


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.  Those  of  potash  and  soda  he  also 
formed,  by  heating  their  sulphites  with 
sulphur ;  when,  a  quantity  of  sulphurous 
acid  was  disengaged,  and  neutral  salts 
were  formed.  M.  Gay-Lussac  farther  in- 
forms us,  that  boiling  a  solution  of  a  sul- 
phite with  sulphur,  determines  the  forma- 
tion of  the  sulphuretted  sulphite,  or  hy- 
posulphite ;  and  that  iron,  zinc,  and  man- 
ganese, treated  with  liquid  sulphurous 
acid,  yield  sulphuretted  sulphites;  from 
which  it  follows,  that  a  portion  of  the  sul- 
phurous acid  is  decomposed  by  the  metal, 
and  that  the  resulting  oxide  combines  with 
the  other  portion  of  the  sulphurous  acid 
and  the  liberated  sulphur.  The  hyposul- 
phites are  more  permanent  than  the  sul- 
phites ;  they  do  not  readily  pass  by  the 
action  of  the  air  into  the  state  of  sulphate; 
and  though  decomposable  at  a  high  heat, 
they  resist  the  action  of  fire  longer  than 
the  sulphites.  They  are  decomposed  in 
solution  by  the  sulphuric,  muriatic,  fluo- 
ric, phosphoric,  and  arsenic  acids;  sulphu- 
ipus  acid  is  evolved,  sulphur  is  precipita- 
ted, and  a  new  salt  is  formed.  Such  is  the 
account  given  of  these  by  M.  Gay-Lussac, 
and  copied  into  the  second  volume  of  the 
Traite  de  Chimie  of  M.  Thenard,  publish- 
6d  in  1814. 

No  additional  information  was  communi- 
fcated  to  the  world  on  this  subject  till  Jan- 
uary 1819,  when  an  ingenious  paper  on 
the  hyposulphites  appeared  in  the  Edin- 
burgh Philosophical  Journal,  followed  soon 
by  two  others  in  the  same  periodical  work, 
by  Mr.  Herschel. 

In  order  to  obtain  hyposulphurous  acid, 
Mr.  Herschel  mixed  a  dilute  solution  of  hy- 
posulphite of  strontites  with  a  slight  excess 
of  dilute  sulphuric  acid,  and  after  agitation 
poured  the  mixture  on  three  niters.  The 
first  was  received  into  a  solution  of  carbo- 
nate of  potash,  from  which  it  expelled  car- 
bonic acid  gas.  The  second  portion  be- 
ing received  successively  into  nitrates  of 
Silver  and  mercury,  precipitated  the  me- 
tals copiously  in  the  state  of  sulphurets, 
but  produced  no  effect  on  solutions  of  cop- 
per, iron,  or  zinc.  The  third,  being  tasted, 
was  acid,  astringent  and  bitter.  When 
fresh  filtered  it  was  clear,  but  it  became 
milky  on  standing,  depositing  sulphur,  and 
colouring  sulphurous  acid.  A  moderate 
exposure  to  air,  or  a  gentle  heat,  caused 
its  entire  decomposition, 
r  The  habitudes  of  oxide  of  silver  in  union 
with  this  acid  are  very  peculiar.  Hyposul- 
phite of  soda  being  poured  on  newly  pre- 
cipitated oxide  of  silver,  hyposulphite  of 
silver  was  formed,  and  caustic  soda  elimi- 
nated ;  the  only  instance,  says  Mr.  Her- 
schel, yet  known  of  the  direct  displace- 
ment of  a  fixed  alkali  by  a  metallic  oxide, 
•via  hwnida.  On  the  other  hand,  hyposul- 
nhurous  acid  newly  disengaged  from  the 
Vot.  r.  [  15  } 


hyposulphite  of  barytes,  by  dilute  sulphu- 
ric acid,  readily  dissolved,  and  decompos- 
ed muriate  of  s'ilver,  forming  a  sweet  solu- 
tion, from  which  alcohol  separated  the 
metal  in  the  state  of  hyposulphite,  "  Thus 
the  affinity  between  this  acid  and  base, 
unassisted  by  any  double  decomposition,  is 
such  as  to  form  an  exception  to  all  the  or- 
dinary rules  of  chemical  union."  This 
acid  has  a  remarkable  tendency  to  form 
double  salts  with  the  oxides  of  silver  and 
alkaline  bases.  The  hyposulphite  of  sil- 
ver and  soda  has  an  intensely  sweet  taste.. 
When  hyposulphite  of  ammonia  is  poured 
on  muriate  of  silver,  it  dissolves  it ;  and  if 
into  the  saturated  solution,  alcohol  be 
poured,  a  white  salt  is  precipitated,  which 
must  be  forcibly  squeezed  between  blot- 
ting paper  and  dried  in  vacua.  It  is  very 
soluble  in  water.  Its  sweetness  is  unmix- 
ed with  any  other  flavour,  and  so  intense 
as  to  cause  pain  in  the  throat.  One  grain 
of  the  salt  communicates  a  perceptible 
sweetness  to  32.000  grains  of  water.  If 
the  alcoholic  liquid  be  evaporated,  thin 
lengthened  hexangular  plates  are  some- 
times formed,  which  are  not  altered  by 
keeping,  and  consist  of  the  same  princi- 
ples. 

The  best  way  of  obtaining  the  alkaline 
hyposulphites  is  to  pass  a  current  of  sul^ 
phurous  acid  gas  through  a  lixiviwn,  form- 
ed by  boiling  a  watery  solution  of  alkali, 
or  alkaline  earth,  along  with  sulphur.  The 
whole  of  the  sulphurous  acid  is  converted 
into  the  hyposulphite,  and  pure  sulphur, 
unmixed  with  any  sulphite,  is  precipitat- 
ed, while  the  hyposulphite  remains  in  so- 
lution. 

Mr.  Herschel,  from  his  experiments  on 
the  hyposulphite  of  lime,  has  deduced  the 
prime  equivalent  of  hyposulphurous  acid, 
to  be  5.925.  He  found  that  100  parts 
crystallized  hyposulphite  of  lime,  were; 
equivalent  to  121.77  hyposulphite  of  lead, 
and  yielded  of  carbonate  of  lime,  by  car- 
bonate of  ammonia,  a  quantity  equivalent 
to  21.75  gr.  of  lime.  Therefore  the  theo- 
ry of  equivalent  ratios  gives  us  this  rule  : 

As  21.75  gr.  lime  are  to  its  prime  equi- 
valent 3.56,  so  are  121.77  gr.  of  hyposu^- 
phite  of  lead,  to  its  prime  equivalent.  In 
numbers  21.75  :  3.56  :  :  121.77  :  19.93. 
From  this  number,  if  we  deduct  the  prime 
of  the  oxide  of  lead  =  14,  the  remainder 
5.93  will  be  the  double  prime  of  hyposul- 
phurous acid.  Now  this  number  does  not 
materially  differ  from  6.  Hence  we  see 
that  the  hyposulphites,  for  their  neutral 
condition,  require  of  this  feeble  acid  2 
prime  proportions.  One  prime  propor- 
tion of  it  is  obviously  made  up  of  1  prime 
of  sulphur  =  2,  -{- 1  oxygen  =  1 ;  and  the 
acid  equivalent  is  =*  3.  The  crystallized 
hyposulphite  of  lime  is  composed  of  6.  acid 
-f-  3.56  lime  -f-  6.75  water,  being  6  primes 
of  the  last  constituent, 


ACI 


ACI 


It  ought  to  be  stated,  that  when  a  solu- 
tion of  a  hyposulphite  is  boiled  down  to 
a  certain  degree  of  concentration,  it  be- 
gins to  be  rapidly  decomposed,  with  the 
deposition  of  sulphur  and  sulphite  of  lime. 
To  obtain  the  salt  in  crystals,  the  solution 
must  be  evaporated  at  a  temperature  not 
exceeding  140°  Fahr.  If  it  be  then  filter- 
ed while  hot,  it  will  yield  on  cooling,  large 
and  exceedingly  beautiful  crystals,  which 
assume  a  great  variety  of  complicated 
forms.  They  are  soluble  in  nearly  their 
own  wreight  of  water  at  37°  Fahr.  and  the 
temperature  of  the  solution  falls  to  31°. 
The  specific  gravity  of  their  saturated  so- 
lution at  60°  is  1.300;  and  when  it  is 
1.114,  the  liquid  contains  one-fifth  of  its 
weight.  The  crystals  are  permanent  in 
the  air. 

Hyposulphites  of  potash  and  soda  yield 
deliquescent  crystals  of  a  bitter  taste,  and 
both  of  them  dissolve  muriate  of  silver. 
The  ammoniacal  «alt  is  not  easily  procured 
in  regular  crystals.  Its  taste  is  pungent 
and  disagreeable.  The  barytic  hyposul- 
phite is  insoluble  ;  the  strontitic  is  soluble 
^nd  crystallizable.  Like  the  other  hypo- 
sulphites it  dissolves  silver ;  and  while  its 
own  taste  is  purely  bitter,  it  produces  a 
sweet  compound  with  muriate  of  silver, 
which  alcohol  throws  down  in  a  sirupy 
ibrm.  Hyposulphite  of  magnesia  is  a  bit- 
ter tasted,  soluble,  crystallizable,  and  non- 
deliquescent  salt.  All  the  hyposulphites 
burn  with  a  sulphurous  flame.  The  sweet- 
ness of  liquid  hyposulphite  of  soda,  com- 
bined with  muriate  of  silver,  surpasses 
honey  in  intensity,  diffusing  itself  over  the 
^whole  mouth  and  fauces  without  any  disa- 
greeable or  metallic  flavour.  A  coil  of 
zinc  wire  speedily  separates  the  silver  in 
a  metallic  state,  thus  affording  a  ready 
analysis  of  muriate  of  silver.  Muriate  of 
lead  is  also  soluble  in  the  hyposulphites, 
but  less  readily.* 

*  Acid  (HYPOSULPHURIC).  MM.  Gay- 
Lussac  and  Welther  have  recently  an- 
nounced the  discovery  of  a  new  acid  com- 
bination of  sulphur  and  oxygen,  interme- 
diate between  sulphurous  and  sulphuric 
acids,  to  which  they  have  given  the  name 
of  hyposulphuric  acid.  It  is  obtained  by 
passing  a  current  of  sulphurous  acid  gas 
over  the  black  oxide  of  manganese.  A 
combination  takes  place  ;  the  excess  of 
the  oxide  of  manganese  is  separated  by 
dissolving  the  hyposulphate  of  manganese 
in  water.  Caustic  barytes  precipitates  the 
manganese,  and  forms  with  the  new  acid 
a  very  soluble  salt,  which,  freed  from  ex- 
cess of  barytes  by  a  current  of  carbonic 
acid,  crystallizes  regularly,  like  the  nitrate 
or  muriate  of  barytes.  Hyposulphate  of 
barytes  being  thus  obtained,  sulphuric 
acid  is  cautiously  added  to  the  solution, 
\vhich  throws  down  the  barytes,  and  leaves 


the  hyposulphuric  acid  in  the  water.  This 
acid  bears  considerable  concentration  un- 
der the  receiver  of  the  air-pump.  It  con- 
sists  of  five  parts  of  oxygen  to  four  of  sul- 
phur. The  greater  number  of  the  hypo- 
sulphates,  both  earthy  and  metallic  are  so- 
luble and  crystallize  ;  those  of  barytes  and 
lime  are  unalterable  in  the  air.  Suberic 
acid  and  chlorine  do  not  decompose  the 
barytic  salt  The  barytic  salt  in  crystals, 
consists  of  barytes  9.7  +  hyposulphuric 
acid  9.00  -f  water  2.25  =  20,95. 

The  following  table  exhibits  the  com- 
position of  the  different  acid  compounds 
of  sulphur  and  oxygen : 
Hyposulphurous  acid  20  sul.  -f- 10  oxygen 
Sulphurous  acid  10        -j-  10 

Hyposulphuric  acid      8        -j-  10 
Sulphuric  acid  2|      -f-  10 

Or  if  we  prefer  to  consider  the  quantity  of 
sulphur  in  each  acid  as  =  2,  the  oxygen 
combines  with  it  in  the  following  propor- 
tions : — 1 ;  2  ;  2.5 ;  3. 

Hyposulphuric  acid  is  distinguished  by 
the  following  properties : 

1st,  It  is  decomposed  by  heat  into  sul- 
phurous and  sulphuric  acids. 

2(1,  It  forms  soluble  salts  with  barytes^ 
strontites,  lime,  lead,  and  silver. 

3d,  The  hyposulphates  are  all  soluble. 

4t/i,  They  yield  sulphurous  acid  whe* 
their  solutions  are  mixed  with  acids,  only 
if  the  mixture  becomes  hot  of  itself,  or  be 
artificially  heated. 

5th,  They  disengage  a  great  deal  of  sul- 
phurous acid  at  a  high  temperature,  and 
are  converted  into  neutral  sulphates. 

Before  quitting  the  acids  of  sulphur,  it 
deserves  to  be  mentioned,  that  Dr.  Gules 
of  Paris,  has,  by  means  of  a  chest  or  case, 
called  Boete  Fumigatoire,  applied  the  va- 
pour of  burning  sulphur,  or  sulphurous 
acid  gas,  mixed  with  air,  to  the  surface  of 
the  body,  as  an  air  bath,  with  great  advan- 
tage, in  many  chronic  diseases  of  the  skin, 
the  joints,  the  glands,  and  the  lymphatic 
system.* 

ACID  (TARTARIC).  The  casks  in  which 
some  kinds  of  wine  are  kept  become  in- 
crusted  with  a  hard  substance,  tinged 
with  the  colouring  matter  of  the  wine, 
and  otherwise  impure,  which  has  long 
been  known  by  the  name  of  argal,  or  tar- 
tar, and  distinguished  into  red  and  white 
according  to  its  colour.  This  being  puri- 
fied by  solution,  filtration,  and  crystalliza- 
tion, was  termed  cream  or  crystals  of  tartar,. 
It  was  afterwards  discovered,  that  it  con- 
sisted of  a  peculiar  acid  combined  witk 
potash ;  and  the  supposition  that  it  was 
formed  during  the  fermentation  of  the 
wine,  was  disproved  by  Boerhaave,  Neu- 
mann, and  others,  who  showed  that  it  ex- 
isted ready  formed  in  the  juice  of  the 
grape.  It  has  likewise  been  found  in  other 
fruits,  particularly  before  tlxey  are  too 


ACI 


AC1 


3  hydrogen 

4  carbon 

5  oxygen 


ripe  ;  aftd  in  the  tamarind,  sumac,  balm,    the  acid  prime  equivalent ;  and  it  may  be 
carduus  benedictus,  and  the  roots  of  rest-    made  up  of 
harrow,  germander,  and  sage.    The  sepa- 
ration of  tartaric  acid  from  this  acidulous 
salt,  is  the  first  discovery  of  Scheele  that 
is  known.    He  saturated  tht  superfluous 
acid  by  adding  chalk  to  a  solution  of  the 
supertartrate  in  boiling  water  as  long  as 
any  effervescence  ensued,  and  expelled    The  crystallized  acid  is  a  compound  of 
the  acid  from  the  precipitated  tartrate  of    8.375  acid  +  1.125  water  =  9.5 ;  or  in  100 
lime  by  means  of  the  sulphuric.     Or  four    parts  88.15  acid  +  11.85  water, 
parts  of  tartar  may  be  boiled  in  twenty  or        The  tartrates  in  their  decomposition  by 
twenty -four  of  water,  and  one  part  of  sul-    fire,  comport  themselves  like  all  the  other 
phuric  acid  added  gradually.    By  continu-    vegetable  salts,  except  that  those  with  ex- 

•  .1  1  «f  iL  1        I.       A.  1*  A.  1>  '11  Lf  *   J  1  J    J.T-  11          J?  71- 


=  0.3  75  4.48- 

=»  3.000  35.82 

=»  5.000  59.70 

8.375  100.00 


ing  the  boiling  the  sulphate  of  potash  will 
fall  down.  When  the  liquor  is  reduced  to 


cess  of  acid  yield  the  smell  ofcaromel  when 
heated,  and  afford  a  certain  quantity  of 


one-half,  it  is  to  be  filtered,  and  if  any  more    the  pyro tartaric  acid.  All  the  soluble  neu- 


sulphate  be  deposited  by  continuing  the 
boiling1,  the  filtering  must  be  repeated. 
When  no  more  is  thrown  down,  the  liquor 
is  to  be  evaporated  to  the  consistence  of  a 
sirup,  and  thus  crystals  of  tartaric  acid, 
equal  to  half  the  weight  of  the  tartar  em- 
ployed, will  be  obtained. 

The  tartaric  acid  may  be   procured  in 


tral  tartrates  form  with  tartaric  acid,  bitar- 
trates  of  sparing  solubility ;  while  all  the 
insoluble  tartrates  may  be  dissolved  in  an 
excess  of  their  acid.  Hence,  by  pouring 
gradually  an  excess  of  acid  into  barytes, 
strontites  and  lime-waters,  the  precipitates 
formed  at  first  cannot  fail  to  disappear ; 
while  those  obtained  by  an  excess  of  the 


needly  or  laminated  crystals,  by  evaporat-    same  acid,  added  to  concentrated  solutions 


ing  a  solution  of  it.  Its  taste  is  very  acid 
and  agreeable,  so  that  it  may  supply  the 
place  of  lemon-juice.  It  is  very  soluble  in 
water.  Burnt  in  an  open  fire,  it  leaves  a 


of  potash,  soda,  or  ammonia,  and  the  neu- 
tral tartrates  of  these  bases,  as  well  as  of 
magnesia  and  copper,  must  be  permanent. 
The  first  are  alwavs  flocculent ;  the  se- 


coaly  residuum;    in  close  vessels  it  gives    cond  always  crystalline;   that  of  copper 


out  carbonic  acid  and  carburetted  hydro- 
gen gas.  By  distilling  nitric  acid  off  the 
crystals  they  may  be  converted  into  oxalic 
acid,  and  the  nitric  acid  passes  to  the  state 
of  nitrous. 

*  To  extract  the  whole  acid  from  tartar, 
M.  Thenard  recommends,  after  saturating 
the  redundant  acid  with  chalk,  to  add  mu- 
riate of  lime  to  the  supernatant  neutral 
tartrate,  by  which  means  it  is  completely 
decomposed.  The  insoluble  tartrate  of 
lime  being  washed  with  abundance  of  wa- 
%  ter,  is  then  to  be  treated  with  three-fifths 
of  its  weight  of  strong  sulphuric  acid,  di- 
luted previously  with  five  parts  of  water. 
But  Fourcroy's  process  as  improved  by 
Vauquelin,  seems  still  better.  Tartar  is 
treated  with  quicklime  and  boiling  water 
in  the  proportion,  by  the  theory  of  equi- 
valents, of  100  of  tartar  to  30  of  dry  lime, 
or  40  of  the  slaked.  A  caustic  magma  is 
obtained,  which  must  be  evaporated  to 
dryness,  and  gently  heated.  On  digesting 
this  in  water,  a  solution  of  caustic  potash  is 
obtained,  while  tartrate  of  lime  remains ; 
from  which  the  acid  may  be  separated  by 
the  equivalent  quantity  of  oil  of  vitriol. 

According  to  Berzelius,  tartaric  acid  is 
a  compound  of  3.807  hydrogen  +  35.980 
carbon  +  60.213  oxygen  =  100;  to  which 
result  he  shows  that  of  M.  Gay-Lussac  and 
Thenard  to  correspond,  when  allowance 
is  made  for  a  certain  portion  of  water, 
which  they  had  omitted  to  estimate.  The 
Analysis  of  tartrate  of  lead,  gives  8.384  for 


alone,  is  in  a  greenish-white  powder.  It 
likewise  follows,  that  the  greater  number 
of  acids  ought  to  disturb  the  solutions  of 
the  alkaline  neutral  tartrates,  because 
they  transform  these  salts  into  bitartrates  ; 
and  on  the  contrary,  they  ought  to  effect 
the  solution  of  the  neutral  insoluble  tar- 
trates, which  indeed  always  happens,  un- 
less the  acid  cannot  dissolve  the  base  of 
the  tartrate.  The  order  of  apparent  affi- 
nities of  tartaric  acid  are,  lime,  barytes, 
strontites,  potash,  soda,  ammonia,  and 
magnesia. 

The  tartrates  of  potash,  soda,  and  am- 
monia, are  not  only  susceptible  of  combin- 
ing together,  but  also  with  the  other  tar^ 
trates,  so  as  to  form  double  or  triple  salts, 
We  may  thus  easily  conceive  why  the  tar- 
trates of  potash,  soda,  and  ammonia,  do 
not  disturb  the  solutions  of  iron  and  man- 
ganese ;  and  on  the  other  hand  disturb  the 
solutions  of  the  salts  of  barytes,  strontites, 
lime,  and  lead.  In  the  first  case,  double 
salts  are  formed,  however  small  a  quantity 
of  tartrate  shall  have  been  employed ;  in 
the  second,  no  double  salt  is  formed  unless 
the  tartrate  be  added  in  very  great  ex- 
cess.* 

The  tartrates  of  lime  and  barytes  are 
white,  pulverulent,  and  insoluble. 

Tartrate  of  strontian,  formed  by  the 
double  decomposition  of  muriate  of  stron- 
tian and  tartrate  of  potash,  according  to 
Vauquelin,  is  soluble,  crystallizable,  and 
consists  of  52.88  etrontian  and  47.12  acid. 


ACI 


ACI 


That  of  magnesia  forms  a  gelatinous  or 
gummy  mass. 

Tartrate  of  potash,  the  tartarized  kali  of 
the  London  college,  and  -vegetable  salt  of 
some,  formerly  called  soluble  tartar,  be- 
cause much  more  so  than  the  supertar- 
trate,  crystallizes  in  oblong  squares,  be- 
velled at  the  extremities.  It  has  a  bitterish 
taste,  and  is  decomposed  by  heat,  as  its  so- 
lution is  even  by  standing  some  time.  It 
is  used  as  a  mild  purgative. 

The  supertartrate  of  potash,  already 
mentioned  at  the  beginning  of  this  article, 
is  much  used  as  a  cooling  and  gently  open- 
ing medicine,  as  well  as  in  several  c^iemi- 
cal  and  pharmaceutical  preparations.  Dis- 
solved in  water,  with  the  addition  of  a  lit- 
tle sugar,  and  a  slice  or  two  of  lemon- 
peel,  it  forms  an  agreeable  cooling  drink 
by  the  name  of  imperial,-  and  if  an  infu- 
sion of  green  balm  be  used  instead  of  wa- 
ter, it  makes  one  of  the  pleasantest  liquors 
of  the  kind  with  which  we  are  acquainted. 
Mixed  with  an  equal  weight  of  nitre,  and 
projected  into  a  red-hot  crucible,  it  deto- 
nates, and  forms  the  ivhite  flux  /  treated 
in  the  same  way  with  half  its  weight  of 
nitre,  it  forms  the  black  jftuac  ,•  and  simply 
mixed  with  nitre  in  various  proportions,  it 
is  called  raw  jlux.  It  is  likewise  used  in 
dyeing,  in  hat-making,  in  gilding,  and  in 
other  arts. 

*  The  blanching  of  the  crude  tartar  is 
aided  by  boiling  its  solution  with  ^ff  of 
pipe  clay. 

According  to  the  analysis  of  Berzelius, 
it  consists  of  70.45  acid  -f  24.8  potash  -f 
4.75  water  =  100 ;  or 

2  primes  acid,      =  16.75        70.30 
1  potash,  =    5.95        24.95 

1  water,  =    1.125        4.75 

23.825    100.00 

60  parts  of  water  dissolve  4  of  bitartrate 
at  a  boiling  heat;  and  only  1  at  60°  Fahr. 
It  is  quite  imsoluble  in  alcohol.  It  becomes 
very  soluble  in  water,  by  adding  to  it  one- 
fifth  of  its  weight  of  borax ;  or  even  by 
the  addition  of  boracic  acid.  It  appears  by 
Berzelius,  that  neutral  tartrate  of  potash, 
dried  in  the  sun,  differs  from  the  bitar- 
trate, in  containing  no  water  qf  crystalli- 
zation. He  states  it  to  be  a  compound  of 
58.69  acid  +  41.31  potash  =  100;  which 
afford  155.7  tartrate  of  lead.  Now,  8.375  : 
5.95  :  :  58.5  :  41.5;  which  are  the  equiva- 
lent proportions. 

On  considering  the  great  solvent  pro- 
perty of  cream  of  tartar,  and  that  it  is  even 
capable  of  dissolving  various  oxides,  which 
are  insoluble  in  tartaric  acid,  as  the  pro- 
toxide of  antimony,  M.  Gay-Lussac  has 
recommended  it  as  a  useful  agent  in  che- 
mical analysis.  He  thinks  that  in  many 
«sases  it  acts  the  part  of  a  single  acid,  Ac- 


cording to  this  view,  tartar  emetic  would 
be  a  compound  of  the  cream-tartar  acid, 
and  protoxide  of  antimony.  Cream  of  tar- 
tar generally  contains  from  3  to  5  per  cent 
of  tartrate  of  lime,  which  are  in  a  great 
measure  separated  when  3  parts  of  tartar 
are  boiled  with  1  of  borax  for  a  few  mi- 
nutes in  a  sufficient  quantity  of  water. 
The  soluble  cream  of  tartar  which  is  ob- 
tained by  this  process  is  deliquescent ;  it 
dissolves  in  its  own  weight  of  water  at 
54.5°,  and  in  half  its  weight  of  boiling 
water.  Its  solution  is  very  imperfectly 
decomposed  by  the  sulphuric,  nitric,  and 
muriatic  acids.  4  parts  of  tartar  and  1  of 
boracic  acid  form  a  permanent  saline  com- 
pound,  very  soluble  in  water.  Alum  also 
increases  the  solubility  of  tartar.* 

By  saturating  the  superfluous  acid  in  this 
supertartrate  with  soda,  a  triple  saltisform- 
ed,  which  crystallizes  in  large  regular 
prisms  of  eight  nearly  equal  sides,  of  a  bitter 
taste,  efflorescent,  and  soluble  in  about 
five  parts  of  water.  It  consists,  according 
to  Vauquelin,  of  54  parts  tartrate  of  pot- 
ash and  46  tartrate  of  soda,  and  was  once 
in  much  repute  as  a  purgative,  by  the 
name  of  Rochelle  salt,  or  set  de  Seignette. 

The  tartrate  of  soda  is  much  less  solu- 
ble than  this  triple  salt,  and  crystallizes  in 
slender  needles  or  thin  plates. 

The  tartrate  of  ammonia  is  a  very  solu- 
ble, bitter  salt,  and  crystallizes  easily.  Its 
solution  is  spontaneously  decomposable. 

This  too  forms  with  tartrate  of  potash  a 
triple  salt,  the  solution  of  which  yields,  by 
cooling,  fine  pyramidal  or  prismatic  efflo- 
rescent crystals.  Though  both  the  neutral 
salts  that  compose  it  are  bitter,  this  is  not, 
but  has  a  cooling  taste. 

ACID  (TUNGSTOUS).  What  has  been  thus 
called  appears  to  be  an  oxide  of  TCXGSTEIT. 

*  ACID  (TUNGSTIC)  has  been  found  only 
in  two  minerals;  one  of  which  formerly 
called  tungsten,  is  a  tungstate  of  lime,  and 
is  very  rare  ;  the  other  more  common,  is 
composed  of  tungstic  acid,  oxide  of  iron, 
and  a  little  oxide  of  manganese.  The  acid 
is  separated  from  the  latter  in  the  follow- 
ing way.  The  wolfram  cleared  from  its  si- 
liceous gangue,  and  pulverized,  is  heated 
in  a  matrass  \\  ith  five  or  six  times  its  weight 
of  muriatic  acid,  for  half  an  hour.  The  ox- 
ides of  iron  and  manganese  being  thus  dis- 
solved, we  obtain  the  tungstic  acid  under 
the  form  of  a  yellow  powder.  After  wash- 
ing it  repeatedly  with  water,  it  is  then  di- 
gested in  an  excess  of  liquid  ammonia, 
heated,  which  dissolves  it  completely. 
The  liquor  is  filtered  and  evaporated  to 
dryness  in  a  capsule.  The  dry  residue  be- 
ing ignited,  the  ammonia  flies  off,  and 
pure  tungstic  acid  remains.  If  the  whole 
of  the  wolfram  has  not  been  decomposed 
in  this  operation,  it  must  be  subjected  to 
the  muriatic  acid  ag-ajn, 


ACI 


ACT 


It  is  tasteless,  and  does  not  affect  vege- 
table colours.  The  tungstates  of  the  alka- 
lis and  magnesia  are  soluble  and  crystalli- 
zable,  the  other  earthy  ones  are  insoluble, 
as  well  as  those  of  the  metallic  oxides. 
The  acid  is  composed  of  100  parts  metal- 
lie  tungsten,  and  25  or  ^6.4  oxygen.* 

ACID  (URIC).  The  same  with  LITHIC 
ACID  ;  which  see. 

ACID  (Zooxic).  In  the  liquid  procured 
by  distillation  from  animal  substances, 
winch  had  been  supposed  to  contain  only 
carbonate  of  ammonia  and  an  oil,  Berthol- 
let  imagined  he  had  discovered  a  peculiar 
acid,  to  which  he  gave  the  name  of  zoonic. 
Thenard,  however,  has  demonstrated  that 
it  is  merely  acetic  acid  combined  with  an 
animal  matter. 

*  ACID  (ZUMIC).  An  acid  called  by  M. 
Braconnot,  Nanceic,  in  honour  of  the  town 
of  Nancy,  where  he  lives.  He  discovered 
it  in  many  acescent  vegetable  substances  ; 
in  sour  rice ;  in  putrefied  juice  of  beet- 
root ;  in  sour  decoction  of  carrots,  peas, 
&c.  He  imagines  that  this  acid  is  genera- 
ted at  the  same  time  as  vinegar  in  organic 
substances,  when  they  become  sour.  It 
is  without  colour,  does  not  crystallize,  and 
has  a  very  acid  taste. 

He  concentrates  the  soured  juice  of 
the  beet-root  till  it  become  almost  solid, 
digests  it  with  alcohol,  and  evaporates 
the  alcoholic  solution  to  the  consistence 
of  sirup.  He  dilutes  this  with  water, 
and  throws  into  it  carbonate  of  zinc  till  it 
be  saturated.  He  passes  the  liquid  through 
a  filter,  and  evaporates  till  a  pellicle  ap- 
pear. The  combination  of  the  new  acid 
with  oxide  of  zinc  crystallizes.  After  a 
second  crystallization,  he  dissolves  it  in 
water,  pours  in  an  excess  of  water  of 
barytes,  decomposes  by  sulphuric  acid  the 
bary  tic  salt  formed,  separates  the  deposite 
by  a  filter,  and  obtains,  by  evaporation, 
the  new  acid,  pure. 

It  forms  with  alumina  a  salt  resembling 
gum,  and  with  magnesia  one  unalterable 
in  the  air,  in  little  granular  crystals, 
soluble  in  25  parts  of  water  at  66°  Fahr ; 
with  potash  and  soda  it  forms  uncrystal- 
lizable  salts,  deliquescent  and  soluble  in 
alcohol ;  with  lime  and  strontites,  soluble 
granular  salts  ;  with  barytes,  an  uncrystal- 
lizable  nondeliquescent  salt  having  the 
aspect  of  gum;  with  white  oxide  of 
manganese,  a  salt  which  crystallizes  in 
tetrahedral  prisms,  soluble  in  12  parts  of 
water  at  60° ;  with  oxide  of  zinc,  a  salt 
crystallizing  in  square  prisms,  terminated 
by  summits  obliquely  truncated,!  soluble 
in  50  parts  of  water  at  66° ;  with  iron,  a 
salt  crystallizing  in  slender  four-sided 
needles,  of  sparing  solubility  and  not 
changing  in  the  air;  with  red  oxide  of 
iron,  a  white  nonerystallizing  salt;  with 
oxide  of  tin,  a  salt  crystallizing  in  wedge- 


form  octahedrons ;  with  oxide  of  lead  an 
uncrystallizable  salt,  not  deliquescent, 
and  resembling  a  gum ;  with  black  oxide 
of  mercury,  a  very  soluble  salt,  which 
crystallizes  in  needles.* 

ACIDIFIABLE.  Capable  of  being  con- 
verted into  an  acid  by  an  acidifyng  prin- 
ciple. (See  ACID).  Substances  posses- 
sing this  property  are  called  radicals,  or 
acidijlable  bases. 

ACIDUIE.  A  term  applied  by  the  French 
chemists  to  those  salts,  in  which  the  base 
is  combined  with  such  an  excess  of  acid, 
that  they  manifestly  exhibit  acid  proper- 
ties ;  such  as  the  supertartrate  of  potash. 

*  ACOWITA.      A    poisonous    vegetable 
principle,  probably  alkaline,  recently  ex- 
tracted from  the   Jlconitum  napelhis,  or 
Wolfsbane,  by  M.  Brandes.    The  details 
of  the  analysis   have    not  reached  this 
country.* 

*  ACTIWOLITE,     Strahlstein  of  Werner. 
Jbnphibole    Jlctinote  hexaedre   fof    Hauy. 
There  are  three  varieties  of  this  mineral : 
the    crystallized,  the  asbestous,   and  the 
glassy. 

Isty  Crystallized  actinolite.  Colour  leek 
green,  and  green  of  darker  shades.  It 
crystallizes  in  long  oblique  hexahedra! 
prisms  with  irregular  terminations.  Crys- 
tals frequently  striated  lengthwise,  some- 
times acicular.  Its  lustre  is  shining.  It 
is  translucent.  Occasionally  it  is  found  in 
silky  fibres.  Its  sp.  gr.  varies  from  3.0  to 
3.3.  Fracture  usually  radiated ;  sometimes 
it  is  foliated  with  an  indistinct  twofold 
cleavage.  It  scratches  glass. 

2d,  Asbestous  actinolite.  Colours  green, 
verging  on  gray  and  brown,  and  smalt, 
blue.  Massive  and  in  elastic  capillary 
crystals,  which  are  grouped  in  wedge- 
shaped,  radiated  or  promiscuous  masses. 
Internal  lustre  pearly.  Melts  before  the 
blow-pipe  into  a  dark  glass.  Fracture 
intermediate  between  fibrous  and  nar- 
row radiated.  Fragments  wedge-shaped. 
Opaque.  Soft.  Tough  but  sectile.  Sp. 
gr.  2.7  to  2.9. 

3d,  Glassy  actinelite.  Colours,  mountain 
green,  and  emerald  green.  In  thin  six 
sided  needle-form  crystals.  Has  cross 
rents.  Sp.  gr.  from  3.0  to  3.2.  The 
composition  of  actinolite  is  very  differently 
stated  by  different  analysts.  Laugier's 
results  with  glassy  actinolite  are  the  folr 
lowing,  and  they  approximate  to  those 
of  Vauquelin  on  asbestous  actinolite ; 
silica  50,  lime  9.75,  magnesia  19.25,  oxide 
of  iron  11,  alumina  0.75,  oxide  of  maganese 
0.5,  oxide  of  chromium  3,  potash  0.5, 
moisture  5,  loss  0.25.  28.2.  of  alumina 
and  3. 84  oftungstic  acid  were  found  in 
100  parts  of  asbestous  actinolite  from 
Cornwall,  analyzed  by  Dr.  Thomson. 
Actinolite  is  found  chiefly  in  primitive 
districts,  with  a  magnesian  basis.  It 


ADA 


ADI 


Accompanies  talc,  and  some  micaceous 
rocks.  Its  principal  localities  are  Ziller- 
thal,  in  the  Tyrol ;  Mont  St.  Gothard ;  near 
Saltzburg,  in  Saxony ;  in  Norway  and  in 
Piedmont.  In  Great  Britain,  it  is  found 
in  Cornwall  and  Wales ;  and  in  Glen  Elg, 
the  isles  of  Lewis  and  Sky.  It  is  never 
found  in  secondary  mountains.* 

ADAMANT.     See  DIAMOND. 

ADAMANTINE  SPAR.  This  stone,  which 
comes  to  us  from  the  peninsula  of  Hither 
India,  and  also  from  China,  has  not  en- 
gaged the  attention  of  the  chemical  world 
till  within  a  few  years  past.  It  is  remark- 
able for  its  extreme  hardness,  whi$h  ap- 
proaches to  that  of  the  diamond,  and  by 
virtue  of  which  property  it  is  used  for 
polishing  gems. 

Two  varieties  of  this  stone  are  known 
in  Europe.  The  first  comes  from  China. 
It  is  crystallized,  in  six-sided  prisms,  with- 
out pyramids,  the  length  of  which  varies 
from  half  an  inch  to  an  inch,  and  their 
thickness  is  about  three  quarters  of  an 
inch.  Its  colour  is  gray  of  different  shades. 
The  larger  pieces  are  opaque  ;  but  thin 
pieces  and  the  edges  of  the  prisms  are 
transparent.  Its  fracture  is  brilliant,  and 
its  texture  spathose ;  which  causes  its 
surface  to  appear  lightly  striated.  Its 
crystals  are  covered  with  a  very  fine  and 
Strongly  adherent  crust  of  plates  of  silvery 
mica,  mixed  with  particles  of  red  feldspar. 
A  yellow  superficial  covering  of  sulphate 
©f  iron  was  observed  upon  one  speci- 
men. 

This  stone  is  so  hard  that  it  not  only 
cuts  glass  as  easily  as  a  diamond,  but  like- 
wise marks  rock  crystal  and  several  other 
hard  stones.  Its  specific  gravity  is  3.7*0. 

Small  crystalline  grains  of  magnetical 
ferruginous  calx  are  occasionally  found  in 
the  adamantine  spar  of  China,  which  may 
be  separated  by  the  magnet  when  the 
stone  is  pulverized. 

The  second  variety,  which  comes  from 
India,  is  called  Corundum  by  the  inhabi- 
tants of  Bombay.  It  differs  from  the  for- 
mer by  a  white  colour,  a  texture  more  evi- 
dently spathose,  and  lastly,  because  the 
grains  of  magnetical  iron  are  smaller  than 
in  the  former  specimens,  and  are  not  in- 
terspersed through  its  substance,  but  only 
at  its  surface. 

From  its  hardness  it  is  extremely  diffi- 
cult to  analyze.  M.  Chenevix,by  repeat- 
edly heating  it  red  hot,  and  then  plunging 
it  into  cold  water,  caused  it  to  appear  fis- 
sured in  every  direction.  He  then  put  it 
into  a  steel  mortar,  about  three  quarters 
of  an  inch  in  diameter,  and  three  inches 
deep,  to  which  a  steel  pestle  was  closely 
fitted.  A  few  blows  on  the  pestle  caused 
it  to  crumble,  and  the  fragments  were  then 
easily  reduced  to  an  impalpable  powder 
by  an  agate  pestle  and  mortar.  This  pow- 
der was  fused  in  a  crucible  of  platinum 


with  twice  its  weight  of  calcined  borax, 
and  the  glass  was  dissolved  by  boiling  in 
muriatic  acid  about  twelve  hours.  The 
precipitates  from  this  solution  being  ex- 
amined, a  specimen  from  China  was  found 
to  give  from  100  parts,  86.50  of  alumina, 
5.25  of  silex,  6.50  of  iron :  one  from  Ava, 
alumina  87,  silex  6.5,  iron  4.5 :  one  from 
Malabar,  alumina  86.5,  silex  7,  iron  4 :  one 
from  the  Carnatic,  alumina  91,  silex  5,  iron 
1.5. 

The  Rev.  Mr.  W.  Gregor  analyzed  a 
specimen  from  Thibet,  in  the  collection  of 
Mr.  Rashleigh,  which  gave  him  alumina 
81.75,  silex  12.125,  oxide  of  titanium  4, 
water  0.937,  but  no  iron. 

This  stone  has  been  said  to  have  been 
found  in  different  parts  of  Europe,  and 
near  Philadelphia  in  America ;  but  most, 
if  not  all  of  the  specimens  have  proved  not 
to  be  the  adamantine  spar.  Lately,  how- 
ever, Prof.  Pini  has  discovered  a  stone  in 
Italy,  the  characters  of  which,  as  given  by 
him,  agree  with  those  of  the  adamantine 
spar.  See  CORUNDUM. 

ADHESION.  See  COHESION. 
*  ADHESIVE  SLATE.  See  SLATE.* 
ADIPOCERE.  The  attention  of  chemists 
has  been  much  excited  by  the  spontaneous 
conversion  of  animal  matter  into  a  sub- 
stance considerably  resembling  spermace- 
ti. The  fact  has  long  been  well  known, 
and  is  said  to  have  been  mentioned  in  the 
works  of  Lord  Bacon,  though  I  have  not 
seen  the  passage.  On  the  occasion  of  the 
removal  of  a  very  great  number  of  human 
bodies  from  the  ancient  burying-place  des 
Innocens  at  Paris,  facts  of  this  nature  were 
observed  in  the  most  striking  manner. 
Fourcroy  may  be  called  the  scientific  dis- 
coverer of  this  peculiar  matter,  as  well  as 
the  saponaceous  ammoniacal  substance 
contained  in  bodies  abandoned  to  sponta- 
neous destruction  in  large  masses.  This 
chemist  read  a  memoir  on  the  subject  in 
the  year  1789  to  the  Royal  Academy  of 
Sciences,  from  which  1  shall  abstract  the 
general  contents. 

At  the  time  of  clearing  the  before  men- 
tioned burying-place,  certain  philosophers 
were  specially  charged  to  direct  the  pre- 
cautions requisite  for  securing  the  health 
of  the  workmen.  A  new  and  singular  ob- 
ject of  research  presented  itself,  which 
had  been  necessarily  unknown  to  prece- 
ding chemists.  It  was  impossible  to  fore- 
tell what  might  be  the  contents  of  a  soil 
overloaded  for  successive  ages  with  bodies 
resigned  to  the  putrefactive  process.  This 
spot  differed  from  common  burying- 
grounds,  where  each  individual  object  is 
surrounded  by  a  portion  of  the  soil.  It 
was  the  burying-ground  of  a  large  district, 
wherein  successive  generations  of  the  in- 
habitants had  been  deposited  for  upwards 
of  three  centuries.  It  could  not  be  fore- 
seen that  the  entire  decomposition  might 


ADI 


ADI 


fce  retarded  for  more  than  forty  ye*afs; 
neither  was  there  any  reason  to  suspect 
that  any  remarkable  difference  would  arise 
from  the  singularity  of  situation. 

The  remains  of  the  human  bodies  im- 
mersed in  this  mass  of  putrescence  were 
found  in  three  different  states,  according 
to  the  time  they  had  been  buried,  the 
place  they  occupied,  and  their  relative 
situations  with  regard  to  each  other.  The 
most  ancient  were  simply  portions  of 
bones,  irregularly  dispersed  in  the  soil, 
which  had  been  frequently  disturbed.  A 
second  state,  in  certain  bodies  which  had 
always  been  insulated,  exhibited  the  skin, 
the  muscles,  tendons,  and  aponeuroses, 
dry,  brittle,  hard,  more  or  less  gray,  and 
similar  to  what  are  called  mummies  in  cer- 
tain caverns  where  this  change  has  been 
observed,  as  in  the  catacombs  at  Rome, 
and  the  vault  of  the  Cordeliers  at  Tou- 
louse. 

The  third  and  most  singular  state  of 
these  soft  parts  was  observed  in  the  bodies 
which  filled  the  common  graves  or  repo- 
sitories. By  this  appellation  are  under- 
Stood  caviiies  of  thirty  feet  in  depth  and 
twenty  on  each  side,  which  were  dug  in 
flie  bury  ing-ground  of  the  Innocents,  and 
were  appropriated  to  contain  the  bodies 
of  the  poor;  which  were  placed  in  very 
close  rows,  each  in  its  proper  wooden 
bier.  The  necessity  for  disposing  a  great 
number  obliged  the  men  charged  with  this 
employment  to  arrange  them  so  near  each 
other,  that  these  cavities  might  be  consi- 
dered when  filled  as  an  entire  mass  of  hu- 
man bodies,  separated  only  by  two  planks 
of  about  half  an  inch  thick.  Each  cavity 
contained  between  one  thousand  and  fif- 
teen hundred.  When  one  common  grave 
of  this  magnitude  was  filled,  a  covering  of 
about  one  foot  deep  of  earth  was  laid  upon 
it,  and  another  excavation  of  the  same  sort 
was  made  at  some  distance.  Each  grave 
remained  open  about  three  years,  which 
was  the  time  required  to  fill  it.  Accord- 
Ing  to  the  urgency  of  circumstances,  the 
graves  were  again  made  on  the  same  spot 
after  an  interval  of  time  not  less  than  fif- 
teen years,  nor  more  than  thirty.  Expe- 
rience had  taught  the  workmen,  that  this 
time  was  not  sufficient  for  the  entire  de- 
struction of  the  bodies,  and  had  shown 
them  the  progressive  changes  which  form 
the  object  of  Mr.  Fourcroy's  memoir. 

The  first  of  these  large  graves  opened 
in  the  presence  of  this  chemist,  had  been 
closed  for  fifteen  years.  The  coffins  were 
in  good  preservation,  but  a  little  settled, 
and  the  wood  (I  suppose  deal)  had  a  yel- 
low tinge.  When  the  covers  of  several 
were  taken  off,  the  bodies  were  observed 
at  the  bottom,  leaving  a  considerable  dis- 
tance between  their  surface  and  the  cover, 
and  flattened  as  if  they  h$d  suffered  a 


strong  compression.  The  linen  which  had 
covered  them  was  slightly  adherent  to  the 
bodies ;  and,  with  the  form  of  the  differ- 
ent regions,  exhibited,  on  removing  the 
linen,  nothing  but  irregular  masses  of  a 
soft  ductile  matter  of  a  gray  white  colour. 
These  masses  environed  the  bones  on  all 
sides,  which  had  no  solidity,  but  broke  by 
any  sudden  pressure.  The  appearance  of 
this  matter,  its  obvious  composition  and 
its  softness,  resembled  common  white 
cheese;  and  the  resemblance  was  more 
striking  from  the  print  which  the  threads 
of  the  linen  had  made  upon  its  surface. 
This  white  substance  yielded  to  the  touch, 
and  became  soft  when  rubbed  for  a  time 
between  the  fingers. 

No  very  offensive  smell  was  emitted 
from  these  bodies.  The  novelty  and  sin- 
gularity of  the  spectacle,  and  the  example 
of  the  grave-diggers,  dispelled  every  idea 
either  of  disgust  or  apprehension.  These 
men  asserted  that  they  never  found  this 
matter,  by  them  called  grtu  (fat),  in  bo- 
dies interred  alone  ;  but  that  the  accumu- 
lated bodies  of  the  common  graves  only 
were  subject  to  this  change.  On  a  very 
attentive  examination  of  a  number  of  bo- 
dies passed  to  this  state,  M.  Fourcroy  re- 
marked, that  the  conversion  appeared  in 
different  stages  of  advancement,  so  that, 
in  various  bodies,  the  fibrous  texture  and 
colour,  more  or  less  red,  were  discernible 
within  the  fatty  matter ;  that  the  masses 
covering  the  bones  were  entirely  of  the 
same  nature,  offering  indistinctly  in  all  the 
regions  a  gray  substance,  for  the  most  part 
soft  and  ductile,  sometimes  dry,  always 
easy  to  be  separated  in  porous  fragments, 
penetrated  with  cavities,  and  no  longer 
exhibiting  any  traces  of  membranes,  mus. 
cles,  tendons,  vessels,  or  nerves.  On  the 
first  inspection  of  these  white  masses,  it 
might  have  been  concluded  that  they  were 
simply  the  cellular  tissue,  the  compart- 
ments and  vesicles  of  which  they  very  well 
represented. 

By  examining  this  substance  in  the  dif- 
ferent regions  of  the  body,  it  was  found 
that  the  skin  is  particularly  disposed  to  this 
remarkable  alteration.  It  was  afterwards 
perceived  that  the  ligaments  and  tendon* 
no  longer  existed,  or  at  least  had  lost  their 
tenacity :  so  that  the  bones  were  entirely 
unsupported,  and  left  to  the  action  of  their 
own  weight.  Whence  their  relative  places 
were  preserved  in  a  certain  degree  by 
mere  juxtaposition;  the  least  effort  being 
sufficient  to  separate  them.  The  grave- 
diggers  availed  themselves  of  this  circum- 
stance in  the  removal  of  the  bodies.  For 
they  rolled  them  up  from  head  to  feet, 
and  by  that  means  separated  from  each 
other  the  extremities  of  the  bones,  which 
had  formerly  been  articulated.  In  all  these 
frocltes  whitb  wer$  changed  intp  the  fatty 


ADI 


matter,  the  abdominal  cavity  had  disap- 
peared. The  teguments  and  muscles  of 
this  region  being  converted  into  the  white 
matter,  like  the  other  soft  parts,  had  sub- 
sided upon  the  vertebral  column,  and  were 
so  flattened  as  to  leave  no  place  for  the 
viscera,  and  accordingly  there  was  scarce- 
ly ever  any  trace  observed  in  the  almost 
obliterated  cavity.  This  observation  was 
for  a  long  time  matter  of  astonishment  to 
the  investigators.  In  vain  did  they  seek 
in  the  greater  number  of  bodies  the  place 
and  substance  of  the  stomach,  the  intes- 
tines, the  bladder,  and  even  the  liver,  the 
spleen,  the  kidneys,  and  the  matri^in  fe- 
males. All  these  viscera  were  confound- 
ed together,  and  for  the  most  part  no  tra- 
ces of  them  were  left.  Sometimes  only 
certain  irregular  masses  were  found,  of  the 
same  nature  as  the  white  matter,  of  differ- 
ent bulks,  from  that  of  a  nut  to  two  or 
three  inches  in  diameter,  in  the  regions  of 
the  liver  or  of  the  spleen. 

The  thorax  likewise  offered  an  assem- 
blage of  facts  no  less  singular  and  interest- 
ing. The  external  part  of  this  cavity  was 
flattened  and  compressed  like  the  rest  of 
the  organs  ;  the  ribs,  spontaneously  lux- 
ated in  their  articulations  with  the  ver- 
tebrae, were  settled  upon  the  dorsal  co- 
lumn ;  their  arched  part  left  only  a  small 
space  on  each  side  between  them  and  the 
vertebrae.  The  pleura,  the  mediastinum, 
the  large  vessels,  the  aspera  arteria,  and 
even  the  lungs  and  the  heart,  were  no 
longer  distinguishable ;  but  for  the  most 
part  had  entirely  disappeared,  and  in  their 
place  nothing  was  seen  but  some  parcels 
of  the  fatty  substance.  In  this  case,  the 
matter  which  was  the  product  of  decom- 
position of  the  viscera,  charged  with  blood 
and  various  humours,  differs  from  that  of 
the  surface  of  the  body,  and  the  long 
bones,  in  the  red  or  brown  colour  pos- 
sessed by  the  former.  Sometimes  the  ob- 
servers found  in  the  thorax  a  mass  irregu- 
larly rounded,  of  the  same  nature  as  the 
latter,  which  appeared  to  them  to  have 
arisen  from  the  fat  and  fibrous  substance 
of  the  heart.  They  supposed  that  this 
mass,  not  constantly  found  in  all  the  sub- 
jects, owed  its  existence  to  a  superabun- 
dance of  fat  in  this  viscus,  where  it  was 
found.  For  the  general  observation  pre- 
sented itself,  that  in  similar  circumstances, 
the  fat  parts  undergo  this  conversion  more 
evidently  than  the  others,  and  afford  a 
larger  quantity  of  the  white  matter. 

The  external  region  in  females  exhibit- 
ed the  glandular  and  adipose  mass  of  the 
breasts  converted  into  the  fatty  matter 
very  white  and  v  ery  homogeneous. 

The  head  was,  as  has  already  been  re- 
marked, environed  with  the  fatty  matter ; 
the  face  was  no  longer  distinguishable  in 
the  greatest  number  of  subjects;  the 


mouth  disorganized  exhibited  neither 
tongue  nor  palate  ;  and  the  jaws,  luxated 
and  more  or  less  displaced,  were  environ- 
ed with  irregular  layers  of  the  white  mat- 
ter. Some  pieces  of  the  same  matter  usu- 
ally occupied  the  place  of  the  parts  situ- 
ated in  the  mouth ;  the  cartilages  of  the 
nose  participated  in  the  general  alteration 
of  the  skin  ;  the  orbits  instead  of  eyes  con- 
tained white  masses  ;  the  ears  were  equal- 
ly disorganized;  and  the  hairy  scalp,  hav- 
ing undergone  a  similar  alteration  to  that 
of  the  other  organs,  still  retained  the  hair. 
M.  Fourcroy  remarks  incidentally,  that  the 
hair  appears  to  resist  every  alteration  much 
longer  than  any  other  part  of  the  body. 
The  cranium  constantly  contained  the 
brain  contracted  in  bulk  ;  blackish  at  the 
surface,  and  absolutely  changed  like  the 
other  organs.  In  a  great  number  of  sub- 
jects which  were  examined,  this  viscus 
was  never  found  wanting,  and  it  was  al- 
ways in  the  above-mentioned  state ;  which 
proves  that  the  substance  of  the  brain  is 
greatly  disposed  to  be  converted  into  the 
fat  matter. 

Such  was  the  state  of  the  bodies  found 
in  the  burial-ground  des  Innocens.  Its 
modifications  were  also  various.  Us  con- 
sistence in  bodies  lately  changed,  that  is 
to  say,  from  three  to  five  years,  was  soft 
and  very  ductile ;  containing  a  great  quan- 
tity of  water.  In  other  subjects  converted 
into  this  matter  for  a  long  time,  such  as 
those  which  occupied  the  cavities  which 
had  been  closed  thirty  or  forty  years,  this 
matter  is  drier,  more  brittle,  and  in  den- 
ser flakes.  In  several  which  were  deposit- 
ed in  dry  earth,  various  portions  of  the 
fatty  matter  had  become  semi-transparent. 
Tfce  aspect,  the  granulated  texture,  and 
brittleness  of  this  dried  matter,  bore  a 
considerable  resemblance  to  wax. 

The  period  of  the  formation  of  this  sub- 
stance had  likewise  an  influence  on  its 
properties.  In  general,  all  that  which  had 
been  formed  for  a  long  time  was  white, 
uniform,  and  contained  no  foreign  sub- 
stance, or  fibrous  remains ;  such,  in  par- 
ticular, was  that  afforded  by  the  skin  of 
the  extremities.  On  the  contrary,  in  bo- 
dies recently  changed,  the  fatty  matter 
was  neither  so  uniform  nor  so  pure  as  in 
the  former  ;  but  it  was  still  found  to  con- 
tain portions  of  muscles,  tendons,  and  liga- 
ments, the  texture  of  which,  though  al- 
ready altered  and  changed  in  its  colour, 
was  still  distinguishable.  Accordingly,  as 
the  conversion  was  more  or  less  advan- 
ced, these  fibrous  remains  were  more  or 
less  penetrated  with  the  fatty  matter,  in- 
terposed as  it  were  between  the  intersti- 
ces of  the  fibres.  This  observation  shows, 
that  it  is  not  merely  the  fat  which  is  thus 
changed,  as  was  natural  enough  to  think 
at  first  sight.  Other  facts  confirm  this  as. 


ADI 


AUI 


sertion.  The  skin,  as  has  been  remarked, 
becomes  easily  converted  into  very  pure 
white  matter,  as  does  likewise  the  brain, 
neither  of  which  has  been  considered  by 
anatomists  to  be  fat.  It  is  true,  neverthe- 
less, that  the  unctuous  parts,  and  bodies 
charg-ed  with  fat,  appear  more  easily  and 
speedily  to  pass  to  the  state  under  con- 
sideration. This  was  seen  in  the  marrow, 
which  occupied  the  cavities  of  the  longer 
bones  And  again,  it  is  not  ro  be  supposed, 
but  that  the  greater  part  of  these  bodies 
had  been  emaciated  by  the  illness  which 
terminated  their  lives ;  notwithstanding 
which,  they  were  all  absolutely  turned  in- 
to this  fatty  substance. 

An  experiment  made  by  M.  Poulletier 
de  la  Salle,  and  Fourcroy  likewise  evinced 
that  a  conversion  does  not  take  place  in 
the  fat  alone.  M.  Poulletier  had  suspended 
in  his  laboratory  a  small  piece  of  the  hu- 
man liver,  to  observe  what  would  arise  to 
it  by  the  contact  of  the  air.  It  partly  pu- 
trefied, without,  however,  emitting  any 
very  noisome  smell.  Larvae  of  the  dermes- 
tes  and  bruchus  attacked  and  penetrated 
it  in  various  directions  ;  at  last  it  became 
dry,  and  after  more  than  ten  years'  sus- 
pension, it  was  converted  into  a  white  fria- 
ble substance  resembling  dried  agaric, 
which  might  have  been  taken  for  an  earthy 
substance.  In  this  state  it  had  no  percep- 
tible smell.  M.  Poulletier  was  desirous  of 
knowing  the  state  of  this  animal  matter, 
and  experiment  soon  convinced  him  and 
M.  F.  that  it  was  very  far  from  being  in 
the  state  of  an  earth.  It  melted  by  heat, 
and  exhaled  in  the  form  of  vapour,  which 
iiad  the  smell  of  a  very  fetid  fat ;  spirit  of 
wine  separated  a  concrescible  oil,  which 
appeared  to  possess  all  the  properties  of 
spermaceti.  Each  of  the  three  alkalis  con- 
verted it  into  soap,  and  in  a  word  it  ex- 
hibited all  the  properties  of  the  fatty  mat- 
ter of  the  burial-ground  of  the  Innocents 
exposed  for  several  months  to  the  air. 
Here  then  was  a  glandular  organ,  which 
in  the  midst  of  the  atmosphere  had  under- 
gone a  change  similar  to  that  of  the  bodies 
in  the  burying-place ;  and  this  fact  suffi- 
ciently shows,  that  an  animal  substance 
which  is  very  far  from  being  of  the  nature 
of  grease,  may  be  totally  converted  into 
this  fatty  substance. 

Among  the  modifications  of  this  remark- 
able substance  in  the  burying-ground  be- 
fore mentioned,  it  was  observed  that  the 
dry,  friable,  and  brittle  matter,  was  most 
commonly  found  near  the  surface  of  the 
earth,  and  the  soft  ductile  matter  at  a 
greater  depth.  M.  Fourcroy  remarks,  that 
this  dry  matter  did  not  differ  from  the 
other  merely  in  containing  less  water,  but 
likewise  by  the  volatilization  of  one  of  its 
principles. 

The   grave-diggers   assert,    that   near 
Voi.  i.  [16] 


three  years  are  required  to  convert  a  boety 
into  this  fatty  substance.  But  Dr.  Gibbes 
of  Oxford  found,  that  lean  beef  secured  in 
a  running  stream  was  converted  into  this 
fatty  matter  at  the  end  of  a  month.  He 
judges  from  facts,  that  running  water  is 
most  favourable  to  this  process.  He  took 
three  lean  pieces  of  mutton,  and  poured 
on  each  a  quantity  of  the  three  common 
mineral  acids.  At  the  end  of  three  days, 
each  was  much  changed :  that  in  the  ni- 
tric acid  was  very  soft,  and  converted  in- 
to the  fatty  matter ;  that  in  the  muriatic 
acid  was  not  in  that  time  so  much  altered; 
the  sulphuric  acid  had  turnQd  the  other 
black.  M.  Lavoisier  thinks  that  this  pro- 
cess may  hereafter  prove  of  great  use  in 
society.  It  is  not  easy  to  point  out  what 
animal  substance,  or  what  situation,  might 
be  the  best  adapted  for  an  undertaking  of 
this  kind.  M.  L.  points  out  fecal  matters ; 
but  I  have  not  heard  of  any  conversion 
having  taken  place  in  these  animal  re- 
mains, similar  to  that  of  the  foregoing. 

The  result  of  M.  Fourcroy's  inquiries 
into  the  ordinary  changes  of  bodies  recent- 
ly deposited  in  the  earth,  was  not  very  ex- 
tensive. The  grave-diggers  informed  him, 
that  these  bodies  interred  do  not  percep- 
tibly change  colour  for  the  first  seven  or 
eight  days ;  that  the  putrid  process  disea- 
gages  elastic  fluid,  which  inflates  the  ab- 
domen, and  at  length  bursts  it ;  that  this 
event  instantly  causes  vertigo,  faintness, 
and  nausea  in  such  persons  as  unfortu- 
nately are  within  a  certain  distance  of  the 
scene  where  it  takes  place  ;  but  that  when 
the  object  of  its  action  is  nearer,  a  sudden 
privation  of  sense,  and  frequently  death, 
is  the  consequence.  These  men  are  taught 
by  experience,  that  no  immediate  danger 
is  to  be  feared  from  the  disgusting  busi- 
ness they  are  engaged  in,  excepting  at 
this  period,  which  they  regard  with  the 
utmost  terror.  They  resisted  every  in- 
ducement and  persuasion  which  these 
philosophers  made  use  of,  to  prevail  on 
them  to  assist  their  researches  into  the  na- 
ture of  this  active  and  pernicious  vapour. 
M.  Fourcroy  takes  occasion  from  these 
facts,  as  well  as  from  the  pallid  and  un- 
wholesome appearance  of  the  grave-dig- 
gers, to  reprobate  burials  in  great  towns 
or  their  vicinity. 

Such  bodies  as  are  interred  alone,  in 
the  midst  of  a  great  quantity  of  humid 
earth,  are  totally  destroyed  by  passing1 
through  the  successive  degrees  of  the  or- 
dinary putrefaction  ;  and  this  destruction 
is  more  speedy,  the  warmer  the  tempera- 
ture. But  if  these  insulated  bodies  be  dry 
and  emaciated;  if  the  place  of  deposition 
be  likewise  dry,  and  the  locality  and  other 
circumstances  such,  that  the  earth,  so  far 
from  receiving  moisture  from  the  atmos- 
phere, becomes  still  more  effectually 


ADI 


ADI 


parched  by  the  solar  rays;— the  animal 
Cilices  are '  volatilized  and  absorbed,  the 
solids  contract  and  harden,  and  a  peculiar 
species  of  mummy  is  produced.  But  eve- 
ry circumstance  is  very  different  in  the 
common  burying-grounds.  Heaped  toge- 
ther almost  in  contact,  the  influence  of  ex- 
ternal bodies  affects  them  scarcely  at  all, 
and  they  become  abandoned  to  a  peculiar 
disorganization,  which  destroys  their  tex- 
ture, and  produces  the  new  and  most  per- 
manent state  of  combination  here  describ- 
ed. From  various  observations  which  1  do 
not  here  extract,  it  was  found,  that  this 
fatty  matter  was  capable  of  enduring  in 
these  burying-places  for  thirty  of  forty 
years,  and  is  at  length  corroded  and  car- 
ried oft*  by  the  aqueous  putrid  humidity 
which  there  abounds. 

Among  other  interesting  facts  afforded 
by  the  chemical  examination  of  this  sub- 
stance, are  the  following  from  experi- 
ments by  M.  Fourcroy. 

1.  This  substance  is  fused  at  a  less  de- 
gree of  heat  than  that  of  boiling  water, 
and  may  be  purified  by  pressure  through 
a  cloth,  which  disengages  a  portion  of  fi- 
brous and  bony  matter.  2.  The  process 
of  destructive  distillation  by  a  very  gradu- 
ated heat  was  begun,  but  not  completed 
on  account  of  its  tediousness,  and  the  lit- 
tle promise  of  advantage  it  afforded.  The 
products  which  came  over  were  water 
charged  with  volatile  alkali,  a  fat  oil,  con- 
crete volatile  alkali,  and  no  elastic  fluid 
during  the  time  the  operation  was  contin- 
ued. 3.  Fragments  of  the  fatty  matter  ex- 
posed to  the  air  during  the  hot  and  dry 
summer  of  1786  became  dry,  brittle,  and 
almost  pulverulent  at  the  surface.  On  a 
careful  examination,  certain  portions  were 
observed  to  be  semi-transparent,  and  more 
brittle  than  the  rest  These  possessed  all 
the  apparent  properties  of  wax,  and  did 
not  afford  volatile  alkali  by  distillation. 
4.  With  water  this  fatty  matter  exhibited 
all  the  appearances  of  soap,  and  afforded 
a  strong  lather.  The  dried  substance  did 
not  form  the  saponaceous  combination 
with  the  same  facility  or  perfection  as  that 
which  was  recent.  About  two-thirds  of 
this  dried  matter  separated  from  the  water 
by  cooling,  and  proved  to  be  the  semi- 
transparent  substance  resembling  wax. 
This  was  taken  from  the  surface  of  the 
soapy  liquor,  which  being  then  passed 
through  the  filter,  left  a  white  soft  shining 
tnatter,  which  was  fusible  and  combusti- 
ble. 5.  Attempts  were  made  to  ascertain 
the  quantity  of  volatile  alkali  in  this  sub- 
stance by  the  application  of  lime,  and  of 
the  fixed  alkalis,  but  without  success :  for 
it  was  difficult  to  collect  and  appreciate 
the  first  portions  which  escaped,  and  like- 
wise to  disengage  the  last  portions.  The 
Caustic  volatile  alkali,  with  the  assistance 


of  a  gentle  heat,  dissolved  the  fatty  mat- 
ter, and  the  solution  became  perfectly 
clear  and  transparent  at  the  boiling  tem- 
perature of  the  mixture,  which  was  185° 
F.  6.  Sulphuric  acid,  of  the  specific  gra- 
vity of  2.0,  was,  poured  upon  six  times  its 
weight  of  the  fatty  matter,  and  mixed  by 
agitation.  Heat  was  produced,  and  a  gas 
or  effluvium  of  the  most  insupportable 
putrescence  was  emitted,  which  infected 
the  air  of  an  extensive  laboratory  for  se- 
veral days.  M.  Fourcroy  says,  that  the 
smell  cannot  be  described,  but  that  it  is 
one  of  the  most  horrid  and  repulsive  that 
can  be  imagined.  It  did  not,  howev  er, 
produce  any  indisposition  either  in  him- 
self or  his  assistants.  By  dilution  with  wa- 
ter, and  the  ordinary  processes  of  evapo- 
ration and  cooling,  properly  repeated,  the 
sulphates  of  ammonia,  and  of  lime  were 
obtained.  A  substance  was  separated  from 
the  liquor,  which  appeared  to  be  the  waxy 
matter,  somewhat  altered  by  the  action  of 
the  acid.  7.  The  nitrous  and  muriatic 
acids  were  also  applied,  and  afforded  phe- 
nomena worthy  of  remark,  but  which  for 
the  sake  of  conciseness  are  here  omitted. 
8.  Alcohol  does  not  act  on  this  matter  at 
the  ordinary  temperature  of  the  air  But 
by  boiling  it  dissolves  one-third  of  its  own 
weight,  which  is  almost  totally  separable 
by  cooling  as  low  as  55°.  The  alcohol,  af- 
ter this  process,  affords  by  evaporation  a 
portion  of  that  waxy  matter  which  is  se- 
parable by  acids,  and  is  therefore  the  only 
portion  soluble  in  cold  alcohol.  The  quan- 
tity of  fatty  matter  opera'  ed  on,  was  4 
ounces,  or  2304  grains,  of  which  the  boil- 
ing spirit  took  up  the  whole  except  26 
grains,  which  proved  to  be  a  mixture  of 
20  grains  of  ammoniacal  soap,  and  6  or  8 
grains  of  the  phosphates  of  soda  and  of 
lime.  From  this  experiment,  which  was 
three  times  repeated  with  similar  results, 
it  appears  that  alcohol  is  well  suited  to  af- 
ford an  analysis  of  the  fatty  matter.  It  does 
not  dissolve  the  neutral  salts  ;  when  cold 
it  dissolves  that  portion  of  concrete  animal 
oil  from  which  the  volatile  alkali  had  flown 
off,  and  when  heated  it  dissolves  the 
whole  of  the  truly  saponaceous  matter, 
which  is  afterwards  completely  separated 
by  cooling.  And  accordingly  it  was  found, 
that  a  thin  plate  of  the  fatty  matter,  which 
had  lost  nearly  the  whole  of  its  volatile  al- 
kali, by  exposure  to  the  air  for  three  years, 
was  almost  totally  dissolved  by  the  cold  al- 
cohol. 

The  concrete  oily  or  waxy  substance 
obtained  in  these  experiments  constitutes 
the  leading  object  of  research,  as  being 
the  peculiar  substance  with  which  the 
other  well  known  matters  are  combined. 
It  separates  spontaneously  by  the  action  of 
the  air,  as  well  as  by  that  of  acids.  These 
last  separate  it  in  a  state  of  greater  purity 


ADI 


the  less  disposed  the  acid  may  be  to  ope- 
rate in  the  way  of  combustion.  It  is  requi- 
site, therefore,  for  this  purpose,  that  the 
fatty  matter  should  be  previously  diffused 
in  12  times  its  weight  of  hot  water ;  and 
the  muriatic  or  acetous  acid  is  preferable 
to  the  sulphuric  or  the  nitrous.  The  co- 
lour of  the  tvaxy  matter  is  grayish  ;  and 
tho-.igh  exposure  to  the  air,  and  also  the 
action  of  the  oxygenat.  d  muriatic  acid  did 
produce  tn  apparent  whiteness,  it  never- 
theless disappeared  by  subsequent  fusion. 
No  metiod  was  discovered  by  which  it 
•ould  b~  permanently  bleached. 

The  nature  of  this  wax  or  fat  is  differ- 
ent from  that  of  any  other  known  substance 
of  ths  like  kind.  When  slowly  cooieil  af- 
ter fusion,  its  texture  appears  crystalline 
or  shivery,  like  spermaceti ;  but  a  speedy 
cooling  gives  it  a  semi-transparency  re- 
sembling wax.  Upon  the  whole,  never- 
theless, it  seems  to  approach  more  nearly 
to  the  former  than  to  the  latter  of  these 
bodies.  It  has  less  smell  than  spermaceti, 
and  melts  at  i27°F. ;  Dr.  Bostock  says 
92°.  Spermaceti  requires  6°  more  of  heat 
to  fuse  it,  (according  to  Dr.  Bostock  2j°). 
The  spermaceti  did  not  so  speedily  be- 
come brittle  by  cooling  as  the  adipocere. 
One  ounce  of  alcohol  of  the  strength  be- 
tween 39  and  40  degrees  of  Baume's  areo- 
meter, dissolved  when  boiling  hot  12  gros 
of  this  substance,  but  the  same  quantity  in 
like  circumstances  dissolved  only  30  or  06 
grains  of  spermaceti.  The  separation  of 
these  matters  was  also  remarkably  differ- 
ent, the  spermaceti  being  more  speedily 
deposited,  and  in  a  much  more  regular 
and  crystalline  form.  Ammonia  dissolves 
with  singular  facility,  and  even  in  the  cold, 
this  concrete  oil  separated  from  the  fatty 
matter ;  and  by  heat  it  forms  a  transparent 
solution,  which  is  a  true  soap.  But  no  ex- 
cess of  ammonia  can  produce  such  an  ef- 
fect with  spermaceti 

M.  Fourcroy  concludes  his  memoir  with 
some  speculations  on  the  change  to  which 
animal  substances  in  peculiar  circum- 
stances are  subject.  In  the  modern  che- 
mistry, soft  animal  matters  are  considered 
as  a  compos.tionof  the  oxides  of  hydrogen 
and  carbonated  azote,  more  complicated 
than  those  of  vegetable  matters,  and 
therefore  more  incessantly  tending  to  al- 
teration. If  then  the  carbon  be  conceived 
to  unite  with  the  oxygen,  either  of  the 
xvater  which  is  present,  or  of  the  other 
animal  matters,  and  thus  escape  in  large 
quantities  in  the  form  of  carbonic  acid 
gas,  we  shall  perceive  the  reason  why  this 
conversion  is  attended  with  so  great  a  loss 
of  weight,  namely,  about  nine-tenths  of 
the  whole.  The  azote,  a  principle  so  abun- 
dant in  animal  matters,  will  form  ammonia 
by  combining  with  the  hydrogen ;  part  of 
this  will  escape  in  the  vaporous  form,  and 


ADI 

the  rest  will  remain  fixed  in  the  fatty  mat* 
ter.  The  residue  of  the  animal  mattera 
deprived  of  a  great  part  of  their  carbon, 
of  their  oxygen,  and  the  whole  of  their 
azote,  will  consist  of  a  much  greater  pro- 
portion of  hydrogen,  together  with  car- 
bon and  a  minute  quantity  of  oxygen. 
This,  according  to  the  theory  of  M.  Four- 
croy,  constitutes  the  waxy  matter,  or  adi- 
pocere,  which  in  combination  with  ammo- 
nia forms  the  animal  soap,  into  which  the 
dead  bodies  are  thus  converted. 

Muscular  fibre,  macera:  ed  in  dilute  nitric 
acid,  and  afterwards  well  washed  in  warm 
water,  atiords  pure  adipocere,  of  a  light 
yellow  colour,  nearly  of  the  consistence  of 
tallow,  of  a  homogeneous  texture,  and  of 
course  free  from  ammonia.  This  is  the 
mode  in  which  it  is  now  commonly  pro- 
cured for  chemical  experiment. 

Ambergris  appears  to  contain  adipocere 
in  large  quantity,  rather  more  than  half  of 
it  being  of  this  substance. 

*  This  curious  substance  has  been  more 
recently  examined  by  Chevreul.  He  found 
it  composed  of  a  small  quantity  of  ammo- 
nia, potash,  and  lime,  united  to  much  mar- 
garine, and  to  a  very  little  of  another  fatty 
matter  different  from  that.  Weak  muri- 
atic acid  seizes  the  three  alkaline  bases. 
On  treating  the  residue  with  a  solution  of 
potash,  the  margarine  is  precipitated  in  the 
form  of  apearly  subs1. ance,  while  the  other 
fat  remains  dissolved.  Fourcroy  being-  of 
opinion  that  the  fatty  matter  of  animai  car- 
cases, the  substance  of  biliary  calculi,  and 
spermaceti,  were  nearly  identical,  gave 
them  the  same  name  of  adipocere  ;  but  it 
appears  from  the  researches  of  M.  Che- 
vreul that  these  substances  are  very  dif- 
ferent from  each  other. 

In  the  Philosophical  Transactions  for 
1813  there  is  a  very  interesting-  paper  on 
the  above  subject  by  Sir  E.  Home  and  Mr. 
Brande.  He  adduces  many  curious  facts 
to  prove  that  adipocere  is  formed  by  an 
incipient  and  incomplete  putrefaction. 
Mary  Howard,  aged  44,  died  on  the  1 2th 
May  1790,  and  was  buried  in  a  grave  ten 
feet  deep  at  the  east  end  of  Shoreditch 
church-yard,  ten  feet  to  the  east  of  the 
great  common  sewer,  which  runs  from 
north  to  south,  and  has  always  a  current  of 
water  in  it,  the  us.ial  level  of  which  is  eight 
feet  below  the  level  of  the  ground,  and 
two  feet  above  the  level  of  the  coffins  in 
the  graves.  In  August  181 )  the  body  >vas 
taken  up,  with  some  others  buried  near  it, 
for  the  purpose  of  building  a  vault,  and 
the  flesh  in  all  of  them  was  converted  into 
adipocere  or  spermaceti.  At  the  full  and 
new  moon  the  tide  raises  water  into  the 
graves,  which  at  other  times  are  dry.  To 
explain  the  extraordinary  quantities  of  fat 
or  adipocere  formed  by  animals  of  a  cer- 
tain intestinal  construction,  Sir  E.  ob- 


ADI 


AER 


serves,  that  the  current  of  water  which 
passes  through  their  colon,  while  the  locu- 
lated  lateral  parts  are  full  of  solid  matter, 
places  the  solid  contents  in  somewhat  sim- 
ilar circumstances  to  dead  bodies  in  the 
banks  of  a  common  sewer. 

The  circmstance  of  ambergris,  which 
contains  60  per  cent,  of  fat,  being  found  in 
immense  quantities  in  the  lower  intestines 
of  the  spermaceti  whales,  and  never  higher 
tip  than  seven  feet  from  the  anus,  is  an  un- 
deniable proof  of  fat  being  formed  in  the 
intestines ;  and  as  ambergris  is  only  met 
with  in  whales  out  of  health,  it  is  most 
probably  collected  there,  from  the  absor- 
bents,  under  the  influence  of  disease,  not 
acting  so  as  to  take  it  in. o  the  constitution. 
In  the  human  colon,  solid  masses  of  fat 
are  sometimes  met  with  in  a  diseased  state 
of  that  canal,  and  are  called  scybala,  A 
description  and  analysis  by  Dr.  Lire  of  a 
mass  of  ambergris,  extracted  in  Perthshire 
from  the  rectum  of  a  living  woman,  were 
published  in  a  London  Medical  Journal 
in  September  1817.  There  is  a  case  com- 
municated by  Dr.  Babington,  of  fat  form- 
ed in  the  intestines  of  a  girl  four  and  a  half 
years  old,  and  passing  oil  by  stool.  Mr. 
Brande  found,  on  the  suggestion  of  Sir  E. 
Home,  that  muscle  digested  in  bile,  is  con- 
vertible into  fat,  at  the  temperature  of 
about  100°.  If  the  substance,  however, 
pass  rapidly  into  putrefaction,  no  fat  is 
formed.  Faeces  voided  by  a  gouty  gen- 
tleman after  six  days  constipation,  yielded, 
on  infusion  in  water,  a  fatty  film.  This 
process  of  forming  fat  in  the  lower  intes- 
tines by  means  of  bile  throws  considera- 
ble light  upon  the  nourishment  derived 
from  clysters,  a  fact  well  ascertained,  but 
which  could  not  be  explained.  It  also  ac- 
counts for  the  wasting  of  the  body  which 
so  invariably  attends  all  complaints  of  the 
lower  bowels.  It  accounts  too  for  all  the 
varieties  in  the  turns  of  the  colon,  which 
we  meet  with  in  so  great  a  degree  in  dif- 
ferent animals.  This  property  of  the  bile 
explains  likewise  the  formation  of  fatty 
concretions  in  the  gall  bladder  so  common- 
ly met  with,  and  which,  from  these  experi- 
ments, appear  to  be  produced  by  the  ac- 
tion of  the  bile  on  the  mucus  secreted  in 
the  gall  bladder ;  and  it  enables  us  to  un- 
derstand how  want  of  the  gall  bladder  in 
children,  from  mal-formation,  is  attended 
•with  excessive  leanness,  notwithstanding 
a  great  appetite,  and  leads  to  an  early 
death.  Fat  thus  appears  to  be  formed  in 
the  intestines,  and  from  thence  received 
into  the  circulation,  and  deposited  in  al- 
most every  part  of  the  body.  And  as  there 
appears  to  be  no  direct  channels  by  which 
any  superabundance  of  it  can  be  thrown 
out  of  the  body,  whenever  its  supply  ex- 
ceeds the  consumption,  its  accumulation 
Becomes  a  disease,  and  often  a  very  dis- 


tressing one.    See  BILIARY  concretions 
and  MARGARINE.* 

*  ADIT,  in  mining,  is  a  subterraneous 
passage  slightly  inclined,  about  six  feet 
high  and  two  or  three  feet  vide,  begun  at 
the  bottom  of  a  neighbouring-  valley  and 
continued  up  to  the  vein,  for  the  purpose 
of  carrying  out  the  minerals  and  drawing 
off  the  water.     If  the  mine  require  drain-* 
ing  by   a   steam-engine   from  %   greater 
depth,  the  water  need  be  raised  only  to 
the  level  of  the  adit.     There  is  a^ood  ac- 
count of  the  Cornish  adits  by  Mr.  V/.  Phil- 
lips, Trans.  Geol.  Soc.  vol.  ii.-,  and  cf  adits 
in   general,    article  Galerie,  Brongiuart's 
Mineralogy,  vol.  ii.* 

ADOPTER.  A  vessel  with  two  necks 
placed  between  a  retort  and  a  receiver, 
and  serving  to  increase  the  length  of  the 
neck  of  the  former.  See  LABORATORY. 

*  ADUI.AHIA.     See  FELDSPAR.* 
AERATED  ALKALINE  WATER.     See  Aw* 

(CARBONIC). 

AEIUAL  Acin.     See  ACID  (CARBONIC). 

*  AKROLITE  or  METEORIC  STONE.     See 

MiTEOROLITB.* 

*  AEROMETER.    The  name  given  by  Dr« 
M.  Hall  to  an  ingenious  instrument  of  his 
invention  for  making  the  necessary  cor- 
rections in  pneumatic  experiments,  to  as- 
certain the  mean  bulk  of  the  gases.     It 
consists  of  a  bulb  of  glass  4|  cubic  inches 
capacity,  blown  at  the  end  of  a  long  tube 
whose  capacity  is  one  cubic  inch.     This 
tube  is  inserted  into  another  tube  of  near- 
ly equal  length,  supported  on  a  sole.  The 
first  tube  is  sustained  at  any  height  within 
the  second  by  means  of  a  spring.     Five 
cubic  inches  of  atmospheric  air,  at  a  me- 
dium pressure  and  temperature,  are  to  be 
introduced  into  the  bulb  and  tube,  of  the 
latter  of  which  it  will  occupy  one-half; 
the  other  half  of  this  tube,  and  part  of  the 
tube  into  which  it  is  inserted,  are  to  be 
occupied  by  the  fluid  of  the  pneumatic 
trough,  whether  water  or  mercury.     The 
point  of  the  tube  at  which  the  air  and  fluid 
meet,  is  to  be  marked  by  the  figure  5,  de- 
noting 5  cubic  inches.     The  upper  and 
lower  halves  of  the  tube  are  each  divided 
into  5  parts,  representing-  tenths  of  a  cubic 
inch.    The  external  tube  has  a  scale  of  in- 
ches attached.     Journal  of  Science,  vol.  v. 
See  GAS.* 

*  AEROSTATION.  A  name  commonly,  but 
not  very  correctly,  given  to  the  art  of  rais- 
ing heavy  bodies  into  the  atmosphere,  by 
the  buoyancy  of  heated  air,  or  gases  of 
small  specific  gravity,  enclosed  in  a  bag, 
which,  from  being  usually  of  a  spheroidal 
form,  is  called  a  balloon.     Of  all  the  possi- 
ble shapes,  the  globular  admits  the  great, 
est  capacity  under  the  least  surface.  Hence, 
of  two  bags  of  the  same  capacity,  if  one  be 
spherical,  and  the  other  of  any  other  shape, 
the  former  will  contain  the  least  quantity 


A&A 


AGA 


of  cloth,  of  the  least  surface.  The  sphe- 
roidal form  is  therefore  best  fitted  for 
aerostation.  Varnished  lu: estring  or  mus- 
lin is  employed  for  the  envelopes.  The 
following  table  shows  the  relation  betwixt 
the  diameters,  surfaces,  and  capacities  of 
spheres .- 


Diameters. 

Surfaces. 

Capacities. 

1 

3.141 

0.523 

2 

12.567 

4.188 

3 

28.274 

14.137 

4 

50.265 

33.51 

5 

78.54 

65.45 

10 

314.159 

523.6 

15 

706.9 

1767.1 

20 

1256.6 

4189. 

25 

1963.5 

8181. 

30 

2827. 

14137. 

40 

5026. 

33510. 

Having  ascertained  by  experiment  the 
weight  of  a  square  foot  of  the  varnished 
cloth,  we  find,  by  inspection  in  the  above 
table,  a  multiplier  whence  we  readily  com- 
pute the  total  weight  of  the  balloon.  A 
cubic  foot  of  atmospheric  air  weighs  527 
gr.  and  a  cubic  foot  of  hydrogen  about  40. 
But  as  the  gas  employed  to  fill  balloons  is 
never  pure,  we  must  estimate  its  weight 
at  something  more.  And  perhaps,  taking 
every  thing  into  account,  we  shall  find  it 
a  convenient  and  sufficiently  precise  rule 
for  aerostation,  to  consider  every  cubic 
foot  of  included  gas,  to  have  by  itself  a 
bouyancy  of  fully  one  ounce  avoirdupois. 
Hence  a  balloon  of  10  feet  diameter  will 
have  an  ascensional  force  of  fully  524  oz. 
or  33  Ibs.  minus  the  weight  of  the  314  su- 
perficial feet  of  cloth  ;  and  one  of  30  feet 
diameter,  a  buoyancy  of  fully  14137  oz.  or 
nearly  890  Ibs.  minus  the  weight  of  the 
2827  feet  of  cloth.  On  this  calculation  no 
allowance  need  be  made  for  the  seams  of 
the  balloon.  See  the  article  VARXISH.* 

JETITES,  or  EAGLE  STONE,  is  a  name  that 
has  been  given  to  a  kind  of  hollow  geodes 
of  oxide  of  iron,  often  mixed  with  a  larger 
or  smaller  quantity  of  silex  and  alumina, 
containing  in  their  cavity  some  concre- 
tions, which  rattle  on  shaking  the  stone.  It 
is  of  a  dull  pale  colour,  composed  of  con- 
centric layers  of  various  magnitudes,  of  an 
oval  or  polygonal  form,  and  often  polish- 
ed. Eagles  were  said  to  carry  them  to 
their  nests,  whence  their  name  ;  and  su- 
perstition formerly  ascribed  wonderful  vir- 
tues to  them. 

AFFINITY  (CHEMICAL).  See  ATTRAC- 
TION (CHEMICAL). 

AGALMATOLITE.     See  BILDSTEIX. 

AGARICUS.  The  mushroom,  a  genus  of 
the  order  Fungi.  Mushrooms  appear  to 
approach  nearer  to  the  nature  of  animal 
matter,  than  any  other  productions  of  the 
vegetable  kingdom,  as  beside  hydrogen, 
oxygen,  and  carbon,  they  contain  a  con- 
siderable portion  of  nitrogen,  and  yield 


ammonia  by  distillation.  Pix)f.  Proust 
has  likewise  discovered  xin  them  the 
benzoic  acid,  and  phosphate  of  lime. 

A  few  of  the  species  are  eaten  in  this 
country,  but  many  -are  recorded  to  have 
produced  poisonous  effects ;  though  hi 
some  foreign  countries,  particularly  in 
Russia,  very  few  are  rejected.  Perhaps 
it  is  of  importance,  that  they  should  be 
fresh,  thoroughly  dressed,  and  not  of  a 
coriaceous  texture.  The  Russians,  how- 
ever, are  very  fond  of  the  A.  pipcrattis, 
which  we  deem  poisonous,  preserved 
with  salt  throughout  the  winter  :  and  our 
ketchup  is  made  by  sprinkling  mushrooms 
with  salt,  and  letting  them  stand  till  great 
part  is  resolved  into  a  brown  liquor,  which 
is  then  boiled  up  with  spices.  The  A. 
piperatus  has  been  recommended  in 
France  to  consumptive  people.  The  Jl. 
muscarius  has  been  prescribed  in  doses  of 
a  few  grains  in  cases  of  epilepsy  and  palsy, 
subsequent  to  the  drying  up  of  eruptions. 

In  pharmacy  two  species  of  boletus  have 
formerly  been  used  under  the  name  of 
agaric.  The  B.  pini  laricis,  or  male  agaric 
of  the  shops,  was  given  as  a  purgative, 
either  in  substance,  or  in  an  extract  made 
with  vinegar,  wine,  or  an  alkaline  solution  r 
and  the  B.  igniarius,  spunk,  or  touchwood, 
called  female  agaric,  was  applied  exter- 
nally as  a  styptic,  even  after  amputations. 
For  this  purpose  the  soft  inner  substance 
was  taken,  and  beaten  with  a  hammer  to 
render  it  still  softer.  That  of  the  oak  was 
preferred. 

*  The  mushrooms,  remarkable  for  the 
quickness  of  their  growth,  and  decay,  as 
well  as  for  the  foetor  attending  their  spon- 
taneous decomposition,  v/ere  unaccount- 
ably neglected  by  analytical  chemists, 
though  capable  of  rewarding  their  trouble, 
as  is  evinced  by  the  recent  investigations 
and  discoveries  of  MM.  Vauquelin  and 
Braconnot.  The  insoluble  fungous  portion 
of  the  mushroom,  though  it  resembles 
woody  fibre  in  some  respects,  yet  being 
less  soluble  than  it  in  alkalis,  and  yielding 
a  nutritive  food,  is  evindently  a  peculiar 
product,  to  which  accordingly  the  name 
of  fungin  has  been  given.  Two  new- 
vegetable  acids,  the  boletic  and  fungic, 
were  also  fruits  of  these  researches. 

1.  Jlgancus  campestris,  an  ordinary  ar- 
ticle of  food,  analyzed  by  Vauquelin,  gave 
the  following  constituents :  1.  Adipocere. 
On  expressing  the  juice  of  the  agaric,  and 
subjecting  the  remainder  to  the  action  of 
of  boiling  alcohol,  a  fatty  matter  is  extrac- 
ted, which  falls  down  in  white  flakes  as 
the  alcohol  cools.  It  has  a  dirty  white 
colour,  a  fatty  feel  like  spermaceti,  and, 
exposed  to  heat,  soon  melts,  and  then 
exhales  the  odour  of  grease  ;  2.  An  oily 
matter;  3.  Vegetable  albumen  ;  4.  The 
sugar  of  mushrooms ;  5.  An  animal  matter 
soluble  in  water  and  alcohol :  On  being 


AGA 


AGA 


heated  it  evolves  the  odour  of  roasting1 
'meat,  like  osmazome;  6.  An  animal 
matter  not  soluble  in  alcohol ;  7.  Fungin ; 
8.  Acetate  of  potas'h- 

2.  Jlgaricus  volvacew  afforded  Bracon- 
not   fungin,  gelatin,  vegetable  albumen 
much  phosphate  of  potasi\  some  acetate 
of  potash,  sugar  of  mushrooms,  a  brown 
oil,   adipocere,    wax,    a   very  fugaceous 
deleterious  matter,  uncombineci  acid,  sup- 
posed to  be  the   acetic,    benzoxc    acid, 
muriate  of  potash,  and  a  deal  of  water ;  in 
all  14  ingredients. 

3.  Jlgaricus  acris  or  piper  atus,  was  found 
by  Braconnot,  after  a  minute  analysis,  to 
contain  nearly  the  same  ingredients  as  the 
preceding,  without  the  wax  and  benzoic 
acid,  but  with  more  adipocere. 

4.  Jlgaricus  stypticus.      From  twenty 
parts  of  this,  Braconnot  obtained  of  resin 
and  adipocere  1.8,  fungin  16.7,  of  an  un- 
known  gelatinous    substance,   a    potash 
salt,  and  a  fugaceous  acrid  principle  1.5. 

5.  Jlgaricus  bnlbosus,  was  examined  by 
Vauquelin,  who  found  the  following  con- 
stituents; an  animal   matter  insoluble  in 
alcohol,  osmazome,  a  soft  fatty  matter  of 
a  yellow  colour  and   acrid  taste,  an  acid 
salt,   (not  a  phosphate).     The  insoluble 
substances  of  the  agaric  yielded  an  acid 
by   distillation.      In    Orfila's   Toxicology 
several  instances  are  detailed  of  the  fatal 
effects  of  this  species  of  mushroom  on 
the  human  body.     Dogs  were  killed  with- 
in  24  hours  by  small  quantities  of  it  in 
substance,  and   also  by    its  watery  and 
alcoholic   infusions,   but   water    distilled 
from  it   was  not  injurious.     It  is  curious 
that  the  animals  experienced  little  incon- 
venience after  swallowing  it,   during  the 
first  ten  hours ;  stupor,  cholera,   convul- 
sions, and   painful  cramps  are  the  usual 
symptoms  of  the  poison  in  men.     The 
best  remedy  is  an  emetic. 

6.  Jlgaricus  theogolus.     In  this  Vauque- 
lin found  sugar  of  mushrooms,  osmazome, 
a  bitter  acrid  fatty  matter,  an  animal  matter 
not  soluble  in  alcohol,  a  salt  containing  a 
vegetable  acid. 

7.  Jlgaricus    muscarius,      Vauquelin's 
analysis  of  this  species  is  as  follows     The 
two 'animal  matters  of  the  last  agaric,  a 
fatty   matter,  sulphate,    phosphate,    and 
muriate  of  potash,  a  volatile  acid  from  the 
insoluble  matter.     The  following  account 
from  Orfila  of  the  effects  of  this  species 
on   the   animal  economy   is    interesting. 
Several  French  soldiers  ate,  at  two  leagues 
from  Polosck   in   Russia,  mushrooms  of 
the  above  kind.   Four  of  them,  of  a  robust 
constitution,    who  conceived  themselves 
proof  against   the    consequences,  under 
which   their   feebler    companions    were 
beginning  to  suffer,  refused  obstinately  to 
take  an  emetic.     In  the  evening  the  fol- 
lowing   symptoms   appeared:    Anxiety, 


sense  of  suffocation,  ardent  thirst,  intense 
griping  pains,  a  small  and  irregular  pulse, 
universal  cold  sweats,  changed  expression 
pi  countenance,  violet  tint  of  the  nose  and 
lips,  general  trembling,  fetid  stools. 
These  symptoms  becoming  worse,  they 
were  carried  to  the  hospital.  Coldness 
and  livid  colour  of  the  limbs,  a  difcadful 
delirium,  and  acute  pains,  accompanied 
them  to  the  last  moment.  One  of  them 
sunk  a  few  hours  after  his  admission  into 
the  hospital;  the  three  others  had  the 
same  fate  in  the  course  of  the  night.  On 
opening  their  dead  bodies,  the  stomach 
and  intestines  displayed  large  spots  of 
inflammation  and  gangrene ;  and  putre- 
faction seemed  advancing  very  rapidly,* 

AGAIUCUS  MIM: KALIS,  the  mountain  milky 
or  mountain  meal,  of  the  Germans,  is  one 
of  the  purest  of  the  native  carbonates  of 
lime,  found  chiefly  in  the  clefts  of  rocks 
and  at  the  bottom  of  some  lakes,  in  a 
loose  or  semi-indurated  form.  It  has  been 
used  internally  in  haemorrhages,  strangury, 
gravel,  and  dysenteries;  and  externally 
as  an  application  to  old  ulcers,  and  weak 
and  watery  eves. 

M.  Fabroni  calls  by  the  name  of  mineral 
agaric,  or  fossil  meal,  a  stone  of  a  loose 
consistence  found  in  Tuscany  in  consider- 
able abundance,  of  which  bricks  may  be 
made,  either  with  or  without  the  addition 
of  a  twentieth  part  of  argil,  so  light  as  to 
float  in  water;  and  which  he  supposes 
the  ancients  used  for  making  their  floating 
bricks.  This,  however,  is  very  different 
from  the  preceding,  not  being  even  of 
the  calcareous  genus,  since  it  appears,  on 
analysis,  to  consist  of  silex  55  parts,  mag- 
nesia 15,  water  14,  argil  12,  lime  3,  iron 
1.  Kirwan  calls  it  argillo-murite. 

*  AGATE  A  mineral,  whose  basis  is  cat 
cedony,  blended  with  variable  proportions 
of  jasper,  amethyst,  quartz,  opal,  helio- 
trope, and  carnelian.  Ribbon  agate  con- 
sists of  alternate  and  parallel  layers  of  cal- 
cedony  with  jasper,  or  quartz,  or  amethyst. 
The  most  beautiful  comes  from  Siberia 
and  Saxony.  It  occurs  in  porphyry  and 
gneiss. — Brecciated  agate  ;  a  base  of  ame- 
thyst, containing  fragments  of  ribbon  agate, 
constitute  this  beautiful  variety.  It  is  of 
Saxon  origin. — Fortification  agate,  is  found 
in  nodules  of  various  imitative  shapes,  im- 
bedded in  amygdaloid.  This  happens  at 
Oberstein  on  the  Rhine,  and  in  Scotland. 
On  cutting  it  across  and  polishing  it,  the 
interior  zig-zag  parallel  lines  bear  a  consi- 
derable resemblance  to  the  plan  of  a  mo- 
dern fortification.  In  the  very  centre, 
quartz  and  amethyst  are  seen  in  a  splinte- 
ry mass,  surrounded  by  the  jasper  and  cal- 
cedony. — Mocha  stone.  Translucent  cal- 
cedony,  containing  dark  outlines  of  arbor- 
ization, like  vegetable  filaments,  is  called 
Mocha  stone,  from  the  place  in  Arabia 


AGA 


AGR 


where  it  is  chiefly  found.  These  curious 
appearances  were  ascribed  to  depositesof 
iron  or  manganese,  but  more  lately  they 
have  been  thought  to  arise  from  mineral- 
ized plants  of  the  cryptogamous  class. — 
Jlfoss  agate,  is  a  calcedonv  with  variously 
coloured  ramifications  of  a  vegetable  form, 
occasionally  traversed  with  irregular  veins 
of  red  jasper.  Dr.  M'Culloch  has  recent- 
ly  detected,  what  Datibenton  merely  con- 
jectured, in  mocha  and  moss  agates,  aqua- 
tic confervae,  unaltered  both  in  colour  and 
form,  and  also  coated  with  iron  oxide. 
Mosses  and  lichens  have  also  been  observ- 
ed, along  with  chlorite,  in  vegetations.  An 
onyx  agate  set  in  a  ring,  belonging  to  the 
Earl  of  Powis,  contains  the  chrysalis  of  a 
moth.  Agate  is  found  in  most  countries, 
chiefly  in  trap  rocks,  and  serpentine.  Hol- 
low nodules  of  agate  called  geodes,  present 
interiorly  crystals  of  quartz,  colourless  or 
amethystine,  having  occasionally  scattered 
crystals  of  stilbite,  chabasie,  and  capillary 
mesotype.  These  geodes  are  very  com- 
mon. Bitumen  has  been  found  by  M.  Pa- 
trin  in  the  inside  of  some  of  them,  among 
the  hills  of  Dauria,  on  the  right  bank  of 
the  Chilca.  The  small  geodes  of  volcanic 
districts  contain  water  occasionally  in  their 
cavities.  These  are  chiefly  found  in  insu- 
lated blocks  of  a  lava  having  an  earthy 
fracture.  When  they  are  cracked,  the  li- 
quid escapes  by  evaporation ;  it  is  easily 
restored  by  plunging  them  for  a  little  in 
hot  water.  Agates  are  artificially  colour- 
ed by  immersion  in  metallic  solutions. 
Agates  were  more  in  demand  formerly 
than  at  present.  They  were  cut  into  cups 
and  plates  for  boxes ;  and  also  into  cutlass 
and  sabre  handles.  They  are  still  cut  and 
polished  on  a  considerable  scale  and  at  a 
moderate  price,  at  Oberstein.  The  sur- 
face to  be  polished  is  first  coarsely  ground 
by  large  millstones  of  a  hard  reddish  sand- 
stone, moved  by  water.  The  polish  is  af- 
terwards given  on  a  wheel  of  soft  wood, 
moistened  and  imbued  with  a  fine  powder 
of  a  hard  red  tripoli  found  in  the  neigh- 
bourhood. M.  Faujas  thinks  that  this  tri- 
poli is  produced  by  the  decomposition  of 
the  porphyrated  rock  that  serves  as  a 
gangue  to  the  agates.  The  ancients  em- 
ployed agates  for  making  cameos.  (See 
CALCEDONT.)  Agate  mortars  are  valued 
by  analytical  chemists,  for  reducing  hard 
minerals  to  an  impalpable  powder.  For 
some  interesting  optical  properties  of 
agates,  see  LIGHT.* 

The  oriental  agate  is  almost  transparent, 
and  of  a  vitreous  appearance.  The  occi- 
dental is  of  various  colours,  and  often  vein- 
ed with  quartz  or  jasper.  It  is  mostly 
found  in  small  pieces  covered  with  a  crust, 
and  often  running  in  veins  through  rocks 
like  flint  and  petrosilex,  from  which  it 
does  not  seem,  to  differ  greatly.  Agates 


are  most  prized,  when  the  internal  figure 
nearly  resembles  some  animal  or  plant. 

AGGREGATE.  When  bodies  of  the  same 
kind  are  united,  the  only  consequence  is, 
that  one  larger  body  is  produced.  In  this 
case,  the  united  mass  is  called  an  aggre- 
gate, and  does  not  differ  in  its  chemical 
properties  from  the  bodies  from  which  it 
was  originally  made.  Elementary  writers 
call  the  smallest  parts  into  which  an  ag- 
gregate can  be  divided  without  destroying 
its  chemical  properties,  integrant  parts. 
Thus  the  integrant  parts  of  common  salt 
are  the  smallest  parts  which  can  be  con- 
ceived to  remain  without  change ;  and  be- 
yond these,  any  further  subdivision  cannot 
be  made  without  developing  the  compo- 
nent parts,  namely,  the  alkali  and  the 
acid ;  which  are  still  further  resolvable  in- 
to their  constituent  principles. 

*  AGRICULTURE,  considered  as  a  depart- 
ment of  chemistry,  is  a  subject  of  vast  im- 
portance, but  hitherto  much  neglected. 
When  we  consider  that  every  change  in  the 
arrangements  of  matter  is  connected  with 
the  growth  and  nourishment  of  plants; 
the  comparative  values  of  their  produce 
as  food ;  the  composition  and  constitution 
of  soils ;  and  the  manner  in  which  lands 
are  enriched  by  manure,  or  rendered  fer- 
tile by  the  different  processes  of  cultiva- 
tion, we  shall  not  hesitate  to  assign  to  che- 
mical agriculture,  a  high  place  among  the 
studies  of  man.  If  land  be  unproductive, 
and  a  system  of  ameliorating  it  is  to  be  at- 
tempted, the  sure  method  of  attaining  this 
object  is  by  determining  the  causes  of  its 
sterility,  which  must  necessarily  depend 
upon  some  defect  in  the  constitution  of 
the  soil,  which  may  easily  be  discovered 
by  chemical  analysis.  Some  lands  of  good 
apparent  texture  are  yet  eminently  bar- 
ren; and  common  observation  and  com- 
mon practice  afford  no  means  of  ascertain- 
ing the  cause,  or  of  removing  the  effect. 
The  application  of  chemical  tests  in  such 
cases  is  obvious;  for  the  soil  must  contain 
some  noxious  principle  which  may  be  easi- 
ly discovered,  and  probably  easily  destroy- 
ed. Are  any  of  the  salts  of  iron  present  ? 
They  may  be  decomposed  by  lime.  Is 
there  an  excess  of  siliceous  sand?  The 
system  of  improvement  must  depend  on 
the  application  of  clay  and  calcareous  mat- 
ter. Is  there  a  defect  of  calcareous  mat- 
ter? The  remedy  is  obvious.  Is  an  excess 
of  vegetable  matter  indicated  ?  It  may  be 
removed  by  liming,  paring,  and  burning, 
Is  there  a  deficiency  of  vegetable  matter? 
It  is  to  be  supplied  by  manure.  Peat  earth 
is  a  manure ;  but  there  are  some  varieties 
of  peats  which  contain  so  large  a  quantity 
of  ferruginous  matter  as  to  be  absolute!)! 
poisonous  to  plants.  There  has  been  n 
question  on  which  more  difference  of  op 
nion  has  existed,  than  that  of  the  state  i 


AIR 


AIR 


which  tnanure  ought  to  be  ploughed  into 
land ;  whether  recent,  or  when  it  has  gone 
through  the  process  of  fermentation.  But 
whoever  will  refer  to  the  simplest  princi- 
ples of  chemistry,  cannot  entertain  a  doubt 
on  the  subject.  As  soon  as  dung.begins 
to  decompose,  it  throws  off'  its  volatile 
parts,  which  are  the  most  valuable  and 
most  efficient.  Dung  which  has  ferment- 
ed so  as  to  become  a  mere  soft  cohesive 
mass,  has  generally  lost  from  one-third  to 
one-half  of  its  most  useful  constituent  ele- 
ments. See  the  articles,  ANALYSIS,  MA- 
NURE, SOILS,  VEGETATION,  and  Sir  H.  Da- 
vy's Agricult.  Chem.  * 

AIR  was,  till  lately,  used  as  the  generic 
name  for  such  invisible  and  exceedingly 
rare  fluids  as  possess  a  very  high  degree 
of  elasticity,  and  are  not  condensable  into 
the  liquid  state  by  any  degree  of  cold  hi- 
therto produced ;  but  as  this  term  is  com- 
monly employed  to  signify  that  compound 
of  aeriform  fluids  which  constitutes  our 
atmosphere,  it  has  been  deemed  advisable 
to  restrict  it  to  this  signification,  and  to 
employ  as  the  generic  term  the  word  GAS, 
(which  see,)  for  the  different  kinds  of  air, 
except  what  relates  to  our  atmospheric 
compound. 

Am  (ATMOSPHERICAL  or  COXMOX).  The 
immense  mass  of  permanently  elastic  fluid 
which  surrounds  the  globe  we  inhabit, 
must  consist  of  a  general  assemblage  of 
every  kind  of  air  which  can  be  formed  by 
the  various  bodies  that  compose  its  sur- 
face. Most  of  these,  however,  are  absorb- 
ed by  water ;  a  number  of  them  are  decom- 
posed by  combination  with  each  other; 
and  some  of  them  are  seldom  disengaged 
in  considerable  quantities  by  the  proces- 
ses of  nature.  Hence  it  is  that  the  lower 
atmosphere  consists  chiefly  of  oxygen  and 
nitrogen,  together  with  moisture  and  the 
occasional  vapours  or  exhalations  of  bo- 
dies. The  upper  atmosphere  seems  to  be 
composed  of  a  large  proportion  of  hydro- 
gen, a  fluid  of  so  much  less  specific  gravi- 
ty than  any  other,  that  it  must  naturally 
ascend  to  the  highest  place,  where,  being 
occasionally  set  on  fire  by  electricity,  it 
appears  to  be  the  cause  of  the  aurora  bo- 
realis  and  fire-balls.  It  may  easily  be  un- 
derstood, that  this  will  only  happen  on 
the  confines  of  the  respective  masses  of 
common  atmospherical  air,  and  of  the  in- 
flammable air;  that  the  combustion  will 
extend  progressively,  though  rapidly,  in 
flashings  from  the  place  where  it  commen- 
ces ;  and  thai  when  by  any  means  a  stream 
of  inflammable  air,  in  its  progress  toward 
1he  upper  atmosphere,  is  set  on  fire  atone 
end,  its  ignition  may  be  much  more  rapid 
lhan  what  happens  higher  up,  where  oxy- 
£  en  is  wanting,  and  at  the  same  time  more 
definite  in  its  figure  and  progression,  so  as 
to  form  the  appearance  of  a  fire-ball. 


*  To  the  above  speculations,  it  may  pro 
bably  be  objected,  that  the  air  on  the  sum- 
mit of  Mont  Blanc,  and  that  brought  down 
from  still  greater  heights  by  M.  Gay-Lus- 
sac,  in  an  aerostatic  machine,  gave,  on 
analysis,  no  product  of  hydrogen.  But  the 
lowest  estimate  of  the  height  of  luminous 
meteors,  is  prodigiously  greater  lhan  the 
highest  elevaxions  to  which  man  has  reach- 
ed.* See  COMBUSTION. 

That  the  air  of  the  atmosphere  is  so 
transparent  as  to  be  invisible,  except  by 
the  blue  colour  it  reflects  when  in  very 
large  masses,  as  is  seen  in  the  sky  or  re- 
gion above  us,  or  in  viewing-  extensive 
landscapes;  that  it  is  without  smell,  ex- 
cept that  of  electricity,  which  it  sometimes 
very  manifestly  exhibits;  altogether  with- 
out taste,  and  impalpable :  not  condensa- 
ble by  any  degree  of  cold  into  the  dense 
fluid  state,  though  easily  changing  its  di- 
mensions with  its  temperature ;  that  it 
gravitates  and  is  highly  elastic,  are  among 
the  numerous  observations  and  discove- 
ries, which  do  honour  to  the  sagacity  of 
the  philosophers  of  the  seventeenth  cen- 
tury. They  likewise  knew  that  this  fluid 
is  indispensably  necessary  to  combustion ; 
but  no  one,  except  the  great,  though  ne- 
glected, John  Mayow,  appears  to  have 
formed  any  proper  notion  of  its  manner  of 
acting  in  that  process. 

The  air  of  the  atmosphere,  like  other 
fluids,  appears  to  be  capable  of  holding1 
bodies  in  solution.  It  takes  up  water  in 
considerable  quantities,  with  a  diminution 
of  its  own  specific  gravity ;  from  which 
circumstance,  as  well  as  from  the  conside- 
ration that  water  rises  very  plentifully  in 
the  vaporous  state  in  vacua,  it  seems  pro- 
bable, that  the  air  suspends  vapour,  not  so 
much  by  a  real  solution,  as  by  keeping  its 
particles  asunder,  and  preventing  their 
condensation.  Water  likewise  dissolves 
or  absorbs  air. 

Mere  heating  or  cooling'  does  not  affect 
the  chemical  properties  of  atmospherical 
air;  but  actual  combustion,  or  any  process 
of  the  same  nature,  combines  its  oxygen, 
and  leaves  its  nitrogen  separate.  When- 
ever a  process  of  this  kind  is  carried  on  in 
a  vessel  containing  atmospherical  air, 
which  is  enclosed  either  by  inverting  the 
vessel  over  mercury,  or  by  stopping  its 
aperture  in  a  proper  manner,  it  is  found 
that  the  process  ceases  after  a  certain  time; 
and  that  the  remaining  air,  *(if  a  combus- 
tible body  capable  of  solidifying  the  oxy- 
gen, such  as  phosphorus,  have  been  em- 
ployed,)* has  lost  about  a  fifth  part  of  its 
volume,  and  is  of  such  a  nature  as  to  be 
incapable  of  maintaining  any  combustion 
for  a  second  time,  or  of  supporting  the 
life  of  animals.  From  these  experiments 
it  is  clear,  that  one  of  the  following  deduc- 
tions must  be  true:-— 1.  The  combustible 


body  has  emil 


AIR 


)ody  lias  emitted  some  principle,  which, 
by  combining"  with  the  air,  has  rendered 
it  unfit  for  the  purpose  of  further  combus- 
tion ;  or,  2.  It  has  absorbed  part  of  the  air 
which  was  fit  for  that  purpose,  and  has  left 
a  residue  of  a  different  nature ;  or,  3.  Both 
events  have  happened ;  namely,  that  the 
pure  part  of  the  air  has  been  absorbed,  and 
a  principle  has  been  emitted,  which  has 
changed  the  original  properties  of  the  re- 
mainder. 

The  facts  must  clear  up  these  theories. 
The  first  induction  cannot  be  true,  because 
the  residual  air  is  not  only  of  less  bulk,  but 
of  less  specific  gravity,  than  before.  The 
air  cannot  therefore  have  received  so  much 
as  it  has  lost.  The  second  is  the  doctrine 
of  the  philosophers  who  deny  the  exist- 
ence of  phlogiston,  or  a  principle  of  in- 
flammability ;  and  the  third  must  be  adopt- 
ed by  those  who  maintain  that  such  a  prin- 
ciple escapes  from  bodies  during-  combus- 
tion. This  residue  was  called  phlogisti- 
cated  air,  in  consequence  of  such  an  opi- 
nion. 

In  the  opinion  that  inflammable  air  is 
the  phlogiston,  it  is  not  necessary  to  reject 
the  second  inference,  that  the  air  has  been 
no  otherwise  changed  than  by  the  mere 
subtraction  of  one  of  its  principles :  for  the 
pure  or  vital  part  of  the  air  may  unite  with 
inflammable  air  supposed  to  exist  in  a  fix- 
ed state  in  the  combustible  body ;  and  if 
the  product  of  this  union  still  continues 
fixed,  it  is  evident,  that  the  residue  of  the 
air  after  combustion  will  be  the  same  as  it 
would  have  been,  if  the  vital  part  had  been 
absorbed  by  any  other  fixed  body.  Or,  if 
the  vital  air  be  absorbed,  while  inflamma- 
ble air  or  phlogiston  is  disengaged,  and 
unites  with  the  aeriform  residue,  this  re- 
sidue will  not  be  heavier  than  before,  un- 
less the  inflammable  air  it  has  gained  ex- 
ceeds in  weight  the  vital  air  it  has  lost ; 
and  if  the  inflammable  air  falls  short  of 
that  weight,  the  residue  will  be  lighter. 

These  theories  it  was  necessary  to  men- 
tion; but  it  has  been  sufficiently  proved 
by  various  experiments,  that  combustible 
bodies  take  oxygen  from  the  atmosphere, 
and  leave  nitrogen ;  and  that  when  these 
two  fluids  are  again  mixed,  in  due  propor- 
tions, they  compose  a  mixture  not  differ- 
ing from  atmospherical  air. 

The  respiration  of  animals  produces  the 
same  effect  on  atmospherical  air  as  com- 
bustion does,  and  their  constant  heat  ap- 
pears to  be  an  effect  of  the  same  nature. 
When  an  animal  is  included  in  a  limited 
quantity  of  atmospherical  air,  it  dies  as 
soon  as  the  oxygen  is  consumed ;  and  no 
other  air  will  maintain  animal  life  but  oxy- 
gen, or  a  mixture  which  contains  it.  Pure 
oxygen  maintains  the  life  of  animals  much 
longer  than  atmospherical  air,  bulk  for 
bulk. 

Vofc.  f.  {  17  ] 


AIR 

*  It  is  to  be  particularly  observed,  how* 
ever,  that,  in  many  cases  of  combustion, 
the  oxygen  of  the  air,  in  combining  with 
the  combustible  body,  produces  a  com- 
pound, not  solid  or  liquid,  but  aeriform. 
The  residual  air  will  therefore  be  a  mix- 
ture of  the  nitrogen  of  the  atmosphere 
with  the  consumed  oxygen,  converted  in- 
to another  gas.  Thus,  in  burning  char- 
coal, the  carbonic  acid  gas  generated, 
mixes  with  the  residual  nitrogen,  and 
makes  up  exactly,  when  the  effect  of  heat 
ceases,  the  bulk  of  the  original  air.  The 
breathing  of  animals,  in  like  manner, 
changes  the  oxygen  into  carbonic  acid 
gas,  without  altering  the  atmospherical 
volume.* 

There  are  many  provisions  in  nature  by 
which  the  proportion  of  oxygen  in  the  at- 
mosphere, which  is  continually  consumed 
in  respiration  and  combustion,  is  again 
restored  to  that  fluid.  In  fact  there  ap- 
pears, as  far  as  an  estimate  can  be  formed 
of  the  great  and  general  operations  of  na- 
ture, to  be  at  least  as  great  an  emission  of 
oxygen,  as  is  sufficient  to  keep  the  gene- 
ral mass  of  the  atmosphere  at  the  same 
degree  of  purity.  Thus,  in  volcanic  erup- 
tions there  seems  to  be  at  least  as  much 
oxygen  emitted  or  extricated  by  fire  from 
various  minerals,  as  is  sufficient  to  main- 
tain the  combustion,  and  perhaps  even  to 
meliorate  the  atmosphere.  And  in  the 
bodies  of  plants  and  animals,  which  ap- 
pear in  a  great  measure  to  derive  their  sus- 
tenance and  augmentation  from  the  atmos- 
phere and  its  contents,  it  is  found  that  a 
large  proportion  of  nitrogen  exists.  Most 
plants  emit  oxygen  in  the  sunshine,  from 
which  it  is  highly  probable  that  they  im- 
bibe and  decompose  the  air  of  the  atmos- 
phere, retaining  carbon,  and  emitting  the 
vital  part.  Lastly,  if  to  this  we  add  the 
decomposition  of  water,  there  will  be  nu- 
merous occasions  in  which  this  fluid  will 
supply  us  with  disengaged  oxygen ;  while, 
by  a  very  rational  supposition,  its  hydro- 
gen may  be  considered  as  having  entered 
into  the  bodies  of  plants  for  the  formation 
of  oils,  sugars,  mucilages,  &c.  from  which 
it  may  be  again  extricated. 

To  determine  the  respirability  or  purity 
of  air,  it  is  evident  that  recourse  must  be 
had  to  its  comparative  efficacy  in  maintain- 
ing- combustion,  or  some  other  equivalent 
process.  This  subject  will  be  considered 
under  the  article  EUDTOMETKH. 

From  the  latest  and  most  accurate  expe- 
riments, the  proportion  of  oxygen  in  at- 
mospheric air  is  by  measure  about  21  per 
cent ;  and  it  appears  to  be  very  nearly  the 
same,  whether  it  be  hi  this  country  or  on 
the  coast  of  Guinea,  on  low  plains  or  lofty 
mountains,  or  even  at  the  height  of  7250 
yards  above  the  level  of  the  sea,  as  ascer* 
turned  by  Gay-Lussar  in  his  aerial  voyage 


AIR 


AIR- 


in  September  1805.  The  remainder  of 
the  air  is  nitrogen,  with  a  small  portion  of 
aqueous  vapour,  amounting  to  about  1  per 
cent,  in  the  driest  weather,  and  a  still  less 
portion  of  carbonic  acid,  not  exceeding  a 
thousandth  part  of  the  whole. 

As  oxygen  and  nitrogen  differ  in  specific 
gravity  in  the  proportion  of  135  to  i21,  ac- 
cording to  Kirwan,  and  of  139  to  l2u  ac- 
cording to  Davy,  it  has  been  presumed, 
that  the  oxygen  would  be  more  abundant 
in  the  lower  regions,  and  the  nitrogen  in 
the  higher,  if  they  constituted  a  mere 
mechanical  mixture,  which  appears  con- 
trary to  the  fact.  On  the  other  hand  it 
has  been  urged,  that  they  cannot  be  in 
the  state  of  chemical  combination,  be- 
cause they  both  retain  their  distinct  pro- 
perties unaltered,  and  no  change  of  tem- 
perature or  density  takes  place  on  their 
union.  But  perhaps  it  may  be  said,  that, 
as  they  have  no  repugnance  to  mix  with 
each  other,  as  oil  and  water  have,  the 
continual  agitation  to  which  the  atmos- 
phere is  exposed,  may  be  sufficient  to 
prevent  two  fluids,  differing  not  more 
than  oxygen  and  nitrogen  in  gravity,  from 
separating  by  subsidence,  though  simply 
mixed.  On  the  contrary,  it  may  be  ar- 
gued, that  to  say  chemical  combination 
cannot  take  place  without  producing  new 
properties,  which  did  not  exist  before  in 
the  component  parts,  is  merely  begging 
the  question;  for  though  this  generally 
appears  to  be  the  case,  and  ofteu  in  a  very 
striking  manner,  yet  combination  does  not 
always  produce  a  change  of  properties,  as 
appears  in  M.  Biot;s  experiments  with  va- 
rious substances,  of  which  we  may  instance 
water,  the  refraction  of  which  is  precisely 
the  mean  of  that  of  the  oxygen  and  hy- 
drogen, which  are  indisputably  combined 
in  it. 

To  get  rid  of  the  difficulty,  Mr.  Dalton 
of  Manchester  framed  an  ingenious  hypo- 
thesis, that  the  particles  of  different  gases 
neither  attract  nor  repel  each  other;  so 
that  one  gas  expands  by  the  repulsion  of 
its  own  particles,  without  any  more  inter 
ruption  from  the  presence  of  another  gas, 
than  if  it  were  in  a  vacuum.  This  would 
account  for  the  state  of  atmospheric  air, 
it  is  true ;  but  it  does  not  agree  with  cer- 
tain facts.  In  the  case  of  the  carbonic 
acid  g-as  in  the  Grotto  del  Cano,  and  over 
the  surface  of  brewers'  vats,  why  does 
not  this  gas  expand  itself  freely  upward, 
if  the  superincumbent  gases  do  not  press 
upon  it  ?  Mr.  Dalton  himself  too  instances 
as  an  argument  for  his  hypothesis,  that 
oxygen  and  hydrogen  gases,  when  mixed 
by  agitation,  do  not  separate  on  standing. 
But  why  should  either  oxygen  or  hydro- 
gen require  agitation,  to  diffuse  it  through 
a  vacuum,  in  which,  according  to  Mr. 
Dalton,  it  is  placed? — C. 


The  theory  of  Berthollet  appears  con- 
sistent with  all  the  facts,  and  sufficient  to 
account  for  the  phenomenon.  If  two  bo- 
dies be  capable  of  chemical  combination, 
their  particles  must  have  a  mutual  attrac- 
tion for  each  other.  This  attraction,  how- 
ever, may  be  so  opposed  by  concomitant 
circumstances,  that  it  may  be  diminished 
in  any  degree.  Thus  we  know,  that  the 
affinity  of  aggregation  may  occasion  a  bo- 
dy to  combine  slowly  with  a  substance  for 
which  it  has  a  powerful  affinity,  or  even 
entirely  prevent  its  combining  with  it;  the 
presence  of  a  third  substance  may  equally 
prevent  the  combination ;  and  so  may  the 
absence  of  a  certain  quantity  of  caloric. 
But  in  all  these  cases  the  attraction  of  the 
particles  must  subsist,  though  diminished 
or  counteracted  by  opposing  circum- 
stances. Now  we  know  that  oxygen  and 
nitrogen  are  capable  of  combination; 
their  particles,  therefore,  must  attract 
each  other;  but  in  the  circumstances  in 
which  they  are  placed  in  our  atmosphere, 
that  attraction  is  prevented  from  exerting; 
itself  to  such  a  degree  as  to  form  them  in- 
to a  chemical  compound,  though  it  ope- 
rates with  sufficient  force  to  prevent  their 
separating  by  their  difference  of  specific 
gravity.  Thus  the  state  of  the  a'mosphere 
is  accounted  for,  and  every  difficulty  ob- 
viated, without  any  new  hypothesis. 

*  The  exact  specific  gravity  of  atmos- 
pherical  air,  compared  to  that  of  water,  is 
a  very  nice  and  important  problem.  By 
reducing  to  60°  Fahr.  and  to  30  inches  of 
the  barometer,  the  results  obtained  with 
great  care  by  MM.  Biot  and  Arago,  the 
specific  gravity  of  atmospherical  air  ap- 
pears to  be  0.001220,  water  being  repre- 
sented by  1.000000.  This  relation  ex- 
pressed fractionally  is  y£^  or  water  is  820 
times  denses  than  atmospherical  air.  Mr. 
Rice,  in  the  77th  and  78th  numbers  of 
the  Annals  of  Philosophy,  deduces  from 
Sir  George  Shuckburgh  s  experiments 
0.00120855  for  the  specific  gravity  of  air. 
This  number  gives  water  to  air  as  827.437 
to  1.  If  with  Mr.  Rice  we  take  the  cubic 
inch  of  water  ~*  252.525  gr.  then  100  cu- 
bic inches  of  air  by  Biot's  experiments  will 
weigh  30. 808  gr.  and  by  Mr.  Rice  s  esti- 
mate 30.519.  He  considers  with  Dr.  ProuJ: 
the  atmosphere  to  be  a  compound  of  4 
volumes  of  nitrogen,  and  1  of  oxygen ;  the 
specific  gravity  of  the  first  being  to  that 
of  the  second"  as  1.1111  to  0.9722. 

Hence 

0.8  vol.  nitr.    sp.  gr.  0.001166=  0.000940 

0.2         oxy.  0.001340 « 0.000268 

0.001208 

The  numbers  are  transposed  in  the  An- 
nals of  Philosophy  by  some  mistake.. 


ALA 


ALB 


M  M.  Biot  and  Arago  found  the  speci- 
fic gravity  of  oxygen  to  be  -     -     l.la;59 
and  that  of  nitrogen,    -    -    -    -     0.96913 
air  being  reckoned,      -     -     -    -     1.00000 
Or  compared  to  water  as  unity, — 
Nitrogen  is          0.001182338 
Oxygen,  0,001346379 

And  0.8  nitrogen  =  0,00094587 

0.2  oxygen  =-  0.00026927 

0.00121514 


And  0.79  nitrogen  =-     0.000934 

0.21  oxygen  =     0.000283 

0.001217 

A  number  which  approaches  very  nearly 
to  the  result  of  experiment.  Many  ana- 
logies, it  must  be  confessed,  favour  Dr. 
Prout's  proportions;  but  the  greater  num- 
ber of  experiments  on  the  composition 
and  density  of  the  atmosphere  agree  with 
Biot's  results.  Nothing  can  decide  these 
fundamental  chemical  proportions  except 
a  new,  elaborate,  and  most  minutely  accu- 
rate series  of  experiments.  We  shall  then 
know  whether  the  atmosphere  contains 
in  volume  20  or  21  per  cent  of  oxygen. 
See  METEOUOLOGY.* 

ALABASTEU.  Among  the  stones  which 
are  known  by  the  name  of  marble,  and 
have  been  distinguished  by  a  considerable 
variety  of  denominations  by  statuaries,  and 
others  whose  attention  is  more  directed 
to  their  external  character  and  appear- 
ance than  their  component  parts,  alabas- 
ters are  those  which  have  a  greater  or  less 
degree  of  imperfect  transparency,  a  gran- 
ular texture,  are  softer,  take  a  duller  po- 
lish than  marble,  an^[  are  usually  of  a 
whiter  colour.  Some  stones,  however,  of 
a  veined  and  coloured  appearance,  have 
been  considered  as  alabasters,  from  their 
possessing  the  first  mentioned  criterion  ; 
and  some  transparent  and  yellow  sparry 
Stones  have  also  received  this  appellation. 

Chemists  are  at  present  agreed  in  ap- 
plying this  name  only  to  such  opaque, 
consistent,  and  semi-transparent  stones,  as 
are  composed  of  lime  united  with  the  sul- 
phuric acid.  But  the  term  is  much  more 
frequent  among  masons  and  statuaries 
than  chemists.  Chemists  in  general  con- 
found the  alabasters  among  the  selenites, 
gypsums,  or  plaster  of  Paris,  more  espe- 
cially when  they  allude  only  to  the  com- 
ponent parts,  without  having  occasion  to 
consider  the  external  appearance,  in 
which  only  these  several  compounds  dif- 
fer from  each  other. 

As  the  semi-opaque  appearance  and 
granular  texture  arise  merely  from  a  dis- 
turbed or  successive  crystallization,  which 
would  else  have  formed  transparent  spars, 
it  is  accordingly  found,  that  the  calcareous 
stalactites,  or  drop-stones,  formed  by  the- 


transitioa  of  water  through  the  roofs  d£ 
caverns  in  a  calcareous  soil,  do  not  differ 
in  appearance  from  the  alabaster,  most  of 
which  is  also  formed  in  this  manner.  But 
the  calcareous  stalactites  here  spoken  of 
consist  of  calcareous  earth  and  carbonic 
acid;  while  the  alabaster  of  the  chemists 
is  formed  of  the  same  earth  and  sulphuric 
acid,  as  has  already  been  remarked. 

*  ALBKV  A  mineral  discovered  at  Mo- 
naberg,  near  Aussig,  in  Bohemia ;  and  be- 
ing of  an  opaque  white  colour,  has  been 
called,  by  Werner,  albin.  Aggregated 
crystalline  laminae  constitute  massive  albin. 
Small  crystals  of  it  in  right  prisms,  whose 
summits  consist  of  four  quadrangular 
planes,  are  found  sprinkled  over  mamme- 
lated  masses  in  cavities.*  See  ZEOLITE. 

ALBUM  GRJECTJM.  Innumerable  are  the  in- 
stances of  fanciful  speculation  and  absurd 
credulity  in  the  invention  and  application 
of  subjects  in  the  more  ancient  ma-terra 
medica.  The  white  and  solid  excrement 
of  dogs,  which  subsist  chiefly  on  bones, 
has  been  received  as  a  remedy  in  the 
medical  art,  under  the  name  of  Album 
Grxcum.  It  consists,  for  the  most  part, 
of  the  earth  of  bones,  or  lime  in  combin- 
ation with  phosphoric  acid. 

ALBUMEN.  This  substance,  which  derives 
its  name  from  the  Latin  for  the  white  of 
an  egg,  in  which  it  exists  abundantly,  and 
in  its  purest  natural  state,  is  one  of  the 
chief  constituent  principles  of  all  the 
animal  solids.  Beside  the  white  of  egg, 
it  abounds  in  the  serum  of  blood,  the 
vitreous  and  crystalline  humours  of  the 
eye,  and  the  fluid  of  dropsy.  Fourcroy 
claims  to  himself  the  honour  of  having 
discovered  it  in  the  green  feculae  of  plants 
in  general,  particularly  in  those  of  the 
cruciform  order,  in  very  young  ones,  and 
in  the  fresh  shoots  of  trees,  though 
Rouelle  appears  to  have  detected  i'  there 
long  before.  Vauquelin  says  it  exists  also 
in  the  mineral  wa  er  of  Plombieres. 

Mr.  Seguin  has  found  it  in  remarkable 
quantity  in  such  vegetables  as  ferment 
without  yeast,  and  afford  a  vinous  liquor; 
and  from  a  series  of  experiments  he  infers 
that  albumen  is  the  true  principle  of 
fermentation,  and  that  its  action  is  more 
powerful  in  proportion  to  its  solubility, 
three  different  degrees  of  which  he  found 
it  to  possess. 

The  chief  characteristic  of  albumen  is 
its  coagulability  by  the  action  of  heat.  If 
the  white  of  an  egg  be  exposed  to  a  heat 
of  about  134°  F.  white  fibres  begin  to 
appear  in  it,  and  at  160°  it  coagulates  into 
a  solid  mass.  In  a  heat  not  exceeding 
212°  it  dries,  shrinks,  and  assumes  the 
appearance  of  horn.  It  is  soluble  in  cold 
water  before  it  has  been  coagulated,  but 
not  after ;  and  when  diluted  with  a  very 
large  portion,  it  does  not  coagulate  easily. 


ALB 


ALB 


Pure  alkalis  dissolve  it,  even  after  coagu- 
lation. It  is  precipitated  by  muriate  of 
mercury,  nitro-muriate  of  tin,  acetate  of 
lead,  nitrate  of  silver,  muriate  of  gold, 
infusion  of  galls,  and  tannin.  The  acids 
and  metallic  oxides  coagulate  albumen, 
On  the  addition  of  concentrated  sulphuric 
acid,  it  becomes  black,  and  exhales  a 
nauseous  smell.  Strong  muriatic  acid 
gives  a  violet  tinge  to  the  coagulum,  and 
at  length  becomes  saturated  with  ammonia. 
Nitric  acid,  at  70°  R  disengages  from  it 
abundance  of  azotic  gas  ;  and  if  the  heat 
be  increased  prussic  acid  is  formed,  after 
which  carbonic  acid  and  carburette^d  hy- 
drogen are  evolved,  and  the  residue 
consists  of  water  containing  a  little  oxalic 
acid,  and  covered  with  a  lemon  coloured 
fat  oil.  If  dry  potash  or  soda  be  triturated 
with  albumen,  either  liquid  or  solid, 
ammpniacal  gas  is  evolved,  and  the  cal- 
cination of  the  residuum  yields  an  alkaline 
prussiate. 

On  exposure  to  the  atmosphere  in  a 
moist  state,  albumen  passes  at  once  to  the 
state  of  putrefaction. 

*  Solid  albumen  may  be  obtained  by 
agitating  white  of  egg  with  ten  or  twelve 
times  its  weight  of  alcohol.  This  seizes 
the  water  which  held  the  albumen  in  solu- 
tion; and  this  substance  is  precipitated 
under  the  form  of  white  flocks  or  filaments, 
which  cohesive  attraction  renders  insolu- 
ble, and  which  consequently  may  be  freely 
washed  with  water.  Albumen  thus  ob- 
tained is  like  fibrin,  solid,  white,  insipid, 
inodorous,  denser  than  water,  and  without 
action  on  vegetable  colours.  It  dissolves 
in  potash  and  soda  more  easily  than 
fibrin;  but  in  acetic  acid  and  ammonia 
with  more  difficulty.  When  these  two 
animal  principles  are  separately  dissolved 
in  potash,  muriatic  acid  added  to  the 
albuminous  does  not  disturb  the  solution, 
but  it  produces  a  cloud  in  the  other. 

Fourcroy  and  several  other  chemists 
have  ascribed  ihe  characteristic  coagula- 
tion of  albumen  by  heat  to  its  oxygenation. 
But  cohesive  attraction  is  the  real  cause 
of  the  phenomenon.  In  proportion  as  the 
temperature  rises,  the  particles  of  water 
and  albumen  recede  from  each  other, 
their  affinity  diminishes,  and  then  the  albu- 
men precipitates.  However,  by  uniting 
albumen  with  a  large  quantity  of  water, 
we  diminish  its  coagulating  property  to 
such  a  degree,  that  heat  renders  the  solu- 
tion merely  opalescent.  A  new-laid  egg 
yields  a  soft  coagulum  by  boiling ;  but 
when,  by  keeping,  a  portion  of  the  water 
has  transuded  so  as  to  leave  a  void  space 
within  the  shell,  the  concentrated  albu- 
men affords  a  firm  coagulum.  An  analo- 
gous phenomenon  is  exhibited  by  acetate  of 
alumina,  a  solution  of  which,  being  heat- 
ed, gives  a  precipitate  in  flakes,  which  re- 


dissolve  as  the  caloric  which  separated  the 
particles  of  acid  and  base  escapes,  or  as  the 
temperature  falls.  A  solution  containing 
T^  of  dry  albumen  forms  by  heat  a  solid 
coagulum  ;  but  when  it  contains  only  Tl^f 
it  gives  a  glairy  liquid.  One  thousandth 
part,  however,  on  applying  heat,  occa- 
sions opalescence.  Putrid  white  of  egg,  and 
the  pus  of  ulcers,  have  a  similar  smell. 
According  to  Dr.  Bostock,  a  drop  of  a 
saturated  solution  of  corrosive  sublimate 
letfall  into  water  containing  -%-QQ-Q  of  albu- 
men, occasions  a  milkuiess  and  curdy  pre- 
cipitate. On  adding  a  slight  excess  of  the 
mercurial  solution  to  the  albuminous  li- 
quid, and  applying  heat,  the  precipitate 
which  falls,  being  dried,  contains  in  every 
7  parts,  5  of  albumen.  Hence  that  salt  is 
the  most  delicate  test  of  this  animal  pro- 
duct. The  yellow  pitchy  precipitate  oc- 
casioned by  tannin,  is  brittle  when  dried, 
and  not  liable  to  putrefaction.  But  tannin, 
or  infusion  of  galls,  is  a  much  nicer  test  of 
gelatin  than  of  albumen. 

The  cohesive  attraction  of  coagulated 
albumen  makes  it  resist  putrefaction.  In 
this  state  it  may  be  kept  for  weeks  under 
water  without  suffering  change.  By  long 
digestion  in  weak  nitric  acid,  albumen 
seems  convertible  into  gelatin.  Bv  the 
analysis  of  Gay-Lussac  and  Thenaru,  lOO 
parts  of  albumen  are  foruied  of  52  titte  car- 
bon, 23.872  oxygen,  7.540  hydrogen, 
15.70.5 ni;:rogen;or,  in  other  terms,of  52.683 
carbon,  27. 12'/  oxygen  and  hydrogen,  in 
the  proportions  for  constituting  water, 
15.705  nitrogen,  arid  4.285  hydrogen  in 
excess.  The  negative  pole  of  a  voltaic 
pile  in  high  activity  coagulates  albumen; 
bui  if  the  pile  be  feeble,  coagulation  goes 
on  only  at  the  positive  surface.  Albumen, 
in  such  a  state  of  concentration  as  it  exists 
in  serum  of  blood,  can  dissolve  some  me- 
tallic oxides,  particularly  the  protoxide  of 
iron.  Orfila  has  found  white  of  egg  to  be 
the  best  antidote  to  the  poisoning  effects 
of  corrosive  sublimate  on  the  human  sto- 
mach. As  albumen  occasions  precipitates 
with  the  solutions  of  almost  every  metal- 
lic salt,  probably  it  may  act  beneficially 
against  other  species  of  mineral  poison.* 

From  its  coagulability  albumen  is  of 
great  use  in  clarifying  liquids.  See  CLA- 

1UFICATIO1V. 

It  is  likewise  remarkable  for  the  pro- 
perty of  rendering  leather  supple,  for 
which  purpose  a  solution  of  whites  of  eggs 
in  water  is  used  by  leather-dressers ;  and 
hence  Dr.  Lobb  of  Yeovil  in  Somerset- 
shire was  induced  to  employ  this  solution 
in  cases  of  contraction  and  rigidity  of  the 
tendons,  and  derived  from  it  apparent 
success. 

Whites  of  eggs  beaten  in  a  basin  with  a 
Jump  of  alum,  till  they  coagulate,  form  the 


ALC 


ALC 


vlnmcurdof  Riverius,  or  alum  cataplasm  of 
the  London  Pharmacopoeia,  used  to  re- 
move inflammations  of  the  eyes. 

*  ALBURNUM.     The  interior  white  bark 
of  trees.* 

*  AicARRAZAi.    A  species  of  porous 
pottery  made  in  Spain,  for  the  purpose  of 
cooling  water  by  its  transudation  and  co- 
pious evaporation  from  the  sides  of  the 
vessel.     M.  Darcet  gives  the  following  as 
the  analysis  of  the  clay  which  is  employed 
for  the   purpose :    60   calcareous    earth, 
mixed  with  alumina  and  a  little  peroxide 
of  iron,  and  36  of  siliceous  earth,  mixed 
with  a  little  alumina.    In  working  up  the 
earths  with  water,  a  quantity  of  salt  is  ad- 
ded, and  dried  in  it.     The  pieces  are  only 
half  baked.* 

*  ALOUEMT.    A  title  of  dignity,  given 
in  the  dark  ages,  by  the  adepts,  to  the 
mystical  art  by  which  they  professed  to 
find  the  philosopher's  stone,  that  was  to 
transmute  base  metals  into  gold,  and  pre- 
pare the  elixir  ot  life.     Though  avarice, 
fraud,  and  folly  were  their  motives,  yet 
their  experimental  researches  were  instru- 
mental in  promoting  the  progress  of  che- 
mical  discovery.    Hence,  in    particular, 
metallic  pharmacy  derived  its  origin.* 

ALCOHOL.  This  term  is  applied  in  strict- 
ness only  to  the  pure  spirit  obtainable  by 
distillation  and  subsequent  rectification 
from  all  liquids  that  have  undergone  vi- 
nous fermentation,  and  from  none  but  such 
as  are  susceptible  of  it.  But  it  is  common- 
ly used  to  signify  this  spirit  more  or  less 
imperfectly  freed  from  water,  in  the  state 
in  which  it  is  usually  met  with  in  the  shops, 
and  in  which,  as  it  was  first  obtained  from 
the  juice  of  the  grape,  it  was  long  distin- 
gs  ished  by  the  name  of  spirit  of  wine.  At 
.present  it  is  extracted  chiefly  from  grain 
or  molasses  in  Europe,  and  from  the  juice 
of  the  sugar-cane  in  the  West  Indies ;  and 
in  the  diluted  state  in  which  it  commonly 
ficcurs  in  trade,  constitutes  the  basis  of 
the  several  spirituous  liquors  called  bran- 
dy, rum,  gin,  whiskev ,  and  cordials,  how- 
ever variously  denominated  or  disguised. 

As  we  are  not  able  to  compound  alco- 
hol immediately  from  its  ultimate  consti- 
tuents, we  have  recourse  to  the  process 
of  fermentation,  by  which  its  principles 
are  first  extricated  from  the  substances  in 
which  they  were  combined,  and  then  uni- 
ted into  a  new  compound ;  to  distillation, 
by  which  this  new  compound,  the  alcohol 
is  separated  in  a  state  of  dilution  with  wa- 
ter, and  contaminated  with  essential  oil ; 
and  to  rectification,  by  which  it  is  ultimate- 
ly freed  from  these. 

It  appears  to  be  essential  to  the  fermen- 
tation of  alcohol,  that  the  fermenting  fluid 
should  contain  saccharine  matter,  which 
is  indispensable  to  that  species  of  fermen- 
tation called  vinous.  In  France,  where  a 


great  deal  of  wine  is  made,  particularly  at 
the  commencement  of  the  vintage,  that 
is  too  weak  to  be  a  saleable  commodity,  it 
is  a  common  practice  to  subject  this  wine 
to  distillation,  in  order  to  draw  oft'  the 
spirit ;  and  as  the  essential  oil  that  rises  in 
this  process  is  of  a  more  pleasant  flavour 
than  that  of  malt  or  molasses,  the  French 
brandies  are  preferred  to  any  other; 
though  even  in  the  flavour  of  these  there 
is  a  difference,  according  to  the  wine  from 
which  they  are  produced.  In  the  West 
Indies  a  spirit  is  obtained  from  the  juice 
of  the  sugar-cane,  which  is  highly  impreg- 
nated with  its  essential  oil,  and  well  known 
by  the  name  of  rum.  The  distillers  in  this 
country  use  grain,  or  molasses,  whence 
they  distinguish  the  products  by  the  name 
of  malt  spirits,  and  molasses  spirits.  It  is 
said  that  a  very  good  spirit  may  be  ex- 
tracted from  the  husks  of  gooseberries  or 
currants,  after  wine  has  been  made  from 
them. 

As  the  process  of  malting  developes  the 
saccharine  principle  of  grain,  it  would  ap. 
pear  to  render  it  fitter  for  the  purpose ; 
though  it  is  the  common  practice  to  use 
about  three  parts  of  raw  grain  with  one  of 
malt.  For  this,  two  reasons  may  be  assign- 
ed :  by  using  raw  grain  the  expense  of 
malting  is  saved,  as  well  as  the  duty  on 
malt ;  and  the  process  of  malting  requires 
some  nicety  of  attention,  ><ince,  if  it  be 
carried  too  far,  part  of  the  saccharine  mat- 
ter is  lost,  and  if  it  be  stopped  too  soon, 
this  matter  will  not  be  wholly  developed. 
Besides,  if  the  malt  be  dried  too  quickly, 
or  by  an  unequal  heat,  the  spirit  it  yields 
will  be  less  in  quantity,  and  more  unplea- 
sant in  flavour.  Another  object  of  econo- 
mical consideration  is,  what  grain  will  af- 
ford the  most  spirit  in  proportion  to  its 
price,  as  well  as  the  best  in  quality.  Bar- 
ley appears  to  produce  less  spirit  than 
wheat ;  and  if  three  parts  of,  raw  wheat 
be  mixed  with  one  of  majted  barley,  the 
produce  is  said  to  be  particularly  fine. 
This  is  the  practice  of  the  distillers  in  Hol- 
land for  producing-  a  spirit  of  the  finest 
quality ;  but  in  England  they  are  express- 
ly prohibited  from  using  more  than  one 
part  of  wheat  to  two  of  other  grain.  Rye, 
however,  affords  still  more  spirit  than 
wheat. 

*  The  practice  with  the  distillers  in 
Scotland  is  to  use  one  part  of  malted  with 
from  four  to  nine  parts  of  unmalted  grain. 
This  mixture  yields  an  equal  quantity  of 
spirit,  and  at  a  much  cheaper  rate  than 
when  the  former  proportions  are  taken.* 

Whatever  be  the  grain  employed,  it  may 
be  coarsely  ground,  and  then  mixed  care- 
fully with  a  little  cold  water,  to  prevent 
its  running  into  lumps ;  water  about  90* 
F.  may  then  be  added,  till  it  is  sufficiently 
diluted ;  and,  lastly,  a  sufficient  quantity 


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of  yeast.  The  whole  is  then  to  be  allow- 
ed to  ferment  in  acovered  vessel,  to  which, 
however,  the  air  can  have  access.  Atten- 
tion must  be  paid  to  the  temperature  ;  for 
if  it  exceed  77°  F.  the  fermentation  will 
be  too  rapid  ;  if  it  be  below  60°,  the  fer- 
mentation will  cease.f  The  mean  between 
these  will  generally  be  found  most  favour- 
able. In  this  country  it  is  the  more  com- 
mon practice  to  mash  the  grain  as  for 
brewing  malt  liquors,  and  boil  the  wort. 
But  in  whichever  way  it  be  prepared,  or 
if  the  wash,  so  the  liquor  intended  for  dis- 
tillation is  called,  be  made  from  molasses 
and  water,  due  attention  must  be  gaid  to 
the  fermentation,  that  it  be  continued  till 
the  liquor  grows  fine,  and  pungent  to  the 
taste,  whicn  will  generally  be  about  the 
third  day,  but  not  so  long  as  to  permit  the 
acetous  fermentation  to  commence. 

In  this  state  the  wash  is  to  be  commit- 
ted to  the  still,  of  which,  including  the 
head,  it  should  occupy  at  least  three- 
fburihs;  and  distilled  with  a  gentle  heat 
as  long  as  any  spirit  comes  over,  which 
will  be  till  about  half  the  wash  is  consum- 
ed. The  more  slowly  the  distillation  is 
conducted,  the  less  will  the  product  be 
contaminated  with  essential  oil,  and  the 
less  danger  will  there  be  of  empyreuma. 
A  great  saving  of  time  and  fuel,  however, 
s»ay  be  obtained  by  making  the  still  very 
broad  and  shallow,  and  contriving  a  free 
exit  for  the  steam.  This  has  been  carried 
to  such  a  pitch  in  Scotland,  that  a  still  mea- 
suring 43  gallons,  and  containing  16  gal- 
lons of  wash,  has  been  charged  and  work- 
ed no  less  than  four  hundred  and  eighty 
limes  in  the  space  ef  twenty -four  hours. 
This  would  be  incredible,  were  it  not  esta- 
blished by  unquestionable  evidence.  See 
LABORATORY,  article  STILL. 

*  The  above  wonderful  rapidity  of  dis- 
tillation has  nuw  ceased,  since  the  excise 
duties  have  been  levied  or  the  quantity  of 
spirit  produced,  and  not,  as  formerly,  by 
the  size  of  the  still.  Hence,  too,  the  spi- 
rit is  probably  improved  in  flavour.* 

The  first  product,  technically  termed 
iota  tvine,  is  again  to  be  subjected  to  dis- 
tillation, the  latter  portions  of  what  comes 
over,  called  faints,  being  set  apart  to  put 
into  the  wash  still  at  some  future  opera- 
tion. Thus  a  large  portion  of  the  watery 
partis  left  behind.  This  second  product, 
termed  mtv  spirit,  being  distilled  again,  is 
called  rectified  spirit.  It  is  calculated,  that 
a  hundred  gallons  of  malt  or  corn  wash  will 
not  produce  above  twenty  of  spirit,  con- 
taining 60  parts  of  alcohol  to  50  of  water; 
the  same  of  cyder  wash,  15  gallons;  and 
of  molasses  wash,  22  gallons.  The  most 

•j-  This  is  a  mistake ;  fermentation  will 
go  on  very  slowly  10  degrees  lower. 


spirituous  wines  of  France,  those  of  Lati- 
guedoc,  Guienne,and  Rousillon,  yield,  ac- 
cording to  Chaptal,  from  20  to  25  gallons 
of  excellent  brandy  from  100  ;  but  those 
of  Burgundy  and  Champagne  much  less. 
Brisk  wines,  containing  much  carbonic 
acid,  from  the  fermentation  having  been 
stopped  at  an  early  period,  yield  the  least 
spirit. 

The  spirit  thus  obtained  ought  to  be  co- 
lourless, and  free  from  any  disagreeable 
flavour ;  and  in  this  state  it  is  fittest  for 
pharmaceutical  purposes,  or  the  extraction 
of  tinctures.  But  for  ordinary  sale  some- 
thing more  is  required.  The  brandy  of 
France,  which  is  most  in  esteem  here, 
though  perfectly  colourless  when  first 
made,  and  often  preserved  so  for  use  in 
that  country,  by  being  kept  in  glass  or 
stone  bottles,  is  put  into  new  oak  casks 
for  exportation,  whence  it  soon  acquires 
an  amber  colour,  a  peculiar  flavour,  and 
something  like  an  unctuosity  of  consis- 
tence. As  it  is  not  only  prized  for  these 
qualities,  but  they  are  commonly  deemed 
essential  to  it,  the  English  distiller  imi- 
tates by  design  these  accidental  qualities. 
The  most  obvious  and  natural  method  of 
doing  this  would  be  by  impregnating  a 
pure  spirit  with  the  extractive,  resinous, 
and  colouring  matter  of  oak  shavings ;  but 
other  modes  have  been  contrived.  The 
dulcified  spirit  of  nitre,  as  it  is  called,  is 
commonly  used  to  give  the  flavour ;  and 
catechu,  or  burnt  sugar,  to  impart  the  de- 
sired colour.  A  French  writer  has  recom- 
mended three  ounces  and  a  half  of  finely 
powered  charcoal,  and  four  ounces  and  a 
half  of  ground  rice,  to  be  digested  for  a 
fortnight  in  a  quart  of  malt  spirit. 

The  finest  gin  is  said  to  be  made  in  Hol- 
land, from  a  spirit  drawn  from  wheat  mix- 
ed with  a  third  or  fourth  part  of  malted 
barley,  and  twice  rectified  over  juniper 
berries;  but  in  general,  rye  meal  is  used 
instead  of  wheat.  They  pay  so  much  re- 
gard to  the  water  employed,  that  many 
send  vessels  to  fetch  it  on  purpose  from 
the  Meuse;  but  all  use  the  softest  and 
clearest  river  water  they  can  get.  In  Eng- 
land it  is  the  common  practice  to  add  oil 
of  turpentine,  in  the  proportion  of  two 
ounces  to  ten  gallons  of  raw  spirit,  with 
three  handfuls  of  bay  salt,  and  draw  off 'till 
the  faints  begin  to  rise. 

But  corn  or  molasses  spirit  is  flavoured 
likewise  by  a  variety  of  aromatics,  with  or 
without  sugar,  to  please  different  palates ; 
all  of  which  are  included  under  the  gene- 
ral technical  term  of  compounds  or  cordials. 

Other  articles  have  been  employed, 
though  not  generally,  for  the  fabrication 
of  spirit,  as  carrots  and  potatoes ;  and  we 
are  lately  informed  by  Professor  Proust, 
that  from  the  fruit  of  the  carob  tree  ho 


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has  obtained  good  brandy  in  the  propct- 
tion  ot  a  pint  from  five  pounds  of  the  dried 
fruit. 

To  obtain  pure  alcohol,  different  pro- 
cesses have  been  recommended ;  but  the 
purest  rectified  spirit  obtained  as  above 
described,  being  that  which  is  least  con- 
taminated with  foreign  matter,  should  be 
employed.  Rouclle  recommends  to  draw 
oil  half  the  spirit  in  a  water  bath;  to  rec- 
tify this  twice  more,  drawing  off  two-thirds 
each  time ;  to  add  water  to  this  alcohol, 
which  wJlturn  it  milky  by  separating  the 
essental  oil  remaining  in  it ;  to  distil  the 
spirit  from  this  water ;  and  finally  rectify 
it  by  one  more  distillation. 

Baume  sets  apart  the  first  running,  when 
about  a  fourth  is  come  over,  and  contin- 
ues the  distillation  till  he  has  drawn  off" 
about  as  much  more,  or  till  the  liquor  runs 
oft'  milky.  The  last  running  he  puts  into 
the  still  again,  and  mixes  the  first  half  of 
what  comes  over  with  the  preceding  first 
product.  This  process  is  again  repeated, 
and  all  the  first  products  being  mixed  to- 
gether, are  distilled  afresh.  When  about 
half  the  liquor  is  come  over,  this  is  to  be 
set  apart  as  pure  alcohol. 

Alcohol  in  this  state,  however,  is  not  so 
pure  as  when,  to  use  the  language  of  the 
old  chemists,  it  has  been  dephlegmated,  or 
still  further  freed  from  water,  by  means  of 
some  alkaline  salt.  Boerhaave  recom- 
mended, for  this  purpose,  the  muriate  of 
soda,  deprived  of  its  water  of  crystalliza- 
tion by  heat,  and  added  hot  to  the  spirit. 
But  the  subcarbonate  of  potash  is  prefera- 
ble. About  a  third  of  the  weight  of  the 
alcohol  should  be  added  to  it  in  a  glass 
vessel,  well  shaken,  and  then  suffered  to 
subside.  The  salt  will  be  moistened  by 
the  water  absorbed  from  the  alcohol ; 
which  being  decanted,  more  of  the  salt  is 
to  be  added,  and  this  is  to  be  continued  till 
the  salt  falls  dry  to  the  bottom  of  the 
vessel.  The  alcohol  in  this  state  will  be 
reddened  by  a  portion  of  the  pure  potash, 
which  it  will  hold  in  solution,  from  which 
it  must  be  freed  by  distillation  in  a  water 
bath.  Dry  muriate  of  lime  may  be  substi- 
tuted advantageously  for  the  alkali. 

As  alcohol  is  much  lighter  than  water, 
its  specific  gravity  is  adopted  as  the  test 
of  its  purity.  Fourcroy  considers  it  as 
rectified  to  the  highest  point  when  its  spe- 
oific  gravity  is  829,  that  of  water  being 
1000 ;  and  perhaps  this  is  nearly  as  far  as 
it  can  be  carried  by  the  process  of  Rou- 
elle  or  Baume  simply.  Mr.  Bories  found 
*he  first  measure  that  came  over  from 
twenty  of  spirit  at  836  to  be  820,  at  the 
temperature  of  71°  F.  Sir  Charles  Blag- 
den,  by  the  addition  of  alkali,  brought  it 
to  813,  at  60°  F.  Chaussier  professes  to 
have  reduced  it  to  798  ;  but  he  gives 
998,35  as  the  specific  gravity  of  water. 


Lowitz  asserts,  that  he  has  obtained  it  at 
791,  by  adding  as  much  alkali  as  nearly  to 
absorb  the  spirit ;  but  the  temperature  is 
not  indicated.  In  the  shops  it  is  about  835 
or  840 ;  according  to  ihe  London  College 
it  should  be  815. 

It  is  by  no  means  an  easy  undertaking 
to  determine  the  strength  or  relative  value 
of  spirits,  even  with  sufficient  accuracy  for 
commercial  purposes.  The  following  re- 
quisites must  be  obtained  before  this  can 
be  well  done  :  the  specific  gravity  of  a 
certain  number  of  mixtures  of  alcohol  and 
water  must  be  taken  so  near  each  other, 
as  that  the  intermediate  specific  gravities 
may  not  perceptibly  differ  from  those  de- 
duced from  the  supposition  of  a  mere  mix- 
ture of  the  fluids;  the  expansions  of  varia- 
tions of  specific  gravity  in  these  mixtures 
must  be  determined  at  different  tempera- 
tures ;  some  easy  method  must  be  con- 
trived of  determining  the  presence  and 
quantity  of  saccharine  or  oleaginous  mat- 
ter which  the  spirit  may  hold  in  solution, 
and  the  effect  of  such  solution  on  the  spe- 
cific gravity  ;  and  lastly,  the  specific  gra- 
vity of  the  fluid  must  be  ascertained  by  a 
proper  floating  instrument  with  a  graduat- 
ed stem.,,  or  set  of  weights  ;  or,  which  may 
be  more  convenient,  with  both. 

The  strength  of  brandies  in  commerce 
is  judged  by  the  phial,  or  by  burning. 
The  phial  proof  consists  in  agitating  the 
spirit  in  a  bottle,  and  observing  the  form 
and  magnitude  of  the  bubbles  that  collect 
round  the  edge  of  the  liquor,  technically 
termed  the  bead,  which  are  larger  the 
stronger  the  spirit.  These  probably  de- 
pend on  the  solution  of  resinous  matter 
from  the  cask,  which  is  taken  up  in  greater 
quantities,  the  stronger  the  spirit.  It  is 
not  difficult,  however,  to  produce  this  ap- 
pearance by  various  simple  additions  to 
weak  spirit.  The  proof  by  burning  is 
also  fallacious ;  because  the  magnitude  of 
the  flame,  and  quantity  of  residue,  in  the 
same  spirit,  vary  greatly  with  the  form  of 
the  vessel  it  is  burned  in.  If  the  vessel 
be  kept  cool,  or  suffered  to  become  hot, 
if  it  be  deeper  or  shallower,  the  results 
will  not  be  the  same  in  each  case.  It  does 
not  follow,  however,  but  that  manufactu- 
rers and  others  may  in  many  instances  re- 
ceive considerable  information  from  these 
signs,  in  circumstances  exactly  alike,  and 
in  the  course  of  operations  wherein  it 
would  be  inconvenient  to  recur  continu- 
ally to  experiments  of  specific  gravity. 

The  importance  of  this  object,  as  well 
for  the  purposes  of  revenue  as  of  com- 
merce, induced  the  British  government  to 
employ  Dr.  Blagden,  now  Sir  Charles,  to 
institute  a  very  minute  and  accurate  series 
of  experiments.  These  may  be  consider- 
ed as  fundamental  results ;  for  which  rea- 
son, I  shall  give  a  summary  of  tliein  in  this 


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place,  from  the  Philosophical  Transactions 
for  1790. 

The  first  object  to  which  the  experi- 
ments were  directed  was  to  ascertain  the 
quantity  and  law  resulting- from  the  mutual 
penetration  of  water  and  spirit. 

All  bodies  in  general  expand  by  heat; 
but  the  quantity  of  this  expansion,  as  well 
as  the  law  of  its  progression,  is  probably 
not  the  same  in  any  two  substances.  In 
water  and  spirit  they  are  remarkably  dif- 
ferent. The  whole  expansion  of  pure  spi- 
rit from  30°  to  100°  of  Fahrenheit's  ther- 
mometer is  not  less  than  l-25th  of  its 
whole  bulk  at  30° ;  whereas  that  oftvater, 
in  the  same  interval,  is  onl>  1-1 45th  of  its 
bulk.  The  laws  of  their  expansion  are 
still  more  different  than  the  quantities.  If 
the  expansion  of  quicksilver  be,  as  usual, 
taken  for  the  standard,  (our  thermome- 
ters being  constructed  with  that  fluid,) 
the  expansion  of  spirit  is,  indeed,  progres- 
sively increasing  with  respect  to  that  stan- 
dard, but  not  much  so  within  the  above- 
mentioned  interval ;  while  water  kept 
from  freezing  to  30°,  which  may  easily  be 
done,  will  absolutely  contract  as  it  is  heat- 
ed for  ten  or  more  degrees,  that  is,  to  40° 
or  42°  of  the  thermometer,  and  will  then 
begin  to  expand  as  its  heat  is  augmented, 
at  first  slowly,  and  afterward  gradually 
more  rapidly,  so  as  to  observe  upon  the 
whole  a  very  increasing  progression.  Now, 
mixtures  of  these  two  substances  will,  as 
inay  be  supposed,  approach  to  the  less  or 
the  greater  of  these  progressions,  accord- 
ing as  they  are  compounded  of  more  spi- 
rit or  more  water,  while  their  total  expan- 
sion will  be  greater,  according  as  more 
spirit  enters  into  their  composition ;  but 
the  exact  quantity  of  the  expansion,  as 
well  as  law  of  the  progression,  in  all  of 
them,  can  be  determined  only  by  trials. 
These  were,  therefore,  the  two  other  prin- 
cipal objects  to  be  ascertained  by  experi- 
ment. 

The  person  engaged  to  make  these  ex- 
periments was  Dr.  Dollfuss,  an  ingenious 
Swiss  gentleman  then  in  London,  who  had 
distinguished  himself  by  several  publica- 
tions on  chemical  subjects.  As  he  could 
not  conveniently  get  the  quantity  of  spirit 
he  wanted  lighter  than  825,  at  60°  F.,  he 
fixed  upon  this  strength  as  the  standard 
for  alcohol. 

These  experiments  of  Dr.  Dollfuss  were 
repeated  by  Mr.  Gilpin,  clerk  of  the  Roy- 
al Society;  and  as  the  deductions  in  this 
account  will  be  taken  chiefly  from  that 
]ast  set  of  experiments,  it  is  proper  here 
to  describe  minutely  the  method  observed 
by  Mr.  Gilpin  in  his  operation.  This  natu- 
rally resolves  itself  into  two  parts :  the  way 
ef  making  the  mixtures,  and  the  way  of 
ascertaining  their  specific  gravity. 

1.  The  mixtures  were  ma'de  by  weight, 


as  the  only  accurate  method  of  fixing  the 
proportions.    In  fluids  of  such  very  une- 
qual expansions  by  heat  as  water  and  alco- 
hol, if  measures  had  been  employed,  in- 
creasing or  decreasing  in  regular  propor- 
tions to  each  other,  the  proportions  of  the 
masses  would  have  been  sensibly  irregu- 
lar :  now  the  latter  was  the  object  in  view, 
namely,  to  determine  the  real  quantity  of 
spirit  in  any  given  mixture,  abstracting 
the  consideration  of  its  temperature.    Be- 
sides, if  the  proportions  had  been  taken 
by  measure,  a  different  mixture  should 
have  been  made  at  every  different  degree 
of  heat.    But  the  principal  consideration 
was,  that  with  a  very  nice  balance,  such  as 
was  employed  on  this  occasion,  quantities 
can  be  determined  to  much  greater  exact- 
ness by  weight  than  by  any  practicable 
way  of  measurement.     The  proportions 
were  therefore  always  taken  by  weight. 
A  phial  being  provided  of  such  a  size  as 
that  it  should  be  nearly  full  with  the  mix- 
ture, was  made  perfectly  clean  and  dry, 
and  being  counterpoised,  as  much  of  the 
pure  spirit  as  appeared  necessary   was 
poured  into  it.     The  weight  of  this  spirit 
was  then  ascertained,  and  the  weight  of 
distilled  water  required  to  make  a  mixture 
of  the  intended  proportions  was  calcula- 
ted.   This  quantity  of  water  was  then  add- 
ed, with  all  the  necessary  care,  the  last 
portions  being  put  in  b^  means  of  a  well- 
known  instrument,  which  is  composed  of 
a  small  dish  terminating  in  a  tube  drawn 
to  a  fine  point:  the  top  of  the  dish  being 
covered  with  the  thumb,  the  liquor  in  it 
is  prevented  from  running  out  through  the 
tube  by  the  pressure  of  the  atmosphere, 
but  instantly  begins  to  issue  by  drops,  or 
a  very  small  stream,   upon  raising   the 
thumb.     Water  being  thus  introduced  in- 
to the  phial,  till  it  exactly  counterpoised 
the  weight,  which  having  been  previously 
computed,  was  put  into  the  opposite  scale, 
the  phial  was  shaken,  and  then  well  stop- 

Eed  with  its  glass  stopple,  over  which 
:ather  was  tied  very  tight,  to  prevent 
evaporation.  No  mixture  was  used  till  it 
had  remained  in  the  phial  at  least  a  month, 
for  the  full  penetration  to  have  taken 
place ;  and  it  was  always  well  shaken  be- 
fore it  was  poured  out  to  have  its  specific 
gravity  tried. 

2.  There  are  two  common  methods  of 
taking  the  specific  gravity  of  fluids ;  one, 
by  finding  the  weight  which  a  solid  body 
loses  by  being  immersed  in  them;  the 
other,  by  filling  a  convenient  vessel  with 
them,  and  ascertaining  the  increase  of 
weight  it  acquires.  In  both  cases  a  stan- 
dard must  have  been  previously  taken, 
which  is  usually  distilled  water ;  namely, 
in  the  first  method,  by  finding  the  weight 
lost  by  the  solid  body  in  the  water ;  and 
in  the  second  method,  the  weight  of  the 


ALC 


ALC 


vessel  filled  with  water.  The  latter  was 
preferred,  for  the  following-  reasons : — 

When  a  ball  of  glass,  which  is  the  pro- 
perest  kind  of  solid  body,  is  weighed  in 
any  spirituous  or  watery  fluid,  the  adhe- 
sion of  the  fluid  occasions  some  inaccura- 
cy, and  renders  the  balance  comparatively 
sluggish.  To  what  degree  this  effect  pro- 
ceed is  uncertain ;  but  from  some  expe- 
riments made  by  Mr.  Gilpin  with  that 
view,  it  appears  to  be  very  sensible. 
Moreover,  in  this  method  a  large  surface 
must  be  exposed  to  the  air  during  the 
operation  of  weighing,  which,  especially 
in  the  higher  temperatures,  would  give  oc- 
casion to  such  an  evaporation  as  to  alter 
essentially  the  strength  of  the  mixture.  It 
eeemed  also  as  if  the  temperature  of  the 
fluid  under  trial  could  be  determined  more 
exactly  in  the  method  of  filling  a  vessel, 
than  in  the  other:  for  the  fluid  cannot 
well  be  stirred  while  the  ball  to  be  weigh- 
ed remains  immersed  in  it;  and  as  some 
time  must  necessarily  be  spent  in  the 
weighing,  the  change  of  heat  which  takes 
place  during  that  period  will  be  unequal 
through  the  mass,  and  may  occasion  a  sen- 
sible error.  It  is  true,  on  the  other  hand, 
that  in  the  method  of  filling  a  vessel,  the 
temperature  could  not  be  ascertained  with 
the  utmost  precision,  because  the  neck  of 
the  vessel  employed,  containing  about  ten 
grains,  was  filled  up  to  the  mark  with  spi- 
rit not  exactly  of  the  same  temperature, 
as  will  be  explained  presently :  but  this 
error,  it  is  supposed,  would  by  no  means 
equal  the  other,  and  the  utmost  quantity 
of  it  may  be  estimated  very  nearly.  Fi- 
nally, it  was  much  easier  to  bring  the  fluid 
to  any  given  temperature  when  it  was  in 
a  vessel  to  be  weighed,  than  when  it  was 
to  have  a  solid  body  weighed  in  it ;  be- 
cause in  the  former  case  the  quantity  was 
smaller,  and  the  vessel  containing  it  more 
manageable,  being  readily  heated  with  the 
hand  or  warm  water,  and' cooled  with  cold 
water :  and  the  very  circumstance,  that  so 
much  of  the  fluid  was  not  required,  prov- 
ed a  material  convenience.  The  particu- 
lar disadvantage  in  the  method  of  weigh- 
ing in  a  vessel,  is  the  difficulty  of  filling  it 
with  extreme  accuracy ;  but  when  the  ves- 
sel is  judiciously  and  neatly  marked,  the 
error  of  filling  will,  with  due  care,  be  ex- 
ceedingly minute.  By  several  repetitions 
of  the  same  experiments,  Mr.  Gilpin  seem- 
ed to  bring  it  within  the  l-15000th  part  of 
the  whole  weight. 

The  above-mentioned  considerations  in- 
duced T)r.  Blagden,  as  well  as  the  gentle- 
men employed  in  the  experiments,  to  give 
the  preference  to  weighing  the  fluid  it- 
self; and  that  was  accordingly  the  method 
practised  both  by  Dr.  Dollfuss  and  Mr. 
Gilpin  in  their  operations. 

The  vessel  chosen  as  most  convenient 
Yoi.  i.  [18] 


for  the  purpose  was  a  hollow  glass  ball, 
terminating  in  a  neck  of  small  bore.  That 
which  Dr.  Dollfuss  used  held  5800  grains 
of  distilled  water ;  but  as  the  balance  was 
so  extremely  accurate,  it  was  thought  ex- 
pedient, upon  Mr.  Gilpin's  repetition  of 
the  experiments,  to  use  one  of  only  2965 
grains  capacity,  as  admitting  the  heat  of 
any  fluid  contained  in  it  to  bf:  more  nicely 
determined.  The  ball  of  this  vessel,  which 
may  be  called  the  weighing-  bottle,  mea- 
sured about  2.8  inches  in  diameter,  and 
was  spherical,  except  a  slight  flattening 
on  the  part  opposite  to  the  neck,  which 
served  as  a  bottom  for  it  to  stand  upon. 
Its  neck  was  formed  of  a  portion  of  a  ba- 
rometer tube,  .25  of  an  inch  in  bore,  and 
about  1£  inch  long;  it  was  perfectly  cy- 
lindrical, and,  on  its  outside,  very  near  the 
middle  of  its  length,  a  fine  circle  or  ring 
was  cut  round  it  with  a  diamond,  as  the 
mark  to  which  it  was  to  be  filled  with  the 
liquor.  This  mark  was  made  by  fixing 
the  bottle  in  a  lathe,  and  turning  it  round 
with  great  care,  in  contact  with  the  dia- 
mond. The  glass  of  this  bottle  was  not 
very  thick;  it  weighed  916  grains,  and 
with  its  silver  cap  936. 

When  the  specific  gravity  of  any  liquor 
was  to  be  taken  by  means  of  this  bottle, 
the  liquor  was  first  brought  nearly  to  the 
required  temperature,  and  the  bottle  was 
filled  with  it  up  to  the  beginning  of  the 
neck  only,  that  there  might  be  room  for 
shaking-  it.  A  very  fine  and  sensible  ther- 
mometer was  then  passed  through  the 
neck  of  the  bottle  into  the  contained  li- 
quor, which  showed  whether  it  was  above 
or  below  the  intended  temperature.  In 
the  former  case  the  bottle  was  brought  in- 
to colder  air,  or  even  plunged  for  a  mo- 
ment into  cold  water;  the  thermometer 
in  the  mean  time  being  frequently  put  in- 
to the  contained  liquor,  till  it  was  found 
to  sink  to  the  right  point.  In  like  man- 
ner, when  the  liquor  was  too  cold,  the 
bottle  was  brought  into  warmer  air,  im- 
mersed in  warm  water,  or  more  common- 
ly held  between  the  hands,  till  upon  re- 
peated trials  with  the  thermometer  the 
just  temperature  was  found.  It  will  be 
understood,  that  during  the  course  ot  this 
heating  or  cooling,  the  bottle  was  very 
frequently  shaken  between  each  immer- 
tion  of  the  thermometer ;  and  the  top  of 
the  neck  was  kept  covered,  either  with 
the  finger,  or  a  silver  cap  made  on  pur- 
pose, as  constantly  as  possible.  Hot  wa- 
ter was  used  to  raise  the  temperature  only 
in  heats  of  80°  and  upwards,  inferior  heats 
being  obtained  by  applying  the  hands  to 
the  bottle ;  when  the  hot  water  was  em- 
ployed, the  ball  of  the  bottle  was  plunged 
into  it,  and  again  quickly  lifted  out,  with 
the  necessary  shaking- interposed,  as  often 
as  was  necessary  for  communicating  tbe 


ALC 


ALC 


required  heat  to  the  liquor ;  but  care  was 
taken  to  wipe  the  bottle  dry  after  each 
immersion,  before  it  was  shaken,  lest  any 
adhering  moisture  might  by  accident  get 
into  it.  The  liquor  having  by  these  means 
been  brought  to  the  desired  temperature; 
the  next  operation  was  to  fill  up  the  bot- 
tle exactly  to  the  mark  upon  the  neck, 
which  was  done  with  some  of  the  same  li- 
quor, by  means  of  a  glass  funnel  with  a 
very  small  bore.  Mr.  Gilpin  endeavoured 
to  get  that  portion  of  the  liquor  which 
was  employed  for  this  purpose,  pretty 
nearly  to  the  temperature  of  the  liquor 
contained  in  the  bottle ;  but  as  the^whole 
quantity  to  be  added  never  exceeded  ten 
grains,  a  difference  of  ten  degrees  in  the 
heat  of  that  small  quantity,  which  is  more 
than  it  ever  amounted  to,  would  have  oc- 
casioned an  error  of  only  l-30th  of  a  de- 
gree in  the  temperature  of  the  mass. 
Enough  of  the  liquor  was  put  in  to  fill  the 
neck  rather  above  the  mark,  and  the  su- 
perfluous quantity  was  then  absorbed  to 
great  nicety,  by  bringing  into  contact  with 
it  the  fine  point  of  a  small  roll  of  blotting 
paper.  As  the  surface  of  the  liquor  in  the 
neck  would  be  always  concave,  the  bot- 
tom or  centre  of  this  concavity  was  the 
part  made  to  coincide  with  the  mark  round 
the  glass ;  and  in  viewing  it  care  was  ta- 
ken, that  the  near  and  opposite  sides  of 
the  mark  should  appear  exactly  in  the 
same  line,  by  which  means  all  parallax  was 
avoided.  A  silver  cap,  which  fitted  tight, 
was  then  put  upon  the  neck,  to  prevent 
evaporation;  and  the  whole  apparatus 
was  in  that  state  laid  in  the  scale  of  the 
balance,  to  be  weighed  with  all  the  exact- 
ness possible. 

The  spirit  employed  by  Mr.  Gilpin  was 
furnished  to  him  by  Dr.  Dollfuss,  under 
whose  inspection  it  had  been  rectified  from 
mm  supplied  by  government.  Its  speci- 
fic gravity,  at  60  degrees  of  heat,  was 
.82514.  It  was  first  weighed  pure,  in  the 
above-mentioned  bottle,  at  every  five  de- 
grees of  heat,  from  SO  to  100  inclusively. 
Then  mixtures  were  formed  of  it,  and  dis- 
tilled water,  in  every  proportion,  from 
l-20th  of  the  water  to  equal  parts  of  water 


and  spirit ;  the  quantity  of  water  added 
being  successively  augmented,  in  the  pro- 
portion of  five  grains  to  one  hundred  of 
the  spirit ;  and  these  mixtures  were  also 
weighed  in  the  bottle,  like  the  pure  spirit, 
at  every  five  degrees  of  heat.  The  num- 
bers hence  resulting  are  delivered  in  the 
following  table;  where  the  first  column 
shows  the  degrees  of  heat;  the  second 
gives  the  weight  of  the  pure  spirit  con- 
tained in  the  bottle  at  those  different  de- 
grees ;  the  third  gives  the  weight  of  a 
mixture  in  the  proportions  of  100  parts  by 
weight  of  that  spirit  to  5  of  water,  and  so 
on  successively  till  the  water  is  to  the  spirit 
as  100  to  5.  They  are  the  mean  of  three 
several  experiments  at  least,  as  Mr.  Gilpin 
always  filled  and  weighed  the  bottle  over 
again  that  number  of  times,  if  not  oftener. 
The  heat  was  taken  at  the  even  degree, 
as  shown  by  the  thermometer,  without  any 
allowance  in  the  first  instance,  because  the 
coincidence  of  the  mercury  with  a  division 
can  be  perceived  more  accurately  than 
any  fraction  can  be  estimated;  ?ndthe  er- 
rors of  the  thermometers,  if  any,  it  was 
supposed  would  be  less  upon  the  grand 
divisions  of  5  degrees  than  in  any  others. 
It  must  be  observed,  that  Mr.  Gilpin  used 
the  same  mixture  throughout  all  the  dif- 
ferent temperatures,  heating  it  up  from 
30°  to  100° ;  hence  some  small  error  in  its 
strength  may  have  been  occssioned  in  the 
higher  degrees,  by  more  spirit  evaporat- 
ing than  water:  but  this,  it  is  believed, 
must  have  been  trifling,  and  greater  in- 
convenience would  probably  have  result- 
ed from  interposing  a  fresh  mixture. 

The  precise  specific  gravity  of  the  pure 
spirit  employed  was  .82514 ;  but  to  avoid 
an  inconvenient  fraction,  it  is  taken,  in 
constructing  the  table  of  specific  gravi- 
ties, as  .825  only,  a  proportional  deduc- 
tion being  made  from  all  the  other  num- 
bers. Thus  the  following  table  gives  the 
true  specific  gravity,  at  the  different  de- 
grees of  heat,  of  a  pure  rectified  spirit, 
the  specific  gravity  of  which  at  60°  is 
.825,  together  with  the  specific  gravities 
of  different  mixtures  of  it  with  water,  at 
those  different  temperatures. 


ALC 


ALC 


Real  Specific  Gravities  at  the  different  Temperatures. 


Heat. 

The 
pure 
spirit 

100 
grains 
of  spirit 
to  5  gr. 
of  water 

100 
grains 
of  spirit 
to  10  gr. 
of  water 

100 
grains 
of  spirit 

to  15  gr. 
of  water 

100      | 
grains    ] 
of  spirit 
to  20  gr. 
of  water 

100 
grains 
of  spirit 
to  25  gr. 
of  water 

100 
grairs 
of  spirit 
to  30  gr. 
ot  water 

100 
grains 
of  spirit 
to  35  gr. 
of  water 

100 
graius 
of  spirit 
to  40  gr. 
of  water 

100 
grains 
of  spirit 
to  45  gr. 
of  water 

100 
grains 
of  spirit 
to  50  gr. 
of  water 

30C 

•83396 

•84995 

•8o95/ 

•o6825 

•87585 

•88282 

•88921 

•89511 

•90054 

.90558 

•91023 

35 

83672 

84769 

85^29 

86587 

87357 

88059 

88701 

89294 

89839 

90345 

90811 

40 

83445 

84539)  85507 

86351 

87134 

87338 

83481 

89073 

89617 

90127 

90596 

45 

83214 

843101  85277 

86131 

86905 

87613 

88255 

88849 

89396 

89909 

90380 

50 

82977 

84076 

85042 

85902 

86676 

87384 

88030 

88626 

89174 

89684 

90160 

55 

82736 

83834 

84802 

85664 

86441 

87150 

87796 

88393 

88945 

89458 

89933 

60 

82500 

83599 

84568 

85430 

86208 

86918 

87569 

88169 

88720 

89232 

89707 

65 

82262 

83J6J!  84334 

85193 

85976 

86686 

87337 

87938 

88490 

89006 

89479 

70 

82023 

83124 

84092 

84951 

35736 

86451 

87105 

87705 

88254 

88773 

89252 

75 

8178'J 

32d78 

838ol 

84710 

85496 

86212 

86864 

87466 

88018 

88538 

89018 

80 

81530 

32631 

83603 

84467 

85248 

85966 

86622 

87228 

87776 

88301 

88781 

85 

81291 

82396 

83371 

84243 

85C36 

85757 

86411 

87021 

87590 

88120 

88609 

90 

81044 

82150  83126 

84001 

84797 

85518 

86172 

86787 

87360 

87889 

88376 

95 

80794 

81900 

82877 

83753 

845JO 

85272 

85928 

8C542 

87114 

87654 

88146 

too 

805*8 

81657 

82639 

83513 

84038 

85031 

85688 

86302 

86879 

87421 

87915 

100 

100      1      100 

100 

160 

TOO 

100 

100 

100 

100 

Heat. 

grains 
of  spirit 
to  56  gr. 
of  water 

grains 

Of  spirit 

to  60  gr. 
of  svater 

grains 
of  spirit 

10  03  gr. 

of  water 

grains 
of  spirit 
to  70  gr. 

Of  wa?er 

grains 
OT  spirit 
to  75  gr. 
of  water 

grains 
of  spirit 
to  80  gr. 
of  water 

grains 
of  spirit 
to  85  gr. 
of  water 

grains 
of  spirit 
to  90  gr. 
of  water 

grains 
of  spirit 
to  95  gr. 
of  water 

gr.    of 
spirit  to 
100  gr. 
of  water 

30° 

•91449 

•91847 

•92217 

•92563 

.92889 

•93151 

•93474 

•93741 

•93991 

•94222 

35 

91241 

91640 

92009 

92355 

92680 

92986 

93274 

93541 

93790 

94025 

40 

91026 

91428 

91799 

92151 

92476 

92783 

93072 

93341 

93592 

93827 

45 

90812 

91211 

91584 

91937 

92264 

92570 

92859 

93131 

93382 

93621 

50 

90596 

90997 

91370 

91723 

92051 

92358 

92647 

92919 

93177 

93419 

55 

90367 

90768 

91144 

91502 

91837 

92145 

92436 

92707 

92963 

93208 

60 

90144 

90549 

90927 

91287 

91622 

91933 

92225 

92499 

92758 

93002 

65 

89920 

90328 

90707 

91066 

91400 

91715 

92010 

92283 

92546 

92794 

70 

89695 

90104 

90484 

90847 

91181 

91493 

91793 

92069 

92333 

92580 

75 

89464 

89872 

90252 

90617 

90952 

91270 

91569 

91849 

92111 

92364 

80 

89225 

89639 

90021 

90385 

90723 

91046 

91340 

91622 

91891 

92142 

85 

89043 

89460 

89843 

90209 

90558. 

90882 

91186 

91465 

91729 

91969 

90 

88817 

89230 

89617 

89988 

90342 

90668 

90967 

91248 

91511 

91751 

95 

88588 

89003 

89390 

89763 

90119 

90443 

90747 

91029 

91290 

91531 

100 

88357 

88769 

89158 

89536 

89889 

90215 

90522 

90805 

91066 

91310 

95 

90 

85 

80       |        75 

70 

65 

60 

55 

50 

Heat. 

grains  of 
spirit  to 

grains  of 
spirit  to 

grains  of 
spirit  to 

grains  of  grains  o1 
spirit  to  spirit   to 

grains  of 
spirit  to 

grains  of 
spirit   to 

grains  ol 
spirit  te 

grains  of 
spirit   to 

grains  of 
spirit  to 

100  gr.of 

100  gr.  of 

100  gr.  of 

100  gr.of 

100  gr.  of 

100  gr.  ol 

100  gr.  of 

100  gr.of 

100  gr.of 

100  gr  o 

water. 

water. 

water. 

water. 

water. 

water. 

water. 

water. 

water. 

water. 

30° 

.94447 

.94675 

.94920 

.95173 

.95429 

.95681 

.95944 

.96209 

.96470 

.96719 

35 

94249 

94484 

94734 

94988 

95246 

95502 

95772 

96048 

96315 

96579 

40 

94058 

94295 

94547 

94802 

95060 

95328 

95602 

95879 

96159 

96434 

45 

93860 

94096 

94348 

94605 

94871 

95143 

95423 

95705 

95993 

96280 

50 

93658 

93897 

94149 

94414 

94683 

94958 

95243 

95534 

95831 

96126 

55 

93452 

93696 

93948 

94213 

94486 

94767 

95057 

95357 

95662 

9596o 

60 

93247 

93493 

93749 

94018 

94296 

94579 

94876 

95181 

95493 

95804 

65 

93040 

93285 

93546 

93822 

94099 

94388 

94689 

95000 

95318 

95635 

70 

92828 

93076 

93337 

93616 

93898 

94193 

94500 

94813 

95139 

95469 

75 

92613 

92865 

93132 

93413 

93695 

93989 

94301 

94623 

94957 

95392 

80 

92393 

92646 

92917 

93201 

93488 

93785 

94102 

94431 

94768 

95111 

ALC 


ALC 


Heat. 

45        .       40 
grains  ofgr.iins  of 
sv'irit   to'spirit  t« 
lOOgr.  of  100  gr.  of 

grains  of 
spirit   to 
lor  gr.  of 

30 
grains  of 
spirit  to 
lOOgr.of 

25                20                15 
grains  of]  grains  oflgrains  of 
spirit   to'spirit    to  spirit   to 
l"0gr.of  100  gr  of|100gr.  of 

10 
grains  of 
spirit  to 
100  gr.  of 

s 

grains  of 
spirit  to 
lOOgr.of 

Water. 

water. 

water. 

water. 

water. 

water.      |  water. 

water. 

water. 

30° 

.96967 

.97200 

.97418 

.97635 

.97860 

.98108 

.98412 

.98804 

.99334 

35 

96840 

97086 

97319 

97556 

97801 

98U76 

98397 

98804 

99344 

40 

96706 

96967 

97220 

97472 

97737 

98033 

98373 

98795 

99345 

45 

9  .563 

96840 

97110 

97384 

97666 

97980 

98338 

98774 

99338 

50 

96420 

96708 

96995 

97284 

97589 

97920 

98293 

98745 

99316 

55 

96272 

96575 

96877 

97181 

97500 

97847 

982.-9 

987u2 

99284 

60 

96122 

96437 

96752 

97074 

97410 

97771 

98176 

98654 

99244 

65 

95962 

96288 

96620 

96959 

97309 

97688 

98106 

98594 

99194 

70 

95802 

96143 

96484 

96836 

97203 

97596 

98028 

98527 

99134 

75 

95638 

95987 

96344 

96708 

97086 

97495 

97943 

98454 

99066 

80 

95467 

95826 

96192 

96568 

96963 

97385 

97845 

98367 

98991 

From  this  table,  when  the  specific  gra- 
vity of  any  spirituous  liquor  is  ascertained, 
it  will  be  easy  to  find  the  quantity  of  rec- 
tified spirit  of  the  above-mentioned  stand- 
ard, contained  in  any  given  quantity  of  it, 
either  by  weight  or  measure. 

Dr.  Blagden  concludes  this  part  of  the 
report  with  observing,  that  as  the  experi- 
ments were  made  with  pure  spirit  and  wa- 
ter, if  any  extraneous  substances  are  con- 
tained in  the  liquor  to  be  tried,  the  speci- 
fic gravity  in  the  tables  will  not  give  ex- 
actly the  proportions  of  water  and  spirit 
in  it.     The  substances  likely  to  be  found 
in  spirituous  liquors,  wher»  no  fraud  is 
suspected,  are  essential  oils,  sometimes 
empyreumatic,    miio^aginous   or    extrac- 
tive matter,  and  perhaps  some  saccharine 
matter.   The  effect  of  these,  in  the  course 
of  trade,  seems  to  be  hardly  such  as  would 
be  worth  the  cognizance  of  the  excise,  nor 
could  it  easily  be  reduced  to  certain  rules. 
Essential  and  empyreumatic  oils  are  near- 
ly of  the  same  specific  gravity  as  spirit,  in 
general  rather  lighter,  and  therefore,  not- 
withstanding the  mutual  penetration,  will 
probably  make  little  change  in  the  speci- 
fic gravity  of  any  spirituous  liquor  in  which 
they  are  dissolved.   The  other  substances 
are  all  heavier  than  spirit ;  the  specific 
gravity  of  common  gum  being  1.482,  and 
of  sugar  1.606,  according  to  the  tables  of 
M.  Brisson.     The  effect  of  them  therefore 
will  be  to  make  spirituous  liquors  appear 
less  strong  than  they  really  are.     An  idea 
was  once  entertained  of  endeavouring  to 
determine  this  matter  with  some  preci- 
sion; and  accordingly  Dr.  Dollfuss  evapo- 


cimal  by  six  nearly,  equal  to  what  would 
indicate  in  the  above-mentioned  mixture, 
about  one-seventh  of  a  grain  of  water  more 
than  the  truth,  to  100  of  spirit ;  a  quantity 
much  too  minute  for  the  consideration  of 
government. 

*  'I  he  strength  of  spirits  is  determined, 
according  to  the  existing  laws,  by  Sikes* 
hydrometer  ;  but  as  many  dealers  use  Di- 
cas's,  I  shall  describe  it  here,  and  the  for- 
mer under  DISTII I.ATION. 

It  consists  of  a  light  copper  ball,  termi- 
nating below  with  a  ballast  bottom,  and 
above  with  a  thin  stem,  divided  into  ten 
parts.  The  upper  extremity  of  the  stem 
is  pointed,  to  receive  the  little  brass  poi- 
ses, or  discs,  having  each  a  hole  in  its  cen- 
tre. These  poises  are  numbered  0,  10, 
20,  30,  &c.  up  to  350,  which  is  the  lightest 
of  the  series.  The  intermediate  units  are 
given  by  the  subdivisions  on  the  stem.  A 
graduated  ivory  scale,  with  a  sliding  rule 
and  thermometer,  accompanies  the  hydro- 
meter, to  make  the  correction  for  tempe- 
rature. The  first  thing  in  using  this  in- 
strument is  to  plunge  the  thermometer 
into  a  glass  cylinder  containing  the  spirits 
to  be  tried.  The  sliding  rule  has  then 
the  degree  of  temperature  indicated, 
moved  opposite  to  zero.  The  hydrome- 
ter is  now  placed  in  the  liquid,  and  such 
a  poise  is  put  on  as  to  submerge  a  portion 
of  the  stem.  The  weight,  added  to  the 
number  on  the  stem,  gives  a  sum,  opposite 
to  which  on  the  scale  we  find  a  quantity, 
by  which  the  particular  spirit  may  exceed 
or  fall  short  of  proof.  Thus,  if  it  mark  20 
under  proof,  it  signifies  that  every  100 


rated  1000  grains  of  brandy,  and  the  same     gallons  of  that  spirit  would  require  to  have 
dty   of  rum,  to  dryness;  the  former    20  gallons  of  water  abstracted  from  it  to 

bring  it  up  to  proof.  If  it  mark  10  over 
proof,  we  learn  that  every  100  gallons  con- 
tain too  little  water,  by  10  gallons.  When 
the  thermometer  degree  of  60°  is  put  op- 
posite to  zero,  then  the  weights  and  value 
of  the  spirits  have  the  following1  relations 
on  this  scale. 


quantity 

left  a  residuum  of  40  grains,  the  latter  only 
of  8|  grains.  The  40  grains  of  residuum 
from  the  brandy,  dissolved  again  in  a  mix- 
ture of  100  of  spirit,  with  50  of  water,  in- 
creased its  specific  gravity  .00041 ;  hence 
the  effect  of  this  extraneous  matter  upon 
the  specific  gravity  of  the  brandy  contain- 
ing it,  would  be  to  increase  the  fifth  de- 


ALC 


ALC 


102.5  denotes  20  under  proof 
122.0  10 

143.5  Proof 

167.  10  over  proof 

193.  20 

221.  30 

251.  40 

284.5  50 

322.5  60 

350.5  Alcohol. 

There  is,  besides,  an  upper  line  on  the 
scale,  which  exhibits  the  relation  of  spirit 
to  water  reckoned  unity.  Thus,  above  10 
percent,  over  proof  in  the  second  line, 
we  find  in  the  upper  line  8.  From  which 
we  learn,  that  8  of  that  spirit  by  bulk, 
will  take  1  of  water  to  bring  it  down  to 
proof.  At  60°  Fahr.  1  find  that  10  over 
proof  on  Dicas  corresponds  to 

Specific  gravity  0.9085 

3£  over  proof  to  0.9169 

Proof,  0.9218 

Now,  by  Gilpin's  tables  this  indicates  a 
compound  of  100  grains  of  alcohol  0.825, 
and  85  grains  of  water.  But  by  Lowitz's 
table  in  Crell's  Annals,  the  above  specific 
gravity  corresponds  to  48  alcohol  of  0.791 
at  the  temperature  of  68°,  united  to  52  of 
water,  and  cooled  down  to  60.  Equal 
weights  of  that  strong  alcohol  and  water, 
give,  at  60°,  a  specific  gravity  of  0.9175. 
By  the  Act  of  Parliament  of  1762,  the  spe- 
cific gravity  of  proof  was  fixed  at  0.916. 
It  is  at  present  to  water  as  12  to  13,  or  -=» 
0.923.  See  DISTILLATION.* 

The  most  remarkable  characteristic  pro- 
perty of  alcohol,  is  its  solubility  or  combi- 
nation in  all  proportions  with  water ;  a 
property  possessed  by  no  other  combus- 
tible substance,  *  except  the  acetic  spirit 
obtained  by  distilling  the  dry  acetates.* 
When  it  is  burned  in  a  chimney  which 
communicates  with  the  worm-pipe  of  a 
distilling  apparatus,  the  product,  which  is 
condensed,  is  found  to  consist  of  water, 
which  exceeds  the  spirit  in  weight  about 
one-eighth  part;  *or  more  accurately, 
100  parts  of  alcohol,  by  combustion,  yield 
136  of  water.*  If  alcohol  be  burned  in 
closed  vessels  with  vital  air,  the  product 
is  found  to  be  water  and  carbonic  acid. 
Whence  it  is  inferred  that  alcohol  con- 
sists of  hydrogen,  united  either  to  carbo- 
nic acid  or  its  acidifiable  base;  and  that 
the  oxygen  uniting  on  the  one  part  with 
the  hydrogen,  forms  water;  and  on  the 
other  with  the  base  of  the  carbonic  acid, 
forms  that  acid. 

*  The  most  exact  experiments  on  this 
subject  are  those  recently  made  by  M.  de 
Saussure.  The  alcohol  he  used  had,  at 
62.8°,  a  specific  gravity  of  0.8302 ;  and  by 
Richter's  proportions,  it  consists  of  13.8 
water,  and  86.2  of  absolute  alcohol.  The 
vapour  of  alcohol  was  made  to  traverse  a 
narrow  porcelain  tube  ignited,  from  which 


the  products  passed  along  a  glass  tube 
about  six  feet  in  length,  refrigerated  by 
ice.    A  little  charcoal  was  deposited  in 
the  porcelain,  and  a  trace  of  oil  in  the 
glass  tube.     The  resulting  gas  being  ana- 
lyzed in  an  exploding  eudiometer,  with 
oxygen,  was  found  to  resolve  itself  into 
carbonic  acid  and  water.     Three  volumes 
of  oxygen  disappeared  for  every  two  vo- 
lumes of  carbonic  acid  produced ;  a  pro- 
portion which  obtains,  in  the  analysis  by 
oxygenation    of   olefiant    gas.    Now,   as 
nothing  resulted  but  a  combustible  gas  of 
this  peculiar  constitution,  and  condensed 
water  equal  to  ^454  of  the  original  weight 
of  the  alcohol,  we  may  conclude,  that  va- 
pour of  water  and  olefiant  gas  are  the  sole 
constituents  of  alcohol.     Subtracting  the 
13.8  per  cent,  of  water  in  the  alcohol  at 
the  beginning  of  the  experiment,  the  ab- 
solute alcohol  of  Richter  will  consist  of 
13.7  hydrogen,  51.98  carbon,  and  34.32 
oxygen.     Hence    M.   Gay-Lussac    infers, 
that  alcohol,  in  vapour,  is  composed  of 
one  volume  olefiant  gas,  and  one  volume 
of  the   vapour  of  water,   condensed   by 
chemical  affinity  into  one  volume. 

The  sp.  gr.  of  olefiant  gas  is       0.97804 
Of  aqueous  vapour  is  0.62500 

Sum  =.  1.60304 
And  alcoholic  vapour  is  =  1.6133 

These  numbers  approach  nearly  to  those 
which  would  result  from  two  prime  equi- 
valents of  olefiant  gas,  combined  with  one 
of  water;  or  ultimately,  three  of  hydro- 
gen, two  of  carbon,  and  one  of  oxygen.* 

A  considerable  number  of  the  uses  of 
this  fluid  as  a  menstruum,  will  pass  under 
our  observation  in  the  various  articles  of 
this  work.  The  mutual  action  between 
alcohol  and  acids  produces  a  light,  vola- 
tile, and  inflammable  oil,  called  ether. 
See  ETHER.  Pure  alkalis  unite  with  spirit 
of  wine,  and  form  alkaline  tinctures.  Few 
of  the  neutral  salts  unite  with  this  fluid, 
except  such  as  contain  ammonia.  The 
carbonated  fixed  alkalis  are  not  soluble  in 
it.  From  the  strong  attraction  which  ex- 
ists between  alcohol  and  water,  it  unites 
with  this  last  in  saline  solutions,  and  in 
most  cases  precipitates  the  salt.  This  is 
a  pleasing  experiment,  which  never  fails 
to  surprise  those  who  are  unacquainted 
with  chemical  effects.  If,  for  example,  a 
saturated  solution  of  nitre  in  water  be  ta- 
ken, and  an  equal  quantity  of  strong  spi- 
rit of  wine  be  poured  upon  it,  the  mixture 
will  constitute  a  weaker  spirit,  which  is 
incapable  of  holding  the  nitre  in  solution ; 
it  therefore  falls  to  the  bottom  instantly, 
in  the  form  of  minute  crystals. 

The  degrees  of  solubility  of  many  neu- 
tral salts  in  alcohol  have  been  ascertained 
by  experiments  made  by  Macquer,  of 
which  an  account  is  published  in  the  Me- 


ALC 


ALC 


moirs  of  the  Turin  Academy,  The  alco- 
hol he  employed  was  carefully  freed  from 
superabundant  water  by  repeated  rectifi- 
cations, without  addition  of  any  interme- 
diate substance.  The  salts  employed  in 
his  experiments  were  previously  deprived 
of  their  water  of  crystallization  by  a  care- 
ful drying1.  He  poured  into  a  matrass, 
upon  each  of  the  salts  thus  prepared,  half 
an  ounce  of  his  alcohol,  and  set  the  mat- 
rass in  a  sand-bath.  When  the  spirit  be- 
gan to  boil,  he  filtrated  it  while  it  was  hot, 


Qitantity         Salts  soluble  in 

ef  grains.  200  grains  oj  spirit- 

4  Nitrate  of  potash 

5  Muriate  of  potash 
0  Sulphate  of  soda 

15  Nitrate  of  soda 

0  Muriate  of  soda 

0  Sulphate  of  ammonia 

108  Nitrate  of  ammonia 

24  Muriate  of  ammonia 

288  Nitrate  of  lime 

288  Muriate  of  lime 

84  Nitrate  of  silver 

204  Muriate  of  mercury 

4  Nitrate  of  iron 

36  Muriate  of  iron 

48  Nitrate  of  copper 

48  Muriate  of  copper 


and  left  it  to  cool,  that  he  might  observe 
the  crystallizations  which  took  place.  He 
then  evaporated  the  spirit,  and  weighed 
the  saline  residuutns.  He  repeated  these 
experiments  a  second  time,  with  this  dif- 
ference, that  instead  of  evaporating  the 
spirit  in  which  the  salt  had  been  digested, 
he  set  fire  to  it  in  order  to  examine  the 
phenomena  which  its  flame  might  exhibit. 
The  principal  results  of  his  experiments 
are  subjoined. 


Peculiar  phenomena  of  the  fame. 


C  Flame  larger,  higher,  more  ardent,  yellow, 
£     and  luminous. 

Large,  ardent,  yellow,  and  luminous. 

Considerably  red. 

Yellow,  luminous,  detonating. 

Larger,  more  ardent,  and  reddish. 

None. 

Whiter,  more  luminous. 

None. 
C  Larger,  more  luminous,  red  and  decrepitat- 

C    .ing- 
Like  that  of  the  calcareous  nitre. 
None. 

Large,  yellow,  luminous  and  decrepitating. 
Red  and  decrepitating. 
More  white,  luminous  and  sparkling. 
More  white,    luminous  and   green,    much 
smoke.      The    saline  residuum  became 
.     black  and  burnt. 
Fine  green,  white,  and  red  figurations. 


Macquer  accompanies  the  relation  of 
his  experiments  with  many  judicious  re- 
flections, not  easily  capable  of  abridg- 
ment. 

*  The  alcohol  he  employed  in  the  above 
experiments  had  a  specific  gravity  of  0.840. 
In  analytical  researches,  alcohol  affords 
frequently  a  valuable  agent  for  separating 
salts  from  each  other.  We  shall  there- 
fore introduce  the  following  additional 
table,  derived  chiefly  from  the  experi- 
ments of  Wenzel ; — 

100  parts  of  alcohol  dissolve  of 
Temp. 


Succinic  acid, 
Acetate  of  soda, 
Nitrate  of  silver, 
Refined  sugar, 
Boracic  acid, 
Nitrate  of  soda, 
Acetate  of  copper, 
Muriate  of  ammonia, 


74.0  parts 

46.5 

41.7 

24.6 

20.0 

9.6 

7.5 

7.1 


Nitrate  of  Cobalt  at 

54.5° 

100 

Copper 

54.5 

100 

Alumina 

54.5 

100 

Lime 

125 

Magnesia 

180.5 

290 

Muriate  of  Zinc 

54.5 

100 

Alumina 

54.5 

100 

Magnesia 

180.5 

547 

Iron 

180.5 

100 

Copper 
Acetate  of  Lead 

180.5 
154.5 

100 
100 

At  the  boiling  point,  100  parts  of  alco- 
hol dissolve  of  muriate  of  lime     100  parts 
Nitrate  of  ammonia,  89 

Corrosive  sublimate,  88.8 


Superarseniate  of  potash,  3.75 
Oxalate  of  potash,  -  2.92 
Nitrate  of  potash,  -  2.08 
Muriate  of  potash,  2.08 

Arseniate  of  soda,  -  1.58 
Arsenious  acid,  -  1.25 
Tartrate  of  potash,  0.42 

It  appears  from  the  experiments  of  Kir- 
wan,  that  dried  muriate  of  magnesia  dis- 
solves more  abundantly  in  strong  than  in 
weak  alcohol.  100  parts  of  specific  gravi- 
ty 0.900,  dissolve  21.25;  of  0.848,  23.75; 
of  0.834,  36.25;  and  of  0.817,  50  parts. 
The  same  holds  to  a  more  limited  extent 
with  acetate  of  lime  ;  2.4  grains  being  so- 
luble in  100  of  the  first  alcohol,  and  4.88 
in  100  of  the  last.  The  other  salts  which 
he  tried  dissolved  more  sparingly  in  the 
stronger  than  in  the  weaker  alcohol.  The 
temperature  of  the  spirit  was  generally 
60Q. 
All  deliquescent  salts  are  soluble  in  al- 


ALC 


ALC 


cohol.  Alcohol  holding  the  strontitic 
salts  in  solution,  gives  a  flame  of  a  rich 
purple.  The  cupreous  salts  and  boracic 
acid  give  a  green ;  the  soluble  calcareous, 
a  reddish;  the  barytic,  a  yellowish.  For 
the  effect  of  other  salts  on  the  colour  of 
the  flame,  see  a  preceding  table. 

The  alcohol  of  0. 825  has  been  subjected 
to  a  cold  of  —  91°  without  congealing. 
But  Mr.  Hutton  has  given,  in  the  Edin- 
burgh Encyclopaedia,  article  Cold,  an  ac- 
count of  his  having  succeeded  in  solidify- 
ing it  by  a  cold  of—  110°.  The  alcohol 
he  employed  had  a  density  of  0.798  at  60P. 
His  process  has  been  kept  secret.  The 
boiling  point  of  alcohol  of  0.825  is  176°, 
Alcohol  of  0.810  boils  at  173.5°.  For  the 
force  of  its  vapour  at  different  tempera- 
tures, and  its  specific  heat,  see  VAPOUR. 

M.  Gay-Lussac  having  shown  that  this 
liquid  is  a  compound  of  olefiant  gas  and 
water,  potassium  ought  to  disengage 
from  it,  hydrogen  and  olefiant  gas.  In 
the  absolute  alcohol  of  Richter  there  is 
no  water,  independent  of  that  which  is 
essential  to  its  constitution.  See  FERMEN- 
TATION. 

When  chlorine  is  made  to  pass  through 
alcohol  in  a  WouhVs  apparatus,  there  is  a 
mutual  action.  Water,  an  oily  looking 
substance,  muriatic  acid,  a  little  carbonic 
acid,  and  carbonaceous  matter,  are  the 
products.  This  oily  substance  does  not 
redden  turnsole,  though  its  analysis  by 
heat  shows  it  to  contain  muriatic  acid.  It 
is  white,  denser  than  water,  has  a  cooling 
taste  analogous  to  mint,  and  a  peculiar, 
but  not  ethereous  odour.  It  is  very  solu- 
ble in  alcohol,  but  scarcely  in  water.  The 
strongest  alkalis  hardly  operate  on  it. 

It  was  at  one  time  maintained,  that  al- 
cohol did  not  exist  in  wines,  but  was  ge- 
nerated and  evolved  by  the  heat  of  distil- 
lation. On  this  subject  M.  Gay-Lussac 
made  some  decisive  experiments.  He 
agitated  wine  with  litharge  in  fine  powder, 
till  the  liquid  became  as  limpid  as  water, 
and  then  saturated  it  with  subcarbonate  of 
potash.  The  alcohol  immediately  sepa- 
rated and  floated  on  the  top.  He  distilled 
another  portion  of  wine  in  vacuo,  at  59° 
Fahr.  a  temperature  considerably  below 
that  of  fermentation.  Alcohol  came  over. 
Mr.  Brande  proved  the  same  position  by 
saturating  wine  with  subacetate  of  lead, 
and  adding  potash. 

MM.  Adam  and  D up ortal  have  substitut- 
ed for  the  redistillations  used  in  converting 
wine  or  beer  into  alcohol,  a  single  process 
of  great  elegance.  From  the  capital  of 
the  still  a  tube  is  led  into  a  large  copper 
recipient.  This  is  joined  by  a  second  tube, 
to  a  second  recipient,  and  so  on  through 
n.  series  of  four  vessels,  arranged  like  a 
Woulfe's  apparatus.  The  last  vessel  com- 
municates with  the  worm  of  the  first  re- 


frigeratory, This,  the  body  of  the  still 
and  the  two  recipients  nearest  it,  are 
charged  with  the  wine  or  fermented  li- 
quor. When  ebullition  takes  place  in  the 
still,  the  vapour  issuing  from  it  communi- 
cates soon  the  boiling  temperature  to  the 
liquor  in  the  two  recipients.  From  these 
the  volatilized  alcohol  will  rise  and  pass 
into  the  third  vessel,  which  is  empty. 
After  communicating  a  certain  heat  to  it, 
a  portion  of  the  finer  or  less  condensable 
spirit  will  pass  into  the  fourth,  and  thence, 
in  a  little,  into  the  worm  of  tbe  first  refri- 
geratory. The  wine  round  the  worm  will 
likewise  acquire  heat,  but  more  slowly. 
The  vapour  that  in  that  event,  may  pass 
uncondensed  through  the  first  worm,  is 
conducted  into  a  second,  surrounded  with 
cold  water.  Whenever  the  still  is  worked 
off,  it  is  replenished  by  a  stop-cock  from 
the  nearest  recipient,  which,  in  its  turn, 
is  filled  from  the  second,  and  the  second 
from  the  first  worm  tub.  It  is  evident, 
from  this  arrangement,  that  by  keeping 
the  3d  and  4th  recipients  at  a  certain  tem- 
perature, we  may  cause  alcohol,  of  any 
degree  of  lightness,  to  form  directly  at 
the  remote  extremity  of  the  apparatus. 
The  utmost  economy  of  fuel  and  time  is 
also  secured,  and  a  better  flavoured  spirit 
is  obtained.  The  arriere  gout  of  bad  spirit 
can  scarcely  be  destroyed  by  infusion  with 
charcoal  and  redistillation.  In  this  mode 
of  operating,  the  taste  and  smell  are  ex- 
cellent, from  the  first.  Several  stills  on 
the  above  principle  have  been  constructed 
at  Glasgow  for  the  West  India  distillers, 
and  have  been  found  extremely  advanta- 
geous. The  excise  laws  do  not  permit 
their  employment  in  the  home  trade.* 

If  sulphur  in  sublimation  meet  with  the 
vapour  of  alcohol,  a  very  small  portion 
combines  with  it,  which  communicates  a 
hydrosulphurous  smell  to  the  fluid.  The 
increased  surface  of  the  two  substances 
appears  to  favour  the  combination.  It  had 
been  supposed,  that  this  was  the  only  way 
in  which  they  could  be  united;  but  M. 
Favre  has  lately  asserted,  that,  having  di- 
gested two  drams  of  flowers  of  sulphur 
in  an  ounce  of  alcohol,  over  a  gentle  fire 
not  sufficient  to  make  it  boil,  for  twelve 
hours,  he  obtained  a  solution  that  gave 
twenty-three  grains  of  precipitate.  A  si- 
milar mixture  left  to  stand  for  a  month  in 
a  place  exposed  to  the  solar  rays,  afforded 
sixteen  grains  of  precipitate ;  and  another, 
from  which  the  light  was  excluded,  gave 
thirteen  grains.  If  alcohol  be  boiled  with 
one-fourth  of  its  weight  of  sulphur  for  an 
hour,  and  filtered  hot,  a  small  quantity  of 
minute  crystals  will  be  deposited  on  cool- 
ing; and  the  clear  fluid  will  assume  an 
opaline  hue  on  being  diluted  with  an 
equal  quantity  of  water,  in  which  state  it 
will  pass  the  filter,  nor  will  any  sediment 


ALC 


ALK 


fee  deposited  for  several  hours.  The  al- 
eohol  used  in  the  last-mentioned  experi- 
ment did  not  exceed  .840. 

Phosphorus  is  sparingly  soluble  in  alco- 
hol, but  in  greater  quantity  by  heat  than 
in  cold.  The  addition  of  water  to  this 
solution  affords  an  opaque  milky  fluid, 
which  gradually  becomes  clear  by  the 
subsidence  of  the  phosphorus. 

Earths  seem  to  have  scarcely  any  action 
upon  alcohol.  Quick-lime,  however,  pro- 
duces some  alteration  in  this  fluid,  by 
changing  its  flavour  and  rendering  it  of  a 
yellow  colour.  A  small  portion  is  proba- 
bly taken  up.  • 

Soaps  are  dissolved  with  great  facility 
in  alcohol,  with  which  they  combine  more 
readily  than  with  water.  None  of  the  me- 
tals, or  their  oxides,  are  acted  upon  by 
this  fluid.  Resins,  essential  oils,  camphor, 
bitumen,  and  various  other  substances, 
are  dissolved  with  great  facility  in  alcohol, 
from  which  they  may  be  precipitated  by 
the  addition  of  water.  From  its  property 
of  dissolving  resins,  it  becomes  the  men- 
struum of  one  class  of  varnishes.  See 
VARNISH. 

Camphor  is  not  only  extremely  soluble 
in  alcohol,  but  assists  the  solution  of  re- 
sins in  it.  Fixed  oils,  when  rendered  dry- 
ing by  metallic  oxides,  are  soluble  in  it,  as 
well  as  when  combined  with  alkalis. 

Wax,  spermaceti,  biliary  calculi,  urea, 
and  all  the  animal  substances  of  a  resinous 
nature,  are  soluble  in  alcohol ;  but  it  cur- 
dles milk,  coagulates  albumen,  and  har- 
dens the  muscular  fibre  and  coagulum  of 
the  blood. 

The  uses  of  alcohol  are  various.  As  a 
solvent  of  resinous  substances  and  essen- 
tial oils,  it  is  employed  both  in  pharmacy 
and  by  the  perfumer.  When  diluted  with 
an  equal  quantity  of  water,  constituting 
what  is  called  proof  spirit,  it  is  used  for 
extracting  tinctures  from  vegetable  and 
other  substances,  the  alcohol  dissolving 
the  resinous  parts,  and  the  water  the  gum- 
my. From  giving  a  steady  heat  without 
smoke  when  burnt  in  a  lamp,  it  was  for- 
merly much  employed  to  keep  water 
feoiling  on  the  tea-table.  In  thermometers 
for  measuring  great  degrees  of  cold,  it  is 
preferable  to  mercury,  as  we  cannot  bring 
it  to  freeze.  It  is  in  common  use  for  pre- 
serving many  anatomical  preparations, 
and  certain  subjects  of  natural  history ; 
but  to  some  it  is  injurious,  the  molluscs 
for  instance,  the  calcareous  covering  of 
which  it  in  time  corrodes.  It  is  of  con- 
siderable use  too  in  chemical  analysis,  as 
appears  under  the  different  articles  to 
which  it  is  applicable. 

Trom  the  great  expansive  power  of  al- 
cohol, it  has  been  made  a  question,  whe- 
ther it  might  not  be  applied  with  advantage 
in  the  working  of  steam  engines.  From  a 


series  of  experiments  made  by  Betan- 
court,  it  appears,  that  the  steam  of  alco- 
hol has,  in  all  cases  of  equal  temperature, 
more  than  double  the  force  of  that  of  wa- 
ter ;  and  that  the  steam  of  alcohol  at  174° 
F.  is  equal  to  that  of  water  at  212°  :  thus 
there  is  a  considerable  diminution  of  the 
consumption  of  fuel,  and  where  this  is  so 
expensive  as  to  be  an  object  of  great  im- 
pertance,  by  contriving  the  machinery  so 
as  to  prevent  the  alcohol  from  being  lost, 
it  may  possibly  at  some  future  time  be  used 
with  advantage,  if  some  other  fluid  of 
great  expansive  power,  and  inferior  price, 
be  not  found  more  economical. 

It  was  observed  at  the  beginning  of  this 
article,  that  alcohol  might  be  decomposed 
by  transmission  through  a  red-hot  tube  : 
it  is  also  decomposable  by  the  strong  acids, 
and  thus  affords  that  remarkable  product, 
ETHER  and  OLEUM  Visi. 

ALE.     See  BEER. 

ALEMBIC,  or  STILL.  This  part  of  che- 
mical apparatus,  used  for  distilling  or 
separating  volatile  products,  by  first  rais- 
ing them  by  heat,  and  then  condensing 
them  into  the  liquid  state  by  cold,  is  of 
extensive  use  in  a  variety  of  operations. 
It  is  described  under  the  article  LABORA- 
TORY. 

ALEM BROTH  SALT.  Corrosive  muriate 
of  mercury  is  rendered  much  more  solu- 
ble in  water,  by  the  addition  of  muriate  of 
ammonia.  From  this  solution  crystals  are 
separated  by  cooling,  which  were  called 
sal  alembroth  by  the  earlier  chemists,  and 
appeared  to  consist  of  ammonia,  muriatic 
acid,  and  mercury. 

ALGAROTH  (POWDER  OF).  Among  the 
numerous  preparations  which  the  alchemi- 
cal researches  into  the  nature  of  antimony 
have  afforded,  the  powder  of  algaroth  is 
one.  When  butter  of  antimony  is  thrown 
into  water,  it  is  not  totally  dissolved;  but 
part  of  the  metallic  oxide  falls  down  in 
the  form  of  a  white  powder,  which  is  the 
powder  of  algaroth.  It  is  violently  purga- 
tive and  emetic  in  small  doses  of  three  or 
four  grains.  See  ANTIMONY. 

ALKAHEST.  The  pretended  universal 
solvent,  or  menstruum,  of  the  ancient  che- 
mists. Kunckel  has  very  well  shown  the 
absurdity  of  searching  for  a  universal  sol- 
vent, by  asking,  "  If  it  dissolve  all  substan- 
ces, in  what  vessels  can  it  be  contained?'* 

ALKALESCENT.  Any  substance  in  which 
alkaline  properties  are  beginning  to  be 
developed,  or  to  predominate,  is  termed 
alkalescent.  The  only  alkali  usually  ob- 
served to  be  produced  by  spontaneous  de- 
composition is  the  volatile ;  and  from 
their  tendency  to  produce  this,  some  spe- 
cies of  vegetables,  particularly  the  cruci- 
form, are  styled  alkalescent,  as  are  some 
animal  substances.  See  FERMENTATION 
(PUTRID). 


ALK 


ALK 


*  AIKAII.  A  term  derived  from  kali  the 
Arabic  name  of  a  plant,  from  the  ashes  of 
which  one  species  of  alkaline  substance 
can  be  extracted.  Alkalis  may  be  defined, 
those  bodies  which  combine  with  acids, 
so  as  to  neutralize  or  impair  their  activity, 
and  produce  salts.  Acidity  and  alkalinity 
are  therefore  two  correlative  terms  of  one 
species  of  combination.  When  Lavoisier 
introduced  oxygen  as  the  acidifying-  prin- 
ciple, Morveau  proposed  hydrogen  as  the 
alkalifying  principle,  from  its  being  a  con- 
stituent of  volatile  alkali  or  ammonia.  But 
the  splendid  discovery  by  Sir  H.  Davy,  of 
the  metallic  bases  of  potash  and  soda,  and 
of  their  conversion  into  alkalis,  by  combi- 
nation with  oxygen,  has  banished  for  ever 
that  hypothetical  conceit.  It  is  the  mode 
in  which  the  constituents  are  combined, 
rather  than  the  nature  of  the  constituents 
themselves,  which  gives  rise  to  the  acid 
or  alkaline  condition.  Some  metals,  com- 
bined with  oxygen  in  one  proportion,  pro- 
duce a  body  possessed  of  alkaline  proper- 
ties, in  another  proportion  of  acid  proper* 
ties.  And  on  the  other  hand,  ammonia 
and  prussic  acid  prove  that  both  the  alka- 
line and  acid  conditions  can  exist  inde- 
pendent of  oxygen.  These  observations 
by  generalizing  our  notions  of  acids  and 
alkalis,  have  rendered  the  definitions  of 
them  very  imperfect.  The  difficulty  of 
tracing  a  limit  between  the  acids  and  al- 
kalis is  still  increased,  when  we  find  a  body 
sometimes  performing  the  functions  of  an 
acid,  sometimes  of  an  alkali.  Nor  can  we 
diminish  this  difficulty  by  having  recourse 
to  the  beautiful  law  discovered  by  Sir  H. 
Davy,  that  oxygen  and  acids  go  to  the 
positive  pole,  and  hydrogen,  alkalis,  and 
inflammable  bases  to  the  negative  pole. 
We  cannot  in  fact  give  the  name  of  acid 
to  all  the  bodies  which  go  to  the  first  of 
these  poles,  and  that  of  alkali  to  those 
that  go  to  the  second;  and  if  we  wished 
to  define  the  alkalis  by  bringing  into  view 
their  electric  energy,  it  Would  be  neces- 
sary to  compare  them  with  the  electric 
energy  which  is  opposite  to  them.  Thus 
we  are  always  reduced  to  define  alkalini- 
ty by  the  property  which  it  has  of  saturat- 
ing acidity,  because  alkalinity  and  acidity 
are  two  correlative  and  inseparable  terms. 
M.  Gay-Lussac  conceives  the  alkalinity 
which  the  metallic  oxides  enjoy  to  be  the 
result  of  two  opposite  properties,  the  al- 
kalifying  property  of  the  metal^  and  the 
acidifying  of  oxygen,  modified  both  by 
the  combination  and  by  the  proportions. 

The  alkalis  may  be  arranged  into  three 
classes  :  1st,  Those  which  consist  of  a  me- 
tallic basis  combined  with  oxygen.  These 
are  three  in  number,  potash,  soda  and 
lithia.  2d,  That  which  contains  no  oxygen, 
viz.  ammonia.  3d,  Those  containing  oxy- 
gen, hydrogen,  and  carbon.  In  this  class  we 
Vot.  r,  [19-] 


have  aconlta,  atropia,  brucia,  cicuta,  daturrt 
delphia,  hyosciama,  morphia,  strychnia* 
and  perhaps  some  other  truly  •vegetable 
alkalis.  The  order  of  vegetable  alkalis 
may  be  as  numerous  as  that  of  vegetable 
acids.  The  earths,  lime,  barytes,  and 
strontites  were  enrolled  among  the  alka- 
lis by  Fourcroy ;  but  they  have  been  kept 
apart  by  other  systematic  writers,  and  are 
called  alkaline  earths. 

Besides  neutralizing  acidity,  and  there- 
by giving  birth  to  salts,  the  first  four  alka- 
lis have  the  following  properties  : 

1st,  They  change  the  purple  colour  of 
many  vegetables  to  a  green,  the  reds  to 
a  purple,  and  the  yellows  to  a  brown.  If 
the  purple  have  been  reddened  by  acid, 
alkalis  restore  the  purple. 

2d,  They  possess  this  power  on  vege- 
table colours  after  being  saturated  with 
carbonic  acid,  by  which  criterion  they  are 
distinguishable  from  the  alkaline  earths. 

3d^  They  have  an  acrid  and  urinous 
taste. 

4th,  They  are  powerful  solvents1  or  cor- 
rosives of  animal  matter ;  with  which,  as 
well  as  with  oils  in  general,  they  combine, 
so  as  to  produce  neutrality. 

5th,  They  are  decomposed,  or  volati- 
lized, at  a  strong  red  heat. 

6th,  They  combine  with  water  in  every 
proportion,  and  also  largely  with  alcohol. 

7th,  They  continue  to  be  soluble  in 
water  when  neutralized  with  carbonic 
acid ;  while  the  alkaline  earths  thus  be- 
come insoluble. 

It  is  needless  to  detail  at.  length  Dr. 
Murray's  speculations  on  alkalinity.  They 
seem  to  flow  from  a  partial  view  of  che- 
mical phenomena.  According  to  him, 
either  oxygen  or  hydrogen  may  generate 
alkalinity,  but  the  combination  of  both 
principles  is  necessary  to  give  this  condi- 
tion its  utmost  energy.  "  Thus  the  class 
of  alkalis  will  exhibit  the  same  relations 
as  the  class  of  acids.  Some  are  compounds 
of  a  base  with  oxygen  ;  such  are  the 
greater  number  of  the  metallic  oxides,  and 
probably  of  the  earths.  Ammonia  is  a 
compound  of  a  base  with  hydrogen.  Pot- 
ash, soda,  barytes,  strontites,  and  proba- 
bly lime,  are  compounds  of  bases  with 
oxygen  and  hydrogen ;  and  these  last, 
like  the  analogous  order  among  the  acids, 
possess  the  highest  power."  Now,-surely, 
perfectly  dry  and  caustic  barytes,  lime, 
and  strontites,  as  well  as  the  dry  potash 
and  soda  obtained  by  Gay-Lussac  and 
Thenard,  are  not  inferior  in  alkaline  pow- 
er to  the  same  bodies  after  they  are  slack- 
ed or  combined  with  water.  100  parts  of 
lime  destitute  of  hydrogen,  that  is,  pure 
oxide  of  calcium,  neutralize  78  parts  of 
carbonic  acid.  But  132  parts  of  Dr.  Mur- 
ray's strongest  lime,  that  is  the  hydrate,- 
are  required  sto  produce  the  same  alktf- 


ALK 


ALL 


line  effect.  If  we  ignite  nitrate  of  barytes, 
we  obtain,  as  is  well  known,  a  perfectly 
dry  barytes,  or  protoxide  of  barium;  but 
if  we  ignite  crystallized  barytes,  we  ob- 
tain the  same  alkaline  earth  combined 
with  a  prime  equivalent  of  water.  These 
two  different  states  of  barytes  were  de- 
monstrated by  M.  Berthollet  in  an  excel- 
lent paper  published  in  the  2d  volume  of 
the  Memoires  D'Arcueil,  so  far  back  as 
1809.  "  The  first  barytes,"  (that  from 
crystallized  barytes),  says  he,  "  presents 
all  the  characters  of  a  combination ;  it  is 
engaged  with  a  substance  which  diminish- 
es its  action  on  other  bodies,  whicn  ren- 
ders it  more  fusible,  and  which  gives  it  by 
fusion  the  appearance  of  glass.  This  sub- 
stance is  nothing1  else  but  water ;  but  in 
fact,  by  adding  a  little  water  to  the  second 
barytes  (that  from  ignited  nitrate),  and  by 
urging-  it  at  the  fire,  we  give  it  the  pro- 
perties of  the  first  "  Page  47.  100  parts 
of  barytes  void  of  hydrogen,  or  dry  bary- 
tes, neutralize  28J  of  dry  carbonic  acid. 
"Whereas  11 1|  parts  of  the  hydrate,  or 
what  Dr.  Murray  has  styled  the  most  en- 
ergetic, are  required  to  produce  the  same 
effect.  In  fact,  it  is  not  hydrogen  which 
combines  with  the  pure  barytic  earth,  but 
hydrogen  and  oxygen  in  the  state  of  wa- 
ter. The  proof  of  this  is,  that  when  car- 
bonic acid  and  that  hydrate  unite,  the  ex- 
act quantity  of  water  is  disengaged.  The 
protoxide  of  barium,  or  pure  barytes,  has 
never  been  combined  with  hydrogen  by 
any  chemist.* 

ALKALI  (PHLOGISTICATED,  or  PJIUSSIAW.) 
When  a  fixed  alkali  is  ignited  with  bul- 
lock's blood,  or  other  animal  substances, 
and  lixiviated,  it  is  found  to  be  in  a  great 
measure  saturated  with  the  prussic  acid  : 
from  the  theories  formerly  adopted  re- 
specting this  combination,  it  was  distin- 
guished by  the  name  of  phlogisticated  al- 
kali. See  ACID  (Pnussic.) 

ALKALI  (VOLATILE.)     See  AMMONIA. 

*  ALKALI  MET  EH.  The  name  first  given 
by  M.  Descroizilles  to  an  instrument  or 
measure  of  his  graduation,  for  determining 
the  quantity  of  alkali  in  commercial  pot- 
ash and  soda,  by  the  quantity  of  dilute  sul- 
phuric acid  of  a  known  strength  which  a 
certain  weight  of  them  could  neutralize. 
His  method  was  unnecessarily  operose. 
A  much  simpler,  and  very  accurate  mode, 
was  exhibited  by  Dr.  Ure  before  the  Li- 
nen Board  of  Dublin  in  June  1816,  and 
soon  afterwards  submitted  in  manuscript 
to  Dr.  Henry,  who  has  since  then  expung- 
ed the  description  of  M.  Descroizilles'  al- 
kalimeter  from  his  valuable  elements,  and 
substituted  one  on  Dr.  Ure's  principle. 
More  recently  Dr.  Ure  has  been  occupied 
in  completing  the  arrangement  of  an  in- 
strument for  giving  increased  facility  and 
dispatch  to  chemical  analysis  in  general. 


It  will  apply  to  alkalis,  acids,  earths,  me- 
tals, 8cc.  He  hopes  to  be  able,  very  soon, 
to  submit  its  construction  and  performance 
to  the  tribunal  of  the  public.  Meanwhile 
directions  will  be  given  in  this  work  under 
the  individual  alkalis,  for  ascertaining  the 
quality  of  commercial  specimens.* 

ALKANET.  The  alkanet  plant  is  a  kind 
of  bugloss,  which  is  a  native  of  the  warm- 
er parts  of  Europe,  and  cultivated  in  some 
of  our  gardens.  The  greatest  quantities 
are  raised  in  Germany  and  France,  parti- 
cularly about  Montpelier,  whence  we  are 
chiefly  supplied  with  the  roots.  These 
are  of  a  superior  quality  to  such  as  are 
raised  in  England.  This  root  imparts  an. 
elegant  deep  red  colour  to  pure  alcohol, 
to  oils,  to  wax,  and  to  all  unctuous  sub- 
stances. The  aqueous  tincture  is  of  a  dull 
brownish  colour ;  as  is  likewise  the  spiri- 
tuous tincture  when  inspissated  to  the  con- 
sistence of  an  extract.  The  principal  use 
of  alkanet  root  is,  that  of  colouring  oils, 
unguents,  and  lip-salves.  Wax  tinged  with 
it,  and  applied  on  warm  marble,  stains  it 
of  a  flesh  colour,  which  sinks  deep  into 
the  stone  ;  as  the  spirituous  tincture  gives 
it  a  deep  red  stain.f 

As  the  colour  of  this  root  is  confined  to 
the  bark,  and  the  small  roots  have  more 
bark  in  proportion  to  their  bulk  than  the 
great  ones,  these  also  afford  most  colour. 

*  ALLANITE.  A  mineral  first  recognized 
as  a  distinct  species  by  Mr.  Allan,  of  Edin- 
burgh, to  whose  accurate  knowledge,  and 
splendid  collection,  the  science  of  mine- 
ralogy has  been  so  much  indebted  in  Scot- 
land. Its  analysis  and  description,  by  Dr. 
Thomson,  were  published  in  the  6th  vo- 
lume of  the  Edinburgh  Ph.  Trans.  M. 
Giesecke  found  it  in  a  granite  rock  in 
West  Greenland.  It  is  massive  and  of  a 
brownish  black  colour.  External  lustre, 
dull;  internal,  shining  and  resinous — frac- 
ture small  conchoidal — opaque— greenish 
gray  streak — scratches  glass  and  horn- 
blende— brittle — spec.  -grav.  35  to  4.O.. 
Froths  and  melts  imperfectly  before  the 

f  On  making  an  infusion  of  alkanet  roots 
in  alcohol,  I  was  surprised  to  find  the  co- 
lour a  deep  blue,  instead  of  being  red. 
Remembering  that  the  alcohol  had  stood 
over  an  alkali,  I  added  some  acid  to  the 
blue  infusion.  It  became  instantly  red; 
and  the  same  colour  appeared  to  be  pro- 
duced originally,  when  the  roots  were 
steeped  in  pure  alcohol.  1  am  surprised, 
that  I  have  not  met  with  any  account  of 
habitudes  so  interesting,  and  which  ac- 
quire additional  value,  when  contrasted 
with  those  of  litmus  and  other  vegetable 
colours,  originally  blue.  These,  redden- 
ed by  an  acid,  are  restored  by  an  alkali ; 
while  alkanet,  made  blue  by  alkalis,  i». 
restored  by  acids. 


ALL 


ALL 


"blow-pipe,  into  a  black  scoria.  It  con- 
sists in  100  parts,  of  silica  35.4,  oxide  of 
•cerium  33.9,  oxide  of  iron  25.4,  lime  9.2, 
alumina  4. 1,  and  moisture  4.0.  It  has  been 
also  found  crystallized  in  four,  six,  or  eight- 
sided  prisms.  It  closely  resembles  gado- 
linite,  but  may  be  distinguished,  from  the 
thin  fragments  of  the  latter  being  trans- 
lucent on  the  edges,  and  of  a  fine  green 
colour,  whereas  those  of  the  former  are 
commonly  opaque  and  of  a  yellowish 
brown.  The  ores  of  cerium  analyzed  by 
Berzelius,  under  the  name  of  cerin,  ap- 
proach very  closely  in  their  composition 
to  allanite.* 

*  ALLOCHROITE.     A  massive  opaque  mi- 
neral of  a  grayish,  yellowish,  or  reddish 
colour.     Quartz  scratches  it,  but  it  strikes 
fire  with  steel.     Jt  has  externally,  a  glis- 
tening, and  internally,  a  glimmering  lustre. 
Its  fracture  is  uneven,  and  its  fragments 
are  translucent  on  the  edges :  sp.  gr.  3.5 
to  3.6.     It  melts  before  the  blow-pipe  into 
a  black  opaque  enamel.     Vauquelin's  ana- 
lysis is  the  following :  Silica  35,  lime  30.5, 
oxide  of  iron  17,  alumina  8,  carbonate  of 
lime  6,  oxide  of  manganese  3.5,  M.  Brong- 
niart  says  it  is  absolutely  infusible  without 
addition,   and  that  it  requires  a  flux  as 
phosphate   of  soda    or   ammonia.     With 
these  it  passes  through  a  beautiful  grada- 
tion of  colours.     It  is  covered  at  first  with 
a  species  of  enamel,  which  becomes  on 
cooling  reddish  yellow,  then  greenish,  and 
lastly  of  a  dirty  yellowish  white.     He  re- 
pres'ents  it  as  pretty  difficult  to  break.    It 
was  found  by  M.   Dandrada  in  the  iron 
mine  of  Virums,  near  Drammen  in  Norway. 
It  is  accompanied  by  carbonate  of  lime, 
protoxide  of  iron,  and  sometimes  brown 
garnets.* 

*  AI.LOPHANE.    A  mineral  of  a  blue,  and 
sometimes  a  green  or  brown  colour,  which 
occurs  massive,   or  in   imitative   shapes. 
Lustre  vitreous;  fracture  imperfectly con- 
choidal;  transparent  or  translucent  on  the 
edges.     Moderately  hard,  but  very  brittle. 
Sp.  gr.   1.89.     Composition,  silica  21.92, 
alumina  32.2,  lime  0.73,  sulphate  of  lime 
0.52,  carbonate  of  copper  3.06,  hydrate  of 
Iron  0.27,  water  41.3.     Stromeyer.     It  ge- 
latinizes in  acids :  It  is  found  in  a  bed  of 
ironshot  limestone  in  gray wacke  slate,  in 
the  forest  of  Thuringia,   It  was  called  Rie- 
xnannite.  * 

AI.IAY,  or  ALT.OY.  Where  any  precious 
metal  is  mixed  with  another  of  less  value, 
the  assayers  call  the  latter  the  alloy,  and 
do  not  in  general  consider  it  in  any  other 
point  of  view  than  as  debasing  or  dimi- 
nishing the  value  of  the  precious  metal. 
Philosophical  chemists  have  availed  them- 
selves of  this  term  to  distinguish  all  metal- 
lic compounds  in  general.  Thus  brass  is 
railed  an  alloy  of  copper  and  zinc ;  bell 
metal  an  alloy  of  copper  and  tin. 


*  Every  alloy  is  distinguished  by  the 
metal  which  predominates  in  its  composi- 
tion, or  which  gives  it  its  value.  Thus 
English  jewellery  trinkets  are  ranked  un- 
der alloys  of  gold,  though  most  of  them 
deserve  to  be  placed  under  the  head  of 
copper.  When  mercury  is  one  of  the  com- 
ponent metals,  the  alloy  is  called  amalgam. 
Thus  we  have  an  amalgam  of  gold,  silver, 
tin,  &c.  Since  there  are  about  30  differ- 
ent permanent  metals,  independent  of 
those  evanescent  ones  that  constitute  the 
bases  of  the  alkalis  and  earths,  there  ought 
to  be  about  870  different  species  of  binary 
alloy.  But  only  132  species  have  been 
hitherto  made  and  examined.  Some  me- 
tals have  so  little  affinity  for  others,  that 
as  yet  no  compound  of  them  has  been  ef- 
fected, whatever  pains  have  been  taken. 
Most  of  these  obstacles  to  alloying;  arise 
from  the  difference  in  fusibility  and  vola- 
tility. Yet  a  few  metals  whose  melting 
point  is  nearly  the  same,  refuse  to  unite. 
It  is  obvious  that  two  bodies  will  not  com- 
bine, unless  their  affinity  or  reciprocal  at- 
traction, be  stronger  than  the  cohesive  at- 
traction of  their  individual  particles.  To 
overcome  this  cohesion  of  the  solid  bo- 
dies, and  render  affinity  predominant,  they 
must  be  penetrated  by  caloric.  If  one  be 
very  difficult  effusion,  and  the  other  very 
volatile,  they  will  not  unite  unless  the  re- 
ciprocal attraction  be  exceedingly  strong. 
But  if  their  degree  of  fusibility  be  almost 
the  same,  they  are  easily  placed  in  the  cir- 
cumstances most  favourable  for  making  an 
alloy.  If  we  are  therefore  far  from  know- 
ing all  the  binary  alloys  which  are  possi- 
ble, we  are  still  further  removed  from 
knowing  all  the  triple,  quadruple,  &c. 
which  may  exist.  It  must  be  confessed, 
moreover,  that  this  department  of  chemis- 
try has  been  imperfectly  cultivated. 

Besides,  alloys, are  not,  as  far  as  we 
know,  definitely  regulated  like  oxides  in 
the  proportions  of  their  component  parts. 
100  parts  of  mercury  will  combine  with  4, 
or  8,  parts  of  oxygen,  to  form  two  distinct 
oxides,  the  black  and  the  red ;  but  with 
no  greater,  less,  or  intermediate  propor- 
tions. But  100  parts  of  mercury  Mall  unite 
with  1,  2,  3,  or  with  any  quantity  up  to  a 
100  or  1000,  of  tin  or  lead.  The  alloys 
have  the  closest  relations  in  their  physical 
properties  with  the  metals.  They  are  all 
solid  at  the  temperature  of  the  atmosphere, 
except  some  amalgams;  they  possess  me- 
tallic lustre,  even  when  reduced  to  a  coarse 
powder;  are  completely  opaque,  and  more 
or  less  dense,  according  to  the  metals 
which  compose  them;  are  excellent  con- 
ductors of  electricity;  crystallize  more  or 
less  perfectly;  some  are  brittle,  others 
ductile  and  malleable;  some  have  a  pecu- 
liar odour;  several  are  very  sonorous  and 
elastic.  When  an  alloy  consists  of  metals 


ALL 


ALL 


•eLhTerently  fusible,  it  is  usually  malleable 
while  cold,  but  brittle  while  hot;  as  is  ex- 
emplified in  brass. 

The  density  of  an  alloy  is  sometimes 
greater,  sometimes  less  than  the  mean 
density  of  its  components,  showing1  that, 
at  the  instant  of  their  union,  a  diminution, 
or  augmentation  of  volume  takes  place. 
The  relation  between  the  expansion  of  the 
separate  metals,  and  that  of  their  alloys, 
has  been  investigated  only  in  a  very  few 
cases.  Alloys  containing1  a  volatile  metal 
are  decomposed,  in  whole  or  in  part,  at  a 
strong  heat.  This  happens  with  those  of 
arsenic,  mercury,  tellurium  and  zinc. 
Those  that  consist  of  two  differently  fusi- 
ble metals,  may  often  be  decomposed,  by 
exposing  them  to  a  temperature  capable 
of  melting  only  one  of  them.  This  opera- 
tion is  called  eliquation.  It  is  practised 
on  the  great  scale  to  extract  silver  from 
copper.  The  argentiferous  copper  is  melt- 
ed with  3£  times  its  weight  of  lead ;  and 
the  triple  alloy  is  exposed  to  a  sufficient 
heat.  The  lead  carries  off  the  silver  in 
its  fusion,  and  leaves  the  copper  under 
the  form  of  a  spongy  lump.  The  silver  is 
afterwards  recovered  from  the  lead  by 
another  operation. 

Some  alloys  oxidize  more  readily  by 
heat  and  air,  than  when  the  metals  are  se- 
parately treated.  Thus  3  of  lead,  and  1 
of  tin,  at  a  dull  red,  burn  visibly,  and  are 
almost  instantly  oxidized.  Each  by  itself 
in  the  same  circumstances,  would  oxidize 
slowly,  and  without  the  disengagement  of 
light. 

The  formation  of  an  alloy  must  be  regu- 
lated by  the  nature  of  the  particular  me- 
tals; to  which  therefore  we  refer. 

The  degree  of  affinity  between  metals 
may  be  in  some  measure  estimated  by  the 
greater  or  less  facility  with  which,  when 
of  different  degrees  of  fusibility  or  vola- 
tility, they  unite,  or  with  which  they  can 
after  union  be  separated  by  heat.  The 
greater  or  less  tendency  to  separate  into 
different  proportional  alloys,  by  long  con- 
tinued fusion,  may  also  give  some  informa- 
tion on  this  subject.  Mr.  Hatchett  re- 
marked, in  his  admirable  researches  on 
metallic  alloys,  that  gold  made  standard 
with  the  usual  precautions  by  silver,  cop- 
per, lead,  antimony,  &c.  and  then  cast  in- 
to vertical  bars,  was  by  no  means  a  uni- 
form compound;  but  that  the  top  of  the 
bar,  corresponding  to  the  metal  at  the  bot- 
tom of  the  crucible,  contained  the  larger 
proportion  of  gold.  Hence,  for  thorough 
combination,  two  red-hot  crucibles  should 
be  employed;  and  the  liquefied  metals 
should  be  alternately  poured  from  the  one 
into  the  other.  And  to  prevent  unneces- 
sary oxidizement  by  exposure  to  air,  the 
crucibles  should  contain,  besides  the  me- 
tal, a  mixture  of  common  salt  and  pound- 


ed charcoal.  The  melted  alloy  should  al- 
so be  occasionally  stirred  up  with  a  rod  of 
pottery. 

The  most  direct  evidence  of  a  chemical 
change  having  taken  place  in  the  two  me- 
tals by  combination,  is  when  the  alloy 
melts  at  a  much  lower  temperature  than 
the  fusing  points  of  its  components.  Iron 
which  is  nearly  infusible,  when  alloyed 
with  gold,  acquires  almost  the  fusibility 
of  this  metal.  Tin  and  lead  form  solder, 
an  alloy  more  fusible  than  either  of  its 
components  ;  but  the  triple  compound  of 
tin,  lead,  and  bismuth,  is  most  remarkable 
on  this  account.  The  analogy  is  here 
strong,  with  the  increase  of  solubility, 
which  salts  acquire  by  mixture,  as  is  exem- 
plified in  the  uncrystallizable  residue  of 
saline  solutions,  or  mother  waters,  as  they 
are  called.  Sometimes  two  metals  will 
not  directly  unite,  which  yet,  by  the  in- 
tervention of  a  third,  are  made  to  com- 
bine. This  happens  with  mercury  and 
iron,  as  has  been  shown  by  Messrs.  Aikin, 
who  effected  this  difficult  amalgamation 
by  previously  uniting  the  iron  to  tin  or 
zinc, 

The  tenacity  of  alloys  is  generally, 
though  not  always,  inferior  to  the  mean  of 
the  separate  metals.  One  part  of  lead 
will  destroy  the  compactness  and  tenacity 
of  a  thousand  of  gold.  Brass,  made  with 
a  small  proportion  of  zinc,  is  more  ductile 
than  copper  itself;  but  when  one-third  of 
zinc  enters  into  its  composition,  it  be- 
comes brittle. 

In  common  cases,  the  specific  gravity 
affords  a  good  criterion  whereby  to  judge 
of  the  proportion  in  an  alloy,  consisting 
of  two  metals  of  different  densities.     But 
a  very  fallacious  rule  has  been   given  in 
some  respectable  works,  for  comparing 
the  specific  gravity  that  should  result  from     , 
given  quantities  of  two  metals  of  known 
densities  alloyed  together,  supposing  no 
chemical  penetration  or  expansion  of  vo- 
lume to  take  place.     Thus  it  has  been 
taught,  that  if  gold  and  copper  be  united 
in  equal  weights,  the  computed  or  mathe-     j 
matical  specific  gravity  of  the  alloy  is  the     j 
arithmetical  mean  of  the  two  specific  gra-     ; 
vities.     This  error  was  pointed  out  by  me     j 
in  a  paper  published  in  the  7th  number  of 
the  Journal  of  Science  and  the  Arts;  and 
the  correct  rule   was  at  the   same  time 
given.     The  details  belong  to  the  article 
Specific   Gravity;  but  the  rule  merits  a 
place  here.     The  specific  gravity  of  the 
alloy  is  found  by  dividing  the  sum  of  the     j 
weights  by  the  sum  of  the  volumes,  com- 
pared to  water,  reckoned  unity.     Or  in     \ 
another  form,  the  rule  maybe  stated  thus : 
Multiply  the  sum  of  the  weights  into  the 
product  of  the  two  specific  gravities  for  a 
numerator,    and   multiply    each    specific 
gravity  into  the  weight  of  the  other  body, 


ALM 


ALO 


and  add  the  two  products  together  for  a 
denominator.  The  quotient  obtained  by 
dividing1  the  numerator  by  the  denomina- 
tor, is  the  true  computed  mean  specific 
gravity;  and  that  found  by  experiment, 
being  compared  with  it,  will  shew  whe- 
ther expansion  or  condensation  of  volume 
has  attended  the  chemical  combination. 
Gold  having  a  specific  gravity  of  19.36, 
and  copper  of  8.87,  being  alloyed  in 
equal  weights,  give  on  the  fallacious  rule 
of  the  arithmetical  mean  of  the  densities, 


19.36  4-  8.87 


14.11;    whereas   the 


rightly  calculated  mean  specific  gravity  is 
only  12.16.  It  is  evident  that  by  compar- 
ing the  former  number  with  chemical  ex- 
periment, we  should  be  led  to  infer  a  pro- 
digious condensation  of  volume  beyond 
what  really  occurs. 

A  circumstance  was  observed  by  Mr. 
Hatchett  to  influence  the  density  of  me- 
tals, which  a  priori  might  be  thought  un- 
important. When  a  bar  of  gold  was  cast 
in  a  vertical  position,  the  density  of  the 
metal  at  the  lower  end  of  the  bar  was 
greater  than  that  of  the  top,  in  the  pro- 
portion of  17.364  to  17.035.  Are  we  to 
infer  that  melted  metal  is  a  compressible 
fluid,  or  rather,  that  particles  passing  in- 
to the  solid  state  under  pressure,  exert 
their  cohesive  attraction  with  adventitious 
strength  ?  Under  the  title  metal,  a  tabular 
view  of  metallic  combinations  will  be 
found,  and  under  that  of  the  particular 
metal,  the  requisite  information  about  its 
alloys. 

ALLUVIAL  FORMATIONS,  in  geology,  are 
recent  deposits  in  valleys  or  in  plains,  of 
the  detritus  of  the  neighbouring  moun- 
tains. Gravel,  loam,  clay,  sand,  brown 
coal,  wood  coal,  bog  iron  ore,  and  calc 
tuff,  compose  the  alluvial  deposites.  The 
gravel  and  sand  sometimes  contain  gold 
and  tin,  if  the  ores  exist  in  the  adjoining 
mountains.  Petrified  wood  and  animal 
skeletons  are  found  in  the  alluvial  clays 
and  sand.* 

ALKOSDS.  Almonds  consist  chiefly  of 
w\  oil  of  the  nature  of  fat  oils,  together 
with  farinaceous  matter.  The  oil  is  so 
plentiful,  and  so  loosely  combined  or  mix- 
ed with  the  other  principles,  that  it  is  ob- 
tained by  simple  pressure,  and  part  of  it 
may  be  squeezed  out  with  the  fingers. 
Five  pounds  and  a  half  have  yielded  one 
pound  six  ounces  of  oil  by  cold  expression, 
and  three  quarters  of  a  pound  more  on 
heating  them.  There  are  two  kinds  of 
almonds,  the  sweet  and  bitter.  The  bit- 
irr  almonds  yield  an  oil  as  tasteless  as  that 
of  the  other,  all  the  bitter  matter  remain- 
ing in  the  cake  after  the  expression. 
Great  part  of  the  bitter  matter  dissolves 
by  digestion,  both  in  watery  and  spirituous 


liquors  ;  and  part  arises  with  both  in  dis- 
tillation. Rember  obtained  from  them 
l-3d  of  watery  extract,  and  3-32ds  of  spiri- 
tuous. Bitter  almonds  are  poisonous  to 
birds,  and  to  some  animals.  A  water  dis- 
tilled from  them,  when  made  of  a  certain 
degree  of  strength,  has  been  found  from 
experiment  to  be  poisonous  to  brutes; 
and  there  are  instances  of  cordial  spirits 
impregnated  with  them  being  poisonous 
to  men.  It  seems,  indeed,  that  the  vege- 
table principle  of  bitterness  in  almonds 
and  the  kernels  of  other  fruits,  is  destruc- 
tive to  animal  life,  when  separated  by  dis- 
tillation from  the  oil  and  farinaceous  mat- 
ter. The  distilled  water  from  laurel  leaves 
appears  to  be  of  this  nature,  and  its  poi- 
sonous effects  are  well  known. 

Sweet  almonds  are  made  into  an  emul- 
sion by  trituration  with  water,  which  on 
standing  separates  a  thick  cream  floating 
on  the  top.  The  emulsion  may  be  cur- 
dled by  heat,  or  the  addition  of  alcohol  or 
acids.  The  whey  contains  gum,  extractive 
matter,  and  sugar,  according  to  Professor 
Proust ;  and  the  curd,  when  washed  and 
dried,  yields  oil  by  expression,  and  after- 
wards by  distillation  the  same  products  as 
cheese.  The  whey  is  a  good  diluent. 

*  Prussic  or  hydrocyanic  acid  is  the  de- 
leterious ingredient  in  bitter  almonds. 
The  best  remedy  after  emetics  is  a  com- 
bination of  sulphate  of  iron  with  bicarbo- 
nate of  potash.* 

ALOES.  This  is  a  bitter  juice,  extracted 
from  the  leaves  of  a  plant  of  the  same 
name.  Three  sorts  of  aloes  are  distin- 
guished in  the  shops  by  the  names  of 
aloe  socotrina,  aloe  hepatica,  and  aloe 
caballina.  The  first  denomination,  which 
is  applied  to  the  purest  kind,  is  taken 
from  the  island  of  Zocotora ;  the  second, 
or  next  in  quality,  is  called  hepatica,  from 
its  liver  colour ;  and  the  third,  caballina, 
from  the  use  of  this  species  being  confined 
to  horses.  These  kinds  of  aloes  are  said 
to  differ  only  in  purity,  though,  from  the 
difference  of  their  flavours,  it  is  probable 
that  they  may  be  obtained  in  some  in- 
stances from  different  species  of  the  same 
plant.  It  is  certain,  however,  that  the  dif- 
ferent kinds  are  all  prepared  at  Morviedro 
in  Spain,  from  the  same  leaves  of  the  com- 
mon aloe.  Deep  incisions  are  made  in  the 
leaves,  from  which  the  juice  is  suffered 
to  flow ;  and  this,  after  decantation  from 
its  sediment,  and  inspissation  in  the  sun, 
is  exposed  to  sale  in  leathern  bags  by  the 
name  of  socotrine  aloes.  An  additional 
quantity  of  juice  is  obtained  by  pressure 
from  the  leaves;  and  this,  when  decanted 
from  its  sediment  and  dried,  is  the  hepatic 
aloes.  And  lastly,  a  portion  of  juice  is 
obtained  by  strong  pressure  of  the  leaves, 
and  is  mixed  with  the  dregs  of  the  two 
preceding  kinds  to  form  the  caballine 


ALU 


ALU 


aloes.  The  first  kind  is  said  to  contain 
much  less  resin.  The  principal  characters 
of  good  aloes  are  these :  it  must  be  glossy, 
not  very  black,  but  brown ;  when  rubbed 
or  cut,  of  a  yellow  colour;  compact,  but 
easy  to  break ;  easily  soluble ;  of  an  un- 
pleasant peculiar  smell,  which  cannot  be 
described,  and  an  extremely  bitter  taste. 
Aloes  appears  to  be  an  intimate  combi- 
nation of  gummy  resinous  matter,  so  well 
blended  together,  that  watery  or  spiri- 
tuous solvents,  separately  applied,  dissolve 
the  greater  part  of  both.  It  is  not  deter- 
mined whether  there  be  any  difference  in 
the  medical  properties  of  these  solutions. 
Both  are  purgative,  as  is  likewise  the  aloes 
in  substance ;  and,  if  used  too  freely,  are 
apt  to  prove  heating,  and  produce  hemor- 
rhoidal  complaints. 

*  Braconnot  imagines  he  has  detected 
in  aloes  a  peculiar  principle,  similar  to  the 
bitter  resinous  which  Vauquelin  has  found 
in  many  febrifuge  barks.  The  recent  juice 
of  the  leaves  absorbs  oxygen,  and  be- 
comes a  fine  reddish  purple  pigment.* 

ALUDKL.  The  process  of  sublimation 
differs  from  distillation  in  the  nature  of  its 
product,  which,  instead  of  becoming  con- 
densed in  a  fluid,  assumes  the  solid  state, 
and  the  form  of  the  receivers  may  of 
course  be  very  different.  The  receivers 
for  sublimates  are  of  the  nature  of  chim- 
neys, in  which  the  elastic  products  are 
condensed,  and  adhere  to  their  internal 
surface.  It  is  evident  that  the  head  of  an 
alembic  will  serve  very  well  to  receive 
and  condense  such  sublimates  as  are  not 
very  volatile.  The  earlier  chemists,  whose 
notions  of  simplicity  were  not  always  the 
most  perfect,  thought  proper  to  use  a 
number  of  similar  heads,  one  above  the 
other,  communicating  in  succession  by 
means  of  a  perforation  in  the  superior  part 
of  each,  which  received  the  neck  of  the 
•capital  immediately  above  it.  These  heads, 
differing  in  no  respect  from  the  usual 
heads  of  alembics,  excepting  in  their  hav- 
ing no  nose  or  beak,  and  in  the  other  cir- 
cumstances here  mentioned,  were  called 
aludels.  They  are  seldom  now  to  be  seen 
in  chemical  laboratories,  because  the  op- 
erations of  this  art  maybe  performed  with 
greater  simplicity  of  instruments,  provi- 
ded attention  be  paid  to  the  heat  and 
other  circumstances. 

*  ALUM.     See  ALUMINA,  Sulphate  of.* 

*  ALUM-EAHTH.     A  massive  mineral,  of 
a  blackish  brown  colour,  a  dull  lustre,  an 
earthy  and  somewhat  slaty  fracture,  sec- 
tile,  and  rather  soft.    By  Klaproth's  analy- 
sis it  contains,  charcoal  19.65,  silica  40, 
alumina  16,  oxide  of  iron  6.4,  sulphur  2.84, 
sulphates  of  lime  and  potash,  each  1.5,  sul- 
phate of  iron  1.8,  magnesia  and  muriate  of 
potash  0.5,  and  water  10.75. 

*  ALUM-SLATE.  1.  Common.  This  mine- 


ral occurs  both  massive  and  in  insulated 
balls,  of  a  grayish  black  colour,  dull  lus- 
tre, straight  slaty  fracture,  tabular  frag- 
ments, streak  coloured  like  itself;  though, 
soft  it  is  not  very  brittle.  Effloresces,  ac- 
quiring the  taste  of  alum. 

2.  Glossy  Alum-slate.  A  massive  mine- 
ral of  a  bluish  black  colour.  The  rents 
display  a  variety  of  lively  purple  tints.  It 
has  a  semi-metallic  lustre  in  the  fracture, 
which  is  straight,  slaty,  or  undulating. 
There  is  a  soft  variety  of  it  approaching 
in  appearance  to  slate  clay.  By  exposure 
to  air,  its  thickness  is  prodigiously  aug- 
mented by  the  formation  of  a  saline  efflo- 
rescence, which  separates  its  thinnest 
plates.  These  afterwards  exfoliate  in  brit- 
tle sections,  causing  entire  disintegration.* 
*  ALUMINA.  One  of  the  primitive  earths, 
which,  as  constituting  the  plastic  princi- 
ple of  all  clays,  loams  and  boles,  was  cal- 
led argil  orthe  argillaceous  earth;  but  now, 
as  being  obtained  in  greatest  purity  from 
alum,  is  styled  alumina.  It  was  deemed 
elementary  matter  till  Sir  H.  Davy's  cele- 
brated electro-chemical  researches  led  to 
the  belief  of  its  being,  like  barytes  and 
lime,  a  metallic  oxide. 

The  purest  native  alumina  is  found  in 
the  oriental  gems,  the  sapphire  and  ruby. 
They  consist  of  nothing  but  this  earth, 
and  a  small  portion  of  colouring  matter. 
The  native  porcelain  clays  or  kaolins, 
however  white  and  soft,  can  never  be  re- 
garded as  pure  alumina.  They  usually 
contain  fully  half  their  weight  of  silica,  and 
frequently  other  earths.  To  obtain  pure 
alumina  we  dissolve  alum  in  20  times  its 
weight  of  water,  and  add  to  it  a  little  of 
the  solution  of  carbonate  of  soda,  to  throw 
down  any  iron  which  may  be  present. 
We  then  drop  the  supernatant  liquid  into 
a  quantity  of  the  water  of  ammonia,  taking 
care  not  to  add  so  much  of  the  aluminous 
solution  as  will  saturate  the  ammonia. 
The  volatile  alkali  unites  with  the  sul- 
phuric acid  of  the  alum,  and  the  earthy 
basis  of  the  latter  is  separated  in  a  white 
spongy  precipitate.  This  must  be  thrown 
on  a  filter,  washed,  or  edulcorated  as  the 
old  chemists  expressed  it,  by  repeated  af- 
fusions of  water,  and  then  dried.  Or  if  an 
alum,  made  with  ammonia  instead  of  pot- 
ash, as  is  the  case  with  some  French 
alums,  can  be  got,  simple  ignition  dissi- 
pates its  acid  and  alkaline  constituents, 
leaving  pure  alumina. 

Alumina  prepared  by  the  first  process 
is  white,  pulverulent,  soft  to  the  touch,  ad- 
heres to  the  tongue,  forms  a  smooth  paste 
without  grittiness  in  the  mouth,  insipid, 
inodorous,  produces  no  change  in  vege- 
table colours,  insoluble  in  water,  but  mix- 
es with  it  readily  in  every  proportion, 
and  retains  a  small  quantity  with  con- 
siderable force ;  is  infusible  in  the  strong- 


ALU 


ALU 


est  heat  of  a  furnace,  experiencing  mere- 
ly a  condensation  of  volume  and  conse- 
quent hardness,  but  it  is  in  small  quanti- 
ties melted  by  the  oxy-hydrogen  blow- 
pipe. Its  specific  gravity  is  2.000,  in  the 
state  of  powder,  but  by  ignition  it  is  aug- 
mented. 

Every  analogy  leads  to  the  belief  that 
alumina  contains  a  peculiar  metal,  which 
may  be  called  aluminum.  The  first  evi- 
dences obtained  of  this  position  are  pre- 
sented in  Sir  H.  Davy's  researches.  Iron 
negatively  electrified  by  a  very  high  pow- 
er being  fused  in  contact  with  pure  alu- 
mina, formed  a  globule  whiter  than  pure 
iron,  which  effervesced  slowly  in  water, 
becoming  covered  with  a  white  powder. 
The  solution  of  this  in  muriatic  acid,  de- 
composed by  an  alkali,  afforded  alumina 
and  oxide  of  iron.  By  passing  potassium 
in  vapour  through  alumina  heated  to 
whiteness,  the  greatest  part  of  the  potas- 
sium became  converted  into  potash,  which 
formed  a  coherent  mass  with  that  part  of 
the  alumina  not  decompounded;  and  in 
this  mass  there  were  numerous  gray  par- 
ticles, having  the  metallic  lustre,  and 
which  became  white  when  heated  in  the 
air,  and  which  slowly  effervesced  in  wa- 
ter. In  a  similar  experiment  made  by  the 
same  illustrious  chemist,  a  strong  red 
heat  only  being  applied  to  the  alumina,  a 
mass  was  obtained,  which  took  fire  spon- 
taneously by  exposure  to  air,  and  which 
effervesced  violently  in  water.  This  mass 
was  probably  an  alloy  of  aluminum  and 
potassium.  The  conversion  of  potassium 
into  its  deutoxide,  dry  potash,  by  alumina, 
proves  the  presence  of  oxygen  in  the  lat- 
ter. When  regarded  as  an  oxide,  Sir  H. 
Davy  estimates  its  oxygen  and  basis  to  be 
to  one  another  as  15  to  33 ;  or  as  10  to  22. 
The  prime  equivalent  of  alumina  would 
thus  appear  to  be  1.0  +  2.2  =*=  3.2. 

But  Berzelius's  analysis  of  sulphate  of 
alumina  seems  to  indicate  2.136  as  the 
quantity  of  the  earth  which  combines  with 
5.  of  the  acid.  Hence  aluminum  will  come 
to  b«  represented  by  2.136  —  1.  =  1.136. 
But  we  shall  presently  show  that  his  ana- 
lysis, both  of  alum  and  sulphate  of  alumi- 
na, may  be  reconciled  to  Sir.  H.  Davy's 
equivalent  prime  ==  3.2.  That  of  alumi- 
num will  become  of  course  2. 2. 

Alumina  which  has  lost  its  plasticity  by 
ignition,  recovers  it  by  being  dissolved  in 
an  acid  or  alkaline  menstruum,  and  then 

Erecipitated.  In  this  state  it  is  called  a 
ydrate,  for  when  dried  in  a  steam-heat  it 
retains  much  water;  and  therefore  re- 
sembles in  composition  wavellite,  a  beau- 
tiful mineral,  consisting  almost  entirely  of 
alumina,  with  about  28  per  cent  of  water. 
Alumina  is  widely  diffused  in  nature.  It  is 
a  constituent  of  every  soil,  and  of  almost 
every  rock.  It  is  the  basis  of  porcelain, 


pottery,  bricks,  and  crucibles.  Its  affinity 
For  vegetable  colouring  matter,  is  made 
use  of  in  the  preparation  of  lakes,  and  in 
the  arts  of  dyeing  and  calico  printing. 
Native  combinations  of  alumina,  constitute 
the  fuller's  earth,  ochres,  boles,  pipe-clays, 

&.C.* 

*  ALUMINA,  (SALTS  of). 
These  salts  have  the  following  general 
characters : 

1.  Most  of  them  are  very  soluble  in  wa- 
ter, and  their  solutions  have  a  sweetish 
acerb  taste. 

2.  Ammonia  throws  down  their  earthy 
base,  even  though  they  have  been  previ- 
ously acidulated  with  muriatic  acid. 

3.  At  a  strong  red  heat  they  give  out  a 
portion  of  their  acid. 

4.  Phosphate  of  ammonia  gives  a  white 
precipitate. 

5.  H)  driodate  of  potash  produces  a  floc- 
culent  precipitate  of  a  white  colour,  pass- 
ing into  a  permanent  yellow. 

6.  They  are  not  affected  by  oxalate  of 
ammonia,  tartaric  acid,  ferroprussiate  of 
potash,  or  tincture  of  galls ;  by  the  first 
two   tests  they    are  distinguished   from 
yttria,  and  by  the  last  two  from  that  earth 
and  glucina. 

7.  If  bisulphate  of  potash  be  added  to  a 
solution  of  an  aluminous  salt,  moderately 
concentrated,  octahedral  crystals  of  alum 
will  form. 

Jlcetate  ofJllumina.  By  digesting  strong- 
acetic  acid  on  newly  precipitated  alumina^ 
this  saline  combination  can  be  directly 
formed.  Vinegar  of  ordinary  strength 
scarcely  acts  on  the  earth.  But  the  salt  is 
seldom  made  in  this  way.  It  is  prepared 
in  large  quantities  for  the  calico  printers, 
by  decomposing  alum  with  acetate  of  lead ; 
or  more  economically  with  aqueous  ace- 
tate of  lime,  having  a  specific  gravity  of 
about  1.050 ;  a  gallon  of  which,  equivalent 
to  nearly  half  a  pound  avoirdupois  of  dry 
acetic  acid,  is  employed  for  every  2f  lt>. 
of  alum.  A  sulphate  of  lime  is  formed  by 
complex  affinity,  which  precipitates,  and 
an  acetate  of  alumina  floats  above.  The 
above  proportion  of  alum  is  much  beyond 
the  equivalent  quantity ;  and  the  specific 
gravity  of  the  liquid  is  consequently  raised 
by  the  excess  of  salt.  It  is  usually  1.080. 
By  careful  evaporation  capillary  crystals- 
are  formed,  which  readily  deliquesce.  M. 
Gay-Lussac  made  some  curious  observa- 
tions on  the  solutions  of  this  salt  Even 
when  made  with  cold  saturated  solutions 
of  alum  and  acetate  of  lead,  and  conse- 
quently but  little  concentrated,  it  be- 
comes turbid  when  heated  to  122°  Fahr. ; 
and  at  a  boiling  heat  a  precipitate  falls  of 
about  one-half  of  the  whole  salt.  On  cool- 
ing, it  is  redissolved.  This  decomposition 
by  heat,  which  would  be  prejudicial  to  the 
calico  printer,  is  prevented  by  the  excess 


ALti 


ALU 


of  alum,  which  is  properly  used  in  actual 
practice.  M.  Gay-Lussac  thinks  this  phe- 
nomenon has  considerable  analogy,  with 
the  coagulation  of  albumen  by  heat ;  the 
particles  of  the  water,  and  of  the  solid  mat- 
ter, being1  carried  by  the  heat  out  of  their 
sphere  of  activity,  separate.  It  is  probably 
a  subacetate  which  falls  down,  as  well  as 
that  which  is  obtained  by  drying1  the  crys- 
tals. Wenzel's  analysis  of  acetate  of  alu- 
mina gives  73.81  acid  to  26.19  base  in  100 
parts.  If  we  suppose  it  to  consist,  like  the 
sulphate,  of  three  primes  of  acid  to  two  of 
alumina,  we  shall  have  for  its  equivalent 
proportions,  20  of  dry  acid  -f-  6.4  •artb, 
or  75.8  -f-  24.2  =  100.  As  alum  contains, 
in  round  numbers,  about  1.9th  of  earthy 
base,  8  oz.  of  real  acetic  acid  present  in 
the  gallon  of  the  redistilled  pyrolignous, 
would  require  about  2J  Ibs.  of  alum,  for 
exact  decomposition.  The  excess  employ- 
ed is  found  to  be  useful. 

The  affinity  between  the  constituents 
of  this  salt  is  very  feeble.  Hence  the  at- 
traction of  cotton  fibre  for  alumina,  aided 
by  a  moderate  heat,  is  sufficient  to  decom- 
pose it. 

The  following  salts  of  alumina  are  in- 
soluble in  water.-— Arseniate,  borate,  phos- 
phate, tungstate,  mellate,  saclactate,  lith- 
ate,  malate,  camphorate.  The  oxalate  is  un- 
erystallizable.  It  consists  of  56  acid  and 
water,  and  44  alumina.  The  tartrate  does 
not  crystallize.  But  the  tartrate  of  potash 
and  alumina  is  remarkable,  according  to 
Thenard,  for  yielding  no  precipitate, 
either  by  alkalis  or  alkaline  carbonates. 
The  supergallate  crystallizes.  There 
seems  to  be  no  dry  carbonate.  A  super- 
nitrate  exists  very  difficult  to  crystallize. 
Its  specific  gravity  is  1.645.  A  moderate 
heat  drives  off  the  acid.  The  muriate  is 
easily  made  by  digesting  muriatic  acid  on 
gelatinous  alumina.  It  is  colourless,  astrin- 
gent, deliquescent,  uncrystallizable,  red- 
dens turnsole,  and  forms  a  gelatinous 
mass  by  evaporation.  Alcohol  dissolves  at 
60°  half  its  weight  of  this  salt.  A  dull  red 
lieat  separates  the  acid  from  the  alumina. 
Its  composition  is,  according  to  Bucholz, 
29.8  acid,  30.0  base,  40.2  water,  in  100 
parts. 

Sulphate  of  alumina  exists  under  several 
modifications.  The  simple  sulphate  is  ea- 
sily made,  by  digesting  sulphuric  acid  on 
pure  clay.  The  salt  thus  fanned  crystalli- 
zes in  thin  soft  plates,  having  a  pearly  lus- 
tre. It  has  an  astringent  taste,  and  is  so 
soluble  in  water  as  to  crystallize  with  dif- 
ficulty. When  moderately  heated  the  wa- 
ter escapes,  and,  at  a  higher  temperature, 
the  acid.  Berzelius  has  chosen  this  salt 
for  the  purpose  of  determining  the  equi- 
valent of  alumina.  He  considers  the  dry 
sulphate  as  a  compound  of  100  parts  of 
sulphuric  acid  with  42.722  earth.  This 


makes  the  equivalent  21.361,  oxygeir  be- 
ing reckoned  10,  if  we  consider  it  a  com- 
pound of  a  prime  proportion  of  each.  But 
if  we  regard  it  as  consisting  of  3  of  acid 
and  2  of  base,  we  shall  have  32.0  for  the 
prime  equivalent  of  alumina.  The  reason 
for  preferring  this  number  will  appear  in 
treating  of  the  next  salt.* 

*  ALUM.  This  important  salt  has  been 
the  object  of  innumerable  researches,  both 
with  regard  to  its  fabrication  and  compo- 
sition.* It  is  produced,  but  in  a  very  small 
quantity,  in  the  native  state  ;  and  this  is 
mixed  with  heterogeneous  matters.  It  ef- 
floresces in  various  forms  upon  ores  dur- 
ing calcination,  but  it  seldom  occurs  crys- 
tallized. The  greater  part  of  this  salt  is 
factitious,  being  extracted  from  various 
minerals  called  alum  ores,  such  as,  1.  Sul- 
phuretted clay.  This  constitutes  the  pu- 
rest of  all  aluminous  ores,  namely,  that  of 
la  Tolfa,  near  Civita  Vecchia,  in  Italy.  It 
is  white,  compact,  and  as  hard  as  indurat- 
ed clay,  whence  it  is  called  petra  alumina" 
ris.  It  is  tasteless  and  mealy ;  one  hun- 
dred parts  of  this  ore  contain  above  forty 
of  sulphur  and  fifty  of  clay,  a  small  quan- 
tity of  potash,  and  a  little  iron.  Bergmann 
says  it  contains  forty -three  of  sulphur  in 
one  hundred,  thirty -five  of  clay,  and  twen- 
ty two  of  siliceous  earth.  This  ore  is  first 
torrefied  to  acidify  the  sulphur,  which  then 
acts  on  the  clay,  and  forms  the  alum. 

2.  The  pyritaceous  clay,  which  is  found 
at  Schwemsal,  in  Saxony,  at  the  depth  of 
ten  or  twelve  feet.     It  is  a  black  and  hard, 
but  brittle  substance,  consisting  of  clay, 
pyrites,  and  bitumen.  It  is  exposed  to  the 
air  for  two  years ;  by  which  means  the  py- 
rites are  decomposed,  and  the  alum  "is 
formed.  The  alum  ores  of  Hesse  and  Liege 
are  of  this  kind ;  but  they  are  first  torre- 
fied, which  is  said  to  be  a  disadvantageous 
method. 

3.  The  schistus  aluvninaris  contains  a 
variable  proportion  of  petroleum  and  py- 
rites intimately  mixed  witli  it.     When  the 
last  are  in  a  very  large  quantity,  this  ore 
is  rejected  as  containing  too  much  iron. 
Professor  Bergmann  very  properly   sug- 
gested, that  by  adding  a  proportion  of 
clay,  this  ore  may  turn  out  advantageously 
for  producing  alum.     But  if  the  petrol  be 
considerable,  it  must  be  torrefied.     The 
mines  of  Becket  in  Normandy,  and  those 
of  Whitby  in  Yorkshire,  are  of  this  spe- 
cies. 

4.  Volcanic  aluminous  ore.  Such  is  that 
of  Solfaterra  near  Naples.  It  is  in  the  form 
of  a  white   saline  earth,  after  it  has  ef- 
floresced in  the  air  ;  or  else  it  is  in  a  stony 
form. 

5.  Bituminous  alum  ore  is  called  shale, 
and  is  in  the  form  of  a  shistus,  impregnat- 
ed with  so  much  oily  matter,  or  bitumen, 
as  to  be. inflammable.     It  is  found  in  Swc- 


ALU 


ALU 


ien,  and  also  in  the  coal  mines  at  White- 
haven,  and  elsewhere. 

Chaptai  lias  fabricated  alum  on  a  large 
scale  from  its  component  parts.  For  this 
purpose  he  constructed  a  chamber  9ifeet 
long1,  48  wide,  and  31  high  in  the  middle. 
The  walls  are  of  common  masonry,  lined 
with  a  pretty  thick  coating  of  plaster.  The 
floor  is  paved  with  bricks,  bedded  in  a 
mixture  of  raw  and  burnt  clay ;  and  this 
pavement  is  covered  with  another,  thfe 
joints  of  which  overlap  those  of  the  first, 
and  instead  of  mortar  the  bricks  are  joined 
with  a  cement  of  equal  parts  of  pitch,  tur- 
pentine, and  wax,  which,  after  having  loeen 
boiled  till  it  ceases  to  swell,  is  used  hot. 
The  roof  is  of  wood,  but  the  beams  are 
very  close  together,  and  grooved  length- 
wise,  the  intermediate  space  being  filled 
up  by  planks  fitted  into  the  grooves,  so 
that  the  whole  is  put  together  without  a 
nail.  Lastly,  the  whole  of  the  inside  is 
covered  with  three  or  four  successive 
coating's  of  the  cement  above  mentioned, 
the  first  being  laid  on  as  hot  as  possible; 
and  the  outside  of  the  wooden  roof  was 
varnished  in  the  same  manner.  The  purest 
and  whitest  clay  being-  made  into  a  paste 
with  water,  and  formed  into  balls  half  a 
foot  in  diameter,  these  are  calcined  in  a 
furnace,  broken  to  pieces,  and  a  stratum 
of  the  fragments  laid  on  the  floor.  A  due 
proportion  of  sulphur  is  then  ignited  in 
the  chamber,  in  the  same  manner  as  for 
the  fabrication  of  sulphuric  acid  ;  and  the 
fragments  of  burnt  clay,  imbibing  this  as 
it  forms,  begin  after  a  few  days  to  crack 
and  open,  and  exhibit  an  efflorescence  of 
sulphate  of  alumina.  When  the  earth  has 
completely  effloresced,  it  is  taken  out  of 
the  chamber,  exposed  for  some  time  in  an 
open  shed,  that  it  may  be  the  more  inti- 
mately penetrated  by  the  acid,  and  is  then 
lixiviated  and  crystallized  in  the  usual 
manner.  The  cement  answers  the  pur- 
pose of  lead  on  this  occasion  very  effec- 
tually, and  accordingly  to  M.  Chaptai, 
costs  no  more  than  lead  would  at  three 
farthings  a-pound. 

Curaudau  has  lately  recommended  a 
process  for  making  alum  without  evapo- 
ration. One  hundred  parts  of  clay  and  five 
of  muriate  of  soda  are  kneaded  into  a  paste 
witli  water,  and  formed  into  loaves.  With 
these  a  reverberatory  furnace  is  filled,  and 
a  brisk  fire  is  kept  up  for  two  hours.  Be- 
ing powdered,  and  put  into  a  sound  cask, 
one-fourth  of  their  weight  of  sulphuric 
acid  is  poured  over  them  by  degrees, 
stirring  the  mixture  well  at  each  addition. 
As  soon  as  the  muriatic  gas  is  dissipated, 
a  quantity  .of  water  equal  to  the  acid  is 
added,  and  the  mixture  stirred  as  before. 
When  the  heat  is  abated,  a  little  more  wa- 
ter is  poured  in,  and  this  is  repeated  till 
eight  or  ten  times  as  much  water  as  there 
Veu.  il  {  20  ] 


'fras  acid  is  added.  When  the  whole  has 
settled,  the  clear  liquor  is  drawn  off  into 
leaden  vessels,  and  a  quantity  of  water 
equal  to  this  liquor  is  poured  on  the  sedi- 
ment. The  two  liquors  being  mixed,  % 
solution  of  potash  is  added  to  ihern,  the 
alkali  in  which  is  equal  to  one-fourth  of 
the  weight  of  the  sulphuric  acid.  Sul- 
phate of  potash  may  be  used,  but  twice  as 
much  of  this  as  of  the  alkali  is  necessary. 
After  a  certain  time  the  liquor  by  cooling 
affords  crystals  of  alum  equal  to  three 
times  the  weight  of  the  acid  used.  It  is 
refined  by  dissolving  it  in  the  smallest  pos- 
sible quantity  of  boiling  water.  The  re- 
sidue may  be  washed  with  more  water,  to 
be  employed  in  lixiviating  a  fresh  portion 
of  the  ingredients. 

As  the  mother  water  still  contains  alum, 
with  sulphate  of  iron  very  much  oxided,  it 
is  well  adapted  to  the  fabrication  of  prusr 
sian  blue.  This  mode  of  making  alum  is 
particularly  advantageous  to  the  manufac- 
turers of  prussian  blue,  as  they  may  calcine 
their  clay  at  the  same  time  with  their  ani» 
mal  matters,  without  additional  expense ; 
they  will  have  no  need  in  this  case  to  add 
potash  ;  and  the  presence  of  iron,  instead 
of  being  injurious,  will  be  very  useful.  If 
they  wished  to  make  alum  for  sale,  they 
might  use  the  solution  of  sulphate  of  pot- 
ash, arising  from  the  washing  of  their  prus- 
sian blue,  instead  of  water,  to  dissolve 
the  combination  of  alumina  and  sulphuric 
acid. 

The  residuums  of  distillers  of  aquafortis 
are  applicable  to  the  same  purposes,  as 
they  contain  the  alumina  and  potash  re- 
quisite, and  only  require  to  be  reduced  to 
powder,  sprinkled  with  sulphuric  acid, 
and  lixiviated  with  water,  in  the  manner 
directed  above.  The  mother  waters  of 
these  alums  are  also  useful  in  the  fabrica- 
tion of  prussian  blue.  As  the  residuum  of 
aquafortis  contains  an  over-proportion  of 
potash,  it  will  be  found  of  advantage  to 
add  an  eighth  of  its  weight  of  clay  calcin- 
ed as  above. 

*  The  most  extensive  alum  manufacto- 
ry in  Great  Britain  is  at  Hurlett,  near  Pais- 
ley, on  the  estate  of  the  Earl  of  Glasgow. 
The  next  in  magnitude  is  at  Whitby  ;  of 
whose  state  and  processes  an  instructive 
account  was  published  by  Mr.  Winter,  in 
the  25th  volume  of  Nicholson's  Journal. 
The  stratum  of  aluminous  schistus  is  about 
29  miles  in  width,  and  it  is  covered  by 
strata  of  alluvial  soil,  sandstone,  ironstone, 
shell,  and  clay.  The  alum  schist  is  gene- 
rally found  disposed  in  horizontal  lamina:. 
The  upper  part  of  the  rock  is  the  most 
abundant  in  sulphur ;  so  that  a  cubic  yard 
taken  from  the  top  of  the  stratum,  is  5 
limes  more  valuable  than  the  same  bulk, 
100  feet  below. 

IT  a  quantity  of  the  sdhistus  be  laid  in  a 


ALU 


ALU 


heap  and  moistened  with  sea  water,  it  will 
take  fire  spontaneously,  and  will  continue 
to  burn  till  the  whole  inflammable  matter 
be  consumed.  Its  colour  is  bluish  gray. 
Its  specific  gravity  is  2.48.  It  imparts  a 
bituminous  principle  to  alcohol.  Fused 
with  an  alkali,  muriatic  acid  precipitates 
a  large  proportion  of  silex. 

The  expense  of  digging  and  removing 
to  a  distance  of  200  vards  one  cubic  yard 
of  the  schistose  rock,  is  about  sixpence- 
halfpenny.  A  man  can  earn  from  2s.  6d. 
to  3s.  a-day.  The  rock,  broken  into  small 
pieces,  is  laid  on  a  horizontal  bed  of  fuel, 
composed  of  brushwood,  &c.  When  about 
4  feet  in  height  of  the  rock  is  piled  on, 
fire  is  set  to  the  bottom,  and  fresh  rock 
continually  poured  upon  the  pile.  This 
is  continued  until  the  calcined  heap  be 
raised  to  the  height  of  90  or  100  feet.  Its 
horizontal  area  has  also  been  progressive- 
ly extended  at  the  same  time,  till  it  forms 
a  great  bed  nearly  200  feet  square,  having 
about  100,000  yards  of  solid  measurement. 
The  rapidity  of  the  combustion  is  allayed 
by  plastering  up  the  crevices  with  small 
schist  moistened.  Notwithstanding  of  this 
precaution,  a  great  deal  of  sulphuric  or 
sulphurous  acid  is  dissipated.  130  tons 
of  calcined  sciiist  produce  on  an  average 
1  ton  of  alum.  This  result  has  been  de- 
ducedfrom  an  average  of  150,000  tons. 

The  calcined  mineral  is  digested  in  wa- 
ter contained  in  pits  that  usually  contain 
about  60  cubic  yards.  The  liquid  is  drawn 
off  into  cisterns,  and  afterwards  pumped 
up.  again  upon  fresh  calcined  mine.  This 
is  repeated  until  the  specific  gravity  be- 
comes .15.  The  half  exhausted  schist  is 
then  covered  with  water,  to  take  up  the 
whole  soluble  matter.  The  strong  liquor 
is  drawn  off  into  settling  cisterns,  where 
the  sulphate  of  lime,  iron,  and  earth,  are 
deposited.  At  some  works  the  liquid  is 
boiled,  which  aids  its  purification.  It  is 
then  run  into  leaden  pans,  10  feet  long,  4 
feet  9  inches  wide,  2  feet  2  inches  deep 
at  the  one  end,  and  2  feet  8  inches  at  the 
other.  This  slope  makes  them  be  easily 
emptied.  Here  the  liquor  is  concentra- 
ted at  a  boiling  heat.  Every  morning  the 
pans  are  emptied  into  a  settling  cistern, 
and  a  solution  of  muriate  of  potash,  either 
pretty  pure  from  the  manufacturer,  or 
crude  and  compound  from  the  soap-boiler, 
is  added.  The  quantity  of  muriate  neces- 
sary is  determined  by  a  previous  experi- 
ment in  a  basin,  and  is  regulated  for  the 
workmen  by  the  hydrometer.  By  this 
addition,  the  pan  liquor,  which  had  ac- 
quired a  specific  gravity  of  1.4  or  1.5,  is 
reduced  to  1.35.  After  being  allowed  to 
settle  for  two  hours,  it  is  run  off  into  the 
coolers  to  be  crystallized.  At  a  greater 
sp.  gravity  than  1.35,  the  liquor,  instead 


of  crystallizing,  would,  when  it  cools,  pre- 
sent us  with  a  solid  magma,  resembling 
grease.  Urine  is  occasionally  added,  to 
bring  it  down  to  the  proper  density. 

After  standing  4  days,  the  mother  wa- 
ters are  drained  off,  to  be  pumped  into  the 
pans  on  the  succeeding  day.  The  crys- 
tals of  alum  are  washed  in  a  tub,  and  drain- 
ed. They  are  then  put  into  a  lead  pan, 
with  as  much  water  as  will  make  a  satu- 
rated solution  at  the  boiling  point.  V\  hen- 
ever  this  is  effected,  the  solution  is  run  off 
into  casks.  At  the  end  of  10  or  16  days, 
the  casks  are  unhooped  and  taken  asun- 
der. The  alum  is  found  exteriorily  in  a 
solid  cake,  but  in  the  interior  cavity,  in 
large  pyramidal  crystals,  consisting  of  oc- 
tahedrons, inserted  successively  into  one 
another.  This  last  process  is  called  roch- 
ing.  Mr.  Winter  says,  that  22  tons  of  mu- 
riate of  potash  will  produce  100  tons  of 
alum,  to  which  31  tons  of  the  black  ashes 
of  the  soap-boiler,  or  7 .;  of  kelp,  are  equi- 
valent. Where  much  iron  exists  in  the 
alum  ore,  the  alkaline  muriate,  by  its  de- 
composition, gives  birth  to  an  uncrystalli- 
zable  muriate  of  iron.  The  alum  manu- 
factured in  the  preceding  mode  is  a  super- 
sulphate  of  alumina  and  potash.  There  is 
another  alum  which  exactly  resembles  it. 
This  is  a  supersulphate  of  alumina  and  am- 
monia. Both  crystallize  in  regular  oc  ahe- 
drons,  formed  by  two  four-sided  pyramids 
joined  base  to  base.  Alum  has  an  asirin- 
gent  sweetish  taste.  Its  sp.  gravity  is 
about  1.71.  It  reddens  the  vegetable 
blues.  It  is  soluble  in  16  parts  of  water 
at  60°,  and  in  fths  of  its  weight  at  212.°  It 
effloresces  superficially  on  exposure  t* 
air,  but  the  interior  remains  long  unchang- 
ed. Its  water  of  crystallization  is  suffi- 
cient at  a  gentle  heat  to  fuse  it.  If  the 
heat  be  increased  it  froths  up,  and  loses 
fully  45  per  cent,  of  its  weight  in  water. 
The  spongy  residue  is  called  burnt  or  cal- 
cined alum,  and  is  used  by  surgeons  as  a 
mild  escharotic.  A  violent  heat  separates 
a  great  portion  of  its  acid. 

Alum  thus  was  analyzed  by  Berzelius: 
1st,  20  parts  (grammes)  of  pure  alum  lost 
by  the  heat  of  a  spirit  lamp  9  parts,  which 
gives  45  per  cent,  of  water.  The  dry  salt 
was  dissolved  in  water,  and  its  acid  preci- 
pitated by  muriate  of  barytes ;  the  sul- 
phate of  which,  obtained  after  ignition, 
weighed 20  parts;  indicating  in  100  parts 
34.3  of  dry  sulphuric  acid.  2d,  Ten  parts 
of  alum  were  dissolved  in  water,  and  di- 
gested with  an  excess  of  ammonia.  Alu- 
mina, well  washed  and  burnt,  equivalent 
to  10.67  per  cent,  was  obtained,  in  ano- 
ther experiment,  10.86  per  cent,  resulted. 
3d,  Ten  parts  of  alum  dissolved  in  water, 
were  digested  with  carbonate  of  strontites, 
till  the  earth  was  completely  separated. 


ALU 

The  sulphate   of  potash,  after  ignition, 
Weighed  1.815,   corresponding  to  0.981 
potash,  or  in  100  parts  to  9.81. 
Alum,  therefore,  consists  of 
Sulphuric  acid,     34.33 
Alumina,  10.86 

Potash,  9.81 

Water,  45.00 

100.00 

or,  Sulphate  of  alumina,  36.85 
Sulphate  of  potash,  1L->.15 
"Water,  -  -  -  -  45.00 

100.00 

Thenard's  analysis,  Ann.  de  Chimie,  vol. 
59.  or  Nicholson's  Journal,  vol.  18.  cum- 
eides  perfectly  with  tiiat  of  Beizelius  in 
the  product  of  sulphate  of  bary  tes.  From 
490  parts  of  alum,  he  obtained  490  oi  the 
ignited  ban  tic  salt ;  but  the  alumina  was 
iu  greater  proportion,  equal  to  12.54  per 
cent,  and  the  sulphate  of  potash  less,  or 
15.7  in  100  parts. 

Dr.  Thomson  considers  it  as  a  com- 
pound of  3  atoms  sulphate  of  alumina,  1 
atom  sulphate  of  potash,  and  "23  atoms 
water,  as  follows : 

Sulphate  of  alumina,  36.70 
Sulphate  of  potash,  18.88 
Water,  -  -  -  -  44.42 

100.00 

But  Vauquelin,  in  his  last  anal}  sis,  found 
•48.58  water;  and  by  Thenard's  statement 
there  are  indicated    34.23  dry  acid, 
7.14  potash, 
12.54  alumina, 
46.09  water, 

100.00 

It  deserves  to  be  remarked,  that  the 
analysis  of  Professor  Berzelius  agrees  with 
the  supposition  that  alum  contains, 
4  sulphuric  acid,  «=  20.0        34.36 
2  alumina,  =>    6.4        11.00 

1  potash,  =    6.0        10.30 

23  water,  <*.  25.8        44.34 

58.2      100.00 

If  we  rectify  Vauquelin's  erroneous  esti- 
mate of  the  sulphate  of  barytes,  his  analy- 
sis will  also  coincide  with  t  ie  above. 
Alum,  therefore,  differs  from  the  simple 
sulphate  of  alumina  previously  described, 
which  consisted  of  3  prime  equivalents  of 
acid,  and  2  of  earth,  merely  by  its  assump- 
tion of  a  prime  of  sulphate  of  potash.  It 
is  probable  that  all  the  aluminous  salts 
have  a  similar  constitution.  It  is  to  be  ob- 
served, moreover,  that  the  number  34. ;>6 
resulting  from  the  theoretic  proportions, 
is,  according  to  Gilbert's  remarks  on  the 
essay  of  Berzelius,  the  just  representation 
of  the  dry  acid  in  100  of  sulphate  of  bary- 


ALU 

tes,  by  a  corrected  analysis,  which  makei 
the  prime  of  barytes  9.57. 

-Should  ammonia  be  suspected  in  alum, 
{t  may  be  detected,  and  its  quantity  esti- 
mated, by  mixing  quicklime  with  the  sa- 
line solution,  and  exposing  the  mixture  to 
heat  in  a  retort,  connected  with  a  Woulfe'* 
apparatus.  The  water  of  ammonia  being 
afterwards  saturated  with  an  acid,  and 
evaporated  to  a  dry  salt,  will  indicate  thfe 
quantity  of  pure  ammonia  in  the  alum.  A 
variety  of  alum,  containing  both  potash 
and  ammonia,  may  also  be  found.  This 
will  occur  where  urine  has  been  used,  as 
well  as  muriate  of  potash,  in  its  fabrica- 
tion. If  any  of  these  bisulphates  of  alu- 
mina and  potash  be  acted  on  in  a  watery 
solution,  by  gelatinous  alumina,  a  neutral 
triple  salt  i's  formed,  which  precipitates  in 
a  nearly  insoluble  state. 

When  alum  in  powder  is  mixed  with 
flour  or  sugar,  and  calcined,  it  forms  the 
pyrophorus  of  Homberg. 

Mr.  Winter  first  mentioned,  that  another 
variety  of  alum  can  be  made  with  soda,  in- 
stead of  potash.  This  salt,  which  crystal- 
lizes in  octahedrons,  has  been  also  made 
with  pure  muriate  of  soda,  and  bisulphate 
of  alumina,  at  the  laboratory  of  Hurlett, 
by  Mr.  W.  Wilson.  It  is  extremely  diffi- 
cult to  form,  and  effloresces  like  the  sul- 
phate of  soda. 

The  only  injurious  contamination  of 
alum  is  sulphate  of  iron.  It  is  detected 
by  ferroprussiate  of  potash.  To  get  rid 
of  it  cheaply,  M.  Thenard  recommended 
dissolving  the  alum  in  boiling  water,  and 
agitating  the  solution  with  rods  as  it  cools. 
The  salt  is  thus  reduced  to  a  fine  granular 
powder,  which  being  washed  two  or  three 
times  with  cold  water,  and  drained,  yields 
a  perfectly  pure  alum.  For  a  very  advan- 
tageous mode  of  concentrating  alum  li- 
quors, as  well  as  those  of  other  salts,  on 
the  great  scale,  see  EVAPORATION. 

Oxymuriate  of  alumina,  or  the  chloride, 
has  been  proposed  by  Mr.  Wilson  of  Dub- 
lin as  preferable  to  solution  of  chlorine, 
for  discharging  the  turkey -red  dye.  He 
prepares  it  by  adding  to  a  solution  of  oxy- 
muriate  of  lime,  at  asp.  gravity  of  1.060, 
a  solution  of  alum  of  the  sp.  grav.  1  100, 
as  long  as  any  precipitate  falls.  The  clear 
liquid  is  to  be  drawn  off  from  the  precipi- 
tate, and  kept  in  close  vessels.  He  says 
that  it  does  not  injure  the  cloth,  nor  annoy 
the  the  workmen,  like  the  liquor  of  un- 
combined  chlorine. — Jinn,  of  Phil,  vol, 
viii.* 

Alum  is  used  in  large  quantities  in  many 
manufactories.  When  added  to  tallow,  it 
renders  it  harder.  Printer's  cushions,  and 
the  blocks  used  in  the  calico  manufactory, 
are  rubbed  with  burnt  alum  to  remove  any 
g^reasiness,  which  might  prevent  the  ink 


AMA 


AMB 


GTf  colour  from  sticking1.  Wood  sufficient- 
ly soaked  in  a  solution  of  alum  does  not 
•asily  take  fire ;  and  the  same  is  true  of 
paper  impregnated  with  it,  which  is  fitter 
to  keep  gunpowder,  as  it  also  excludes 
moisture.  Paper  impregnated  with  alum 
is  useful  in  whitening  silver,  and  silvering 
brass  without  heat.  Alum  mixed  in  milk 
helps  the  separation  of  its  butter.  If  add- 
ed in  a  very  small  quantity  to  turbid  wa- 
ter, in  a  few  minutes  it  renders  it  perfect- 
ly limpid,  without  any  bad  taste  or  quali- 
ty ;  while  the  sulphuric  acid  imparts  to  it 
a  very  sensible  acidity,  and  does  no^  pre- 
cipitate so  soon,  or  so  well,  the  opaque 
earthy  mixtures  that  render  it  turbid,  as  1 
have  often  tried.  It  is  used  in  making 
p\rophorus,  in  tanning  and  many  other 
manufactories,  particularly  in  the  art  of 
dyeing,  in  which  it  is  of  the  greatest  and 
most  important  use,  by  cleansing  and 
opening  the  pores  on  the  surface  of  the 
substance  to  be  dyed,  rendering  it  fit  for 
receiving  the  colouring  particles,  (by 
which  the  alum  is  generally  decompo- 
sed,) and  at  the  same  time  making  the  co- 
lour fixed.  Crayons  generally  consist  of 
the  earth  of  alum,  finely  powdered,  and 
tinged  for  the  purpose.  In  medicine  it  is 
employed  as  an  astringent. 

*  ALUMIXITK.  A  mineral  of  a  snow- 
white  colour,  dull,  opaque,  and  having  a 
•fine  earthy  fracture.  It  has  a  glistening 
streak.  It  is  found  in  kidney-shaped  pieces, 
which  are  soft  to  the  touch,  and  ad- 
here slightly  to  the  tongue.  Sp.  gravity, 
1.67. 

It  consists  of  Sulphuric  acid,       19.25 

Alumina,  32.50 

Water,  47.00 

Silica,  lime,  and  oxide  of  iron,       1.25 


100.00 

It  may  be  represented  very  exactly  by 
2  primes  of  acid,         10      =20 
5  alumina,  16     =  32 


21 


water,     23.6 
Foreign  matter,      0.4 


47.2 
0.8 


50.0     100. 0 

The  conversion  of  the  above  into  alum 
is  easily  explained.  When  the  three 
primes  composing  bisulphate  of  potash 
come  into  play,  they  displace  precisely 
three  primes  (or  atoms)  of  alumina.  Two 
additional  primes  of  water  are  also  intro- 
duced at  the  same  time,  by  the  strong  af- 
finity of  the  bisulphate  for  the  particles  of 
that  liquid. 

The  above  alum  ore  is  found  chiefly 
in  the  alluvial  strata  round  Halle  in  Sax- 
ony.* 

*  AMADOU.  It  is  a  variety  of  the  boletus 
igniarius,  found  on  old  ash  and  other  trees. 
It  is  boiled  in  water  to  extract  its  soluble 
parts,  then  dried,  and  beat  with  a 


to  loosen  its  texture.  It  has  now  the  ap- 
pearance of  very  spongy  doe-skin  leather. 
It  is  lastly  impregnated  with  a  solution  of 
nitre,  and  dried  when  it  is  called  spunk, 
or  German  tinder ;  a  substance  much  used 
on  the  continent  for  lighting  fire,  either 
from  the  collision  of  flint  and  steel,  or  from 
the  sudden  condensation  of  air  in  the  at- 
mospheric pyrophorus.* 

AMALGAM  This  name  is  applied  to  the 
combinations  of  mercury  with  other  me- 
tallic substances.  See  MKRCURY. 

AMBER  is  a  hard,  brittle,  tasteless  sub- 
stance, sometimes  perfectly  transparent, 
but  mostly  semi-transparent  or  opaque, 
and  of  a  glossy  surface  :  it  is  found  of  all 
colours,  but  chiefly  yellow  or  orange,  and 
oft-en  contains  leaves  or  insects ;  its  speci- 
fic gravity  is  from  1.065  to  1.10U  ;  iis  frac- 
ture is  even,  smooth,  and  glossy;  it  is  ca- 
pable of  a  fine  polish,  and  becomes  elec- 
tric by  friction ;  when  rubbed  or  heated, 
it  gives  a  peculiar  agreeable  smell,  par- 
ticularly when  it  melts,  that  is  at  550°  of 
Fahrenheit,  but  it  then  loses  its  transpa- 
rency ;  projected  on  burning  coals,  it 
burns  with  a  whitish  flame,  and  a  whitish, 
yellow  smoke,  but  gives  very  little  soot, 
and  leaves  brownish  ashes  ;  it  is  insoluble 
in  water  and  alcohol,  though  the  latter, 
when  highly  rectified,  extracts  a  reddish 
colour  from  it ;  but  it  is  soluble  in  the  sul- 
phuric acid,  which  then  acquires  a  reddish 
purple  colour,  and  is  precipitable  from  it 
by  water;  no  other  acid  dissolves  it,  nor 
is  i;  soluble  in  essential  or  expressed  oils, 
without  some  decomposition  and  long  di- 
gestion ;  but  pure  alkali  dissolves  it.  By 
distillation  it  affords  a  small  quantity  of 
water,  with  a  little  acetous  acid,  an  oil, 
and  a  peculiar  acid.  See  ACID  (Succi- 
ITIC).  The  oil  rises  at  first  colourless ; 
but,  as  the  heat  increases,  becomes  brown, 
thick,  and  empyreumatic.  The  oil  may 
be  rectified  by  successive  distillations,  or 
it  may  be  obtained  very  light  and  lim- 
pid at  once,  if  it  be  put  into  a  glass  alem- 
bic with  water,  as  the  elder  Rouelle  di- 
rects, and  distilled  at  a  heat  not  greater 
than  212°  Fahr.  It  requires  to  be  kept 
in  stone  bottles,  however,  to  retain  this 
state  ;  for  in  glass  vessels  it  becomes 
brown  by  the  action  of  light. 

Amber  is  met  with  plentifully  in  regu- 
lar mines  in  some  parts  of  Prussia.  The 
upper  surface  is  composed  of  sund,  under 
which  is  a  stratum  of  loam,  and  under  this 
a  bed  of  wood,  partly  entire,  but  chiefly 
mouldered  or  changed  into  a  bituminous 
substance.  Under  the  wood  is  a  stratum 
of  sulphuric  or  rather  aluminous  mineral, 
in  which  the  amber  is  found.  Strong  sul- 
phureous exhalations  are  often  perceived 
in  the  pits. 

*  Detached  pieces  are  also  found  occa- 
sionally on.  the  sea-coast  ja  various  coua., 


AMB 


AMB 


tries.  It  has  been  found  in  gravel  becls 
near  London.  In  the  Itoyal  Cabinet  at 
Berlin  there  is  a  mass  of  18  Ibs.  weight, 
supposed  to  be  the  largest  ever  found. 
Jussieu  asserts,  that  the  delicate  insects  in 
amber,  which  prove  the  tranquillity  of  its 
formation,  are  not  European.  M.  Hauy 
has  pointed  out  the  following1  distinctions 
between  mellite  and  copal,  the  bodies 
which  most  closely  resemble  amber.  iMel- 
lite  is  infusible  by  heat.  A  bit  of  copal 
heated  at  the  end  of  a  knife  takes  fire, 
melting  into  drops,  which  flatten  as  they 
fall;  whereas  amber  burns  with  spitting 
and  frothing;  and  when  its  liquefied  par- 
ticles drop,  they  rebound  from  the  plane 
which  receives  them.  The  origin  of  am- 
ber is  at  present  involved  in  perfect  ob- 
scurity, though  the  rapid  progress  of  ve- 
getable chemistry  promises  soon  to  throw 
light  on  it.  Various  frauds  are  practised 
"with  this  substance.  Neumann  states  as 
the  common  practices  of  workmen  the  two 
following:  The  one  consists  in  surround- 
ing the  amber  with  sand  in  an  iron  pot, 
and  cementing  it  with  a  gradual  fire  for 
forty  hours,  some  small  pieces  placed  near 
the  sides  of  the  vessel  being  occasionally 
taken  out  for  judging  of  the  effect  of  the 
operation :  the  second  method,  which  he 
says  is  that  most  generally  practised,  is  by 
digesting  and  boiling  the  amber  about 
twenty  hours  with  rapeseed  oil,  by  which 
it  is  rendered  both  clear  and  hard. 

*  Werner  has  divided  it  into  two  sub- 
species,  the  white  and  the  yellow ;  but 
there  is  little  advantage  in  the  distinction. 
Its  ultimate  constituents  are  the  same  with 
those  of  vegetable  bodies  in  general;  viz. 
carbon,  hydrogen,  and  oxygen ;  but  the 
proportions  have  not  been  ascertained. 

In  the  second  volume  of  the  Edinburgh 
Philosophical  Journal,  Dr.  Brewster  has 
given  an  account  of  some  optical  proper- 
ties of  amber,  from  which  he  considers  it 
established  beyond  a  doubt  that  amber  is 
an  indurated  vegetable  juice  ;  and  that  the 
traces  of  a  regular  structure,  indicated  by 
its  action  upon  polarized  light,  are  not  the 
effect  of  the  ordinary  laws  of  crystalliza- 
tion by  which  mellite  has  been  formed,  but 
are  produced  by  the  same  causes  which 
influence  the  mechanical  condition  of  gum 
arabic,  and  other  gums,  which  are  known 
to  be  formed  by  the  successive  deposition 
and  induration  of  vegetable  fluids.* 

Amber  is  also  used  in  varnishes.  See 
VARXISH,  and  OIL  of  AMBER. 

AMBKRGUIS  is  found  in  the  sea,  near  the 
coasts  of  various  tropical  countries;  and 
has  also  been  taken  out  of  the  intestines 
of  the  physeter  macrocephalus,  the  sper- 
maceti whale.  As  it  has  not  been  found 
in  any  whales  but  such  as  are  dead  or  sick, 
its  production  is  generally  supposed  to  be 
owing  to  disease,  though  some  have  a  lit- 


tle too  peremptorily  affirmed  it  to  be  the 
cause  of  the  morbid  affection.  As  no  large 
piece  has  ever  been  found  without  a  grea- 
ter or  less  quantity  of  the  beaks  of  the  se- 
pia octopodia,  the  common  food  of  the 
spermaceti  whale,  interspersed  throughout 
its  substance,  there  can  be  little  doubt  of 
its  originating  in  the  intestines  of  the 
whale;  for  if  it  were  occasionally  swallow- 
ed by  it  only,  and  then  caused  disease,  it 
must  much  more  frequently  be  found  with- 
out these,  when  it  is  met  with  floating  iu 
the  sea,  or  thrown  upon  the  shore. 

Ambergris  is  found  of  various  sizes,  ge- 
nerally in  small  fragments,  but  sometimes 
so  large  as  to  weigh  near  two  hundred 
pounds.  When  taken  from  the  whale,  it  is 
not  so  hard  as  it  becomes  afterward  on  ex- 
posure to  the  air.  Its  specific  gravity 
ranges  from  780  to  926.  If  good,  it  ad- 
heres like  wax  to  the  edge  of  a  knife  with 
which  it  is  scraped,  retains  the  impression 
of  the  teeth  or  nails,  and  emits  a  fat  odo- 
riferous liquid  on  being  penetrated  with  a 
hot  needle.  It  is  generally  brittle ;  but, 
on  rubbing  it  with  the  nail,  it  becomes 
smooth  like  hard  soap.  Its  colour  is  either 
white,  black,  ash  coloured,  yellow,  or 
blackish ;  or  it  is  variegated,  namely,  gray 
with  black  specks,  or  gray  with  yellow 
specks.  Its  smell  is  peculiar,  and  not  easy 
to  be  counterfeited.  At  144°  it  melts,  and 
at  212°  is  volatilized  in  the  form  of  a  white 
vapour.  But,  on  a  red-hot  coal,  it  burns, 
and  is  entirely  dissipated.  Water  has  no 
action  on  it ;  acids,  except  nitric,  act  fee- 
bly on  it ;  alkalis  combine  with  it,  and  form 
a  soap  ;  ether  and  the  volatile  oils  dissolve 
it ;  so  do  the  fixed  oils,  and  also  ammonia, 
when  assisted  by  heat;  alcohol  dissolves  a 
portion  of  it,  and  is  of  great  use  in  analy- 
zing it,  by  separating  its  constituent  parts. 
According  to  Bouillon  la  Grange-  who  has 
given  the  latest  analysis  of  it,  3820  parts 
of  ambergris  consist  of  adipocere  2016 
parts,  a  resinous  substance  1167,  benzoic 
acid  425,  and  coal  212.  *  But  Bucholz 
could  find  no  benzoic  acid  in  it.  Dr.  Ure 
examined  two  different  specimens  with 
considerable  attention.  The  one  yielded 
benzoic  acid,  the  other,  equally  genuine 
to  all  appearance,  afforded  none.  See 
APIPOCERE  and  INTESTINAL  CONCRETION. 

An  alcoholic  solution  of  ambergris,  add- 
ed in  minute  quantity  to  lavender  water, 
tooth  powder,  hair  powder,  wash  balls, 
&c.  communicates  its  peculiar  fragrance. 
Its  retail  price  being  in  London  so  high  as 
a  guinea  per  oz.  leads  to  many  adultera- 
tions. These  consist  of  various  mixtures 
of  benzoin,  labdanum,  meal,  &c.  scented 
with  musk.  The  greasy  appearance  and 
smell  which  heated  ambergris  exhibits,  af- 
ford good  criteria,  joined  to  its  solubility 
in  hot  ether  and  alcohol.  * 

It  has  occasionally  been  employed  in 


AMM 


AMM 


medicine,  but  its  use  is  now  confined  ta 
the  perfumer.  Dr.  Swediaur  took  thirty 
grains  of  it  without  perceiving  any  sensi- 
ble effect.  A  sailor,  who  took  half  an 
ounce  of  it,  found  it  a  good  purgative. 

*  AittBLYGOMTE.    A  greenish  coloured 
mineral  of  different  pale  shades,  marked 
on  the  surface  with  reddish  and  yellowish 
brown  spots.     It  occurs  massive  and  crys- 
tallized in  oblique  four-sided  prisms.  Lus- 
tre vitreous;  cleavage  parallel  with  the 
sides  of  an  oblique  four-sided  prism  of 
106°   10'  and  77°  53';  fracture  uneven; 
fragments  rhomb oidal ;  translucent;  hard- 
ness, as  fe'dsj.ar;  brittle;  sp.  gr.  3*0.    In- 
tumesces  with  the  blow-pipe,  and  fuses 
wit. i   Ji  reddish-yellow    phosphorescence 
into  a  white  enamel.    It  occurs  in  granite, 
along  with  green  topaz  and  torn-inline, 
nea^  Pinig  in  Saxonv.     It  seems  to  be  a 
species  of  spodumene.* 

AMKTHYST.  The  amethyst  is  a  gem  of 
a  violet  colour,  and  great  brilliancy,  said 
to  be  as  hard  as  the  ruby  or  sapphire, 
from  which  it  only  differs  in  colour.  This 
Is  called  the  oriental  amethyst,  and  is  very 
rare.  When  it  inclines  to  the  purple  or 
rosy  colour,  it  is  more  esteemed  than 
when  it  is  nearer  to  «he  blue.  These  ame- 
thysts have  the  same  figure,  hardness,  spe- 
cific gravity,  and  other  qualities,  as  the 
best  sapphires  or  rubies,  and  come  from 
the  same  laces,  particularly  from  Persia, 
Arabia,  Armenia,  and  the  West  Indies. 
The  occidental  amethysts  are  merely  co- 
loured crystals  or  quartz.  See  QUARTZ 
and  SAPPHIRK. 

AMIANTHUS,  Mountain  Flax.     See  As- 

BESTUS. 

*  AMMONIA,  called  also  Volatile  Alkali. 
We  shall  first  consider  this  substance  in 
its  purely  scientific  relations,  and  then  de- 
tail its  manufacture  on  the  great  scale,  and 
its  uses  in  the  arts.     There  is  a  saline  bo- 
dy, formerly  brought  from  Egypt,  where 
it"  was  separated  from  soot  by  sublimation, 
but  which  is  now  made  abundantly  in  Eu- 
rope, called  sal  ammoniac.     From   this 
salt,  pure  ammonia  can  be  readily  obtain- 
ed by  the  following  process:  Mix  nnslack- 
ed  quicklime  with  its  own  weight  of  sal 
ammoniac,  each  in  fine  powder,  and  intro- 
duce them  into  a  glass  retort.    Join  to  the 
beak  of  the  retort,  by  a  collar  of  caout- 
chouc, (a  neck  of  an  Indian  rubber  bottle 
answers  well,)  a  glass  tube  about  18  inch- 
es long,  containing  pieces  of  ignited  mu- 
riate of  lime.     This  tube  should  lie  in  a 
horizontal  position,  and  its  free  end,  pre- 
viously bent  obliquely  by  the  blow-pipe, 
should  dip  into  dry  mercury  in  a  pneuma- 
tic trough.     A  slip  of  porous  paper,  as  an 
additional  precaution,  may  be  tied  round 
the  tube,  and  kept  moist  with  ether.     If  a 
gentle  heat  from  a  charcoal  chauffer  or 
lamp  be  now  applied  to  the  bottom  «f  tfcs 


retort,  a  gaseous  body  will  bubble  up 
through  the  mercury.  Fill  a  little  glass 
tube,  sealed  at  one  end,  with  the  gas,  and 
transfer  it,  closely  stopped  at  the  other 
end,  into  a  basin  containing  water.  If  the 
water  rise  instantly  and  fill  the  whole  tube, 
the  gas  is  pure,  and  may  be  received  for 
examination. 

Ammonia  is  a  transparent,  colourless, 
and  consequently  invisible  gas.  possessed 
of  elasticity,  and  the  other  mechanical 
properties  of  the  atmospherical  air.  Its 
specific  gravity  is  an  important  datum  in 
chemical  researches,  and  has  been  rather 
differently  stated.  Now,  as  no  aeriform 
body  is  more  easily  obtained  in  a  pure 
state  than  ammonia,  this  diversity  among 
accurate  experimentalists,  shows  the  nice- 
ty of  this  statical  operation.  MM.  Biot 
and  Arago  make  it  =•  0.59669  by  experi- 
ment, and  by  calculation  from  its  elemen- 
tary gases,  they  make  it  =  0.59438.  Kir- 
wan  says,  that  100  cubic  inches  weigh 
18.16  gr.  at  30  inches  of  bar.  and  61 u  F., 
which  compared  to  air  reckoned  30.519, 
gives  0.59540.  Sir  H.  Davy  determine* 
its  density  to  be  =  0.590,  with  which  esti- 
mate the  theoretic  calculations  of  Dr. 
Prout,  in  the  6th  volume  of  the  Annals  of 
Philosophy,  agree. 

This  gas  has  an  exceedingly  pungent 
smell,  well  known  by  the  old  name  of  spi- 
rits of  hartshorn.  An  animal  plunged  into 
it  speedily  dies.  It  extinguishes  combus- 
tion, but  being  itself  to  a  certain  degree 
combustible,  the  flame  of  a  taper  immers- 
ed in  it,  is  enlarged  before  going  out.  It 
has  a  very  acrid  taste.  Water  condenses 
it  very  rapidly.  The  following  valuable 
table  of  its  aqueous  combinations  has  been 
given  by  Sir  H.  Davy. 

Sp.  Gr.        Jlmmoma.         Water. 
0.8750  32.50  67.50 

0.8875  29.25  70.75 

0.9000  26.00  74.00 

0.9054  25.37  74.63 

0.9166  22.07  77.93 

0.9255  19.54  80.46 

0.9326  17.52  82.48 

0.9385  15.88  84.12 

0.9435  14.53  85.47 

0.9476  13.46  86.54 

0.9513  12.40  87.60 

0.9545  11.56  88.44 

0.9573  10.82  89.18 

0.9597  10.17  89.83 

0.9619  9.60  90.40 

0.9692  9.50  90.50 

Water  is  capable  of  dissolving  easily 
about  one-third  of  its  weight  of  ammonia- 
cal  gas,  or  460  times  its  bulk.  Hence, 
when  placed  in  contact  with  a  tube  filled 
with  this  gas,  water  rushes  into  it  with  ex- 
plosive velocity.  Probably  the  quantity  of 
ammonia  stated  in  the  above  table  is  too 
ki^hby  about  one  per  cent. 


AMM 


AMM 


Br.  Thomson  states,  in  his  System,  vol. 
2d.  page  29.  "  \Vater,  by  my  trials,  is  ca- 
pable of  absorbing  780  times  its  bulk  of 
this  gas ;  while,  in  the  mean  time,  the  bulk 
of  the  liquid  increases  from  6  to  10.  The 
specific  gravity  of  this  solution  is  0.900, 
which  just  accords  with  the  increase  of 
bulk."  Correcting  the  first  error  where  6 
is  substituted  tor  9,  a  less  excusable  error 
comes  to  be  examined.  Taking  the  Doc- 
tor's own  number  for  the  specific  gravity 
of  the  gas,  it  is  evident  that  780  times  the 
volume,  combined  with  water,  would  give 
nearly  36  bv  weight  of  gas  in  100  of  the 
liquid.  But  in  the  very  same  page  he 
says,  "  It  follows,  from  the  experiments  of 
Davy,  that  a  saturated  solution  of  ammo- 
nia is  composed  of  74.63  water  and  25.37 
ammonia."  Hence,  if  that  be  correct,  a 
liquid  containing  36  per  cent  of  ammonia 
is  a  manifest  impossibility.  In  the  very  same 
page  he  gives  Mr.  Dalton's  table,  "  which 
exhibits  the  quantity  of  ammonia  contain- 
ed in  ammoniacal  solutions  of  different 
specific  gravities."  In  this  table,  opposite 
to  the  specific  gravity  0.90  of  the  liquid 
ammonia,  such  as  he  made  in  his  own  tri- 
als, we  have  22.2,  a  far  different  quantity 
from  the  number  36  equivalent  to  his  780 
volumes.  Sir  H.  Davy's  table  differs  very 
little  from  that  of  Mr.  Dalton,  the  truth 
probably  lying  between  them.  It  is  cer- 
tain, indeed,  that  100  parts  of  ammoniacal 
water,  sp.  gr.  0.900,  instead  of  containing 
36  pars,  or  780  volumes,  do  not  contain 
above  24  parts,  or  520  volumes.  Had  Dr. 
Thomsom  consulted  Sir  H.  Davy's  Ele- 
ments of  Chemical  Philosophy,  he  would 
have  found  the  following  statement,  p. 
268.  "  At  the  temperature  of  50°,  under 
a  pressure  equal  to  29.8  inches,  water,  I 
find,  absorbs  about  670  times  its  volume 
of  gas,  and  becomes  of  specific  gravity 
0.875."  In  the  table  of  Sir  H.  Davy,  oppo- 
site 0.875,  we  have  32.5  per  cent  of  am- 
monia. If  any  person  will  take  the  trouble 
of  calculating,  he  will  find  that  670  inches 
of  a  gas,  of  which  100  cubic  inches  weigh 
18  grs  in  combining  with  one  cubic  inch 
of  water  weighing  '252.5  grains,  form  a  so- 
lution that  must  contain  just  32.3  per  cent 
of  the  condensed  gas. 

We  thus  perceive^  that  liquid  ammonia, 
as  the  aqueous  compound  is  termed,  may 
like  spirits  be  very  accurately  valued  by 
its  specific  gravity.  But  it  dilfers  remarka- 
bly from  alcoholic  mixtures  in  this  respect, 
that  the  strongest  ammoniacal  liquor, 
when  it  is  diluted  with  water,  surfers  no 
condensation  of  volume.  The  specific 
gravity  of  the  dilute,  is  the  mean  of  that 
of  its  components.  Hence,  having  one 
point  accurately,  we  can  compute  all  be- 
low it,  by  paying  attention  to  the  rule 
given  under  SPECIFIC  GHAVITT.  To  pro- 
cure aqueous  ammonia,  we  may  uge  either 


a  common  still  and  refrigeratory  o*  a 
Woulte's  apparatus.  The  latter  should  be 
preferred.  Into  a  retort  we  put  a  mixture 
of  two  parts  of  slaked  lime,  and  one  part 
of  [.ulverized  sal  ammoniac,  and  having 
connected  the  beak  of  the  retort  with  the 
Woulfe's  apparatus,  containing  pure  wa- 
ter, we  then  disengage  the  ammonia,  by 
the  application  of  heat.  When  gas  ceases 
to  be  evolved,  the  addition  of  a  little  hot 
water  will  renew  its  disengagement,  and 
ensure  complete  decomposition  of  the 
salt.  Since  sal  ammoniac  contains  nearly  | 
its  weight  of  ammonia,  ten  pounds  of  it 
should  yield  by  economical  treatment,  3Q 
pounds  of  liquid,  whose  specific  gravity  is 
0.950,  which  is  as  strong  as  the  ordinary 
purposes  of  chemistry  and  medicine  re- 
quire ;  and  it  will  form  twice  that  quanti- 
ty, or  60  pounds  of  the  common  water  of 
ammonia,  sold  by  apothecaries,  which  has 
rareh  a  smaller  density  than  0.978  or  0.980. 
There  is  no  temptation  to  make  it  with 
the  ammoniacal  carbonate;  but  if  this  salt 
be  accidentally  present,  it  is  instantly  de- 
tected by  its  causing  a  milkiness  in  lime 
water. 

Ammoniacal  gas,  perfectly  dry,  when 
mixed  with  oxygen,  explodes  with  the 
electric  spark,  and  is  converted  into  water 
and  nitrogen,  as  has  been  shown  in  an  in- 
genious paper  by  Dr.  Henry.  But  the 
simplest,  and  perhaps  most  accurate  mode 
of  resolving  ammonia  into  its  elementary 
constituents,  is  that  first  practised  by  ML 
Berthollet,  the  celebrated  discoverer  of 
its  composition.  This  consists  in  making1 
the  pure  gas  traverse  very  slowly  an  igni- 
ted porcelain  tube  of  a  small  diameter. 
The  process,  as  lately  repeated  by  M. 
Gay-Lussac,  yielded  from  100  cubic  inches 
of  ammonia,  2/0  cubic  inches  of  consti- 
tuent gases  ;  of  which  by  subsequent  ana- 
lysis, 50  were  found  to  be  nitrogen,  and 
150  hydrogen.  Hence  we  see,  that  the 
reciprocal  affinity  of  the  ammoniacal  ele- 
ments had  effected  a  condensation  equal  to 
one-half  of  the  volume  of  the  free  gases., 
It  appears,  by  the  most  recent  determina- 
tions, that  the  specific  gravity  of  hydro- 
gen is  0.0694,  compared  to  air  as  unity, 
and  that  of  nitrogen,  0.9722.  Three  vo- 
lumes of  the  former  will  therefore  weigh 
0.2082,  and  one  of  the  latter,  0.9722 ;  the 
sum  of  which  numbers,  1.1804,  divided  by 
2,  ought  to  coincide  with  the  experimen- 
tal density  of  ammonia.  Now,  it  is  0.5902, 
being  an  exact  correspondence.  And  the 
ratio  of  the  two  weights,  reduced  to  100 
parts,  will  be  82.36  nitrogen  to  17.64  hy- 
drogen. To  reduce  ammonia  to  the  sys- 
tem of  equivalents,  or  to  find  its  saturating 
ratio  on  that  scale  where  oxygen  repre- 
sents unity,  we  have  this  proportion 
0.9722  :  l."75  :  :  1.1804  :  2.1*25,  so  that 
2.125  may  be  called  its  prime  equivalent. 


AMM 


AMM 


We  shall  find  this  number  deduced  from 
analysis,  confirmed  by  the  synthesis  of  all 
the  ammoniacal  salts. 

Dr.  Front,  in  an  able  memoir  on  the 
relation  between  the  specific  gravities  of 
g'aseous  bodies  and  the  weights  of  their 
atoms,  published  in  the  6th  vol.  of  the  An- 
nals of  Philosophy,  makes  the  theoretical 
weight  of  the  atom  of  ammonia  to  be  only 
1.9375  considering1  it  as  a  compound  of  1 
atom  of  azote,  and  li  atoms  of  hydrogen. 
This  statement  appears  to  be  a  logical  in- 
ference from  Mr.  Dalton's  hypothesis  of 
atomical  combination.  For  water,  the 
great  groundwork  of  his  atomic  structure, 
is  represented  as  a  compound  of  one  atom 
oxygen  with  one  atom  of  hydrogen  ;  and 
this  atomical  unit  of  hydrogen  consists  of 
two  volumes  of  the  gas.  Hence  three  vo- 
lumes of  the  gas  must  represent  an  atom 
and  an  half.  But  an  atom  is,  by  its  very 
definition,  indivisible.  Dr.  Front  in  the 
38th  number  of  the  Annals,  restores  the 
true  proportions  of  3  atoms  hydrogen,  -f- 
1  azote.  Our  doctrine  of  equivalent  primes, 
resting  on  the  basis  of  experimental  induc- 
tion, claims  no  knowledge  of  the  atomical 
constitution  of  bodies. 

The  alkaline  nature  of  ammonia  is  de- 
monstrated, not  only  by  its  neutralizing 
acidity,  and  changing  the  vegetable  reds 
to  purple  or  green,  but  also  by  its  being 
attracted  to  the  negative  pole  of  a  voltaic 
arrangement.  When  a  pretty  strong  elec- 
tric power  is  applied  to  ammonia  in  its  li- 
quid or  solid  combinations,  simple  decom- 
position is  effected;  but  in  contact  with 
mercury,  very  mysterious  phenomena  oc- 
cur. Tf  a  globule  of  mercury  be  surround- 
ed with  a  little  writer  of  ammonia,  or  pla- 
ced in  a  little  cavity  in  a  piece  of  sal  am- 
moniac, and  then  subjected  to  the  voltaic 
power  by  two  wires,  the  negative  touch- 
ing the  mercury,  and  the  positive  the  am- 
moniacal compound,  the  globule  is  instant- 
ly covered  with  a  circulating  film,  a  white 
smoke  rises  from  it,  and  its  volume  en- 
larges, whilst  it  shoots  out  ramifications  of 
a  semi-solui  consistence  over  the  salt.  The 
amalgam  has  the  consistence  of  soft  but- 
tsr,  and  may  be  cut  with  a  knife.  When- 
ever the  electrization  is  suspended,  the 
crab-like  fibres  retract  towards  the  cen- 
tral mass,  which  soon,  by  the  constant 
formation  of  white  saline  films,  resumes 
its  pristine  globular  shape  and  size.  The 
enlargement  of  volume  seems  to  amount 
occasionally  to  ten  times  that  of  the  mer- 
Gttry,  when  a  small  globule  is  employed. 
Sir  H.  Davy,  Berzelius,  and  MM.  Gay- 
Lussac  and  Thenard,  have  studied  this 
singular  phenomenon  with  great  care. 
They  produced  the  very  same  substance 
by  putting  an  amalgam  of  mercury  and 
potassium  into  the  moistened  cupel  of  sal 
ammoniac.  It  becomes  five  or  six  times 


larger,  assumes  the  consistence  of  buttery 
whilst  it  retains  its  metallic  lustre. 

What  takes  place  in  these  experiments  ? 
In  the  second  case,  the  substance  of  me- 
tallic aspect  which  we  obtain  is  an  ammo- 
niacal hydruret  of  mercury  and  potassium. 
There  is  formed,  besides,'  muriate  of  pot- 
ash. Consequently  a  portion  of  the  po- 
tassium of  the  amalgam,  decomposes  the 
water,  becomes  potash,  which  itself  de- 
composes the  muriate  of  ammonia.  Thence 
result  hydrogen  and  ammonia,  which,  ia 
the  nascent  state,  unite  to  the  undecom- 
posed  amalgam.  In  the  first  experiment, 
the  substance,  which,  us  in  the  second, 
presents  the  metallic  aspect,  is  only  an 
ammoniacal  hydruret  of  mercury  ;  its  for- 
mation is  accompanied  by  the  perceptible 
evolution  of  a  certain  quantity  of  chlorine 
at  the  positive  pole.  It  is  obvious,  there- 
fore, that  the  salt  is  decomposed  by  the 
electricity.  The  hydrogen  of  the  muria- 
tic acid,  and  the  ammonia,  both  combine 
with  the  mercury.  These  hydrurets  pos- 
sess the  following  properties. 

Their  sp.  gravity  is  in  general  below 
3.0 ;  exposed  for  some  time  to  the  tem- 
perature of  32y  F.  they  assume  consider- 
able hardness,  and  crystallize  in  cubes, 
which  are  often  as  beautiful  and  large  as 
those  of  bismuth.  Ether  and  alcohol  in- 
stantly destroy  these  amalgams,  exciting1 
a  brisk  effervescence  with  them,  and  re- 
producing the  pure  mercurial  globule. 
These  amalgams  are  slightly  permanent  in 
the  air,  if  undisturbed;  but  the  least  agi- 
tation is  fatal  to  their  existence.  MM. 
Gay-Lussac  and  Thenard  found,  by  im- 
mersion in  water,  that  mercury,  in  passing 
to  the  state  of  a  hydruret,  absorbed  3^- 
times  its  volume  of  hydrogen.  The  am- 
moniacal hydruret  of  mercury  and  potas- 
sium may  exist  by  itself;  but  as  soon  as 
we  attempt  to  separate  or  oxidize  the 
potassium,  its  other  constituent  principles 
also  separate.  Hence  this  hydruret  is 
speedily  decomposed  by  the  air,  by  oxy- 
gen gas,  and  in  general  by  all  bodies  that 
act  upon  potassium.  It  is  even  affected 
by  mercury,  so  that  in  treating  it  with  this 
metal,  we  may  easily  determine  the  rela- 
tive quantity  of  ammonia  and  hydrogen 
which  it  contains.  We  need  only  for  this 
purpose  take  up  the  interior  parts  of  the 
hydruret  with  a  little  iron  spoon,  fill  up 
with  it  a  little  glass  tube,  already  nearly 
full  of  mercury  ;  and  closing  this  with  a 
very  dry  stopper,  invert  it  in  mercury 
equally  dry.  The  hydruret  will  rise  to  the 
upper  part  of  the  tube,  will  be  clecompos- 
ea,  especially  by  a  slight  agitation,  and 
will  give  out  hydrogen  and  ammonia  in  the 
ratio  of  l  to  2."5. 

The  mere  ammoniacal  hydrurets  con- 
tain but  a  very  small  quantity  of  hydrogen 
and  ammonia.  By  supposing1  that  in  the 


AMM 


AMM 


ammoniacal  hydniret  of  mercury,  the  hy- 
drogen is  to  the  ammonia  in  the  same  pro- 
portion as  in  the  ammoniacal  hydruret  of 
mercury  and  potassium,  it  will  appear 
that  the  first  is  formed  in  volume,  of  1  of 
mercury,  3.47  hydrogen,  and  8.67  ammo- 
niacal gas,  at  the  mean  pressure  and  tem- 
perature of  30.  and  60°;  or  in  weight,  of 
about  1 800  parts  of  mercury,  with  1  part 
of  hydrogen,  and  1  of  ammonia. 

Ammonia  is  not  affected  by  a  cherry -red 
heat.  According  to  Guyton  de  Morveau, 
it  becomes  a  liquid  at  about  40° — 0°,  or 
atO°,  the  freezing  point  of  mercury  ;  but 
it  is  uncertain  whether  the  appearances  he 
observed  may  not  have  been  owing  to  hy- 
grometric  water,  as  happens  with  chlorine 
gas.  The  ammoniacal  liquid  loses  its  pun- 
gent smell  as  its  temperature  sinks,  till  at 
— 50°,  it  gelatinizes,  if  suddenly  cooled ; 
but  if  slowly  cooled,  it  crystallizes. 

Oxygen,  by  means  of  electricity,  or  a 
mere  red  heat,  resolves  ammoni  t  into  wa- 
ter and  nitrogen.  When  there  is  a  consi- 
derable excess  of  oxygen,  it  acidifies  a 
portion  of  the  nitrogen  into  nitrous  acid, 
whence  many  fallacies  in  analysis  have 
arisen.  Chlorine  and  ammonia  exercise 
so  powerful  an  action  on  each  other,  that 
when  mixed  suddenly,  a  sheet  of  white 
flame  pervades  them.  The  simplest  way 
of  making  this  fine  experiment,  is  to  in- 
vert a  mattrass,  with  a  wide  mouth  and 
conical  neck,  over  another  with  a  taper 
neck,  containing  a  mixture  of  sal  ammo- 
niac and  lime,  heated  by  a  lamp.  As  soon 
as  the  upper  vessel  seems  to  be  full  of  am- 
monia, by  the  overflow  of  the  pungent 
gas,  it  is  to  be  cautiously  lifted  up,  and  in- 
serted, in  a  perpendicular  direction,  into 
a  wide-mouthed  glass  decanter  or  flask, 
filled  with  chlorine.  On  seizing  the  two 
vessels  thus  joined,  with  the  two  hands 
covered  with  gloves,  and  suddenly  invert- 
ing them,  like  a  safidglass,  the  heavy  chlo- 
rine and  light  ammonia,  rushing  in  oppo- 
site directions,  unite,  with  the  evolution 
of  flame.  As  one  volume  of  ammonia  con- 
tains, in  a  condensed  state,  one  and  a  half 
of  hydrogen,  which  requires  for  its  satura- 
tion just  one  and  a  half  of  chlorine,  this 
quantity  should  resolve  the  mixture  into 
muriatic  acid  and  nitrogen,  and  thereby 
give  a  ready  analysis  of  the  alkaline  gas. 
If  the  proportion  of  chlorine  be  less,  sal 
ammoniac  and  nitrogen  are  the  results. 
The  same  thing  happens  on  mixing  the 
aqueous  solutions  of  ammonia  and  chlo- 
rine. But  if  large  bubbles  of  chlorine  be 
letup  into  ammoniacal  water  of  moderate 
strength,  luminous  streaks  are  seen  in  the 
dark  to  pervade  the  liquid,  and  the  same 
reciprocal  change  of  the  ingredients  is  ef- 
fected. 

MM.  Gay-Lussac  and  Thenard  state  that 
when  3  parts  of  ammoniacal  gas,  and  I  of 


chlorine,  are  mixed  together,  they  cojdf- 
dense  into  sal  ammoniac ;  and  azote,  equal 
to  1-lOth  the  wi.ole  volume,  is  given  out. 
This  result  is  at  variance  with  their  own 
theory  of  volumes. 

Three  of  ammoniacal  gas  consist  of  4£ 
hydrogen,  and  1-J  nitrogen  in  a  condensed 
state  ;  1  of  chlorine  seizes  1  of  hydrogen, 
to  form  2  of  muriatic  acid  gas,  which  pre- 
cipitate with  2  of  ammonia  in  a  pulveru- 
lent muriate.  But  the  third  volume  of 
ammonia  had  parted  with  1  volume  of  its 
hydrogen  to  the  chlorine,  and  another 
half-volume  of  hydrogen,  will  unite  with 
0.166  of  a  volume  of  nitrogen,  to  form 

0  66 
-^—  on  0.33  of  redundant  ammonia,  while 

0.33  of  a  volume  of  nitrogen  is  left  un- 
employed. Hence  |  of  a  volume,  or  •£ 
of  the  original  bulk  of  the  mixed  gases, 
ought  to  remain ;  consisting  of  equal  parts 
of  ammonia  and  nitrogen,  instead  of  l-10th 
of  azote,  as  the  French  chemists  state. 

Iodine  has  an  analogous  action  on  am- 
monia; seizing  a  portion  ot  its  hydrogen 
to  form  hydriodic  acid,  whence  hydriodate 
of  ammonia  results ;  while  another  portion 
of  iodine  unites  with  the  liberated  nitro- 
gen, to  form  the  explosive  pulverulent 
iodide. 

Cyanogen  and  ammoniacal  gas  begin  to 
act  upon  each  other  whenever  they  come 
into  contact,  but  some  hours  are  requisite 
to  render  the  effect  complete.  They 
unite  in  the  proportion  nearly  of  1  to  1£, 
forming  a  compound  which  gives  a  dark 
orange-brown  colour  to  water,  but  dis- 
solves  in  only  a  very  small  quantity  in  wa- 
ter. The  solution  does  not  produce  prus-. 
sian  blue  with  the  salts  of  iron. 

By  transmitting  ammoniacal  gas  through 
charcoal  ignited  in  a  tube,  prussic  or  hy- 
drocyanic acid  is  formed. 

The  action  of  the  alkaline  metals  on 
gaseous  ammonia  is  very  curious.  When 
potassium  is  fused  in  that  gas,  a  very  fusi- 
ble olive  green  substance,  consisting  of 
potassium,  nitrogen,  and  ammonia,  is  form- 
ed ;  and  a  volume  of  hydrogen  remains, 
exactly  equal  to  what  would  result  from 
the  action  on  water,  of  the  quantity  of 
potassium  employed.  Hence,  according 
to  M.  Thenard,  the  ammonia  is  divided 
into  two  portions.  One  is  decomposed, 
so  that  its  nitrogen  combines  with  the  po- 
tassium, and  its  hydrogen  remains  free, 
whilst  the  other  is  absorbed  in  whole  or 
in  part  by  the  nitroguret  of  potassium. 
Sodium  acts  in  the  same  manner.  The 
olive  substance  is  opaque,  and  it  is  only 
when  in -plates  of  extreme  thinness  that  itt 
appears  semi-transparent ;  and  it  has  no- 
thing of  the  metallic  appearance ;  it  « 
heavier  than  water;  and  on  minute  in- 
spection seems  imperfectly  crystallized-. 


AMM 

•  When  it  is  exposed  to  a  heat  progressive- 
ly increased,  it  melts,  disengages  ammo- 
nia, and  hydrogen  and  nitrogen,  in  the 
proportions  constituting  ammonia;  then 
it  becomes  solid,  still  preserving-  its  green 
colour,  and  is  converted  into  a  nitroguret 
of  potassium  or  sodium.  Exposed  to  the 
air  at  the  ordinary  temperature,  it  attracts 
only  its  humidity,  but  not  its  oxygen,  and 
is  slowly  transformed  into ammoniacal  gas, 
and  potash  or  soda.  It  burns  vividly  when 
projected  into  a  hot  crucible,  or  when 
heated  in  a  vessel  containing  oxygen. 
Water  and  acids  produce  also  sudden  de- 
composition, with  the  extrication  o^heat. 
Alkalis  or  alkaline  salts  are  produced. 
Alcohol  likewise  decomposes  it  with  sim- 
ilar results.  The  preceding  description 
of  the  compound  of  ammonia  with  potas- 
sium, as  prepared  by  MM.  Gay-Lussac  and 
Thenard,  was  controverted  by  Sir  H. 
Davy. 

The  experiments  of  this  accurate  che- 
mist led  to  the  conclusion,  that  the  pre- 
sence of  moisture  had  modified  their  re- 
sults. In  proportion  as  more  precautions 
are  taken  to  keep  every  thing  absolutely 
dry,  so  in  proportion,  is  less  ammonia  re- 
generated. He  seldom  obtained  as  much 
aa-rpof  thq  quantity  absorbed;  and  he 
never  could  procure  hydrogen  and  nitro- 
gen in  the  proportions  constituting  ammo- 
nia; there  was  always  an  excess  of  nitro- 
gen. The  following  experiment  was 
conducted  with  the  utmost  nicety.  3£ 
gr.  of  potassium  were  heated  in  12  cubic 
inches  of  ammoniacal  gas;  7.5  were  ab- 
sorbed, and  3.2  of  hydrogen  evolved.  On 
distilling1  the  olive-coloured  solid  in  a  tube 
of  platina,  9  cubical  inches  of  gas  were 
given  off,  and  half  a  cubical  inch  remained 
in  the  tube  and  adopters.  Of  the  9  cubi- 
cal inches,  one-fifth  of  a  cubical  inch  only 
was  ammonia;  10  measures  of  the  perma- 
nent gas  mixed  with  7.5  of  oxygen,  and 
acted  upon  by  the  electrical  spark,  left  a 
residuum  of  7.5.  He  infers  that  the  re- 
sults of  the  analysis  of  ammonia,  by  elec- 
tricity and  potassium,  are  the  same. 

On  the  whole,  we  may  legitimately  in- 
fer that  there  is  something  yet  unexplain- 
ed in  these  phenomena.  The  potassium 
separates  from  ammonia,  as  much  hydro- 
gen, as  an  equal  weight  of  it  would  from 
water.  If  two  volumes  of  hydrogen  be 
thus  detached  from  the  alkaline  gas,  the 
remaining  volume,  with  the  volume  of 
nitrogen,  will  be  left  to  combine  with  the 
potassium,  forming  a  triple  compound, 
somewhat  analagous  to  the  cyanides,  a 
compound  capable  of  condensing  ammo- 
nia. For  an  account  of  a  singular  com- 
bination of  ammonia,  by  which  its  volatili- 
ty seems  destroyed,  see  CULORIXE. 

When  ammouiacal  gas  is  transmitted 
over  ignited  wires  of  iron,  copper,  plati- 


AMM 

na,  Sec.  it  is  decomposed  completely,  ami 
though  the  metals  are  not  increased  in 
weight  they  have  become  extremely 
brittle.  Iron,  at  the  same  temperature 
decomposes  the  ammonia,  with  double 
the  rapidity  that  platinum  does.  At  a 
high  temperature,  the  protoxide  of  ni- 
trogen decomposes  ammonia. 

Of  the  ordinary  metals,  zinc  is  the  only 
one  which  liquid  ammonia  oxidizes  and 
then  dissolves.  But  it  acts  on  many  of 
the  metallic  oxides.  At  a  high  tempera- 
ture the  gas  deoxidizes  all  those  which 
are  reducible  by  hydrogen.  The  oxides 
soluble  in  liquid  ammonia,  are  the  oxide 
of  zinc,  the  protoxide  and  peroxide  of 
copper,  the  oxide  of  silver,  the  third  and 
fouth  oxides  of  antimony,  the  oxide  of 
tellurium,  the  protoxides  of  nickel,  cobalt, 
and  iron,  the  peroxides  of  tin,  mercury, 
gold,  and  platinum.  The  first  five  are 
very  soluble,  the  rest  less  so.  These 
combinations  can  be  obtained  by  evapo- 
ration, in  the  dry  state,  only  wi*h  copper, 
antimony,  mercury,  gold,  platinum,  and 
silver;  the  four  last  of  which,  are  very  re- 
markable for  their  detonating  property. 
See  the  particular  metals. 

All  the  acids  are  susceptible  of  combi- 
ning with  ammonia,  and  they  almost  all 
form  with  it  neutral  compounds.  M.  Gay- 
Lussac  made  the  important  discovery, 
that  whenever  the  acid  is  gaseous,  its 
combination  with  ammoniacal  gas,  takes 
place  in  a  simple  ratio  of  determinate 
volumes,  whether  a  neutral  or  a  subsalt 
be  formed. 

AMM  ONI  AC  At  SALTS  have  the  following 
general  characters. — 

1**,  When  treated  with  a  caustic  fixed 
alkali  or  earth,  they  exhale  the  peculiar 
smell  of  ammonia. 

2d,  They  are  generally  soluble  in  wa- 
ter, and  crystallizable. 

3d,  They  are  all  decomposed  at  a  mo- 
derate red  heat;  and  if  the  acid  be  fixed, 
as  the  phosphoric  or  boracic,  the  ammo- 
nia comes  away  pure. 

4th,  When  they  are  dropped  into  a  so- 
hition  of  muriate  of  platina,  a  yellow  pre- 
cipitate falls, 

1.  Jlcetate.  This  saline  compound  was 
formerly  called  the  spirit  of  Mindererus, 
who  introduced  it  into  medicine  as  a  fe- 
brifuge sudorific.  By  saturating  a  pretty 
strong  acetic  acid  with  subcarbonate  of 
ammonia,  enclosing  the  liquid  under  the 
receiver  of  an  air-pump,  along  with  a 
sauccrful  of  sulphuric  acid,  and  exhaust- 
ing the  air,  the  salt  will  concrete  in  acicu- 
lar  crystals,  which  are  nearly  neutral.  It 
may  also  be  made  very  conveniently,  by 
mixing  hot  saturated  solutions  of  acetate 
of  lead,  and  sulphate  of  ammonia,  taking 
100  of  the  first  salt  in  its  ordinary  state, 
to  34.4  of  the'second,  well  dried  at  a  heat 


AMM 


AMM 


of  212'.  Or  even  muriate  of  ammonia 
will  answer  in  the  proportion  of  27.9  to 
100  of  the  acetate.  Acetate  of  ammonia 
has  a  cooling-  sweetish  taste.  It  is  deli- 
quescent, and  volatile  at  all  temperatures ; 
but  it  sublimes  in  the  solid  state  at  250°. 
It  consists  of  75|  of  dry  acetic  acid,  and 
242  ammonia.  When  intended  for  medi- 
cine, it  should  always  be  prepared  from 
pure  acetic  acid,  and  subcarbonate  of  am- 
monia. 

.Arseniate  of  ammonia  may  be  formed  by 
saturating1  the  arsenic  acid  with  ammonia, 
and  evaporating1  the  liquid.  Crystals  of 
a  rhomboidal  prismatic  form  are  obtained. 
Abinarseniate  may  also  be  made  bv  using 
an  excess  of  acid.  At  a  red  heat,  the  am- 
monia of  both  salts  is  decomposed,  and 
the  acid  is  reduced  to  the  metallic  state. 
Under  the  respective  acids,  an  account  of 
several  ammoniacal  salts  will  be  found. 
As  the  muriate,  however,  constitutes  an 
extensive  manufacture,  we  shall  enter 
here  into  some  additional  details  concern- 
ing- its  production. 

Sal  ammoniac  was  originally  fabricated 
in  Egypt.  The  dung-  of  camels  and  other 
animals  constitutes  the  chief  fuel  used  in 
that  country.  The  soot  is  carefully  col- 
lected. Globular  g-lass  vessels,  about  a  foot 
in  diameter,  are  filled  within  a  few  inches 
of  their  mouth  with  it,  and  are  then  ar- 
ranged in  an  oblong-  furnace,  where  they 
are  exposed  to  a  heat  gradually  increased. 
The  upper  part  of  the  glass  balloon  stands 
out  of  the  furnace,  and  is  kept  relatively 
cool  by  the  air.  On  the  3d  day  the  oper- 
ation is  completed,  at  which  time  they 
plunge  an  iron  rod  occasionally  into  the 
mouths  of  the  globes,  to  prevent  them 
from  closing  up,  and  thus  endanger  the 
bursting  of  the  glass. 

The  fire  is  allowed  to  go  out ;  and  on 
breaking  the  cooled  globes,  their  upper 
part  is  found  to  be  lined  with  sal  ammoniac 
in  hemispherical  lumps,  about  2^  inches 
thick,  of  a  grayish  white  colour,  semi- 
transparent,  and  possessed  of  a  degree  of 
elasticity.  26  pounds  of  soot  yield  6  of 
sal  ammoniac.  The  ordinary  mode  of 
manufacturing  sal  ammoniac  in  Europe,  is 
by  combining  with  muriatic  acid  the  am- 
monia resulting  from  the  igneous  decom- 
position of  animal  matters  in  close  vessels. 
Cylinders  of  cast  iron,  fitted  up  as  we  have 
described  under  ACETIC  Acin,  are  charged 
with  bones,  horns,  parings  of  hides,  and 
other  animal  matters;  and  being  exposed 
to  a  full  red  heat,  an  immense  quantity  of 
an  impure  liquid  carbonate  of  ammonia  dis- 
tils over.  Mr.  Minish  contrived  a  cheap 
method  of  converting  this  liquid  into  sal 
ammoniac.  He  digested  it  with  pulve- 
ized  gypsum,  or  simply  made  it  percolate 
through  a  stratum  of  bruised  gypsum; 


whence  resulted  a  liquid  sulphate  of  am- 
monia, and  an  insoluble  carbonate  of  lime. 
The  liquid,  evaporated  to  dry  ness,  was 
mixed  with  muriate  of  soda,  put  into  large 
glass  balloons,  and  decomposed  by  a  sub- 
liming heat.  Sal  ammoniac  was  found 
above  in  its  characteristic  cake,  while  sul- 
phate of  soda  remained  below. 

M.  Leblanc  of  St.  Denis,  near  Paris,  in- 
vented another  method  of  much  ingenui- 
ty, which  is  described  by  a  commission  of 
eminent  French  chemists  in  the  19th  vo- 
lume of  the  Annalgs  de  Chimie,  and  in  the 
Journal  -d-e.  Physique  for  the  year  1794. 
He  used  tight  brick  kilns,  instead  of  iron 
cylinders,  for  holding  the  materials  to  be 
decomposed.  Into  one  he  put  a  mixture 
of  common  salt  and  oil  of  vitriol ;  into  ano- 
ther, animal  matters.  Heat  extricated 
from  the  first,  muriatic  acid  gas,  and  from 
the  second,  ammgnia ;  which  bodies  being 
conducted  by  their  respective  flues  into  a. 
third  chamber  lined  with  lead,  and  con- 
taining a  stratum  of  water  on  its  bottom, 
entered  into  combination,  and  precipitat- 
ed in  solid  sal  ammoniac  on  the  roof  and 
sides,  or  liquid  at  the  bottom. 

In  the  20th  volume  of  the  Annales,  a 
plan  for  employing  bittern  or  muriate  of 
magnesia  to  furnish  the  acid  ingredient  is 
described.  An  ingenious  process  on  the 
same  principles,  was  some  time  ago  com- 
menced at  Borrowstounness  in  Scotland, 
by  Mr.  Astley.  He  imbuetl  in  a  stove- 
room,  heated  by  brick  flues,  parings  of 
skins,  horns,  and  other  animal  matters, 
with  the  muriate  of  magnesia,  or  mother 
water  of  the  sea-saltworks.  The  matters 
thus  impregnated  and  dried,  were  sub- 
jected in  a  close  kiln  to  a  red  heat,  when 
the  sal  ammoniac  vapour  sublimed,  and 
was  condensed  either  in  a  solid  form,  into 
an  adjoining  chamber  or  chimney,  or  else 
into  a  stratum  of  water  on  its  bottom.  Mu- 
riate of  magnesia  at  a  red  heat,  evolves 
muriatic  acid  gas  ;  an  evolution  probably 
aided  in  the  present  case,  by  the  affinity 
of  ammonia. 

From  coal  soot  likewise  a  considerable 
quantity  of  ammonia,  in  the  state  of  carbo- 
nate and  sulphate,  may  be  obtained,  either 
by  sublimation  or  lixiviation  with  water. 
These  ammoniacal  products  can  after- 
wards be  readily  converted  into  the  mu- 
riate, as  above  described.  M.  Leblanc 
used  a  kettle  or  eolipile  for  projecting 
steam  into  the  leaden  chamber  to  promote 
the  combination.  It  is  evident,  that  the 
exact  neutralization,  essential  to  sal  am- 
moniac, might  not  be  hit  at  first  in  these 
operations;  but  it  could  be  afterwards  ef- 
fected by  the  separate  addition  of  a  p6r- 
tion  of  alkaline  or  acid  gas.  As  the  mo- 
ther waters  of  the  Cheshire  salt-works 
contain  only  3£  per  cent,  of  muriate  of 
magnesia,  they  are  not  suitable,  like  thos* 


ANA 


ANA 


6f  sea-salt  works,  for  the  above  manufac- 
ture.* 

*  AiraoviAc  (GUM).     This  is  a  gum-re- 
sin, which  consists,  according1  to  Bracon- 
not,  of  70  resin,  18.4  gum,  4.4  glutinous 
matter,  6  water,  and  1.2  loss  in  100  parts. 
It  forms  a  milky  solution  with  water  ;  is 
partially  soluble  in  alcohol ;  entirely  in 
ether,  nitric  acid,  and   alkalis.     Sp.  gr. 
1.200.     It  has  a  rather  heavy  smell,  and  a 
bitter  sweet  taste.     It  is  in  small  aggluti- 
nated pieces  of  a  yellowish  white  colour. 
It  is  used  in  medicine  as  an  expectorant 
and  antispasmodic.* 

AMMOXITES.  These  petrifactions,  which 
have  likewise  been  distinguished«by  the 
name  of  cornua  ammtmis,  and  are  called 
snake-stones  by  the  vulgar,  consist  chiefly 
of  lime-stone.  They  are  found  of  all  si- 
zes, from  the  breadth  of  half  an  inch  to 
more  than  two  feet  in  diameter ;  some  of 
them  rounded,  other*  greatly  compress- 
ed, and  lodged  in  different  strata  ol  stones 
and  clays.  They  appear  to  owe  their  ori- 
gin to  shells  of  the  nautilus  kind. 

AMOMUM.     Sfee  PIMENTO. 

*.  AMPHIBOLE.     See   IIonirBLEirnE  and 

ACTYNOLITE.* 

*  AMPHIGENE.    See  VESUVIA».* 

*  AMYGDALOID.'   A  com  iound  mineral, 
consisting  of  spheroidal  particles  or  vesi- 
cles of  lithomarge,  green  earth,  calc  spar, 
steatite,  imbedded  in  a  basis  of  fine  grain- 
ed   green-s'one,    or    wacke,    containing 
sometimes  also  crystals,  of  hornblende.* 

ANACARIHUM,  Cashew  Nut,  or  Marking 
Nut.  At  one  extremity  of  the  fruit  of  the 
cashew  tree  is  a  flattish  kidney-shaped 
nut,  between  the  rind  of  which  and  the 
thin  outer  shell  is  a  small  quantity  of  a  red, 
thickish,  inflammable,  and  very  caustic  li- 
quor. '  This  liquor  forms  a  useful  marking 
ink,  as  any  thing  written  on  linen  or  cot- 
ton with  it,  is  of  a  brown  colour,  which 
gradually  grows  blacker,  and  is  very  du- 
rable. 

*  A^ALCTME.     Cubic  Zeolite.    This  mi- 
neral is  generally  found  in   aggregated 
or  cubic  crystals,  whose  solid  angles  are 
replaced  by  three  planes.     External  lus- 
tre between  vitreous  and  pearly ;  fracture, 
flat  conchoidal;  colours,  white,  gray,  or 
reddish;  translucent.    From  its  becoming 
feebly  electrical  by  heat  it  has  got  the 

name  analcime.  Its  sp.  gr.  is  less  than 
2.6.  It  consists  of  58  silica,  18  alumina,  2 
lime,  10  soda,  8£  water,  and  3£  loss  in  100 
parts.  It  is  found  in  granite,  gneiss,  trap 
Tocks  and  lavas,  at  Calton  Hill  Edinburgh, 
sit  Taliskcr  in  Skye,  in  Dumbartonshire, 
in  the  Hartz,  Bohemia,  and  at  the  Ferroe 
Islands.  The  variety  found  at  Somma 
has  been  called  sarcolite,  from  its  flesh 
colour.* 

ANALYSIS.     Chemical  analysis  consists 
of  a  great  variety  of  operations,  perform- 


ed for  the  purpose  of  separating  the  com- 
ponent parts  of  bodies.  In  these  opera- 
tions the  most  extensive  knowledge  of 
such  properties  of  bodies  as  are  already 
discovered  must  be  applied,  in  order  to 
produce  simplicity  of  effect,  and  certainty 
in  the  results.  Chemical  analysis  can 
hardly  be  executed  with  success  by  one 
who  is  not  in  possession  of  a  considerable 
number  of  simple  substances  in  a  state  of 
great  purity,  many  of  which,  from  their 
effects,  are"  called  reagents.  The  word 
analysis  is  applied  by  chemists  to  denote 
that  series  of  operations,  by  which  the 
component  parts  of  bodies  are  determined, 
whether  they  be  merely  separated,  or  ex- 
hibited apart  from  each  other ;  or  whether 
these  distinctive  properties  be  exhibited 
by  causing  them  to  enter  into  new  com- 
binations, without  the  perceptible  inter- 
vention of  a  separate  state.  The  forming 
of  new  combinations  is  called  synthesis; 
and  in  the  chemical  examination  of  bo- 
dies, analysis  or  separation  can  scarcely 
ever  be  effected,  without  synthesis  taking 
place  at  the  same  time. 

As  most  of  the  improvements  in  the 
science  of  chemistry  consist  in  bringing 
the  art  of  analysis  nearer  to  perfection,  it 
is  not  easy  to  give  any  other  rule  to  the 
learner  than  the  general  one  of  consulting 
and  remarking  the  processes  of  the  best 
chemists,  such  as  Scheele,  Bergmann, 
Berthollet,  Kirwan,  Vauquelin,  and  Ber- 
zelius.  The  bodies  which  present  them- 
selves more  frequently  for  examination 
than  others,  are  minerals  and  mineral 
waters.  In  the  examination  of  the  former, 
it  was  the  habit  of  the  earlier  chemists  to 
avail  themselves  of  the  action  of  fire,  with 
very  few  humid  processes,  which  are  such 
as  might  be  performed  in  the  usual  tem- 
perature of  the  atmosphere.  Modern 
chemists  have  improved  the  process  by 
fire,  by  a  very  extensive  use  of  the  blow- 
pipe (see  BLOW-PIPK);  and  have  succeed- 
ed in  determining  the  component  parts  of 
minerals  to  great  accuracy  in  the  humid 
way.  For  the  method  of  analyzing  min- 
eral waters,  see  WATERS  (MIXEHAL)  ;  and 
for  the  analysis  of  metallic  ores,  see  OHES. 

Several  authors  have  written  on  the  ex- 
amination of  earths  and  stones. 

The  first  step  in  the  examination  of  con- 
sistent earths  or  stones  is  somewhat  dif- 
ferent from  that  of  such  as  are  pulveru- 
lent. Their  specific  gravity  should  first 
be  examined;  also  their  hardness,  whe- 
ther they  will  strike  fire  with  steel,  or  can 
be  scratched  by  the  nail,  or  only  by  crys- 
tal, or  stones  of  still  greater  hardness ;  also 
their  texture,  perviousness  to  light,  and 
whether  they  be  manifestly  homogeneous 
or  compound  species,  &c. 

2d,  In  some  cases,  we  should  try  whe- 
ther, they  imbibe  water,  or  whether  \YMer 


ANA 


ANA 


«an  extract  any  thing  from  them  by  ebul- 
lition or  digestion. 

od,  Whether  they  be  soluble  in,  or  ef- 
fervesce with,  acids,  before  or  after  pul- 
verization;   or  whether  decomposable  by 
boiling  in  a  strong  solution  of  potash.  Sec. 
as  gypsums  and  ponderous  spars  are. 
4th,  Whether  they  detonate  with  nitre. 
5th,  Whether  they  yield  the  fluor  acid 
by  distillation  with  sulphuric  acid,  or  am- 
monia by  distilling  them  with  potash. 

6th,  Whether  they  be  fusible  per  se  with 
a  blow-pipe,  and  how  they  are  affected  by 
soda,  borax,  and  microcosmic  salt ;  and 
whether  they  decrepitate  when  gradually 
heated. 

7th,  Stones  that  melt  per  se  with  the 
blow-pipe  are  certainly  compound,  and 
contain  at  least  three  species  of  earth,  of 
which  the  calcareous  is  probably  one ;  and 
if  they  give  fire  with  steel,  the  siliceous  is 
probably  another- 

The  general  process  prescribed  by  the 
celebrated  Vauquelin,  in  the  30tii  volume 
of  the  Annales  de  Chimie,  is  the  clearest 
which  has  yet  been  offered  to  the  chemi- 
cal student. 

If  the  mineral  be  very  hard,  it  is  to  be 
ignited  in  a  covered  crucible  of  platinum, 
and  then  plunged  into  cold  water,  to  ren- 
der it  brittle  and  easily  pulverizable.  The 
weight  should  be  noted  before  and  after 
this  operation,  in  order  to  see  if  any  vola- 
tile matter  has  been  emitted.  For  the  pur- 
pose of  reducing  stones  to  an  impalpable 
powder,  little  mortars  of  highly  hardened 
steel  are  now  made,  consisting  of  a  cylin- 
drical case  and  pestle.  A  mortar  of  agate 
is  also  used  for  subsequent  levigation, 
About  ten  grains  of  the  mineral  should  be 
treated  at  once  .-  and  after  the  whole  100 
grains  have  been  reduced  in  succession  to 
an  impalpable  powder,  they  should  be 
weighed,  to  find  what  increase  may  have 
been  derived  from  the  substance  of  the 
agate.  This  addition  may  be  regarded  as 
silica. 

Of  the  ten  primary  earths,  only  four 
are  usually  met  with  in  minerals,  viz.  silica, 
alumina,  magnesia,  and  lime,  associated 
with  some  metallic  oxides,  which  are  com- 
monly iron,  manganese,  nickel,  copper 
and  chromium. 

If  neither  acid  nor  alkali  be  expected  to 
be  present,  the  mineral  is  mixed  in  a  sil- 
ver crucible,  with  thrice  its  weight  of 
pure  potash  and  a  little  water.  Heat  is 
gradually  applied  to  the  covered  crucible, 
and  is  finally  raised  to  redness ;  at  which 
temperature  it  ought  to  be  maintained  for 
an  hour.  If  the  mass,  on  inspection,  be  a 


dull  green  colour  indicates  the  presence 
of  iron;    a  bright  grass-green,  which  is 
imparted  to   water,  that  of  manganese ; 
and  from  a  greenish-yellow,    chromium 
may  be  expected.     The  crucible,  still  a. 
little  hot,  being  first  wiped,  is  put  into  a 
capsule   of  porcelain  or  platinum ;  when, 
warm  distilled  water  is  poured  upon  the 
alkaline  earthy  mass,  to  detach  it  from  the 
crucible.     Having  transferred  the  whole 
of  it  into  the  capsule,  muriatic  acid  is  pour- 
ed on,  and  a  gentle  heat  applied,  if  neces- 
sary, to  accomplish  its  solution.    If  the  li- 
quid be  of  an  orange-red  colour,  we  infer 
the  presence  of  iron ;  if  of  a  golden-yellow, 
that  of  chromium ;  and  if  of  a  purplish- 
red,  that  of  manganese.    The  solution  is 
next  to  be   evaporated  to  dryness,  on  a 
sand-bath,  or  over  a  lamp,  taking  care  so 
to  regulate  the  heat,  that  no  particles  be 
thrown   out.     Towards  the  end    of   the 
evaporation,  it  assumes  a  gelatinous  con- 
sistence. At  this  period  it  must  be  stirred 
frequently  with  a  platinum  spatula  or  glass 
rod,  to  promote  the  disengagement  of  the 
muriatic  acid  gas.     After  this,  the  heat 
may  be  raised  to  fully  212°  V.  for  a  few 
minutes.    Hot  water  is  to  be  now  poured 
on  in  considerable  abundance,  which  dis- 
solves every  thing1  except  the  silica.     By 
filtration,  this  earth  is  separated  from  the 
liquid;    and  being  edulcorated  with  hot 
water,  it  is  then  dried,  ignited,  and  weigh- 
ed. It  constitutes  a  fine  white  powder,  in- 
soluble in   acids,   and   feeling  gritty  be- 
tween the  teeth.     If  it  be  coloured,  a  lit- 
tle dilute  muriatic  acid  must  be  digested 
on  it,  to  remove  the   adhering  metallic 
particles,   which  must   be   added  to  the 
first  solution.    This  must  now  be  reduced 
by  evaporation  to  the  bulk  of  half  a  pint. 
Carbonate  of  potash  being  then  added,  till 
it  indicates  alkaline  excess,  the  liquid  must 
be  made  to  boil  for  a  little,    A  copious 
precipitation  of  the  earth  and  oxides  is 
thus  produced.    The  whole  is  thrown  on 
a  filter,  and  after  it  is  so  drained  as  to  as- 
sume   a  semi-solid  consistence,  it  is  re- 
moved by  a  platinum  blade,  and  boiled  in 
a  capsule  for  some  time,  with  solution 
of  pure  potash.    Alumina  and  glucina  are 
thus  dissolved,  while  the  other  earths  and 
the  metallic  oxides  remain. 

This  alkalino-earthy  solution,  separated 
from  the  rest  by  filtration,  is  to  be  treated 
with  an  excess  of  muriatic  acid;  after 
which  carbonate  of  ammonia  being  added 
also  in  excess,  the  alumina  is  thrown  down, 
while  the  glucina  continues  dissolved. 
The  first  earth  separated  by  filtration, 
washed,  dried,  and  ignited,  gives  the 


perfect  glass,  silica  may  be  regarded  as  quantity  of  alumina.     The  nature  of  this 

the  chief  constituent  of  the  stone ;  but  if  may  be  further  demonstrated,  by  treating 

the  vitrification  be  very  imperfect  and  the  it  with  dilute  sulphuric  acid,  and  sulphate 

bulk   much  increased,   alumina  may   be  of  potash,  both    in  equivalent  quantities, 

supposed  to  predominate.   A  brownish  or  when  the  whole  wftl  be  converted  into 


ANA 


ANA 


akim.  (See  ALUM).  The  filtered  liquid 
will  deposite  its  glucina,  on  dissipating-  the 
ammonia,  by  ebullition.  It  is  to  be  sepa- 
rated by  nitration,  to  be  washed,  ignited, 
and  weighed. 

The  matter  undissolved  by  the  diges- 
tion of  the  liquid  potash,  may  consist  of 
lime,  magnesia,  and  metallic  oxides.  Di- 
lute sulphuric  acid  must  be  digested  on  it 
for  some  time.  The  solution  is  to  be  evap- 
orated to  dryness,  and  heated  to  expel 
the  excess  of  acid.  The  saline  solid  mat- 
ter being  now  diffused  in  a  moderate 
quantity  of  water,  the  sulphate  of  magne- 
sia will  be  dissolved,  and  along  with,  the 
metallic  sulphates,  may  be  separated  from 
the  sulphate  of  lime  by  the  filter.  The 
latter  being  washed  with  a  little  water, 
dried,  ignited,  and  weighed,  gives,  by  the 
scale  of  equivalents,  the  quantity  of  lime 
in  the  mineral.  The  magnesianand  metal- 
lic solution  being  diluted  with  a  large 
quantity  of  water,  is  to  be  treated  with 
bicarbonate  of  potash,  which  will  precipi- 
tate the  nickel,  iron,  and  chromium,  but 
retain  the  magnesia  and  manganese,  by 
the  excess  of  carbonic  acid.  Hydrosulphu- 
ret  of  potash  will  throw  down  the  manga- 
nese, from  the  magnesian  solution.  The 
addition  of  pure  potash,  aided  by  gentle 
ebullition,  wiH  then  precipitate  the  mag- 
nesia. The  oxide  of  manganese  may  be 
freed  from  the  sulphuretted  hydrogen,  by 
ustulation. 

The  mingled  metallic  oxides  must  be 
digested  with  abundance  of  nitric  acid,  to 
acidify  the  chromium.  The  liquid  is  next 
.  treated  with  potash,  which  forms  a  soluble 
ehromate,  while  it  throws  down  the  iron 
and  nickel.  The  chromic  acid  may  be  se- 
parated from  the  potash  by  muriatic  acid, 
and  digestion  with  heat,  washed,  dried  till 
it  becomes  a  green  oxide,  and  weighed. 
The  nickel  is  separated  from  the  iron,  by 
treating  their  solution  in  muriatic  acid, 
with  water  of  ammonia.  The  latter  oxide 
which  falls,  may  be  separated  by  the  filter, 
dried  and  weighed.  By  evaporating  the 
liquid,  and  exposing  the  dry  residue  to  a 
moderate  heat,  the  ammoniacal  salt  will 
sublime  and  leave  the  oxide  of  nickel  be- 
hind. The  whole  separate  weights  must 
now  be  collected  in  one  amount,  and  if 
they  constitute  a  sum  within  two  per  cent, 
of  the  primitive  weight,  the  analysis  may 
be  regarded  as  giving  a  satisfactory  ac- 
count of  the  composition  of  the  mineral. 
But  if  the  deficiency  be  considerable,  then 
«ome  volatile  ingredient,  or  some  alkali  or 
alkaline  salt,  may  be  suspected. 

A  portion  of  the  mineral  broken  into 
small  fragments,  is  to  be  ignited  in  a  por- 
celain retort,  to  which  a  refrigerated  re- 
ceiver is  fitted.  The  water  or  other  vola- 
tile and  condensable  matter,  if  any  be  pre- 
sent, will  thus  be  obtained.  But  if  no  loss 


of  weight  be  sustained  by  ignition,  alkali, 
or  a  volatile  acid,  may  be  looked  for.  The 
latter  is  usually  the  fluoric.  It  may  be  ex- 
pelled by  digestion  with  sulphuric  acid. 
It  is  exactly  characterized  by  its  property 
of  corroding  glass.* 

Beside  this  general  method,  some  oth- 
ers may  be  used  in  particular  cases. 

Thus,  to  discover  a  small  portion  of  alu- 
mina or  magnesia  in  a  solution  of  a  large 
quantity  of  lime,  pure  ammonia  may  be 
applied,  which  will  precipitate  the  alumi- 
na or  magnesia  (if  any  be),  but  not  the 
lime.  Distilled  vinegar  applied  to  the  pre- 
cipitate will  discover  whether  it  be  alu- 
mina or  magnesia. 

2c//?/,  A  minute  portion  of  lime  orbary- 
tes,  in  a  solution  of  alumina  or  magnesia, 
may  be  discovered  by  the  sulphuric  acid, 
which  precipitates  the  lime  and  barytes  : 
the  solution  should  be  dilute,  else  the  alu- 
mina also  would  be  precipitated.  If  there 
be  not  an  excess  of  acid,  the  oxalic  acid 
is  still  a  nicer  test  of  lime:  100  grains  of 
gypsum  contain  about  33  of  limef  100 
grains  of  sulphate  of  barytes  contain  66  of 
barytes;  100  grains  of  oxalate  of  lime  con- 
tain 43.8  of  lime.  The  insolubility  of  sul- 
phate of  barytes  in  500  times  its  weight 
of  boiling  water,  sufficiently  distinguishes 
it.  From  these  data  the  quantities  are 
easily  investigated. 

3dlyt  A  minute  proportion  of  alumina  in 
a  large  quantity  of  magnesia  may  be  dis- 
covered, either  by  precipitating  the  whole, 
and  treating  it  with  distilled  vinegar;  or 
by  heating  the  solution  nearly  to  ebulli- 
tion, and  adding  more  carbonate  of  mag- 
nesia,  until  the  solution  is  perfectly  neu- 
tral, which  it  never  is  when  alumina  is  con- 
tained in  it,  as  this  requires  an  excess  of 
acid  to  keep  it  in  solution.  By  these 
means  the  alumina  is  precipitated  in  the 
state  of  embryon  alum,  which  contains 
about  half  its  weight  of  alumina  (or,  for 
greater  exactness,  it  may  be  decomposed 
by  boiling  it  in  volatile  alkali).  After  the 
precipitation,  the  solution  should  be  large- 
ly diluted,  as  the  sulphate  of  magnesia, 
which  remained  in  solution  while  hot, 
would  precipitate  when  cold,  and  mix  with 
the  embryon  alum. 

Aithty,  A  minute  portion  of  magnesia  in 
a  large  quantity  of  alumina  is  best  separat- 
ed by  precipitating  the  whole,  and  treat- 
ing the  precipitate  with  distilled  vinegar. 
Lastly,  Lime  and  barytes  are  separated 
by  precipitating  both  with  the  sulphuric 
acid,  and  evaporating  the  solution  to  a 
small  compass,  pouring  off  the  liquor,  and 
treating  the  dried  precipitate  with  500 
times  its  weight  of  boiling  water;  what 
remains  undissolved  is  sulphate  of  bary- 
tes. 

The  inconveniences  of  employing  much 
heat,  are  obvieus,  and  Mr.  Lowitz  informs 


ANA 


ANA 


us,  that  they  may  be  avoided  without  the 
least  disadvantage.  Over  the  flame  of  a 
spirit  lamp,  that  will  hold  an  ounce  and 
half,  and  is  placed  in  a  cylindrical  tin  fur- 
nace four  inches  high  and  three  in  diame- 
ter, with  air-holes,  and  a  cover  perforated 
to  hold  the  crucible,  he  boils  the  stone 
prepared  as  directed  above,  stirring  it  fre- 
quently. His  crucible,  which,  as  well  as 
the  spatula,  is  of  very  line  silver,  holds 
two  ounces  and  a  half,  or  three  ounces. 
As  soon  as  the  matter  is  boiled  dry,  he 
pours  in  as  much  hot  water  as  he  used  at 
first ;  and  this  he  repeats  two  or  three 
times  more,  if  the  refractoriness  ofthe  fos- 
sil require  it.  Large  tough  bubbles  ari- 
sing during  the  boiling,  are  in  general  a 
sign  that  the  process  will  be  attended  with 
success.  Even  the  sapphire,  though  the 
most  refractory  of  all  Mr.  Lowitz  tried, 
was  not  more  so  in  this  than  in  the  dry 
way. 

Sir  H.  Davy  observes,  that  the  boracic 
acid  is  very  useful  in  analyzing  stones  that 
contain  a  fixed  alkali ;  as  its  attraction  for 
the  different  earths  at  the  heat  of  ignition 
is  considerable,  and  the  compounds  it 
forms  with  them  are  easily  decomposed 
by  the  mineral  acids  dissolved  in  water. 
His  process  is  as  follows :  Let  100  grains 
of  the  stone  to  be  examined  be  reduced 
to  a  fine  powder,  mixed  with  200  grains 
of  boracic  acid,  and  fused  for  about  .half 
an  hour  at  a  strong  red  heat  in  a  crucible 
of  platina  or  silver.  Digest  the  fused  mass 
in  an  ounce  and  half  of  nitric  acid  diluted 
with  seven  or  eight  times  the  quantity  of 
water,  till  the  whole  is  decomposed;  and 
then  evaporate  the  solution  till  it  is  re- 
duced to  an  ounce  and  half,  or  two  ounces. 
If  the  stone  contained  silex,  it  will  sepa- 
rate in  this  process,  and  must  be  collect- 
ed on  a  filter,  and  edulcorated  with  dis- 
tilled water,  to  separate  the  saline  matter. 
The  fluid,  mixed  with  all  the  water  that 
has  been  passed  through  the  filter,  being 
evaporated  till  reduced  to  about  half  a 
pint,  is  to  be  saturated  with  carbonate  of 
ammonia,  and  boiled  with  an  excess  of 
this  salt,  till  all  that  will  precipitate  has 
fallen  down.  The  earths  and  metallic 
oxides  being  separated  by  filtration,  mix 
nitric  acid  with  the  clear  fluid  till  it  has  a 
strongly  sour  taste,  and  then  evaporate 
till  the  boracic  acid  remains  free.  Filter 
the  fluid,  evaporate  it  to  dryness,  and  ex- 
pose it  to  a  heat  of  450°  F.  when  the  ni- 
trate of  ammonia  will  be  decomposed, 
and  the  nitrate  of  potash  or  soda  will  re- 
main in  the  vessel.  The  earths  and  me- 
tallic oxides,  that  remained  on  the  filter, 
may  be  distinguished  by  the  common  pro- 
cesses. The  alumina  may  be  separated 
by  solution  of  potash,  the  lime  by  sulphu- 
ric acid,  the  oxide  of  iron  by  succinate  of 
ammonia,  the  manganese  by  hydrosul- 


phuret  of  potash,  and  the  magnesia  by  pure 
soda. 

*  Lately  carbonate  or  nitrate  of  barytes 
has  been  introduced  into  mineral  analysis 
with  great  advantage,  for  the  fluxing1  of 
stones,  that  may  contain  alkaline  mutter. 
See  the  English  Translation  of  M.  The- 
nard's  volume  on  analysis.* 

Under  the  head  of  mineral  analysis,  no- 
thing is  of  so  much  general  importance  as 
the  examination  of  soils,  with  a  view  to 
the  improvement  of  such  as  are  less  pro- 
ductive, by  supplying  the  ingredients  they 
want  in  due  proportions  to  increase  their 
fertility.  To  Lord  Dundonald  and  Mr. 
Kirwan  we  are  much  indebted  for  their 
labours  in  this  field  of  inquiry  ;  but  Sir 
H.  Davy,  assisted  by  the  labours  of  these 
gentlemen,  the  facts  and  observations  of 
Mr.  Young,  and  his  own  skill  in  chemis- 
try, having  given  at  large,  in  a  manner 
best  adapted  for  the  use  of  the  practical 
farmer,  an  account  of  the  methods  to  be 
pursued  for  this  purpose,  we  shall  here 
copy  them. 

The  substances  found  in  soils  are  cer- 
tain mixtures  or  combinations  of  some  of 
the  primitive  earths,  animal  and  vegetable 
matter  in  a  decomposing  state,  certain  sa- 
line compounds,  and  the  oxide  of  iron. 
These  bodies  always  retain  water,  and  ex- 
ist in  very  different  proportions  in  differ- 
ent lands,  and  the  end  of  analytical  ex- 
periments is  the  detection  of  their  quanti- 
ties and  mode  of  union. 

The  earths  commonly  found  in  soils  are 
principally  silex,  or  the  earth  of  flints ;  alu- 
mina, or  the  pure  matter  of  clay  ;  lime,  or 
calcareous  earth;  and  magnesia:  for  the 
characters  of  which  see  the  articles.  Si- 
lex  composes  a  considerable  part  of  hard- 
gravelly  soils,  hard  sandy  soils,  and  hard 
stony  lands.  Alumina  abounds  most  in 
clayey  soils,  and  clayey  loams ;  but  even  in 
the  smallest  particles  of  these  soils,  it  is  ge- 
nerally united  with  silex  and  oxide  of  iron. 
Lime  always  exists  in  soils  in  a  state  of  com- 
bination, and  chiefly  with  carbonic  acid, 
when  it  is  called  carbonate  of  lime.  This 
carbonate  in  its  hardest  state  is  marble  ; 
in  its  softest,  chalk.  Lime  united  with 
sulphuric  acid  is  sulphate  of  lime,  or  gyp- 
sum ;  with  phosphoric  acid,  phosphate  of 
lime,  or  the  earth  of  bones.  Carbonate 
of  lime,  mixed  with  other  substances,  com- 
poses chalky  soils  and  marls,  and  is  found 
in  soft  sandy  soils.  Magnesia  is  rarely 
found  in  soils :  when  it  is;  it  is  combined 
with  carbonic  acid,  or  with  silex  and  alu- 
mina. Animal  decomposing  matter  exists 
in  different  states,  contains  much  carbo- 
naceous substance,  volatile  alkali,  inflam- 
mable aeriform  products,  and  carbonic 
acid.  It  is  found  chiefly  in  lands  lately- 
manured.  Vegetable  decomposing  mat- 
ter usually  contains  still  more  carbonace- 


ANA 


ANA 


ous  substance,  and  differs  from  the  pre- 
ceding principally  in  not  producing  vola- 
tile alkali.  It  forms  a  great  proportion  of 
all  peats,  abounds  in  rich  mould,  and  is 
found  in  larger  or  smaller  quantities  in  all 
lands.  The  saline  compounds  are  few, 
and  in  small  quantity :  they  are  chiefly 
muriate  of  soda,  or  common  salt,  sulphate 
of  magnesia,  muriate  and  sulphate  of  pot- 
ash, nitrate  of  lime,  and  the  mild  alkalis. 
Oxide  of  iron,  which  is  the  same  with  the 
rust  produced  by  exposing  iron  to  air  and 
water,  is  found  in  all  soils,  but  most  abun- 
dantly in  red  and  yellow  clays,  and  red 
and  yellow  siliceous  sands. 

The  instruments  requisite  for  the  analy- 
sis of  soils  are  few.  A  pair  of  scales  capa 
ble  of  holding  a  quarter  of  a  pound  of 
common  soil,  and  turning  with  a  single 
grain  when  loaded :  a  set  of  weights,  from 
a  quarter  of  a  pound  iroy  to  a  grain :  a 
wire  sieve,  coarse  enough  to  let  pepper- 
corn pass  through :  an  Argand  lamp  and 
stand  :  a  few  glass  bottles,  Hessian  cruci- 
bles, and  china  or  queen's  ware  evapora- 
ting basins  :  a  Wedgwood  pestle  and  mor- 
tar :  some  filters  made  of  half  a  sheet  of 
blotting  paper,  folded  so  as  to  contain  a 
pint  of  liquid,  and  greased  at  the  edges :  a 
bone  knife  :  and  an  apparatus  for  collect- 
ing and  measuring  aeriform  fluids. 

The  reagents  necessary  are  muriatic 
acid,  sulphuric  acid,  pure  volatile  alkali 
dissolved  in  water,  solution  of  prussiate  of 
potash,  soap  lye,  and  solutions  of  carbo- 
nate of  ammonia,  muriate  of  ammonia, 
neutral  carbonate  of  potash,  and  nitrate  of 
ammonia. 

1.  When  the  general  nature  of  the  soil 
of  a  field  is  to  be  ascertained,  specimens 
of  it  should  be  taken  from  different  places, 
two  or  three  inches  below  the  surface,  and 
examined  as  to  the  similarity  of  their  pro- 
perties. It  sometimes  happens,  that  on 
plains  the  whole  of  the  upper  stratum  of 
the  land  is  of  the  same  kind,  and  in  this 
case  one  analysis  will  be  sufficient.  But 
in  valleys,  and  near  the  beds  of  rivers, 
there  are  very  great  differences,  and  it 
now  and  then  occurs,  that  one  part  of  a 
field  is  calcareous,  and  another  pai't  silice- 
ous; and  in  this  and  analogous  cases,  the 
portions  different  from  each  other  should 
be  analyzed  separately.  Soils  when  col- 
lected, if  they  cannot  be  examined  imme- 
diately, should  be  preserved  in  phials 
quite  filled  with  them,  and  closed  with 
ground  glass  stopples.  The  most  conve- 
nient quantity  for  a  perfect  analysis  is  from 
two  hundred  grains  to  four  hundred.  It 
should  be  collected  in  dry  weather,  and 
exposed  to  the  air  till  it  feels  dry.  Its 
specific  gravity  may  be  ascertained,  by  in- 
troducing into  a  phial,  which  will  contain 
a  known  quantity  of  water,  equal  bulks  of 
A\  ater  and  of  the  soil ;  which  may  easi- 


ly be  done,  by  pouring  in  water  till  the 
phial  is  half  full,  and  then  adding  the  soii 
till  the  fluid  rises  to  the  mouth.  The  dif- 
ference between  the  weight  of  the  water, 
and  that  of  the  soil,  will  give  the  result. 
Then  if  the  bottle  will  contain  four  hun- 
dred grains  of  water,  and  gains  two  hun- 
dred grains  when  half  filled  with  water 
and  half  with  soil,  the  specific  gravity  of 
the  soil  will  be  2 ;  that  is,  it  will  be  twice 
as  heavy  as  water :  and  if  it  gained  one 
hundred  and  sixty-five  grains,  its  specific 
gravity  would  be  1825,  water  being  1000. 
It  is  of  importance  that  the  specific  gravi- 
ty of  a  soil  should  be  known,  as  it  affords 
an  indication  of  the  quantity  of  animal  and 
vegetable  maiter  it  contains ;  these  sub- 
stances being  alw  ays  most  abundant  in  the 
lighter  soils.  The  o.her  physical  proper- 
ties of  soils  should  likewise  be  examined 
before  the  analysis  is  made,  as  they  de- 
note, to  a  certain  exient,  their  composi- 
tion, and  serve  as  guides  in  directing  the 
experiment  .  Thus  siliceous  soils  are 
generally  rough  to  the  touch,  and  scratch 
glass  when  rubbed  upon  it :  aluminous 
soils  adhere  strongly  to  the  tongue,  and 
emit  a  strong  earthy  smell  when  breathed 
upon :  and  calcareous  soils  are  soft,  and 
much  less  adhesive  than  aluminous  soils. 

2.  boils,  when  as  dry  as  they  can  be 
made  by  exposure  to  the  air,  still  retain  a 
considerable  quantity  of  water,  which  ad- 
heres with  great  obstinacy  to  them,  and 
cannot  be  driven  off  without  considerable 
heat :  and  the  first  process  of  analysis  is  to 
free  them  from  as  much  of  this  water  as 
possible,  without'affecting  their  composi- 
tion in  other  respects,    lliis  may  be  done 
by  heating  the   soil  for  ten   or  twelve 
minutes  in  a  china  basin  over  an  Argand 
lamp,  at  a  temperature  equal  to  oOO°  F. ; 
and  if  a  thermometer  be  not  used,  the  pro- 
per degree  of  heat  may  easily  be  ascer- 
tained by  keeping  a  piece  of  wood  in  the 
basin  in  contact  with  its  bottom ;  for  as 
long  as  the  colour  of  the  wood  remains  un- 
altered, the  heat  is  not  too  high;  but  as 
soon  as  it  begins  to  be  charred,  the  pro- 
cess must  be  stopped.     In  several  expe- 
riments, in  which   Sir  H.  Davy  collected 
the  water  that  came  over  at  this  degree  of 
heat,  he  found  it  pure,  without  any  sensi- 
ble quantity  of  other  volatile  matter  being 
produced.     The   loss  of  weight   in   this 
process  must  be  carefully  noted ;  and  if  it 
amount  to   50  grains  in  400  of  the  soil, 
this  may  be  considered  as  in  the  greatest 
degree  absorbent  and  retentive  of  water, 
and  will  generally  be  found  to  contain  a 
large  proportion   of  aluminous   earth  .  if 
the  loss  be  not  more  than  10  or  20  grains, 
the  land  may  be  considered  as  slightly  ab- 
sorbent and  retentive,  and  the  siliceous 
earth  as  most  abundant. 

3.  None  of  the  loose  stones,  gravel,  or 


ANA 


ANA 


large  vegetable  fibres,  should  be  separa- 
ted from  the  soil,  till  the  water  is  thus  ex- 
pelled ;  for  these  bodies  are  often  highly 
absorbent  and  retentive,  and  consequent- 
ly influence  the  fertility  of  the  land.  But 
after  the  soil  has  been  heated  as  above, 
these  should  be  separated  by  the  sieve, 
after  the  soil  has  been  gently  bruised  in  a 
mortar.  The  weights  of  the  vegetable 
fibres  or  wood,  and  of  the  gravel  and 
stones,  should  be  separately  noted  down, 
and  the  nature  of  the  latter  ascertained: 
if  they  be  calcareous,  they  will  effervesce 
with  acids  ;  if  siliceous,  they  will  scratch 
glass  ;  if  aluminous,  they  will  be  soft,  easi- 
ly scratched  with  a  knife,  and  incapable  of 
effervescing  with  acids. 

4.  Most  soils,  beside  stones  and  gravel, 
Contain  larger  or  smaller  proportions  of 
sand  of  different-degrees  of  fineness ;  and 
the  next  operation  necessary  is  to  separate 
this  sand  from  the  parts  more  minutely  di- 
vided, such  as  clay,  loam,  marl,  and  vege- 
table and  animal  matter.     This  may  be 
done  sufficiently  by  mixing  the  soil  well 
with  water ;  as  the  coarse  sand  will  gene- 
rally fall  to  the   bottom  in  the  space  of  a 
minute,  and  the  finer  in  two  or  three  ;  so 
that  by  pouring  the  water  off  after  one, 
two,  or  three  minutes,  the  sand  will  be  for 
the  most  part  separated  from  the  other 
substances;  which,   with  the  water  con- 
taining them,  must  be  poured  into  a  filter. 
After  the  water  has  passed  through,  what 
remains  on  the  filter  must  be  dried  and 
weighed ;  as  must  also  the  sand ;  and  their 
respective  quantities  must  be  noted  down. 
The  water  must  be  preserved,  as  it  will 
contain  the  saline  matter,  and  the  soluble 
animal  or  vegetable  matter,  if  any  existed 
in  the  soil. 

5.  A  minute  analysis  of  the  sand  thus 
separated  is  seldom  or  never  necessary, 
and  its    nature  may  be  detected  in  the 
same  way  as  that  of  the  stones  anil  gravel. 
It  is  always  siliceous  sand,  or  calcareous 
sand,    or    both   together.     If   it    consist 
wholly  of  carbonate  of  lime,  it  will  dis- 
solve rapidly  in  muriatic  acid  with  effer- 
vescence ;  but  if  it  consists  partly  of  this 
and  partly  of  siliceous  matter,  a  residuum 
will  be  left  after  the  acid  has  ceased  to 
act  on  it,  the  acid  being  added  till  the 
mixture  has  a  sour  taste,  and  has  ceased 
to  effervesce.     This  residuum  is  the  sili- 
ceous part;  which  being  washed,  dried, 
and  heated  strongly   in   a  crucible,  the 
difference  of  its  weight  from  that  of  the 
whole,  will  indicate  the  quantity  of  the 
calcareous  sand. 

6.  The   finely   divided  matter  of  the 
soil  is  usually  very  compound  in  its  na- 
ture ;  it  sometimes  contains  all  the  four 
primitive  earths  of  soils,  as  well  as  animal 
and  vegetable  matter;  and  to  ascertain 
the  proportions  of  these  with  tolerable 

Vot.  r.  [22] 


accuracy,  is  the  most  difficult  part  of  the 
subject.  The  first  process  to  be  perform- 
ed in  this  part  of  the  analysis  is  the  expo- 
sure of  the  fine  matter  of  the  soil  to  the 
action  of  muriatic  acid.  This  acid,  dilu- 
ted with  double  its  bulk  of  water,  should 
be  poured  upon  the  earthy  matter  in  an 
evaporating  basin,  in  a  quantity  equal  to 
twice  the  weight  of  the  earthy  matter. 
The  mixture  should  be  often  siirred,  and 
suffered  to  remain  for  an  hour,  or  an  hour 
and  half,  before  it  is  examined.  If  any 
carbonate  of  lime,  or  of  magnesia,  exist 
in  the  soil,  they  will  have  been  dissolved 
in  this  time  by  the  acid,  which  sometimes 
takes  up  likewise  a  little  oxide  of  iron, 
but  very  seldom  any  alumina.  The  fluid 
should  be  passed  through  a  filter;  the 
solid  matter  collected,  washed  with  dis- 
tilled or  rain  water,  dried  at  a  moderate 
heat,  and  weighed.  Its  loss  will  denote 
the  quantity  of  solid  matter  taken  up. 
The  washings  must  be  added  to  the  solu- 
tion ;  which,  if  not  sour  to  the  taste, 
must  be  made  so  by  the  addition  of  fresh 
acid  ;  and  a  little  solution  of  prussiate  of 
potash  must  be  mixed  with  the  liquor.  If 
a  blue  precipitate  occur,  it  denotes  the 
presence  of  oxide  of  iron,  and  the  solu- 
tion of  the  prussiate  must  be  dropped  in, 
till  no  further  effect  is  produced.  To  as- 
certain its  quantity,  it  must  be  collected 
on  a  filter  in  the  same  manner  as  the  other 
solid  precipitates,  and  heated  red:  the, 
result  will  be  oxide  of  iron.  Into  the 
fluid  freed  from  oxide  of  iron  a  solution 
of  carbonate  of  potash  must  be  poured 
till  all  effervescence  ceases  in  it,  and  till 
its  taste  and  smell  indicate  a  considerable 
excess  of  alkaline  salt.  The  precipitate 
that  falls  down  is  carbonate  of  lime ;  which 
must  be  collected  on  a  filter,  dried  at  a 
heat  below  that  of  redness,  and  after- 
ward weighed.  The  remaining  fluid  must 
be  boiled  for  a  quarter  of  an  hour,  when 
the  magnesia,  if  there  be  any,  will  be  pre- 
cipitated combined  with  carbonic  acid, 
and  its  quantity  must  be  ascertained  in 
the  same  manner  as  that  of  the  carbonate 
of  lime.  If  any  minute  proportion  of  alu- 
mina should,  from  peculiar  circumstances, 
be  dissolved  by  the  acid,  it  will  be  found 
in  the  precipitate  with  the  carbonate  of 
lime,  and  it  may  be  separated  from  it  by 
boiling  for  a  few  minutes  with  soap  lye 
sufficient  to  cover  the  solid  matter:  for 
this  lye  dissolves  alumina,  without  acting 
upon  carbonate  of  lime.  Should  the  fine- 
ly divided  soil  be  sufficiently  calcareous  to 
effervesce  very  strongly  with  acids,  a  sim- 
ple method  of  ascertaining  the  quantity 
of  carbonate  of  lime,  sufficiently  accurate 
in  all  common  cases,  may  be  adopted.  As 
carbonate  of  lime  in  all  its  states  contains 
a  determinate  quantity  of  acid,  which  is 
about  45  parts  in  a  hundred  by  weighty 


ANA 


ANA 


the  quantity  of  this  acid  given  out  during 
the  effervescence  occasioned  by  its  solu- 
tion in  a  stronger  acid,  will  indicate  the 
quantity  of  carbonate  of  lime  present. 
Thus,  if  you  weigh  separately  one  part  of 
the  matter  of  the  soil,  and  two  parts  of 
the  acid  diluted  with  an  equal  quantity  of 
Avater,  and  mix  the  acid  slowly  in  small 
portions  with  the  soil,  till  it  ceases  to  oc- 
casion any  effervescence,  by  weighing  the 
mixture,  and  the  acid  that  remains,  you 
will  find  the  quantity  of  carbonic  acid 
lost ;  and  for  every  four  grains  and  half 
so  lost  you  will  estimate  ten  grains  of 
carbonate  of  lime.  You  may  also  Ofcllect 
the  carbonic  acid  in  the  pneumatic  appa- 
ratus for  ih?  analysis  of  soils,  described  in 
the  article  LAHOHATORY;  and  allow  for 
every  ounce  measure  of  the  carbonic  acid, 
t\vo  grains  of  carbonate  of  lime. 

7.  The  quantity  of  insoluble  animal  and 
vegetable  matter  may  next  be  ascertained 
with  sufficient  precision,  by  heating1  it  to 
a  strong  red  heat  in  a  crucible  over  a  com- 
mon fire,  till  no  blackness  remains  in  the 
mass,    stirring   it   frequently    meanwhile 
with  a  metallic  wire.     The  loss  of  weight 
\vill  ascertain   the  quantity  of  animal  and 
vegetable  matter  there  was,  but  not  the 
proportions  of  each.  If  the  smell  emitted, 
during   this    process,    resemble    that   of 
burnt  feathers,  it  is  a  certain  indication  of 
the  presence  of  some  animal  matter ;  and 
a  copious  blue  flame   almost  always  de- 
notes a  considerable   proportion  of  vege- 
table matter.     Nitrate  of  ammonia,  in  the 
proportion  of  twenty  grains  to  a  hundred 
of  the  residuum  of  the  soil,  will  greatly 
accelerate  this  process,  if  the  operator  be 
in  haste ;  and  not  affect  the  result,  as  it 
will  be  decomposed  and  evaporate. 

8.  What  remains  after  this  decomposi- 
tion of  the  vegetable  and  animal  matter, 
consists  generally  of  minute  particles  of 
earthy  matter,  which  are  usually  a  mixture 
of  alumina  and  silex  with  oxide  of  iron. 
To  separate  these,  boil  them  two  or  three 
hours  in  sulphuric  acid  diluted  with  four 
times  its  weight  of  water,  allowing  a  hun- 
dred and  twenty  grains  of  acid  for  every 
hundred  grains  of  the  residuum.     If  any 
thing  remain  undissolved  by  this  acid,  it 
may  be  considered  as  silex,  and  be  sepa- 
rated, washed,  dried,  and  weighed,  in  the 
usual  manner.     Carbonate  of  ammonia  be- 
ing added  to  the  solution  in  quantity  more 
than  sufficient  to  saturate   the  acid,  the 
alumina  will  be  precipitated;  and  the  ox- 
ide of  iron,  if  any,  may  be  separated  from 
the   remaining  liquid  by   boiling  it.     It 
scarcely  ever  happens,  that  any  magnesia 
or  lime  escapes  solution  in  the  muriatic 
acid;  but  if  it  should,  it  will  be  found  in 
the  sulphuric  acid;  from  which  it  maybe 
separated  as  directed  a'bove  for  the  muri- 
atic.   This  method  of  analysis  is  sufficient- 


ly precise  for  all  common  purposes :  but 
if  very  great  accuracy  be  an  object,  the 
residuum  after  the  incineration  must  be 
treated  with  potash,  and  in  the  manner  in 
which  stones  are  analyzed,  as  given  in  the 
first  part  of  this  article. 

9.  If  the  soil  contained  any  salts,  or 
soluble  vegetable   or  animal  matter,  they 
will  be  found  in  the  water  used  for  sepa- 
rating   the   sand.     This    water  must   be 
evaporated  to  dry  ness  at   a  heat  below 
boiling.     If  the  solid  matter  left  be  of  a 
brown  colour,  and  inflammable,  it  may  be 
considered  as  partly   vegetable  extract. 
If  its  smell,  when   exposed  to   heat,  be 
strong  and  fetid,  it  contains  animal  mu- 
cilaginous, or  gelatinous  matter.     If  it  be 
white  and  transparent,  it  may  be  consid- 
ered as  principally  saline.    Nitrate  of  pot- 
ash or  of  lime  is  indicated  in  this  saline 
matter  by  its  sparkling  when  thrown  on 
burning  coals:  sulphate  of  magnesia  may 
be  detected  by  its  bitter  taste  :    and  sul- 
phate of  potash  produces  no  alteration  in 
a  solution  of  carbonate  of  ammonia,  but 
precipitates  a  solution  of  muriate  of  ba- 
rytes. 

10.  If  sulphate  or  phosphate  of  lime  be 
suspected  in  the  soil,  a  particular  process 
is  requisite  to  detect  it.     A  given  weight 
of  the  entire  soil,  as  four  hundred  grains 
for   instance,  must  be  mixed   with   one 
third   as  much   powdered   charcoal,  and 
kept  at  a  red  heat  in  a  crucible  for  half 
an  hour.     The  mixture  must  then  be  boil- 
ed a  quarter  of  an  hour  in  half  a  pint  of 
water,  and  the   solution,  being   filtered, 
exposed  some  days  to  the  open  air.     ]f 
any  soluble  quantity  of  sulphate  of  lime, 
or  gypsum,    existed  in  the  soil,  a  white 
precipitate    will   gradually  form   in   the 
fluid,  and  the  weight  of  it  will  indicate 
the  proportion. 

Phosphate  of  lime,  if  any  be  present, 
may  be  separated  from  the  soil  after  the 
process  for  gypsum.  Muriatic  acid  must 
be  digested  upon  the  soil  in  quantity 
more  than  sufficient  to  saturate  the  solu- 
ble earths.  The  solution  must  be  eva- 
porated, and  water  poured  upon  the  solid 
matter.  This  fluid  will  dissolve  the  com- 
pounds of  earths  with  the  muriatic  acid, 
and  leave  the  phosphate  of  lime  un- 
touched. 

11.  When  the   examination  of  a  soil  is 
completed,  the  products  should  be  classed, 
and  their  quantities  added  together;  and 
if  they  nearly  equal  the  original  quantity 
of  soil,  the  analysis  may  be  considered  as 
accurate.     It  must  however  be  observed, 
that  when  phosphate  or  sulphate  of  lime 
is  discovered  by  the  independent  process, 
No.  10,  just  mentioned,  a  correction  must 
be  made  for  the  general  process,  by  sub- 
tracting a  sum  equal  to  their  weight  from 
the  quantity  of  carbonate  of  lime  obtain- 


ANA 


ANA 


Phosphate  of  lime, 


Amount  of  all  the  products, 
Loss, 


ed  by  precipitation  from  the  muriatic  acid. 
In  arranging  the  products,  the  form  should 
be  in  the  order  of  the  experiments  by 
which  they  are  obtained.  Thus  400  grains 
of  a  good  siliceous  sandy  soil  may  be  sup- 
posed to  contain,  grains. 
Of  water  of  absorption,  -  -  18 
Of  loose  stones  and  gravel  principal- 
ly siliceous,  ...  -  42 
Of  undecompounded  vegetable  fi- 
bres,   10 

Of  fine  siliceous  sand,          -        -        200 
Of  minutely  divided  matter,  separa- 
ted by"  filtration,  and  consisting 
of, 

Carbonate  of  lime,  -  25 

Carbonate  of  magnesia,        -        4 
Matter    destructible    by    heat, 

principally  vegetable,  -  10 
Silex,  ....  40 
Alumina,  ...  32 

Oxide  of  iron,  4 

Soluble  matter,  principally  sul- 
phate of  potash  and  vegeta- 
ble extract, 

.  3 

2 
—  125 

395 
5 

400 

Tn  this  instance  the  loss  is  supposed 
small ;  but  in  general,  in  actual  experi- 
ments, it  will  be  found  much  greater,  in 
consequence  of  the  difficulty  of  collecting 
the  whole  quantities  of  the  different  pre- 
cipitates; and  when  it  is  within  thirty  for 
four  hundred  grains,  there  is  no  reason  to 
suspect  any  want  of  due  precision  in  the 
processes. 

12.  When  the  experimenter  is  become 
acquainted  with  the  use  of  the  different 
instruments,  the  properties  of  the  re- 
agents, and  the  relations  between  the  ex- 
ternal and  chemical  qualities  of  soils,  he 
will  seldom  find  it  necessary  to  perform, 
in  any  one  case,  all  the  processes  that 
have  been  described.  When  his  soil,  for 
instance,  contains  no  notable  proportion 
of  calcareous  matter,  the  action  of  the 
muriatic  acid,  No.  6.  may  be  omitted:  in 
examining  peat  soils,  he  will  principally 
have  to  attend  to  the  operation  by  fire 
and  air,  No.  7. ;  and  in  the  analysis  of 
chalks  and  loams,  he  will  often  be  able 
to  omit  the  experiment  with  sulphuric 
acid,  No.  8. 

In  the  fn-st  trials  that  are  made  by  per- 
sons unacquainted  with  chemistry,  they 
must  not  expect  much  precision  of  result. 
Many  difficulties  will  be  met  with  ;  but  in 
overcoming  them  the  most  useful  kind  of 
practical  knowledge  will  be  obtained ; 
and  nothing  is  so  instructive  in  experimen- 


tal  science  as  the  detection  of  mistakes. 
The  correct  analyst  ought  to  be  well 
grounded  in  general  chemical  informa- 
tion ;  but  perhaps  there  is  no  better  mode 
of  gaining  it  than  that  of  attempting  origi- 
nal investigations.  In  pursuing  his  ex- 
periments, he  will  be  continually  obliged 
to  learn  from  books  the  history  of  the  sub- 
stances he  is  employing  or  acting  upon  ; 
and  his  theoretical  ideas  will  be  more  va- 
luable in  being  connected  with  practical 
operation,  and  acquired  for  the  purpose 
of  discovery. 

The  analysis  of  vegetables  requires  vari- 
ous manipulations,  and  peculiar  attention, 
as  their  principles  are  extremely  liable  to 
be  altered  by  the  processes  to  which  they 
are  subjected.  It  was  long  before  this 
analysis  was  brought  to  any  degree  of  per- 
fection. 

Some  of  the  immediate  materials  of 
vegetables  are  separated  to  our  hands  by 
Nature  in  a  state  of  greater  or  less  purity  ; 
as  the  gums,  resins,  and  balsams,  that  ex- 
ude from  plants.  The  expressed  juices 
contain  various  matters,  that  may  be  sepa- 
rated by  the  appropriate  reagents.  Mace- 
ration, infusion,  and  decoction  in  water, 
take  up  certain  part*  soluble  in  this  men- 
struum ;  and  alcohol  will  extract  others 
that  water  will  not  dissolve.  The  mode 
of  separating  and  distinguishing  these  ma- 
terials will  easily  be  collected  from  their 
characters,  as  given  under  the  head  VEGE- 
TABLE KINGDOM,  and  under  the  different 
articles  themselves. 

*  As  the  ultimate  constituents  of  all  ve- 
getable substances  are  carbon,  hydrogen, 
and  oxygen,  with  occasionally  azote,  the 
problem  of  their  final  analysis  resolves  into 
a  method  of  ascertaining  the  proportion  of 
these  elementary  bodies.  MM.  Gay-Lus- 
sac  and  Thenard  contrived  a  very  elegant 
apparatus  for  vegetable  and  animal  analy- 
sis, in  which  the  matter  in  a  dried  state 
was  mixed  with  chlorate  of  potash,  and 
formed  into  minute  pellets.  These  pel- 
lets being  projected  through  the  interven- 
tion of  a  stop-cock  of  peculiar  structure 
into  an  ignited  glass  tube,  were  instantly 
resolved  into  carbonic  acid  and  water. 
The  former  product  was  received  over 
mercury,  and  estimated  by  its  condensa- 
tion with  potash  ;  the  latter  was  intercep- 
ted by  ignited  muriate  of  lime,  and  was 
measured  by  the  increase  of  weight  which 
it  communicates  to  this  substance.  By 
previous  trials,  the  quantity  of  oxygen 
which  a  given  weight  of  the  chlorate  of 
potash  yielded  by  ignition  was  known  ; 
and  hence  the  carbon,  hydrogen,  and  oxy- 
gen, derived  from  the  organic  substance, 
as  well  as  the  residual  azote,  of  the  gase- 
ous products. 

M.  Berzelius  modified  the  above  appa- 
ratus, and  employed  the  organic  product 


ANA 


ANH 


jin  combination  with  a  base,  generally  ox- 
ide  of  lead.  He  mixed  a  certain  weight 
of  this  neutral  compound  with  a  known 
quantity  of  pure  chlorate  of  potash,  and 
triturated  the  whole  with  a  large  quantity 
of  muriate  of  soda,  for  the  purpose  of  mo- 
derating the  subsequent  combustion,  This 
mingled  dry  powder  is  put  into  a  glasstube 
about  half  an  inch  diameter,  and  eight  or 
ten  inches  long,  which  is  partially  enclosed 
in  a  fold  of  tin-plate,  hooped  with  iron 
wire.  One  end  of  the  tube  is  hermeti- 
cally sealed  beforehand,  the  other  is  now 
drawn  to  a  pretty  fine  point  by  the  blow- 
pipe. This  termination  is  inser»d  into 
a  glass  globe  about  an  inch  diameter, 
which  joins  it  to  a  long  tube  containing 
dry  muriate  of  lime  in  its  middle,  and  dip- 
ping at  its  other  extremity  into  the  mer- 
cury of  a  pneumatic  trough.  The  first 
tube,  with  its  protecting  tin  case,  being 
exposed  gradually  to  ignition,  the  enclo- 
sed materials  are  resolved  into  carbonic 
acid,  water,  and  azote,  which  come  over, 
and  are  estimated  as  above  described.  M. 
Gay-Lussac  has  more  recently  employed 
peroxide  of  copper  to  mix  with  the  or- 
ganic substance  to  be  analyzed  ;  because 
while  it  yields  its  oxygen  to  hydrogen  and 
carbon,  it  is  not  acted  on  by  azote  ;  and 
thus  the  errors  resulting  from  the  forma- 
tion of  nitric  acid  with  the  chlorate  of  pot- 
ash are  avoided.  Berzelius  has  afforded 
satisfactory  evidence  by  his  analyses,  that 
the  simple  apparatus  which  he  employed 
is  adequate  to  every  purpose  of  chemical 
research.  Dr.  Prout  has  described,  in  the 
Annals  of  Philosophy  for  March  1820,  a 
very  neat  form  of  apparatus  for  comple- 
ting analyses  of  organic  substances  with 
the  heat  of  a  lamp.  Hydrogen  having  the 
power  in  minute  quantities  of  modifying 
the  constitution  of  the  organic  bodies,  re- 
quires to  be  estimated  with  corresponding 
minuteness.  Mr.  Porrett  has  very  inge- 
niously suggested,  that  its  quantity  may 
be  more  accurately  determined  by  the 
proportion  of  oxide  of  copper  that  is  re- 
vived, than  by  the  product  of  water,  Di- 
lute sulphuric  acid  being  digested  on  the 
residual  cupreous  powder,  will  instantly 
dissolve  the  oxide,  and  leave  the  reduced 
metal;  whose  weight  will  indicate,  by  the 
scale  of  equivalents,  the  hydrogen  expen- 
ded in  its  reduction.  One  of  hydrogen 
corresponds  to  9  of  water,  and  32  of  cop- 
per. 

Under  the  different  vegetable  and  ani- 
mal products,  we  shall  take  care  to  state 
their  ultimate  constituents  by  the  most 
correct  and  recent  analyses.  The  pecu- 
liar substances  which  M  ater,  alcohol,  ether, 
and  other  solvents,  can  separate  from  an 
organic  body  may  be  called  the  immedi- 
ate products  of  the  vegetable  or  animal 
kingdom;  while  the  carbon,  hydrogen, 


oxygen,  and  azote,  discoverable  by  igne- 
ous analysis,  are  the  ultimate  constituent 
elements.  To  the  former  class  belong 
sugar,  gum,  starch,  oils,  resins,  gelatin, 
urea,  organic  acids  and  alkalis,  &c.  which 
see.* 

*  AXATASE.     Octohedrite,  oxide  of  tita- 
nium, rutile,  and  titane  rutile.     This  mi- 
neral shows  a  variety  of  colours  by  re- 
flected light,  from  indigo-blue  to  reddish- 
brown.     By  transmitted  light,  it  appears 
greenish-yellow.     It  is  found  usually  in 
small  crystals,  octohedrons,  with  isosceles 
triangular  faces.     Structure  lamellar;  it 
is  semi-transparent,  or  opaque  ;  fragments 
splendent,  adamantine;  scratches  glass; 
brittle  ;  sp.  gr.  3.85.    It  is  a  pure  oxide  of 
titanium.    It  has  been  found  only  in  Dau- 
phiny  and  Norway ;  and  is  a  very  rare  mi- 
neral.    It  occurs  in  granite,  gneiss,  mica 
slate,  and  transition  limestone.* 

*  AIH>ALU&ITE,    A  massive  mineral,  of 
a  flesh  and  sometimes  rose-red  colour.   It 
is,  however,  occasionally  crystallized  in 
rectangular  four-sided  prisms,  verging  on 
rhomboids,    The  structure  of  the  prising 
is  lamellar,  with  joints  parallel  to  their 
sides.     Translucent ;  scratches  quartz ;  is 
easily  broken;   sp.  gr.  3.165.     Infusible 
by  the  blow-pipe  ;  in  which  respect  it  dif- 
fers from  feldspar,  though  called  fdspath 
apyre  by  Haiiy.    It  is  composed  of  52  alu- 
mina, 32  silica,  8  potash,  2  oxide  of  iron, 
and  6  loss,  Vauq.    It  belongs  to  primi- 
tive countries,  and  was  first  found  in  An- 
dalusia in  Spain.     It  is  found  in  mica  slate 
in  Aberdeenshire,  and  in  the  Isle  of  Unst ; 
Dartmoor  in  Devonshire  ;  in  mica  slate  at 
Killiney,  near  Dublin,  and  at  Douce  Moun- 
tain, county  Wicklow.* 

*  ANDHEOLITE.     See  HARMOTOME.* 

*  ANHYDRITE.       Anhydrous    gypsum. 
There  are  six  varieties  of  it. — 

1.  Compact,  has  various  shades,  of  white, 
blue,  and  red ;  massive  and  kidney -sha- 
ped; dull  aspect;  splintery  or  conchoidal 
fracture  ;  translucent  on  the  edges ;  is 
scratched  by  fluor,  but  scratches  calc 
spar  ;  somewhat  tough  ;  specific  gravity 
2.850.  It  is  dry  sulphate  of  lime,  with  a 
trace  of  sea  salt.  It  is  found  in  the  salt 
mines  of  Austria  and  Salzburg,  and  at  the 
foot  of  the  Harz  mountains.  2.  Granular, 
the  scaly  of  Jameson.  Is  found  in  mas- 
sive concretions,  of  which  the  structure  is 
confusedly  foliated.  White  or  bluish  co- 
lour, of  a  pearly  lustre ;  composition  as 
above,  with  pne  per  cent,  of  sea  salt.  It 
occurs  in  the  salt  mines  of  Halle  ;  sp.  gr. 
2.957.  3.  Fibrous.  Massive  ;  glimmer- 
ing, pearly  lustre ;  fracture  in  delicate 
parallel  fibres  ;  scarcely  translucent ;  easi- 
ly broken.  Found  at  Halle,  Ischel,  and 
near  Brunswick.  4.  Radiated.  Blue,  some- 
times spotted  with  red ;  radiated,  splen- 
dent fracture  ;  partly  splintery  ;  translu- 


ANI 


ANI 


cent;  not  hard;  sp.  gr.  2.940.  5.  Spar- 
ry, or  cube  spar.  Milk-white  colour,  pas- 
sing sometimes  into  grayish  and  reddish 
white;  short  four-sided  prisms,  having 
two  of  the  opposite  sides  much  broader 
than  the  other  two  ;  and  occasionally  the 
lateral  edges  are  truncated,  whence  re- 
sults an  eight-sided  prism  ;  lustre,  splen- 
dent, pearly.  Foliated  fracture.  Three- 
fold rectangular  cleavage.  Cubical  frag- 
ments. Translucent.  Scratches  calc  spar. 
Brittle.  Sp.  gr.  2  9.  This  is  the  muria- 
•ite  of  some  writers,  it  is  doubly  re- 
fracting. It  is  said  to  contain  one  per  cent, 
of  sea  salt,  it  is  found  at  Bex  in  Switzer- 
land, and  Halle  in  the  Tyrol.  6.  Silicife- 
pous,  or  vulpinite.  Massive  concretions 
of  a  laminated  structure,  translucent  on 
the  edges,  splendent,  and  brittle.  Gray- 
ish-white, veined  with  bluish-gray.  Sp. 
gr.  2.88.  It  contains  eight  per  cent,  silex. 
The  rest  is  sulphate  of  lime.  It  is  called 
by  statuaries,  Marino  bardiglio  di  Berga- 
mo, and  takes  a  fine  polish.  It  derives 
its  name  from  Vulpino  in  Italy,  where  it 
accompanies  lime.* 

ANIL,  or  NIL  This  plant,  from  the 
leaves  of  which  indigo  is  prepared,  grows 
in  America. 

ANIMAL  KINGDOM.  The  various  bodies 
around  us,  which  form  the  objects  of  che- 
mical research,  have  all  undergone  a  num- 
ber of  combinations  and  decompositions 
before  we  take  them  in  hand  for  exami- 
nation. These  are  all  consequences  of 
the  same  attractions  or  specific  proper- 
ties that  we  avail  ourselves  of;  and  are 
modified  likewise  by  virtue  of  the  situa- 
tions and  temperatures  of  the  bodies  pre- 
sented to  each  other.  In  the  great  mass 
of  unorganized  matter,  the  combinations 
appear  to  be  much  more  simple  than  such 
as  take  place  in  the  vessels  of  organized 
beings,  namely,  plants  and  animals  :  in 
the  former  of  which  there  is  not  any  pecu- 
liar structure  of  tubes  conveying  various 
fluids;  and  in  the  latter  there  is  not  only 
an  elaborate  system  of  vessels,  but  like- 
Avise,  for  the  most  part,  an  augmentation 
of  temperature.  From  such  causes  as 
these  it  is,  that  some  of  the  substances 
afforded  by  animal  bodies  are  never  found 
either  in  vegetables  or  minerals;  and  so 
likewise  in  vegetables  are  found  certain 
products  never  unequivocally  met  with 
among  minerals.  Hence,  among  the  sys- 
tematical arrangements  used  by  chemists, 
the  most  general  is  that  which  divides 
bodies  into  three  kingdoms,  the  animal, 
the  vegetable,  and  the  mineral. 

Animal,  as  well  as  vegetable  bodies, 
may  be  considered  as  peculiar  apparatus 
for  carrying  on  a  determinate  series  of 
chemical  operations.  Vegetables  seem 
capable  of  operating  with  fluids  only,  and 
at  the  temperature  of  the  atmosphere,  as 


we  have  just  noticed.  But  most  animals 
have  a  provision  for  mechanically  divi- 
ding solids  by  mastication,  which  answers 
the  same  purpose  as  grinding,  pounding, 
or  levigation,  does  in  our  experiments; 
that  is  to  say,  it  enlarges  the  quantity  of 
surface  to  be  acted  upon  by  solvents. 
The  process  carried  on  in  the  stomach  ap- 
pears to  be  of  the  same  kind  as  that  which 
we  distinguish  by  the  name  of  digestion ; 
and  the  bowels,  whatever  other  uses  they 
may  serve,  evidently  form  an  apparatus 
for  filtering  or  conveying  off  the  fluids ; 
while  the  more  solid  parts  of  the  aliments, 
which  are  probably  of  such  a  nature  as  not 
to  be  rendered  fluid,  but  by  an  alteration 
which  would  perhaps  destroy  the  texture 
of  the  machine  itself,  are  rejected  as  use- 
less. When  this  filtered  fluid  passes  into 
the  circulatory  vessels,  through  which  it 
is  driven  with  considerable  velocity  by 
the  mechanical  action  of  the  heart,  it  is 
subjected,  not  only  to  all  those  changes 
which  the  chemical  action  of  its  parts  is 
capable  of  producing,  but  is  likewise  ex- 
posed to  the  air  of  the  atmosphere  in  the 
lungs,  into  which  that  elastic  fluid  is  ad- 
mitted by  the  act  of  respiration.  Here  it 
undergoes  a  change  of  the  same  nature 
as  happens  to  other  combustible  bodies 
when  they  combine  with  its  vital  part,  or 
oxygen.  This  vital  part  becomes  con- 
densed, and  combines  with  the  blood,  at 
the  same  time  that  it  gives  out  a  large 
quantity  of  heat,  in  consequence  of  its 
own  capacity  for  heat  being  diminished. 
A  small  portion  of  azote  likewise  is  ab- 
sorbed, and  carbonic  acid  is  given  out. 
Some  curious  experiments  of  Spallanza- 
ni  show,  that  the  lungs  are  not  the  sole 
organs  by  which  these  changes  are  ef- 
fected. Worms,  insects,  shells  of  land 
and  sea  animals,  egg  shells,  fishes,  dead 
animals,  and  parts  of  animals,  even  after 
they  have  become  putrid,  are  capable  of 
absorbing  oxygen  from  the  air,  and  giving 
out  carbonic  acid.  They  deprive  atmos- 
pheric air  of  its  oxygen  as  completely  as 
phosphorus.  Shells,  however,  lose  this 
property  when  their  organization  is  de- 
stroyed by  age.  Amphibia,  deprived  of 
their  lungs,  lived  much  longer  in  the  opea 
air,  than  others  in  air  destitute  of  oxygen. 
It  is  remarkable,  that  a  larva,  weighing  a 
few  grains,  would  consume  almost  asmuck 
oxygen  in  a  given  time  as  one  of  the  am- 
phibia a  thousand  times  its  bulk.  Fishes, 
alive  and  dead,  animals,  and  parts  of  ani- 
mals, confined  under  water  in  jars,  ab- 
sorbed the  oxygen  of  the  atmospheric  air 
over  the  water.  Muscles,  tendons,  bones, 
brain,  fat,  and  blood,  all  absorbed  oxygen 
in  different  proportions;  but  the  blood  did 
not  absorb  most,  and  bile  appeared  not 
to  absorb  any. 
It  would  lead  us  too  far  from  our  pur- 


ANI 


ANI 


pose,  if  we  were  to  attempt  an  explana- 
tion of  the  little  we  know  respecting1  the 
manner  in  which  the  secretions  or  combi- 
nations that  produce  the  various  animal 
and  vegetable  substances  are  effected, 
or  the  uses  of  those  substances  in  the 
economy  of  plants  and  animals.  Most  of 
them  are  very  different  from  any  of  the 
products  of  the  mineral  kingdom.  We 
shall  therefore  only  add,  that  these  or- 
ganized being's  are  so  contrived,  that  their 
existence  continues,  and  all  their  func- 
tions are  performed,  as  long1  as  the  ves- 
sels are  supplied  with  food  or  materials  to 
occupy  the  place  of  such  as  are  cSrried 
off  by  evaporation  from  the  surface,  or 
otherwise ;  and  as  long-  as  no  great  change 
is  made,  either  by  violence  or  disease,  in 
those  vessels,  or  the  fluids  they  contain. 
But  as  soon  as  the  entire  process  is  inter- 
rupted in  any  very  considerable  degree, 
the  chemical  arrangements  become  alter- 
ed; the  temperature  in  land  animals  is 
changed ;  the  minute  vessels  are  acted 
upon  and  destroyed  ;  life  ceases,  and  the 
admirable  structure,  being  no  longer  suf- 
ficiently perfect,  loses  its  figure,  and  re- 
turns, by  new  combinations  and  decom- 
positions, to  the  general  mass  of  unorgani- 
zed matter,  with  a  rapidity  which  is  usual- 
ly greater,  the  more  elaborate  its  construc- 
tion. 

-j-  Within  the  sphere  of  vitality,  peculiar 
laws  of  decomposition  and  recomposition 
seem  to  prevail,  in  like  manner  as  within 
the  sphere  of  the  voltaic  circuit.  Indeed 
each  gland  seems  to  have  a  capacity  to 
induce  peculiar  corpuscular  reactions, 
giving  rise  to  its  appropriate  secretions. 
In  the  living  stomach,  food  passes  to  the 
state  of  chyme  ;  when  in  the  absence  of 
life,  the  same  matter,  at  the  same  tempera- 
ture, would  putrefy  .f 

The  parts  of  vegetable  or  animal  sub- 
Stances  may  be  obtained,  for  chemical 
examination,  either  by  simple  pres- 
sure, which  empties  the  vessels  of  their 
contents;  by  digestion  in  water,  or  in 
other  fluids,  which  dissolve  certain  parts, 
and  often  change  their  nature;  by  destruc- 
tive distillation,  in  which  the  application 
of  a  strong  heat  alters  the  combination  of 
the  parts,  and  causes  the  new  products  to 
pass  over  into  the  receiver  in  the  order  of 
their  volatility;  by  spontaneous  decom- 
position or  fermentation,  wherein  the 
component  parts  take  a  new  arrangement, 
and  form  compounds  which  did  not  for 
the  most  part  exist  in  the  organized  sub- 
stance; or,  lastly,  the  judicious  chemist 
will  avail  himself  of  all  these  several 
methods  singly,  or  in  combination.  He 
will,  according  to  circumstances,  separate 
the  parts  of  an  animal  or  vegetable  sub- 
stance by  pressure,  assisted  by  heat;  or 
by  digestion  or  boiling-  in  various  fluids, 


added  in  the  retort  which  contains  the 
substance  under  examination.  He  will 
attend  particularly  to  the  products  which 
pass  over,  whether  they  be  permanently 
elastic,  or  subject  to  condensation  in  the 
temperatures  we  are  able  to  produce.  In 
some  cases,  he  will  suffer  the  spontaneous 
decomposition  to  precede  the  application 
of  chemical  methods ;  and  in  others,  he 
will  attentively  mark  the  changes  which 
the  products  of  his  operations  undergo  in 
the  course  of  time,  whether  in  closed  ves- 
sels, or  exposed  to  the  open  air.  Thus 
it  is,  that,  in  surveying  the  ample  field  of 
nature,  the  philosophical  chemist  posses- 
ses numerous  means  of  making  discove- 
ries, if  applied  with  judgment  and  sagaci- 
ty ;  though  the  progress  of  discovery,  so 
far  from  bringing  us  nearer  the  end  of  our 
pursuit,  appears  continually  to  open  new 
scenes;  and,  by  enlarging  our  powers  of 
investigation,  never  fails  to  point  out  ad- 
ditional objects  of  enquiry. 

Animal  and  vegetable  substances  ap- 
proach each  other  by  insensible  grada- 
tions ;  so  that  there  is  no  simple  product 
of  the  one  which  may  not  be  found  in 
greater  or  less  quantity  in  the  other.  The 
most  general  distinctive  character  of  ani- 
mal substances  is  that  of  affording  volatile 
alkali  by  destructive  distillation.  Some 
plants,  however,  afford  it  likewise.  Nei- 
ther contain  it  ready  formed ;  but  it  ap- 
pears to  be  produced  by  the  combination 
of  hydrogen  and  azote,  during  the  changes 
produced  either  by  fire,  or  the  putrefac- 
tive process.  See  AIIMIONIA. 

Our  knowledge  of  the  products  of  the 
animal  kingdom,  by  the  help  of  chemical 
analysis,  is  not  yet  sufficiently  matured  to 
enable  us  to  arrange  them  according  to 
the  nature  of  their  component  parts, 
which  appear  to  consist  chiefly  of  hydro- 
gen, oxygen,  carbon,  and  azote ;  and  with 
these,  sulphur,  phosphorus,  lime,  magne- 
sia, and  soda,  are  frequently  combined  in 
variable  proportions. 

*  The  following  are  the  peculiar  chem- 
ical products  of  animal  organization.  Ge- 
latin, albumen,  fibrin,  caseous  matter,  co- 
louring matter  of  blood,  mucus,  urea,  pi- 
cromel,  osmazome,  sugar  of  milk,  and 
sugar  of  diabetes.  The  compound  animal 
products  are  the  various  solids  and  fluids, 
whether  healthy  or  morbid,  that  are  found 
in  the  animal  body;  such  as  muscle,  skin, 
bone,  blood,  urine,  bile,  morbid  concre- 
tions, brain,  &c.* 

When  animal  substances  are  left  expo- 
sed to  the  air,  or  immersed  in  water  or 
other  fluids,  they  suffer  a  spontaneous 
change,  which  is  more  or  less  rapid  ac- 
cording to  circumstances.  The  sponta- 
neous change  of  organized  bodies  is  dis- 
tinguished by  the  name  of  fermentation. 
In  vegetable  bodies  there  are  distinct  sla- 


ANN 


ANN 


ges  or  periods  of  this  process,  which  have 
been  divided  into  the  vinous,  acetous,  and 
putrefactive  fermentations.  Animal  sub- 
stances are  susceptible  only  of  the  two 
latter,  during  which,  as  in  all  other  spon- 
taneous changes,  the  combinations  of 
chemical  principles  become  in  general 
more  and  more  simple.  There  is  no  doubt 
but  much  instruction  might  be  obtained 
from  accurate  observations  of  the  putre- 
factive processes  in  all  their  several  va- 
rieties and  situations ;  but  the  loathsome- 
ness and  danger  attending  on  such  enqui- 
ries have  hitherto  greatly  retarded  our 
progress  in  this  department  of  chemical 
science.  See  FERMENTATION  (PUTREFAC- 
TIVE). 

ANITCE,  improperly  called  gum  anime,  is 
ft  resinous  substance  imported  from  New 
Spain  and  the  Brazils.  There  are  two 
kinds,  distinguished  by  the  names  of  ori- 
ental and  occidental.  The  former  is  dry, 
and  of  an  uncertain  colour,  some  speci- 
mens being  greenish,  some  reddish,  and 
some  of  the  brown  colour  of  myrrh.  The 
latter  is  in  yellowish,  white,  transparent, 
somewhat  unctuous  tears,  and  partly  in 
larger  masses,  brittle,  of  a  light  pleasant 
taste,  easily  melting  in  the  fire,  and  burn- 
ing with  an  agreeable  smell.  Like  resins, 
it  is  totally  soluble  in  alcohol,  and  also  in 
oil.  Water  takes  up  about  l-16th  of  the 
weight  of  this  resin  by  decoction.  The 
spirit,  drawn  off'  by  distillation,  has  a  con- 
siderable degree  of  the  taste  and  flavour 
of  the  anime  ;  the  distilled  water  discovers 
on  its  surface  some  small  portion  of  essen- 
tial oil. 

This  resin  is  used  by  perfumers,  and 
also  in  certain  plasters,  wherein  it  has 
been  supposed  to  be  of  service  in  nervous 
affections  of  the  head  and  other  parts;  but 
there  are  no  reasons  to  think  that,  for 
medical  purposes,  it  differs  from  common 
resins. 

ANNEAL.  We  know  too  little  of  the 
arrangement  of  particles,  to  determine 
what  it  is  that  constitutes  or  produces 
brittleness  in  any  substance.  In  a  consid- 
erable number  of  instances  of  bodies 
which  are  capable  of  undergoing  ignition, 
it  is  found  that  sudden  cooling  renders 
them  hard  and  brittle.  This  is  a  real  in- 
convenience in  glass,  and  also  in  steel, 
when  this  metallic  substance  is  required 
to  be  soft  and  flexible.  The  inconve- 
niences are  avoided  by  cooling  them  very 
gradually,  and  this  process  is  called  an- 
nealing. Glass  vessels,  or  other  articles, 
are  carried  into  an  oven  or  apartment 
near  the  great  furnace,  called  the  leer, 
Where  they  are  permitted  to  cool,  in  a 
greater  or  less  time,  according  to  their 
thickness  and  bulk.  The  annealing  of 
steel,  or  other  metallic  bodies,  consists 
simply  in  heating1  them,  and  suffering 


them  to  cool  again  either  upon  the  hearth 
of  the  furnace,  or  in  any  other  situation 
where  the  heat  is  moderate,  or  at  least  the 
temperature  is  not  very  cold. 

f  Malleability,  ductility  and  toughness, 
in  substances  susceptible  of  the  annealing 
process,  are  probably  dependent  on  the 
quantity  of  caloric  remaining  in  combina- 
tion with  their  particles,  while  in  the  solid 
state.  When  malleable  metals  are  ham- 
mered, they  give  out  heat  and  become 
harder,  more  rigid  and  more  dense,  until 
a  certain  maximum  is  attained.  After- 
wards they  neither  heat  nor  harden,  and 
crush  to  pieces,  if  the  process  be  not 
suspended.  Exposed  to  the  fire  until 
softened.,  on  cooling  they  are  found  to 
have  regained  the  properties  of  which 
percussion  had  deprived  them  ;  and  they 
may  be  again  hammered,  heated,  harden- 
ed, and  condensed.  The  sudden  abstrac- 
tion of  caloric  from  the  exterior  strata  of 
particles  in  a  piece  of  thick  glass,  is  not 
attended  by  a  corresponding  abstraction 
of  this  principle  from  among  the  particles 
within,  owing  to  the  slowness,  with  which 
glass  conducts  heat.  Hence  cohesion  is 
not  general ;  and  the  particles  are  not  ar- 
ranged uniformly,  unless  the  cooling  be 
very  slow,  so  as  to  allow  the  refrigera- 
tion, within  and  without,  to  be  nearly  si- 
multaneous. As  it  never  can  be  perfectly 
simultaneous  in  thick  glass,  it  is  never 
perfectly  well  annealed.  The  process 
would  be  more  perfect,  were  the  articles 
subjected  to  radiant  heat  only ;  as  this, 
when  projected  from  red-hot  surfaces, 
penetrates  through  glass,  as  I  have  ascer- 
tained. By  gradually  making  up  fires  of 
charcoal  at  about  4  inches  distance  on 
each  side  of  a  glass  tube  of  about  an  inch 
and  a  quarter  in  thickness,  and  with  a 
very  small  bore,  I  was  enabled  to  heat 
and  bend  it.  From  its  situation,  it  was 
only  subjected  to  radiant  heat.j- 

ANNOTTO.  The  pellicles  of  the  seeds 
of  the  bixa  orellana,  a  liliaceous  shrub, 
from  15  to  20  feet  high  in  good  ground, 
affbrr|  the  red  masses  brought  into  Eu- 
rope, under  the  name  of  Annotto,  Orlean, 
and  Koucou. 

The  annotto  commonly  met  with  among 
us  is  moderately  hard,  of  a  brown  colour 
on  the  outside,  and  a  dull  red  within.  It 
is  difficultly  acted  upon  by  water,  and  tin- 
ges the  liquor  only  of  a  pale  brownish 
yellow  colour.  In  rectified  spirit  of  wine 
it  very  readily  dissolves,  and  communi- 
cates a  high  orange  or  yellowish-red. 
Hence  it  is  used  as  an  ingredient  in  var- 
nishes, for  giving  more  or  less  of  an 
orange  cast  to  the  simple  yellows.  Alka- 
line salt  renders  it  perfectly  soluble  in 
boiling  water,  without  altering  its  colour. 

Besides  its  use  in  dyeing,  it  is  employed 
for  colouring-  cheese. 


ANT 


ANT 


*  AirrflopHTLLiTE.  A  massive  mineral 
•fa  brownish  colour ;  sometimes  also  crys- 
tallized,   in  thin  flat    six-sided    prisms, 
streaked  lengthwise.    It  has  a  false  metal- 
lic lustre,  glistening1  and  pearly.     In  crys- 
tals, transparent.     Massive,  only  translu- 
cent on  the  edges.    It  does  not  scratch 
glass,  but  fluate  of  lime.     Specific   grav- 
ity 3.2.     Somewhat  hard  but  exceeding- 
ly brittle.      Infusible  alone  before  the 
blow-pipe,  but  with  borax  it  gives  a  grass- 
green  transparent  bead.      It  consists  of 
56  silica,  13.3  alumina,  14  magnesia,  3.33 
lime,  6  oxide  of  iron,  3  oxide  of  manganese, 
1.43  water,  and  2.94  loss  in  100.  It  isffound 
Konigsberg  in  Norway.* 

*  AN  f  HUACITE.    Blind  coal,    Kilkenny 
eoal,  or  glance-coal.     There  are  three  va- 
rieties.    1.  Massive,  the  conchoidal  of  Ja- 
meson.   Its  colour  is  iron-black,    some- 
times tarnished  on  the  surface,   with  a 
splendent  metallic  lustre.     Fracture  con- 
ehoidal,    with    a  pseudo-metallic   lustre. 
It  is  brittle  and  light.     It  yields  no  flame, 
and  leaves   whitish  ashes.     It  is  found  in 
the  newest  floetz  formations,  at  Meissner 
in  Hesse,  aod  Walsall  in  Staffordshire.     2. 
Slatv  anthracite.    Colour  black,  or  bro  wn- 
jsh -black.     Imperfect  slaty  in  one  direc- 
tion, with  a  slight  metallic  lustre.     Brittle. 
Specific  gravity   1.4  to   1.8.     Consumes 
without  flame.     It  is  composed  of  72  car- 
bon, 13  silica,  3.3  alumina,  and  3. 5  oxide  of 
iron.    It  is  found  in  both  primitive  and  se- 
condary rocks  ;  at  Calton  Hill,  Edinburgh ; 
near  Walsall  Staffordshire  ;  in  the  south- 
ern parts  of  Brecknockshire,  Carmarthen- 
shire, and  Pembrokeshire,   whence   it   is 
called  Welsh  culm ;  near  Cumnock,  and 
Kilmarnock,    Ayrshire ;   and  most  abun- 
dantly at  Kilkenny,  Ireland.     3.  Colum- 
nar anthracite.      In  small  short   prisma- 
tic concretions,   of  an  iron-black    colour 
with  a  tarnished  metalliclustre.  It  isbrittle, 
soft,  and  light.  It  yields  no  flame  or  smoke. 
It  forms  a  thick  bed  near   Sanquhar,  in 
Dumfries-shire ;    at    Saltcoats  and    New 
Cumnock,  in  Ayrshire.     It  occurs  also  at 
Meissner  in  Hesse.*  ,  p 

AWTIMOXV.  The  word  antimo  is  al- 
ways used  in  commerce  to  denote  a  metal- 
lic ore,  consisting  of  sulphur  combined 
with  the  metal,  which  is  properly  called 
antimony.  Sometimes  this  sulphuret  is 
termed  crude  antimony,  to  distinguish  it 
from  the  pure  metal,  or  regulus,  as  it  was 
formerly  called.  According  to  Professor 
Proust,  the  sulphuret  contains  26  per  cent 
of  sulphur.  lie  heated  100  parts  of  anti- 
mony with  an  equal  weight  of  sulphur  in 
a  glass  retort,  till  the  whole  was  well  fu- 
sed and  the  excess  of  sulphur  expelled, 
and  the  sulphuret  remaining  was  135. 
The  result  was  the  same  after  repeated 
trials :  100  parts  of  antimony,  with  300 
of  red  sulphuret  of  mercury,  afforded  135 


to  1S6  of  sulphuret.  These  artificial  sulpim- 
rets  lost  nothing  by  being  kept  in  fusion 
an  hour ;  and  heated  with  an  equal  weight 
of  sulphur,  they  could  not  be  made  to 
take  up  more.  Some  of  the  native  sulphu- 
rets  of  the  shops,  however,  appear  to 
have  a  small  portion  more  of  sulphur  uni- 
ted with  them,  as  they  will  take  up  an  ad- 
dition of  7  or  8  per  cent  of  antimony. 

Antimony  is  of  a  dusky  white  colour, 
very  brittle,  and  of  a  plated  or  scaly  tex- 
ture. Its  specific  gravity,  according  to 
Brisson,  is  6.7021,  but  Bergmann  makes 
it  6.86.  Soon  after  ignition  it  melts,  and 
by  a  continuance  of  the  heat  it  becomes 
oxidized,  and  rises  in  white  fumes,  which 
may  afterwards  be  volatilized  a  second 
time,  or  fused  into  a  hyacinthine  glass,  ac- 
cording to  the  management  of  the  heat: 
the  first  were  formerly  called  argentine 
flowers  of  regulus  of  antimony.  In  closed 
vessels  the  antimony  rises  totally  without 
decomposition.  This  metallic  substance 
is  not  subject  to  rust  by  exposure  to  air, 
though  its  surface  becomes  tarnished  by 
that  means  Its  oxides  are  a  little  soluble 
in  water;  and  in  this  respect  they  resem- 
ble the  oxide  of  arsenic,  by  an  approach 
toward  the  acid  state. 

*  There  are  certainly  three,  probably 
four,  distinct  combinations  of  antimony 
and  oxygen:  1.  The  protoxide  of  Berze- 
lius  is  a  blackish-gray  powder,  obtained 
from  a  mixture  of  powder  of  antimony  and 
water,  at  the  positive  pole  of  a  voltaic  cir- 
cuit. Heat  enables  this  oxide  to  absorb 
oxygen  rapidly,  converting  it  into  the  tri- 
toxide.  According  to  Berzelius,  it  con- 
sists of  100  of  metal,  and  4.65  oxygen.  It 
must  be  confessed,  however,  that  the  data 
for  fixing  these  proportions  are  very 
doubtful.  2.  The  deutoxide  may  be  ob- 
tained by  digesting  the  metal  in  powder 
in  muriatic  acid,  and  pouring  the  solution 
into  water  of  potash.  Wash  and  dry  the 
precipitate.  It  is  a  powder  of  a  dirty  white 
colour,  which  melts  at  a  moderate  red 
heat,  and  crystallizes  as  it  cools.  Accord- 
ing to  Berzelius,  it  consists  of  84.3  metal 
-j-  15.7  oxygen.  3.  The  tritoxide,  or  an- 
timonious  acid,  is  the  immediate  product 
of  the  combustion  of  the  metal,  called  of 
old  from  its  fine  white  colour,  the  argen- 
tine flowers  of  antimony.  It  may  also  be 
formed  by  digesting  hot  nitric  acid  on  an- 
timony. When  fused  with  one-fourth  of 
antimony,  the  whole  becomes  deutoxide. 
It  forms  the  salts  called  antimonites  with 
the  different  bases.  According  to  Berze- 
lius, the  tritoxide  consists  of  about  80  me- 
tal -f  20  oxygen.  4.  The  peroxide,  or 
antimonic  acid,  is  formed,  when  the  metal 
in  powder  is  ignited  along  with  six  times 
its  weight  of  nitre  in  a  silver  crucible. 
The  excess  of  potash  and  nitre  being  af- 
terwards separated  by  hot  water,  the  and- 


ANT 


ANT 


moniatc  of  potash  is  then  to  be  decomposed 
by  muriatic  acid,  when  the  insoluble  anti- 
monic  acid  of  a  straw  colour  will  be  ob- 
tained. Nitro-muriatic  acid  likewise  con- 
verts the  metal  into  the  peroxide.  Though 
insoluble  in  water,  it  reddens  the  vegeta- 
ble blues.  It  does  not  combine  with  acids. 
At  a  red  heat  oxygen  is  disengaged,  and 
antimonions  acid  results.  Berzelius  infers 
its  composition  to  be  73.5  metal  +  26.5 
oxygen.  It  is  difficult  to  reconcile  the 
above  three  portions  of  oxygen  to  one 
prime  equivalent  for  antimony.  The  num- 
ber 11.  gives  the  best  approximation  to  Ber- 
zelius's  analyses.  We  shall  then  have  the 

In  100  parts. 
Protoxide  Ilffietal4-loxy.or91.f4-  3.* 

Deutoxide  11  +  2  84.6+15.4 

Tritoxide   11  -j-  3  7U6+21.4 

Peroxide    11  +4  73.4+26.6. 

The  second  and  fourth  numbers  agree 
perfectly  with  experiment ;  the  first  ox- 
ide is  too  imperfectly  known  to  enter  into 
the  argument ;  and  the  third  number, 
though  it  indicates  a  little  more  oxyg'en 
than  Berzclius  assigns,  gives  less  than 
Proust. 

Chlorine  gas  and  antimony  combine 
with  combustion,  and  a  bichloride  results. 
This  was  formerly  prepared  by  distilling 
a  mixture  of  two  parts  of  corrosive  subli- 
mate with  one  of  antimony.  The  sub- 
stance which  came  over  having  a  fatty 
consistence,  was  called  butter  of  antimony. 
It  is  frequently  crystallized  in  four-sided 
prisms.  It  is  fusible  and  volatile  at  a  mo- 
derate heat ;  and  is  resolved  by  water 
alone  into  the  white  oxide  and  muriatic 
acid.  Being  a  bichloride,  it  is  eminently 
corrosive,  like  the  bichloride  of  mercury, 
from  which  it  is  formed.  It  consists  of  45.7 
chlorine  +  54.3  antimony,  according  to 
Dr.  John  Davy's  analysis,  when  the  com- 
position of  the  sulphuret  is  corrected  by 
its  recent  exact  analysis  by  Berzelius.  But 
11.  antimony  +  2  primes  chlorine  =  9.0, 
give  the  proportion  per  cent  of  44.1  + 
55.5;  a  good  coincidence,  if  we  consider 
the  circuitous  process  by  which  Dr.  Da- 
vy's analysis  was  performed.  Three 


analysts  have  found  30,  33,  and  35  to  100 
of  metal.  Berzelius  admits  that  there  may 
be  a  slight  error  in  his  numbers.  The  on- 
ly important  alloys  of  antimony  are  those 
of  lead  and  tin ;  the  former  constitutes 
type  metal,  and  contains  about  one-six- 
teenth of  antimony ;  the  latter  alloy  is  em- 
ployed for  making  the  plates  on  which 
music  is  engraved. 

The  salts  of  antimony  are  of  two  diffe- 
rent orders;  in  the  first,  the  deutoxide 
acts  the  part  of  a  salifiable  base ;  in  the 
second,  the  tritoxide  and  peroxide,  act 
the  part  of  acids,  neutralizing  the  alkaline 
and  other  bases,  to  constitute  the  antimo- 
nites  and  antimoniates. 

The  only  distinct  combination  of  the 
first  order  entitled  to  our  attention,  is  the 
triple  salt  called  tartrate  of  potash  and  an- 
timony, or  tartar  emetic,  and  which,  by 
M.  Gay-Lussac's  new  views,  would  be 
styled  cream-tartrate  of  antimony.  This 
constitutes  a  valuable  and  powerful  medi- 
cine, and  therefore  the  mode  of  preparing 
it  should  be  correctly  and  clearly  defined. 
As  the  dull  white  deutoxide  of  antimony 
is  the  true  basis  of  this  compound  salt, 
and  as  that  oxide  readily  passes  by  mis- 
management into  the  tritoxide  or  antimo- 
nious  acid,  which  is  altogether  unfit  for 
the  purpose,  adequate  pains  should  be 
taken  to  guard  against  so  capital  an  error. 
In  former  editions  of  the  British  Pharma- 
copoeias, the  glass  of  antimony  was  pre- 
scribed as  the  basis  of  tartar  emetic.  More 
complex  and  precarious  formulae  have 
been  since  introduced.  The  new  edition 
of  the  Pharmacopce  Francaise  has  given 
a  recipe,  which  appeal's,  with  a  slight 
change  of  proportions,  to  be  unexception- 
able. Take  of  the  sulphuretted  vitreous 
oxide  of  antimony  levigated,  and  acidulous 
tartrate  of  potash,  equal  parts.  Form  a 
powder,  which  is  to  be  put  into  an  earthen 
or  silver  vessel,  with  a  sufficient  quantity 
of  pure  water.  Boil  the  mixture  for  half 
an  hour,  adding  boiling  water  from  time 
to  time  ;  filter  the  hot  liquor,  and  evapo- 
rate to  dryness  in  a  porcelain  capsule; 
dissolve  in  boiling  water  the  result  of  the 
evaporation,  evaporate  till  the  solution  ac- 
quires the  spec.  grav.  1.161,  and  then  let 


parts  of  corrosive  sublimate,  and  one  of    it  repose,  that  crystals  be  obtained,  which, 

.i_ii'          ._i- •       i  V»v  this  nrnrpss      \vi11  hp  rmrf      "Kv  «jnntli#»i- 


metallic  antimony,  are  the  equivalent 
proportions  for  making  butter  of  antimo- 
ny. Iodine  and  antimony  combine  by 
the  aid  of  heat  into  a  solid  iodide,  of  a 
dark-red  colour.  The  phosphuret  of  this 
metal  is  obtained  by  fusing  it  with  solid 
phosphoric  acid.  It  is  a  white  semi-crys- 
talline substance.  The  sulphuret  of  anti- 
mony exists  abundantly  in  nature.  See 
OIIKS  of  ANTIMONY.  It  consists,  according 
to  Berzelius,  of  100  antimony  +  37.25 
sulphur.  The  proportion  given  by  the 
equivalent  ratio  is  100  +  36.5.  Other 
VOL.  T.  [  23  ] 


by  this  process,  will  be  pure.  By  another 
recipe,  copied,  with  some  alteration  frora 
Mr.  Phillips's  prescription,  into  the  ap- 
pendix of  the  French  Pharmacopoeia,  a 
subsulphate  of  antimony  is  formed  first  of 
all,  by  digesting  two  parts  of  sulphuret  of 
antimony  in  a  moderate  heat,  with  three 
parts  of  oil  of  vitriol.  This  insoluble  sub- 
sulphate  be'ing  well  washed,  is  then  di- 
gested in  a  quantity  of  boiling  water,  with 
its  own  weight  of  cream  of  tartar,  and  eva- 
porated to  the  density  1.161,  after  which 
it  is  filtered  hot.  On  cooling,  crystals  of 


ANT 


ANT 


the  triple  tartrate  are  obtained.  One 
might  imagine,  that  there  is  a  chance  of 
obtaining  by  this  process,  a  mixture  of  sul- 
phate of  potash,  and  perhaps  of  a  triple 
sulphate  of  antimony,  along  with  the  tartar 
emetic.  Probably  this  does  not  happen, 
for  it  is  said  to  yield  crystals,  very  pure, 
very  white,  and  without  any  mixture 
Whatever. 

Pure  tartar  emetic  is  in  colourless  and 
transparent  tetrahedrons  or  octohedrons. 
It  reddens  litmus.  Its  taste  is  nauseous 
and  caustic.  Exposed  to  the  air,  it  efflo- 
resces slowly.  Boiling  water  dissolves 
half  its  weight,  and  cold  water  a  fifteenth 
part.  Sulphuric,  nitric,  and  muriatic  acids, 
•when  poured  into  a  solution  of  this  salt, 
precipitate  its  cream  of  tartar;  and  soda, 
potash,  ammonia,  or  their  carbonates, 
throw  down  its  oxide  of  antimony.  Bary- 
tes,  strontites,  and  lime  waters,  occasion 
not  only  a  precipitate  of  oxide  of  antimo- 
ny, like  the  alkalis,  but  also  insoluble  tar- 
trates  of  these  earths.  That  produced  by 
the  alkaline  hydrosulphurets,  is  wholly 
formed  of  kermes  ;  while  that  caused  by 
sulphuretted  hydrogen,  contains  both 
kermes  and  cream  of  tartar.  The  decoc- 
tions of  several  varieties  of  cinchona,  and 
of  several  bitter  and  astringent  plants, 
equally  decompose  tartar  emetic  ;  and  the 
precipitate  then  always  consists  of  the  ox- 
ide of  antimony,  combined  with  the  vege- 
table matter  and  cream  of  tartar.  Physi- 
cians ought  therefore  to  beware  of  such 
incompatible  mixtures.  When  tartar  eme- 
tic is  exposed  to  a  red  heat,  it  first  black- 
ens, like  all  organic  compounds,  and  af- 
terwards leaves  a  residuum  of  metallic  an- 
timony and  subcarbonate  of  potash.  From 
this  phenomenon  and  the  deep  brownish- 
red  precipitate,  by  hydrosulphurets,  this 
antimonial  combination  may  readily  be  re- 
cognized. rinie  precipitate  may  further 
be  dried  on  a  filter,  and  ignited  with  black 
flux,  when  a  globule  of  metallic  antimony 
will  be  obtained.  Infusion  of  galls  is  an 
active  precipitant  of  tartar  emetic. 

This  salt,  in  an  undue  dose,  is  capable 
of  acting  as  a  poison.  The  best  antidotes 
are  demulcent  drinks,  infusions  of  bark, 
tea,  and  sulphuretted  hydrogen  water, 
which  instantly  converts  the  energetic 
salt  into  a  relatively  mild  sulphuret :  ano- 
dynes are  useful  afterwards.  The  powder 
of  tai-tar  emetic,  mixed  with  hog's  lard, 
and  applied  to  the  skin  of  the  human  bo- 
dy, raises  small  vesications. 

The  composition  of  this  salt,  according 
lo  M.  Thenard,  is  35.4  acid,  o9.6  oxide, 
16.7  potash,  and  8.2  water.  The  presence 
of  the  latter  ingredient  is  obvious,  from 
the  undisputed  phenomenon  of  efflores- 
cence. If  we  adopt  the  new  views  of  M. 
Gay-Lussac,  this  salt  may  be  a  compound 
of  a  prime  equivalent  of  tartar  ==  23,825, 


with  a  prime  equivalent  of  deutoxide  of 
antimony  =  13.  On  this  hypothesis  we 
would  have  the  following  proportions : 

2  primes  acid             =   16,75  45.4 

1  prime  potash          =     5.95  16.2 

1  prime  water            =     1.125  3.1 

1  oxide  of  antimony  =  13.00  35.S 

36.825     100.0 

But  very  little  confidence  can  be  reposed 
in  such  atomical  representations. 

The  deutoxide  seems  to  have  the  pro- 
perty of  combining  with  sulphur  in  vari- 
ous proportions.  To  this  species  of  com- 
pound must  be  referred  the  liver  of  anti- 
mony, glass  of  antimony,  and  crocus  metal- 
lorum  of  the  ancient  apothecaries.  Sul- 
phuretted hydrogen  forms,  with  the  deu- 
toxide of  antimony,  a  compound  which 
possessed  at  one  time  great  celebrity  in 
medicine,  and  of  which  a  modification  has 
lately  been  introduced  into  the  art  of  cal- 
ico printing.  By  dropping  hydrosulphu- 
ret  of  potash,  or  of  ammonia,  into  the 
cream-tar  trate,  or  into  mild  muriate  of  an- 
timony, the  hydrosulphuret  of  the  metal- 
lic oxide  precipitates  of  a  beautiful  deep 
orange  colour.  This  is  kermes  mineral. 
Cluzel's  process  for  obtaining  a  fine  ker- 
mes, light,  velvety,  and  of  a  deep  purple- 
brown,  is  the  following  :  one  part  of  pul- 
verized sulphuret  of  antimony,  22|  parts 
of  crystallized  subcarbonate  of  soda,  and 
200  parts  of  water,  are  to  be  boiled  to- 
gether in  an  iron  pot.  Filter  the  hot  li- 
quor into  warm  earthen  pans,  and  allow 
them  to  cool  very  slowly.  At  the  end  of 
24  hours  the  kermes  is  deposited.  Throw 
it  on  a  filter,  wash  it  with  water  which 
haJ  been  boiled  and  then  cooled  out  of 
contact  with  air.  Dry  the  kermes  at  a 
temperature  of  85°,  and  preserve  in  cork- 
ed phials.  Whatever  ma}  be  the  process 
employed,  by  boiling  the  liquor  after  cool- 
ing and  filtration,  on  new  sulphuret  of  an- 
timony, or  upon  that  which  was  left  in  the 
former  operation,  this  new  liquid  will  de- 
posiie,  on  cooling,  a  new  quantity  of  ker- 
mes. Besides  the  hydrosulphuretted  oxide 
of  antimony,  there  is  formed  a  sulphuret. 
ted  hydrosulphuret  of  potash  or  soda. 
Consequently,  the  alkali  seizes  a  portion 
of  the  sulphur  from  the  antimonial  sulphu- 
ret, water  is  decomposed,  and  whilst  a 
portion  of  its  hydrogen  unites  to  the  alka- 
line sulphuret,  its  oxygen,  and  the  other 
portion  of  its  hydrogen,  combine  with  the 
sulphuretted  antimony.  It  seems,  that  the 
resulting  kermes  remains  dissolved  in  the 
sulphuretted  hydrosulphuret  of  potash  or 
soda;  but  as  it  is  less  soluble  in  the  cold 
than  the  hot,  it  is  partially  precipitated  by 
refrigeration.  If  we  pour  into  the  super- 
natant liquid,  after  the  kermes  is  deposi- 
ted and  removed,  any  acid,  as  the  dilute 


ANT 


APL 


nitric,  sulphuric,  or  muriatic,  we  decom- 
pose the  sulphuretted  hydrosulphuret  of 
potash  or  soda.  The  alkaline  base  being 
laid  hold  of,  the  sulphuretted  hydrogen 
and  sulphur  to  which  they  were  united 
are  set  at  liberty;  the  sulphur  andkermes 
fall  together,  combine  with  it,  mid  form  an 
orange-coloured  compound,  called  the 
golden  sulphuret  of  antimony.  It  is  a  hy- 
droguretted  sulphuret  of  antimony.  Hence, 
when  it  is  digested  with  warm  muriatic 
acid,  a  large  residuum  of  sulphur  is  ob- 
tained, amounting  sometimes  to  12  per 
cent.  Kermes  is  composed  by  Thenard, 
of  20.3  sulphuretted  hydrogen,  4.15  sul- 
phur, 72  76  oxide  of  amimony,  2.79  water 
and  loss ;  and  the  golden  sulphuret  con- 
sists of  17.87  sulphuretted  hydrogen,  68.3 
oxide  of  antimony,  and  12  sulphur. 

By  evaporating  the  supernatant  kermes 
liquid,  and  cooling,  crystals  form,  which 
have  been  lately  employed  by  the  calico 
printer,  to  give  a  topical  orange.  These 
crystals  are  dissolved  in  water,  and  the  so- 
lution being  thickened  with  paste  or  gum, 
is  applied  to  cloth  in  the  usual  way.  When 
the  cloth  is  dried,  it  is  passed  through  a 
dilute  acid,  when  the  orange  precipitate 
is  deposited  and  fixed  on  the  vegetable 
fibres. 

An  empirical  antimonial  medicine,  called 
James's  powder,  has  been  much  used  in 
this  country.  The  inventor  called  it  his 
fever  powder,  and  was  so  successful  in  his 
practice  with  it,  that  it  obtained  very 
great  reputation,  which  it  still  in  some 
measure  retains.  Probably,  the  success  of 
Dr.  James  was  in  great  measure  owing  to 
his  free  use  of  the  bark,  which  he  always 
gave  as  largely  as  the  stomach  would 
bear,  as  soon  as  he  had  completely  evacu- 
ated the  primje  vix  by  the  use  of  his  antimo- 
nial preparation,  with  which  at  first  he 
used  to  combine  some  mercurial.  His  spe- 
cification, lodged  in  chancery,  is  as  follows: 
"  Take  antimony,  calcine  it  with  a  con- 
tinued protracted  heat,  in  aflat*  unglazed, 
earthen  vessel  adding  to  it  from  time  to  time 
a  sufficient  quantity  of  any  animal  oil  and 
salt,  well  dephlegmated ;  then  boil  it  in 
melted  nitre  for  a  considerable  time,  and 
separate  the  powder  from  the  nitre  by 
dissolving  it  in  water."  The  real  recipe 
has  been  studiously  concealed,  and  a  false 
one  published  in  its  stead.  Different  for- 
mulae have  been  offered  for  imitating  it. 
That  of  Dr.  Pearson  furnishes  a  mere  mix- 
ture of  an  oxide  of  antimony,  with  phos- 
phate of  lime.  The  real  powder  of  James, 
according  to  this  chemist,  consists  of  57 
oxide  of  antimony,  with  43  phosphate  of 
lime.  It  seems  highly  probable  that  super- 
phosphate of  lime  would  act  on  oxide  of 
antimony,  in  a  way  somewhat  similar  to 
cream  of  tartar,  and  produce  a  more  che- 
mical combination,  than  what  can  be  de- 


rived from  a  precarious  ustulation  and  cal- 
cination of  hartshorn  shavings  and  sul- 
phuret of  amimony,  in  ordinary  hands. 
The  antimonial  medicines  are  powerful 
deobstruents,  promoting  particularly  the 
cuticular  discharge.  The  union  of  this 
metallic  oxide  with  sulphuretted  hydro- 
gen, ought  undoubtedly  to  favour  its  me- 
dicinal agency  in  chronic  diseases  of  the 
skin.  The  kermes  deserves  more  credit 
than  it  has  hitherto  received  from  British 
physicians. 

The  compounds  formed  by  the  antimo- 
nious  and  antimonic  acids,  with  the  bases, 
have  not  been  applied  to  any  use.  Muriate 
of  barytes  may  be  employed  as  a  test  for 
tartar  emetic.  It  will  show,  by  a  precipi- 
tate insoluble  in-niiric  acid,  if  sulphate  of 
potash  be  present.  If  the  crystals  be  re- 
gularly formed,  mere  tartar  need  not  be 
suspected,* 

For  its  ores,  and  the  reduction  of  the 
metals,  see  OIIES. 

ANTS.     See  Acin  (FOUMIC). 

*  APATITE.     Phosphate  of  lime.     This 
mineral  occurs  both  massive  and  crystal- 
lized.    The  crystals  are  six-sided  prisms, 
low,  and  sometimes  passing  into  the  six- 
sided  table.     Lateral   edges,   frequently 
truncated,  and  the  faces  smooth.    Lustre 
splendent.     Translucent,    rarely  transpa- 
rent.    Scratched  by  fluor  spar.     Brittle. 
Colours,  white,  wine-yellow,   green,  and 
red.     Sp.   grav.  3.1.    Phosphoresces  on 
coals.  Electric  by  heat  and  friction.    Con- 
sists  of  53.7*  lime  -f-  46.25  phosphoric 
acid,  by  Klaproth's  analysis  of  the  variety 
called  asparagus  stone.     It  occurs  in  pri- 
mitive rocks;  in  the  tin  veins  of  the  gra- 
nite of  St.   Michael's  Mount,    Cornwall; 
near  Chudleigh  in  Devonshire  ;  at  Nantes 
in  France  ;  in  St.  Gothard,  and  in  Spain  ; 
and  with  molybdena  in  granite,  near  Col. 
beck,    Cumberland.     Phosphorite  is  mas- 
sive, forming  great  beds  in  the  province 
of  Estremadura.   Yellowish-white  colour. 
Dull  or    glimmering  lustre.     Semi-hard. 
Fracture,  imperfect  curved  foliaied.  Brit- 
tle.    Sp.  grav.  2.8.     Phosphorescent  with 
beat.    Its  composition  by  Pelletier  is  59 
lime,  34  phosphoric  acid,  1  carbonic  acid, 
2.5  fluoric  acid,  2  silica,  1  oxide  of  iron, 
and  0.5  muriatic  acid.* 

*  APHRITK.     Earth  foam  ;  Schaumerde. 
This  carbonate  of  lime  occurs  usually  in  a 
friable  state;  but  sometimes  solid.     Co- 
lour, almost  silver-white.     Massive,  or  in 
fine  particles.     Shining  lustre,    between 
semi-metallic  and  pearly.  Fracture,  curved 
foliated.     Opaque ;  soils   a  little.      Very 
soft,  and  easily  cut.     Feels  fine  and  light. 
It  is  usually  found  in  calcareous  veins,  at 
Gcra  in  Misnia,  and  Eisleben  in  Thuringia. 
It  consists,  by  Bucholz,  of  51.5  lime,   39 
acid,  1  water,  5.7  silica,  3. 3  oxide  of  iron.* 

*  APIOXE.    This  is  commonly  consider* 


AQU 


ed  to  be  a  variety  of  the  garnet;  bnt  the 
difference  between  these  minerals  is  this  : 
the  planes  of  the  aplome  dodecahedrons 
are  striated  parallel  with  their  smaller  di- 
agonal, which,  according  to  Haiiy,  indi- 
cates the  primitive  form  to  be  a  cube,  and 
not.  a  dodecahedron.  Its  colour  is  deep 
orange-brown.  It  is  opaque,  and  harder 
than  quartz.  Sp.  grav.  is  much  less  than 
garnet,  viz.  3.44.  It  consists,  by  Laugier's 
analysis,  of  40  silica,  20  alumina,  14.5 
lime,  14  oxide  of  iron,  2  oxide  of  manga- 
nese, 2  silica  and  iron.  It  is  fusible  into  a 
black  glass,  while  garnet  fuses  into  a  black 
enamel.  It  is  found  on  the  river  Lena  in 
Siberia,  and  also  in  New  Holland.* 

*  AFOPHYLLITE.  lchth\  ophthalmite. 
Fisheyestone.  It  is  found  both  massive 
and  crystallized.  It  occurs  in  square 
prisms,  whose  solid  angles  are  sometimes 
replaced  by  triangular  planes,  or  the 
prisms  are  terminated  by  pyramids  con- 
sisting of  4  rhomboidal  planes.  Structure 
lamellar;  cross  fracture,  fine  grained,  un- 
even. External  lustre,  splendent,  and  pe- 
culiar; internal,  glistening  and  pearly. 
Semi-transparent,  or  translucent.  Mode- 
rately hard,  and  easilv  broken.  Sp.  gr. 
2.49.  It  exfoliates,  then  froths,  and  melts 
into  an  opaque  bead  before  the  blow-pipe. 
It  consists  of  51  silica,  28  lime,  4  potash, 
17  water.  Vauqrelin.  It  is  found  in  the 
iron  mine  of  Utoe  in  Sweden;  at  the  cop- 
per mine  of  Fahlun  ;  at  Arendahl,  Faroe, 
the  Tyrol;  and  I)r  MacCulloch  met  with 
a  solitary  crystal  in  Dunveghn,  in  the  Isle 
of  Sky.* 

APPARATUS.     See  LAF.OIIATORY. 

APPLES.     See  ACID  (MALIC). 

APYROUS.  Bodies  which  sustain  the  ac- 
tion of  a  strong  heat  for  a  considerable 
time,  without  change  of  figure  or  other 
properties,  have  been  called  apyrous ;  but 
the  word  is  seldom  used  in  the  art  of 
chemistry.  It  is  synonymous  with  re- 
fractory. 

A  a'  AFORTTS.  This  name  is  given  to  a 
weak  and  impure  nitric  acid,  commonly 
used  in  the  arts.  It  is  distinguished  by 
the  terms  double  and  single,  the  single 
being  only  half  the  strength  of  the  other. 
The  artists  who  use  these  acids  call  the 
more  concentrated  acid,  which  is  much 
stronger  even  than  the  double  aquafortis, 
spirit  of  nitre.  This  distinction  appears  to 
be  of  some  utility,  and  is  therefore  not  im- 
properly retained  by  chemical  writers. 
See  ACID  (NITRIC-). 

*  Ao.tr  A  MARIXE.     See  BERYT.* 

AauA  RERIA,  or  RKRIS.  This  acid,  be- 
ing compounded  of  a  mixture  of  the  nitric 
and  muriatic  acids,  is  now  termed  by 
chemists  nitro-muriatic  acid. 

AQ.UA  VITTK.  Ardent  spirit  of  the  first 
distillation  has  been  distinguished  in  com- 
merce by  this  name.  The  distillers  of 


ARC 

malt    and    molasses    spirits   call    it   low 
wines. 

AU.UTLA  ALBA.  One  of  the  names  given 
to  the  combination  of  muriatic  acid  and 
mercury  in  that  state,  which  is  more  com- 
monly known  by  the  denomination  of 
merciirius  fluids,  calomel,  or  mild  muriate 
of  mere  in  if. 

ARABIC  (Gusr).  This  is  reckoned  the 
purest  of  gums,  and  does  not  greatly  dif- 
fer from  g-uni  Senegal,  vulgarly  called 
gum  seneca,  which  is  supposed  to  be  the 
strongest,  and  is  on  this  account,  as  well 
as  its  greater  plenty  and  cheapness,  most- 
ly used  by  calico  printers  and  other  ma- 
nufacturers. The  gums  of  the  plum  and 
cherry -tree  have  nearly  the  same  qualities 
as  gum  arabic.  All  these  substances  fa- 
cilitate the  mixture  of  oils  with  water. 

ARAB  K  LASDS.  It  is  a  problem  in  che- 
mistry, and  by  no  means  one  of  the  least 
importance  to  society,  to  determine  what 
are  the  requisites  which  distinguish  fruit- 
ful lands  from  such  as  are  less  productive. 
See  SOILS,  and  ANALYSIS  of  SOILS. 

ARKOR  DIANTK.     See  SILVER. 

AUCHIL,  ARCHILL.*,  KOCKLLA,  ORSEILLE. 
A  whitish  lichen,  growing  upon  rocks  in 
the  Canary  and  Cape  Verd  Islands,  which 
yields  a  rich  purple  tincture,  fugitive  in- 
deed, but  extremely  beautiful.  This  weed 
is  imported  to  us  as  it  is  gathered  :  those 
who  prepare  it  for  the  use  of  the  dyer, 
grind  it  betwixt  stones,  so  as  thoroughly 
to  bruise,  but  not  to  reduce  it  into  pow- 
der, and  then  moisten  it  occasionally  with 
a  strong  spirit  of  urine,  or  urine  itself 
mixed  with  quicklime  :  in  a  few  days  it 
acquires  a  purplish-red,  and  at  length  a 
blue  colour;  in  the  first  state  it  is  called 
archil,  in  the  latter  lacmus  or  litmus. 

The  dyers  rarely  employ  this  drug  by 
itself,  on  account  of  its  dearness,  and  the 
perishableness  of  its  beauty.  The  chief 
use  they  make  of  it  is  for  giving  a  bloom 
to  other  colours,  as  pinks,  &c.  This  is 
effected  by  passing1  the  dyed  cloth  or  silk 
through  hot  water  slightly  impregnated 
with  the  archil.  The  bloom  thus  commu- 
nicated soon  decays  upon  exposure  to  the 
air.  Mr.  Hellot  informs  us,  that  by  the 
addition  of  a  little  solution  of  tin,  this  drug 
gives  a  durable  dye  ;  that  its  colour  is  at 
the  same  time  changed  toward  a  scarlet; 
and  that  it  is  the  move  permanent,  in  pro- 
portion as  it  recedes  the  more  from  its 
natural  colour. 

Prepared  archil  very  readily  gives  out 
its  colour  to  water,  to  volatile  spirits,  and 
to  alcohol;  it  is  the  substance  principally 
made  use  of  for  colouring  the  spirits  of 
thermometers.  As  exposure  to  the  air 
destroys  its  colour  upon  cloth,  the  exclu- 
sion of  the  air  produces  a  like  effect  in 
those  hermetically  sealed  tubes,  the  spirits 
of  large  thermometers  becoming;  in  a  few 


ARG- 


ARS 


years  colourless.  The  Abbe*  Nollet  ob- 
serves, (in  the  French  Memoirs  for  the 
year  1742),  that  the  colourless  spirit,  upon 
breaking  the  tube,  soon  resumes  its  co- 
lour, and  this  for  a  number  of  times  suc- 
cessively ;  that  a  watery  tincture  of  ar- 
chil, included  in  the  tubes  of  thermome- 
ters, lost  its  colour  in  three  days ;  and 
that  in  an  open  deep  vessel,  it  became 
colourless  at  the  bottom,  while  the  upper 
part  retained  its  colour. 

A  solution  of  archil  in  water,  applied  on 
cold  marble,  stains  it  of  a  beautiful  violet 
or  purplish-blue  colour,  far  more  durable 
than  the  colour  which  it  communicates  to 
other  bodies.  M.  du  Fay  says,  he  has 
seen  pieces  of  marble  stained  with  it, 
which  in  two  years  had  suffered  no  sensi- 
ble change.  It  sinks  deep  into  the  mar- 
ble, sometimes  above  an  inch,  and  at  the 
same  time  spreads  upon  the  surface,  un- 
less i  he  edges  be  bounded  by  wax  or  some 
similar  substance.  It  seems  to  make  the 
marble  somewhat  more  brktle. 

There  is  a  considerable  consumption  of 
an  article  of  this  kind,  manufactured  in 
Glasgow  by  Mr-  Mackintosh.  It  is  much 
esteemed  and  sold  by  the  name  of  cud- 
bear We  ha^e  seen  beautiful  specimens 
of  silk  thus  dyed,  the  colours  of  which 
were  said  to  be  very  permanent,  of  va- 
rious shades,  from  pink  and  crimson  to  a 
bright  mazarine  blue. 

Litmus  is  likewise  used  in  chemistry  as 
a  test,  either  staining  paper  with  it,  or  by 
infusing  it  in  water  when  it  is  very  com- 
monly, but  with  great  impropriety,  called 
tincture  of  turnsole.  The  persons  by  whom 
this  article  was  prepared,  formerly  gave 
it  the  name  of  turnsole,  pretending  that  it 
was  extracted  from  the  turnsole,  heliotro- 
pium  tricoccum,  in  order  to  keep  its  true 
source  a  secret.  The  tincture  should  not 
be  too  strong,  otherwise  it  will  have  a 
violet  tinge,  which,  however,  may  be  re- 
moved by  dilution.  The  light  of  the  sun 
turns  it  red  even  in  close  vessels.  It  may 
be  made  with  spirit  instead  of  water. 
This  tincture,  or  paper  stained  with  it,  is 
presently  turned  red  by  acids :  and  if  it 
be  first  reddened  by  a  small  quantity  of 
vinegar,  or  some  weak  acid,  its  blue  co- 
lour will  be  restored  bv  an  alkali. 

f  Litmus  gives  out  its  colouring  matter 
but  feebly  to  strong  alcohol ;  and  watery 
infusions  do  not  keep.  To  preserve  it  in 
a  state  for  use,  an  infusion  in  weak  spirit 
is  best.f 

*  AUCTTZITE.     See  WERSTERITE.* 
An  DENT  SPIRIT.     See  ALCOHOL. 

*  ARF.NOATK.     See  PISTACITE.* 
AREOMETER.     See  HTDKOMETER. 
ARGAL.     Crude   tartar,  in  the  state  in 

which  it  is  taken  from  the  inside  of  wine 
vessels,  is  known  in  the  shops  by  this 
name. 


OF  AMMONIA,   fulminating 
silver. 

ARGILLACEOUS  EARTH,  or  ALUMIXA. 

*  AIIGILLITX.     See  CLAY-SLATK.* 
AHOMATICS.     Plants    which   possess    ft 

fragrant  smell  united  with  pungency,  and 
at  the  same  time  are  warm  to  the  taste, 
are  called  aromatics.  Their  peculiar  fla- 
vour appears  to  reside  in  their  essential 
oil,  and  rises  in  distillation  either  with  wa- 
ter or  spirit. 

ARRACK.  A  spirituous  liquor  imported 
from  the  East  Indies.  It  is  chiefly  manu- 
factured at  Batavia,  and  at  Goa  upon  the 
Malabar  coast. 

*  AURAGON-TTE.     This    mineral    occurs 
massive,  in  fibres  of  a  silky  lustre  ;  and  in 
the  form  of  fibrous  branches,  diverging1 
from  a  centre,  Flos-feni.     It  is  frequently 
crystallized  in  what  appear  at  first  sight 
to  be  regular  six-sided  prisms.     On  close 
inspection  a  longitudinal  crack  will  be  ob- 
served down  each  lateral  face.     It  occurs 
also   in   elongated  octohedrons.     Lustre 
glassy,  fracture  foliated  and  fibrous.    Co- 
lours greenish  and  pearl-gray ;  often  violet 
and  green  in  the  middle ;  and  arranged  in 
the  direction  of  the  fibres,  so  that  the 
longitudinal  fibres  are  green,  the  trans- 
verse   violet-blue.      Double    cleavage — 
translucent — refracts     doubly— scratches 
calcareous    spar,    and    sometimes    even 
glass — brittle— sp.  grav.  2.90.     It  consists 
of  carbonate  of  lime,  with  occasionally  a 
little  carbonate  of  strontites.     It  is  found 
in  Arragon  1-n  Spain,  at  Leogany  in  Salz- 
burg, at  Marienberg  in  Saxony,  and  Ster- 
zing  in  the  Tyrol.     In  the  cavities  of  Ba- 
salt near  Glasgow.     The  finest  specimens 
of  Flos-ferri  ramifications,  come  from  the 
mines  of  Eisenerz  in  Stii-ir.  Beautiful  spe- 
cimens have  been  also  found  in  the  Duf- 
ton  lead  mines  in  England,  i.i  the  work- 
ings of  an  old  coal  mine,  called  Lufton- 
hill  pit  near  Durham.     It  also  occurs  in 
the  trap  rocks  of  Scotland.* 

ARSEXTC,  in  the  metallic  state,  is  of  a 
bluish  white  colour,  subject  to  tarnish, 
and  grows  first  yellowish,  then  black,  by 
exposure  to  air.  It  is  brittle,  and  when 
broken  exhibits  a  laminated  texture.  Its 
specific  gravity  is  5.763.  In  close  vessels 
it  sublimes  entire 'at  356°  F.  but  burns 
with  a  small  flame  if  respirable  air  be  pre- 
sent. 

The  arsenic  met  with  in  commerce  has 
the  form  of  a  white  oxide.  It  is  brought 
chiefly  from  the  cobalt  works  in  Saxony, 
where  zarFre  is  made.  Cobalt  ores  con- 
tain much  arsenic,  which  is  driven  off  by 
long  torrefaction.  The  ore  is  thrown  into 
a  furnace  resembling  a  baker's  oven,  with 
a  flue,  or  horizontal  chimney,  nearly  two 
hundred  yards  long,  into  which  the  fumes 
pass,  and  are  condensed  into  a  grayish  or 
blacki&h  powder.  This  is  refined  by  a 


A11S 


ARS 


second  sublimation  in  close  vessels,  with 
a  little  potash,  to  detain  the  impurities. 
As  the  heat  is  considerable,  it  melts  the 
sublimed  flowers  into  those  crystalline 
masses  which  are  met  with  in  commerce. 
See  ACID  (ARSEMO  s). 

The  metal  may  be  obtained  from  this, 
either  by  quickly  fusing  it  tog-ether  with 
twice  its  weight  of  soft  soap  and  an  equal 
quantity  of  alkali,  and  pouring  it  out, 
when  fused,  into  a  hot  iron  cone ;  or  by 
mixing  it  in  powder  with  oil,  and  exposing 
it  in  a  matrass  to  a  sand  heat.  This  pro- 
cess is  too  offensive  to  be  perform^,  ex- 
cept in  the  open  air,  or  where  a  current 
of  air  carries  off  the  fumes.  The  decom- 
posed oil  first  rises;  and  the  arsenic  is  af- 
terwards sublimed,  in  the  form  of  a  flaky 
metallic  substance.  It  may  likewise  be 
obtained  by  mixing  two  parts  of  the  ar- 
senious  acid  with  one  of  black  flux  ;  put- 
ting the  mixture  into  a  crucible,  with 
another  inverted  over  it,  and  luted  to  it 
with  clay  and  sand  ;  and  applying  a  red 
heat  to  the  lower  crucible.  The  metal 
will  be  reduced,  and  line  the  inside  of  the 
upper  crucible. 

It  is  among  the  most  combustible  of  the 
metals,  burns  with  a  blue  flame,  and  gar- 
lic smell,  and  sublimes  in  the  state  of  ar- 
senious  acid. 

•j-  A  very  striking  characteristic  of  this 
metal  is,  that  it  sublimes  before  it  fuses.f 
Concentrated  sulphuric  acid  does  not 
attack  arsenic  when  cold  •  but  if  it  be 
boiled  upon  this  metal,  sulphurous  acid 
gas  is  emitted,  a  small  quantity  of  sulphur 
sublimes,  and  the  arsenic  is  re'duced  to  an 
oxide. 

Nitrous  acid  readily  attacks  arsenic,  and 
converts  it  into  arsenious  acid,  or,  if  much 
be  employed,  into  arsenic  acid. 

Boiling  muriatic  acid  dissolves  arsenic, 
but  affects  it  very  little  when  cold.  This 
solution  affords  precipitates  upon  the  ad- 
dition of  alkalis.  The  addition  of  a  little 
nitric  acid  expedites  the  solution ;  and 
this  solution,  first  heated  and  condensed  in 
a  close  vessel,  is  wholly  sublimed  into  a 
thick  liquid,  formerly  termed  butter  of 
arsenic.  Thrown  in  powder  into  chlorine 
gas,  it  burns  with  a  bright  white  flame, 
and  is  converted  into  a  chloride. 

None  of  the  earths  or  alkalis  act  upon  it, 
unless  it  be  boiled  a  long  while  in  fine 
pov/der,  in  a  large  proportion  of  alkaline 
solution. 

Nitrates  detonate  with  arsenic,  convert  it 
into  arsenic  acid,  and  this,  combining  with 
the  base  of  the  nitrate,  forms  an  arseniate, 
that  remains  at  the  bottom  of  the  vessel. 

Muriates  have  no  action  upon  it ;  but  if 
three  parts  of  chlorate  of  potash  be  mixed 
with  one  part  of  arsenic  in  fine  powder, 
which  must  be  done  with  great  precaution, 
and  a  very  light  hand,  a  very  small  quan- 


tity of  this  mixture,  placed  on  an  anvil,  and 
struck  with  a  hammer,  will  explode  with 
flame  and  a  considerable  report ;  if  touch- 
ed with  fire,  it  will  burn  with  considerable 
rapidity;  and  if  thrown  into  concentrated 
sulphuric  acid,  at  the  instant  of  contact  a 
flame  rises  into  the  air  like  a  flash  of  light- 
ning, which  is  so  bright  as  to  dazzle  the 
eye. 

Arsenic  readily  combines  with  sulphur 
by  fusion  and  sublimation,  and  forms  a 
yellow  compound  called  orpiment,  or  a  red 
called  realgar.  The  nature  of  these,  and 
their  difference,  are  not  accurately  known, 
but  Fourcroy  considers  ihe  first  as  a  com- 
bination of  sulphur  with  the  oxide,  and 
the  second  as  a  combination  of  sulphur 
with  the  metal  itself,  as  he  found  the  red 
sulphuret  converted  into  the  yellow  by  the 
action  of  acids. 

Arsenic  is  soluble  in  fat  oils  in  a  boiling 
heat ;  the  solution  is  black,  and  has  the 
consistence  ot  an  ointment  when  cold. 
Most  metals  unite  with  arsenic ;  which 
exists  in  the  metallic  state  in  such  alloys 
as  possess  the  metallic  brilliancy. 

*  Iodine  and  arsenic  unite,  forming  an 
iodide  of  a  dark  purple-red  colour,  pos- 
sessing the  properties  of  an  acid.  It  is 
soluble  in  water,  and  its  solution  forms  a 
soluble  compound  with  potash.  Arsenic 
combines  with  hydrogen  into  a  very  nox- 
ious compound,  called  arsenuretted  hy- 
drogen gas.  To  prepare  it,  fuse  in  a  co- 
vered crucible,  3  parts  of  granulated  tin, 
and  1  of  metallic  arsenic  in  powder;  and 
submit  this  alloy,  broken  in  pieces,  to  the 
action  of  muriatic  acid  in  a  glass  retort. 
On  applying  a  moderate  heat,  the  arsenu- 
retted hydrogen  comes  over,  and  may  be 
received  in  a  mercurial  or  water  pneuma- 
tic trough.  Protomuriate  of  tin  remains 
in  the  retort.  When  1  of  arsenic  is  used 
for  15  of  tin,  the  former  metal  is  entirely 
carried  oft' in  the  evolved  hydrogen.  100 
parts  of  this  gas  contain  140  of  hydrogen, 
as  is  proved  by  heating  it  with  tin.  Its 
specific  gravity,  according  to  Sir  H.  Davy, 
is  0.5552  ;  according  to  Trommsdorf, 
0.5293.  Strorneyer  states,  that  by  a  cold 
of  —  22°,  it  condenses  into  a  liquid.  Ex- 
ploded with  twice  its  bulk  of  oxygen,  wa- 
ter and  oxide  of  arsenic  are  formed.  When 
arsenuretted  hydrogen  issuing  from  a  tube 
is  set  on  fire,  it  deposites  a  hydruret  of  ar- 
senic. Sulphur,  potassium,  sodium,  and 
tin,  decompose  this  gas,  combine  with  its 
metal,  and  in  the  case  of  sulphur,  sulphu-> 
retted  hydrogen  results.  By  subtracting 
from  the  specific  gravity  of  the  arsenuret- 
ted gas,  that  of  hydrogen  gas  \-^*  we  have 
the  proportion  of  arsenic  present;  0.55520 
—  0.09716  =  0.45804  =  the  arsenic  in  100 
measures  of  arsenuretted  hydrogen ;  which 
gives  the  proportion  by  weight  of  about  6 
arsenic  to  1  hydrogen ;  but  Stromeyer's 


ASA 


ASB 


analysis  by  nitric  acid  gives  about  50  ar- 
senic to  1  hydrogen,  which  is  probably 
much  nearer  the  true  composition,  A 
prime  equivalent  of  hydrogen  is  to  one  of 
arsenic  as  1  to  76  ;  and  2  consequently  as 
1  to  38.  Gehlen  fell  a  victim  to  his  re- 
searches on  this  gas ;  and  therefore  the 
new  experiments  requisite  to  elucidate  its 
constitution  must  be  conducted  with  cir- 
cumspection. If  chlorine  be  added  to  a 
mixture  of  arsenuretted  and  sulphuretted 
hydrogen,  the  bulk  diminishes,  and  yellow 
coloured  flakes  are  deposited.  Concen- 
trated nitric  acid  occasions  an  explosion 
in  this  gas,  preceded  by  nitrous  fumes ; 
but  if  the  acid  be  diluted,  a  silent  decom- 
position of  the  gas  is  effected.  The  den- 
sity of  the  hydrogen  in  this  compound  gas 
is  0,09716.  Therefore,  by  Stromejer's 
analysis,  we  have  this  proportion  to  cal- 
culate the  specific  gravity  of  the  gas, 
2.19  :  0.09716  :  :  (2.19  +  106)  :  4.827  ;  a 
quantity  nearly  9  times  greater  than  what 
experimen  has  given. 

This  gas  extinguishes  flame,  and  instant- 
ly destroys  animal  life.  Water  has  no  ef- 
fect upon  it.  From  the  experiments  of 
Sir  H.  Davy  and  MM.  Gay-Lussac  and 
Thenard,  there  appears  to  be  a  solid  com- 
pound of  hydrogen  and  arsenic,  or  a  hy- 
druret.  It  is  formed  by  acting  with  the 
negative  pole  of  a  voltaic  battery  on  arae- 
nic  plunged  in  water.  It  is  reddish-brown, 
without  lustre,  taste,  and  smell.  It  is  not 
decomposed  at  a  heat  approaching  to 
cherry-red ;  but  at  this  temperature  it  ab- 
sorbs oxygen  ;  while  water  and  arsenious 
acid  are  formed,  witii  the  evolution  of  heat 
and  light.  The  proportion  of  the  two 
constituents  is  not  known.* 

Arsenic  is  used  in  a  variety  of  arts.  It 
enters  into  metallic  combinations,  wherein 
a  white  colour  is  required.  Glass  manu- 
facturers use  it ;  but  its  effect  in  the  com- 
position of  glass  does  notseemto  be  clear- 
ly explained.  Orpiment  and  realgar  are 
used  as  pigments.  See  Acins  (AIISEMC, 
and  ARSETHOCS). 

As\po3TiDA  is  obtained  from  a  large  um- 
belliferous plant  growing  in  Persia.  The 
root  resembles  a  large  parsnep  externally, 
of  a  black  colour :  on  cutting  it  transverse- 
ly, the  assafcetida  exudes  in  form  of  a  white 
thick  juice,  like  cream ;  which,  from  ex- 
posure to  the  air,  becomes  yellower  and 
yellower,  and  at  last  of  a  dark-brown  co- 
lour. It  is  very  apt  to  run  into  putrefac- 
tion ;  and  hence  those  who  collect  it  care- 
fully defend  it  from  the  sun.  The  fresh 
juice  has  an  excessively  strong  smell, 
which  grows  weaker  and  weaker  upon 
keeping :  a  single  dram  of  the  fresh  fluid 
juice  smells  more  than  a  hundred  pounds 
of  the  dry  asafoetida  brought  to  us.  The 
Persians  are  commonly  obliged  to  hire 
ships  on  purpose  for  its  carnage,  as  scarce- 


ly any  one  will  receive  it  along  with  other 
commodities,  its  stench  infecting  every 
thing  that  comes  near  it. 

'I  he  common  asafoetida  of  the  shops  is 
of  a  yellowish  or  brownish  colour,  unctu- 
ous and  tough,  of  an  acrid  or  biting  taste, 
and  a  strong  disagreeable  smell,  resem- 
bling that  of  garlic.  From  four  ounces 
Neumann  obtained,  by  rectified  spirit, 
two  ounces  six  drams  and  a  half  of  resi- 
nous extract ;  and  afterward,  by  water, 
three  drams  and  half  a  scruple  of  gummy 
extract;  about  six  drams  and  a  scruple  of 
earthy  matter  remaining  undissolved.  Oa 
applying  water  at  first,  he  gained,  from 
four  ounces,  one  ounce  three  scruples  and 
a  half  of  gummy  extract. 

Asafoetida  is  administered  in  nervous 
and  hysteric  affections,  as  a  deobstruent, 
and  sometimes  as  an  anthelmintic.  A  tinc- 
ture of  it  is  kept  in  the  shops,  and  it  en- 
ters into  the  composition  of  the  compound 
galbanum  pill  of  the  London  college,  the 
gum  pill  of  former  dispensatories. 

*  ASBESTOS  or  ASBESTUS.  A  mineral  of 
which  there  are  five  varieties,  all  more  or 
less  flexible  and  fibrous. 

1.  Amianthus  occurs  in  very  long,  fine, 
flexible,  elastic  fibres,  of  a  white,  greenish, 
or  reddish  colour.  It  is  somewhat  unctu- 
ous to  the  touch,  has  a  silky  or  pearly  lus- 
tre, and  is  slightly  translucent.  Sectile  ; 
tough ;  sp.  grav.  from  1  to  2.3.  Melts 
with  difficulty  before  the  blow-pipe,  into 
a  white  enamel.  It  is  usually  found  ia 
serpentine ;  in  the  Tarentaise  in  Savoy ; 
in  long  and  beautiful  fibres,  in  Corsica ; 
near  Bareges,  in  the  Pyrenees ;  in  Dau- 
phiny  and  St.  Gothard ;  at  St.  Keverne. 
Cornwall ;  at  Portsoy,  Scotland ;  in  mica 
slate  at  Glenelg,  Invernesshire,  and  near 
Durham.  It  consists  of  59  silex,  25  mag- 
nesia, 9.5  lime,  3  alumina,  and  2.25  oxide 
of  iron.* 

The  ancients  manufactured  cloth  out  of 
the  fibres  of  asbestos,  for  the  purpose,  it 
is  said,  of  wrapping  up  the  bodies  of  the 
dead,  when  exposed  on  the  funeral  pile. 
Several  moderns  have  likewise  succeeded 
in  making  this  cloth  ;  the  chief  artifice  of 
which  seems  to  consist  in  the  admixture 
of  flax  and  a  liberal  use  of  oil  ;  both  which 
substances  are  afterwards  consumed  by 
exposing  the  cloth  for  a  certain  time  to  a 
red  heat.  Although  the  cloth  of  asbestos, 
when  soiled,  is  restored  to  its  primitive 
whiteness  by  heating  in  the  fire ;  it  is 
found,  nevertheless,  by  several  authentic 
experiments,  that  its  weight  diminishes 
by  such  treatment.  The  fibres  of  asbestos, 
exposed  to  the  violent  heat  of  the  blow- 
pipe, exhibit  slight  indications  of  fusion ; 
though  the  parts,  instead  of  running  to- 
gether, moulder  away,  and  part  fall  down, 
while  the  rest  seem  to  disappear  before 
the  current  of  air.  Ignition  impairs  the 


ASP 


ASS 


flexibility  of  asbestos  in    a    slight   de- 
gree. 

*  2.  Common  Asbestus  occurs  in  masses 
of  fibres  of  a  dull  greenish  colour,  and  of 
a  somewhat  pearly  lustre.  Fragments 
splintery.  It  is  scarcely  flexible,  and  great- 
ly denser  than  amianthus.  It  is  slightly 
unctuous  to  the  touch.  Sp.  grav  2.7. 
Fuses  with  difficulty  into  a  grayish-black 
scoria.  It  is  composed  of  63.9  silica,  16 
magnesia,  12.8  lime,  6  oxide  of  iron,  and 
1.1  alumina.  It  is  more  abundant  than 
amianthus,  and  is  found  usually  in  serpen- 
tine, as  at  Portsoy,  the  Isle  of  Anglesea, 
and  the  Lizard  in  Cornwall.  It  wa"s  found 
in  the  limestone  of  Glentilt,  by  Dr,  Yl'Cul- 
loch,  in  a  pasty  state,  but  it  soon  hardened 
by  exposure  to  air. 

3.  Mountain    Leather  consists   not   of 
parallel  fibres  like  the  preceding,  but  in- 
terwoven and  interlaced  so  as  to  become 
tough.     When  in  very  thin  pieces  it  is 
called  mountain  paper.     Its  colour  is  yel- 
lowish-white, and  its  touch  meagre.     It  is 
found  at    Wanlockhead,  iu   Lanarkshire. 
Its  specific  gravity  is  uncertain. 

4.  Mountain    Cork,  or  Elastic  *flsbestus, 
is,  like  the  preceding,  of  an   interlaced 
fibrous  texture  ;  is  opaque,  has  a  meagre 
feel  and  appearance,  not  unlike  common 
cork,  and  like  it  too,  is  somewhat  elastic. 
It  swims  on  water.     Its  colours  are,  white, 
gray,  and  yellowish-brown.     Receives  an 
impression  from  the  nail ;   very   tough  ; 
cracks  when  handled,  and  melts  with  dif- 
ficulty before  the  blow-pipe.     Sp.  grav. 
from  0.68  to  0.99.     Tt  is  composed  of  sili- 
ca 62,  carbonate  of  lime   13,  carbonate  of 
magnesia  23,  alumina  2.8,  oxide  of  iron  3. 

5.  Mountain  Wood.  Ligniform  asbestus. 
Ts  usually  massive,  of  a  brown  colour,  and 
having  the  aspect  of  wood.  Internal  lus- 
tre glimmering.  Soft,  sectile  and  tough  ; 
opaque;  feels  meagre;  fusible  into  a 
black  slag.  Sp.  grav.  2.0.  It  is  found  in 
the  Tyrol;  Dauphiny ;  and  in  Scotland, 
at  Glentilt,  Portsoy,  and  Kildrumie.* 

ASHCS.  The  fixed  residue  of  combusti- 
ble substances,  which  remains  after  they 
have  been  burned,  is  called  ashes.  In 
chemistry  it  is  most  commonly  used  to  de- 
note the  residue  of  vegetable  combustion. 

*  ASPABAGIX.  White  transparent  crys- 
tals, of  a  peculiar  vegetable  principle, 
\vhich  spontaneously  form  in  asparagus 
juice  \vhich  has  been  evaporated  to  the 
consistence  of  sirup.  They  are  in  the  form 
of  rhomboidal  prisms,  hard  and  brittle, 
having  a  cool  and  slightly  nauseous  taste. 
They  dissolve  in  hot  water,  but  sparingly 
in  cold  water,  and  not  at  all  in  alcohol. 
On  being  heated  they  swell,  and  emit  pen- 
etrating vapours,  which  affect  the  eyes 
and  nose  like  wood-smoke.  Their  solution 
does  not  change  vegetable  blues;  nor  is 
it  affected  by  hydrosulphuret  of  potash, 


oxalate  of  ammonia,  acetate  of  lead,  or  in- 
fusion of  galls.  Lime  disengages  ammonia 
from  it;  though  none  is  evolved  by  tritu- 
rating it  with  potash.  The  asparagusjuice 
should  be  first  heated  to  coagulate  the  al- 
bumen, then  filtered  and  left  to  sponta- 
neous evaporation  for  15  or  20  days. 
Along  with  the  asparagin  crystals,  others 
in  needles  of  little  consistency  appear, 
analogous  to  mannite,  from  which  the  first 
can  be  easily  picked  out.  Vauquelin  and 
Robiquet.  Annales  de  Chimie,  vol.  55. 
and  Nicholson's  Journal,  15.* 

ASPHALTTTM.  This  substance,  likewise 
called  Bitumen  Judaicum,  or  Jews'  Pitch, 
is  a  smooth,  hard,  brittle,  black  or  brown 
substance,  which  breaks  with  a  polish, 
melts  easily  when  heated,  and  when  pure 
burns  without  leaving  any  ashes.  It  is 
found  in  a  soft  or  liquid  state  on  the  sur- 
face of  the  Dead  Sea,§  but  by  age  grows 
dr\  and  hard.  The  same  kind  of  bitumen 
is  likewise  found  in  the  earth  in  other 
parts  of  the  world ;  in  China  •  America, 
particularly  in  the  island  of  Trinidad ;  and 
some  parts  of  Europe,  as  the  Carpathian 
hills,  France,  Neufchattel,  &c.  Its  speci- 
fic gravity,  according  to  Boyle,  is  1.400,. 
to  Kirvvan,  from  1.07  to  1.65.  A  specimen 
from  Albania,  of  the  specific  gravity  of 
1.205,  examined  by  Mr.  Klaproth,  was 
found  to  be  soluble  only  in  oils  and  in 
ether.  Five  parts  of  rectified  oil  of  petro- 
leum dissolved  one  of  the  asphaltum, 
without  heat,  in  24  hours.  Analyzed  in 
the  dry  way,  100  grains  afforded  32  of  bi- 
tuminous oil,  6  of  water  faintly  ammonia- 
cal  30  of  charcoal,  7£  of  silex,  7$  of  alu- 
mina, $  of  lime,  1£  oxide  of  iron,  £  oxide 
of  manganese,  and  36  cubic  inches  of  hy- 
drogen gas. 

According  to  Neumann,  the  asphaltum 
of  the  shops  is  a  very  different  compound 
from  the  native  bitumen;  and  varies,  of 
course,  in  its  properties,  according  to  the 
nature  of  the  ingredients  made  use  of  in 
forming  it.  On  this  account,  and  probably 
from  other  reasons,  the  use  of  asphaltum, 
as  an  article  of  the  materia  medica,  is  al- 
most totally  laid  aside. 

*  The  Egyptians  used  asphaltum  in  em- 
balming, under  the  name  of  mumia  mine- 
ralis  for  which  it  is -well  adapted.  It  was 
used  for  mortar  at  Babylon.* 

ASSAY,  or  ESSAY.  This  operation  con- 
sists in  determining  the  quantity  of  valua- 
ble or  precious  metal  contained  in  any 

§  In  the  Mem.  of  the  Academy  of  Sci- 
ences of  Paris  for  1778,  there  is  an  analy- 
sis of  the  wa'er  of  this  sea  by  Messrs.  Mac- 
quer,  Lavoisier,  and  Sage ;  by  which  it 
appears  to  contain  22  per  cent  of  muriate 
of  magnesia,  16A  of  muriate  of  lime,  and 
6-]-  of  muriate  of  soda.  Its  specific  gravity- 
is  1.25.  It  is  limpid,  and  without  smell. 


ASS 


ASS 


mineral  or  metallic  mixture,  by  analyzing 
a  small  part  thereof.  The  practical  differ- 
ence between  the  analysis  and  the  assay 
of  an  ore,  consists  in  this :  The  analysis, 
if  properly  made,  determines  the  nature 
and  quantities  of  all  the  parts  of  the  com- 
pound ;  whereas,  the  object  of  the  assay 
consists  in  ascertaining1  how  much  of  the 
particular  metal  in  question  may  be  con- 
tained in  a  certain  determinate  quantity 
of  the  material  under  examination.  Thus, 
in  the  assay  of  gold  or  silver,  the  baser 
metals  are  considered  as  of  no  value  or 
consequence;  and  the  problem  to  be  re- 
solved is  simply,  how  much  of  each  is  con- 
tained in  the  ingot  or  piece  of  metal  in- 
tended to  be  assayed.  The  examination 
of  metallic  ores  may  be  seen  under  their 
respective  titles ;  the  present  article  will 
therefore  consist  of  an  account  of  the  as- 
saying of  gold  and  silver. 

To  obtain  gold  or  silver  in  a  state  of  pu- 
rity, or  to  ascertain  the  quantity  of  alloy  it 
may  contain,  it  is  exposed  to  a  strong 
heat,  together  with  lead,  in  a  porous  cru- 
cible. This  operation  is  called  cupellation, 
and  is  performed  as  follows :  The  preci- 
ous metal  is  put,  together  with  a  due  pro- 
portion of  lead,  into  a  shallow  crucible, 
made  of  burned  bones,  called  a  cupel ; 
and  the  fusion  of  the  metals  is  effected  by 
exposing  them  to  a  considerable  heat  in  a 
muffle,  or  small  earthen  oven,  fixed  in  the 
midst  of  a  furnace.  The  lead  continually 
vitrifies,  or  becomes  converted  into  a 
glassy  calx,  which  dissolves  all  the  imper- 
fect metals.  This  fluid  glass,  with  its  con- 
tents, soaks  into  the  cupel,  and  leaves  the 
precious  metals  in  a  state  of  purity.  Du- 
ring the  cupellation,  the  scoriae  running 
down  on  all  sides  of  the  metallic  mass,  pro- 
duce an  appearance  called  circulation ;  by 
which  the  operator  judges  whether  the 
process  be  going  on  well.  When  the  metal 
is  nearly  pure,  certain  prismatic  colours 
flash  suddenly  across  the  surface  of  the 
globule,  which  soon  afterwards  appears 
very  brilliant  and  clean :  this  is  called  the 
brightening,  and  shows  that  the  separa- 
tion is  ended. 

After  gold  has  passed  the  cupel,  it  may 
still  contain  either  of  the  other  perfect 
metals,  platina,  or  silver.  The  former  is 
seldom  suspected ;  the  latter  is  separated 
by  the  operations  called  quartation  and 
parting.  Quartation  consists  in  adding 
three  parts  of  silver  to  the  supposed  gold, 
and  fusing  them  together ;  by  which  means 
the  gold  becomes  at  most  one-fourth  of 
the  mass  only.  The  intention  of  this  is  to 
separate  the  particles  of  gold  from  each 
other,  so  that  they  may  not  cover  and  de- 
fend the  silver  from  the  action  of  the  nitric 
acid,  which  is  to  be  used  in  the  process  of 
parting.  Parting  consists  in  exposing  the 
mass,  previously  hammered  or  rolled  out 
Yea.  i.  [24] 


thin,  to  the  action  of  seven  or  eight  times 
its  weight  of  boiling  nitric  acid  of  a  due 
strength.  The  first  portion  of  nitric  acid 
being  poured  off,  about  half  the  quantity, 
of  a  somewhat  greater  strength,  is  to  be 
poured  on  the  remaining  gold ;  and  if  it 
be  supposed  that  this  has  not  dissolved  all 
the  silver,  it  may  even  be  repeated  a 
second  time.  For  the  first  operation  an 
acid  of  the  specific  gravity  of  1.280  may 
be  used,  diluted  with  an  equal  quantity  of 
water;  for  the  second,  an  acid  about  1.26 
maybe  taken  undiluted.  If  the  acid  be 
not  too  concentrated,  it  dissolves  the  sil- 
ver, and  leaves  the  gold  in  a  porous  mass, 
of  the  original  form ;  but,  if  too  strong, 
the  gold  is  in  a  powdery  form,  which  may 
be  washed  and  dried.  The  weight  of  the 
original  metal  before  cupellation,  and  in 
all  the  subsequent  stages,  serves  to  ascer- 
tain the  degree  of  fineness  of  the  ingot,  or 
ore,  of  which  it  is  a  part. 

In  estimating  or  expressing  the  fineness 
of  gold,  the  whole  mass  spoken  of  is  sup- 
posed to  weigh  twenty-four  carats  of 
twelve  grains  each,  either  real,  or  merely 
proportional,  like  the  assayer's  weights ; 
and  the  pure  gold  is  called  fine.  Thus,  if 
gold  be  said  to  be  23  carats  fine,  it  is  to 
be  understood,  that,  in  a  mass  weighing  24 
carats,  the  quantity  of  pure  gold  amounts 
to  23  carats. 

In  such  small  works  as  cannot  be  assay- 
ed by  scraping  off  a  part,  and  cupelling  it, 
the  assayers  endeavour  to  ascertain  its 
quality  or  fineness  by  the  touch.  This  is 
a  method  of  comparing  the  colour,  and 
other  properties  of  a  minute  portion  of 
the  metal,  with  those  of  small  bars,  the 
composition  of  which  is  known.  These 
bars  are  called  touch-needles;  and  they 
are  rubbed  upon  the  black  basaltes,  which, 
for  this  reason,  is  called  the  touchstone. 
Black  flint  or  pottery  will  serve  the  same 
purpose.  Sets  of  gold  needles  may  con- 
sist of — pure  gold ;  pure  gold  23^  carats, 
with  half  a  carat  of  silver ;  23  carats  of 
gold,  with  one  carat  of  silver ;  22^  carats 
of  gold,  with  1^  carats  of  silver ;  and  so  on, 
till  the  silver  amounts  to  four  carats ;  af- 
ter which  the  additions  may  proceed  by 
whole  carats.  Other  needles  may  be  made 
in  the  same  manner,  with  copper  instead 
of  silver ;  and  other  sets  may  have  the  ad- 
dition consisting  either  of  equal  parts  sil- 
ver and  copper,  or  such  proportions  as 
the  occasions  of  business  require.  The 
examination  by  the  touch  may  be  advan- 
tageously employed  previous  to  quarta- 
tion, to  indicate  the  quantity  of  silver  ne- 
cessary to  be  added. 

In  foreign  countries,  where  trinkets  and 
small  work  are  required  to  be  submitted 
to  the  assay  of  the  touch,  a  variety  of 
needles  are  necessary ;  but  they  are  not 
much  used  in  England,  They  afford,  how- 


ASS 


ASS 


jever,  a  degree  of  information,  winch  is 
more  considerable  than  might  at  first  be 
expected.  The  attentive  assayer  not  only 
compares  the  colour  of  the  stroke  made 
upon  the  touchstone  by  the  metal  under 
examination,  with  that  produced  by  his 
needle;  but  will  likewise  attend  to  the 
sensation  of  roughness,  dr}  ness,  smooth- 
ness, or  greasincss,  which  the  texture  of 
the  rubbed  incta]  excites,  when  abraded 
by  the  stone.  "When  two  strokes,  perfect- 
ly alike  in  colour,  are  made  if^on  the 
stone,  he  may  then  wet  them  with  aqua- 
fortis, which*  will  affect  them  very  differ- 
ently, if  they  be  not  similar  compositions ; 
or  the  stone  itself  may  be  made  red-hot  by 
the  fire,  or  bv  the  blow-pipe,  if  thin  black 
pottery  be  used  ;  in  which  case  the  phe- 
nomena of  oxidation  will  differ,  according 
to  the  nature  and  quantity  of  the  alloy. 

The  French  government  has  from  time 
to  time  caused  various  experimental  in- 
quiries to  be  made  respecting  tbe  art  of 
assaying  gold,  which  have  thrown  much 
light  on  this  subject,  and  greatly  tend  to 
produce  uniformity  in  the  results  of  the 
operation.  The  latest  report  on  this  sub- 
ject may  be  seen  in  the  Annales  de  Chi- 
mie,  vol.  vi.  p.  64. ;  which  may  be  con- 
sulted for  a  full  account  of  the  experi- 
ments and  history  of  former  proceedings. 
The  general  result  is  as  follows,  nearly  in 
the  words  of  the  authors : 

Six  principal  circumstances  appear  to 
affect  the  operation  of  parting:  namely, 
the  quantity  of  acid  used  in  parting,  or  in 
the  first  boiling;  the  concentration  of  this 
acid ;  the  time  employed  in  its  applica- 
tion ;  the  quantity  of  acid  made  use  of  in 
the  reprise,  or  second  operation ;  its  con- 
centration ;  and  the  time  during  which  it 
is  applied.  From  the  experiments  it  has 
been  shown,  that  each  of  these  unfavour- 
able circumstances  might  easily  occasion 
a  loss  of  from  the  half  of  a  thirty -second 
part  of  a  carat,  or  two  thirty-second  parts. 
The  writers  explain  their  technical  lan- 
guage by  observing,  that,  the  whole  mass 
consisting  of  twenty-four  carats,  this  thir- 
ty-second part  denotes  l-768th  part  of  the 
mass.  It  may  easily  be  conceived,  there- 
fore, that  if  the  whole  six  circumstances 
were  to  exist,  and  be  productive  of  errors 
falling  the  same  way,  the  loss  would  be 
very  considerable. 

It  is  therefore  indispensibly  necessary, 
that  one  uniform  process  should  be  fol- 
lowed in  the  assays  of  gold  ;  and  it  is  a 
matter  of  astonishment,  that  such  an  accu- 
rate process  should  not  have  been  pre- 
scribed by  Government  for  assayers  in  an 
operation  of  such  great  commercial  im- 
portance, instead  of  every  one  being  left 
to  follow  his  own  judgment.  The  pro- 
cess recommended  in  the  report  before 
us  is  as  follows:— 


Twelve  grains  of  the  gold  intended  ft* 

be  assayed  must  be  mixed  with  thirty  grains- 
of  fine  silver,  and  cupelled  with  108  grains^ 
of  lead.  The  cupellation  must  be  carefully 
attended  to,  and  all  the  imperfect  buttons 
rejected.  When  the  cupellation  is  end- 
ed, the  button  must  be  reduced  by  lami- 
nation into  a  plate  of  1£  inch,  or  rather 
more,  in  length,  and  four  or  five  lines  in. 
breadth.  This  must  be  rolled  up  upon  a 
quill,  and  placed  in  a  matrass  capable  of 
holding  about  three  ounces  of  liquid,  when 
filled  up  to  its  narrow  part.  Two  ounces 
and  a  half  of  very  pure  aquafortis,  of  the 
strength  of  20  degrees  of  J3aume's  areo- 
meter, must  then  be  poured  upon  it;  and 
the  matrass  being  placed  upon  hot  ashes 
or  sand,  the  acid  must  be  kept  gently  boil- 
ing for  a  quarter  of  an  hour ;  the  acid 
must  then  be  cautiously  decanted  and  an 
additional  quantity  of  1|  ounce,  must  be 
poured  on  the  metal,  and  slightly  boiled 
for  twelve  minutes.  This  being  likewise 
carefully  decanted,  the  small  spiral  piece 
of  metal  must  be  washed  with  filtered  ri- 
ver water,  or  distilled  water,  by  filling  the 
matrass  with  this  fluid.  The  vessel  is  then 
to  be  reversed,  by  applying  the  extremi- 
ty of  its  neck  against  the  bottom  of  a  cru- 
cible of  fine  earth,  the  internal  surface  of 
which  is  very  smooth.  The  annealing 
must  then  be  made,  after  having  separated 
the  portion  of  water  which  had  fallen  into 
the  crucible ;  and,  lastly  the  annealed 
gold  must  be  weighed.  For  the  certainty 
of  this  operation,  two  assays  must  be  made 
in  the  same  manner,  together  with  a  third 
assay  upon  gold  of  twenty-four  carats,  ox' 
upon  gold  the  fineness  of  which  is  perfect- 
ly and  generally  known. 

No  conclusion  must  be  drawn  from  this 
assay,  unless  the  latter  gold  should  prove 
to  be  of  the  fineness  of  twenty -four  carats 
exactly,  or  of  its  known  degree  of  fine- 
ness; for  if  there  be  either  loss  or  surplus, 
it  may  be  inferred  that  the  other  two  as- 
says, having  undergone  the  same  opera- 
tion, must  be  subject  to  the  same  error. 
The  operation  being  made  according  to 
this  process,  by  several  assayers,  in  cir- 
cumstances of  importance,  such  as  those 
which  relate  to  large  fabrications,  the  fine- 
ness of  the  gold  must  not  be  depended 
on,  nor  considered  as  accurately  known, 

§  1^  gross.  Though  these  doses  of  sil- 
ver and  lead  appeared  to  be  proper  for  all 
operations  of  assaying  gold,  the  commissa- 
ries observe,  nevertheless,  that  gold  of 
a  lower  title  than  eighteen  carats  may  be 
alloyed  with  two  parts,  and  even  less,  of 
silver  ;  in  oi'der  that  the  small  mass  of  me- 
tal, when  it  comes  to  be  Iuminated,may  not 
be  too  thin,  so  as  to  break  in  pieces  during 
the  parting. 


ATU 


ATI1 


the  assay ers  have  obtained  a  uni- 
form result,  without  communication  with 
each  other.  The  authors  observe,  however, 
that  this  identity  must  be  considered  as 
existing  to  the  accuracy  of  half  of  the 
thirty -second  part  of  a  carat.  For  not- 
withstanding1 every  possible  precaution  or 
uniformity,  it  very  seldom  happens  that  an 
absolute  agreement  is  obtained  between 
the  different  assays  of  one  and  the  same 
ingot,  because  the  ingot  itself  may  differ 
in  its  fineness  in  different  parts  of  its  mass. 
The  assaying  of  silver  does  not  differ 
'from  that  of  gold,  excepting  that  the  part- 
ing operation  is  not  necessary.  A  cer- 
tain small  portion  of  the  silver  is  ab- 
sorbed by  the  cupel,  and  the  more  when 
a  larger  quantity  of  lead  is  used,  un- 
less the  quantity  of  lead  be  excessive  ; 
in  which  case  most  of  it  will  be  scori- 
fied before  it  begins  to  act  upon  the 
silver.  Messrs.  Hellot,  Tillet,  and  Mac- 

3uer,  from  their  experiments  made  by  or- 
er  of  the  French  Government,  have  as- 
certained, that  four  parts  of  lead  are  re- 
quisite for  silver  of  eleven  pennyweights 
twelve  grains  fine,  or  containing  this 
weight  of  pure  silver,  and  twelve  grains 
of  alloy,  in  twelve  pennyweights;  six 
parts  of  lead  for  silver  of  eleven  pen- 
cyweights  ;  eight  parts  of  lead  for  silver 
of  ten  pennyweights ;  ten  parts  of  lead  for 
silver  of  nine  pennyweights;  and  soon  in 
the  same  progression. 

ASTHIXGEXT  PRINCIPLE.  The  effect 
called  astringency,  considered  as  distin- 
guishable by  the  taste,  is  incapable  of  be- 
ing defined.  It  is  perceived  in  the  husks  of 
nuts,  of  walnuts,  in  green  tea,  and  emi- 
nently in  the  nut-gall.  This  is  probably 
owing  to  the  circumstance,  that  acids  have 
likewise  the  property  of  corrugating  the 
fibres  of  the  mouth  and  tongue,  which  is 
considered  as  characteristic  of  astringency 
as  it  relates  to  taste ;  and  hence  the  .gallic 
acid,  which  is  commonly  found  united 
\viththe  true  astringent  principle,  was  long 
mistaken  for  it.  Seguin  first  distinguished 
them,  and,  from  the  use  of  this  principle 
in  tanning  skins,  has  given  it  the  name  of 
tannin.  Their  characteristic  differences 
are,  the  gallic  acid  forms  a  black  precipi- 
tate with  iron  ;  the  astringent  principle 
forms  an  insoluble  compound  with  albu- 
men. See  TANNIX. 

ATHAXOR.  A  kind  of  furnace,  which 
has  long  since  fallen  into  disuse.  The 
very  long  and  durable  operations  of  the 
ancient  chemists  rendered  it  a  desirable 
requisite,  that  their  fires  should  be  con- 
stantly supplied  with  fuel  in  proportion  to 
the  consumption.  The  athanor  furnace 
was  peculiarly  adapted  to  this  purpose. 
Beside  the  usual  parts,  it  was  provided 
with  a  hollow  tower,  into  which  charcoal 
was  put.  The  upper  part  of  the  tower, 


when  filled,  was  closely  shut  by  a  well- 
fitted  cover;  and  the  lower  part  commu- 
nicated with  the  fire -place  of  the  furnace. 
In   consequence  of  this  disposition,  the 
charcoal  subsided  into  the  fire-place  gra- 
dually as  the  consumption  made  room  for 
it;  but  that  which  was  contained  in  the 
tower  was  defended  from  combustion  by 
the  exclusion  of  a  proper  supply  of  air.  " 
*  ATMOMETER.     The  name  of  an  instru- 
ment  contrived  by  Professor  Leslie,  to 
measure  the  quantity  of  exhalation  from 
a  humid  surface  in  a  given  time.     It  con- 
sists of  a  thin  ball  of  porous  earthen-ware, 
two  or  three  inches  in  diameter,  with  a 
small  neck,  to  which  is  firmly  cemented  a 
long  and  rather  wide  tube  of  glass,  bear- 
ing divisions,  each  of  them  corresponding1 
to  an  internal  annular  section,  equal  to  a 
film  of  liquid  that  would  cover  the  outer 
surface  of  the  ball  to  the  thickness  of  the 
thousandth  part  of  an  inch.     These  divi- 
sions are  ascertained  by  a  simple  calcula- 
tion, and  numbered  downwards  to  the  ex- 
tent of  100  or  200.  To  the  top  of  the  tube 
is  fitted  a  brass  cap,  having  a  collar  of  lea- 
ther, and  which,  after  the  cavity  has  been 
filled  with   distilled  or  boiled  water,  is 
screwed  tight.     The  outside  of  the   ball 
being  now  wiped  dry,  the  instrument  is 
suspended  out  of  doors,  and  exposed- -to 
the  free  action  of  the  air.     The   quantity 
of  evaporation  from  a  wet  ball  is  the  same 
as  from  a  circle  having  twice  the  diameter 
of  the  sphere.      In  the  atmometer,   the 
humidity  transudes   through  the  porous 
substance,  just   as  fast  as   it  evaporates 
from  the  external  surface ;  and  this  waste 
is  measured  by  the  corresponding  descent 
of  water  in  the  stem.     At  the  same  time, 
the  tightness  of  the  collar  taking  off  the 
pressure  of  the  column  of  liquid,  prevents 
it  from  oozing  so  profusely  as  to  drop  from 
the  ball ;  an  inconvenience  which,  in  the 
case   of  very  feeble   evaporation,   might 
otherwise  take   place.     As   the    process 
goes  on,  a  corresponding  portion  of  air  is 
likewise  imbibed  by  the  moisture  on  the 
outside,  and  being   introduced  into  the 
ball,  rises  in  a  small  stream  to  replace  the 
water.     The  rate  of  evaporation  is  nowise 
affected  by  the  quality  of  the  porous  ball. 
It  continues  exactly  the  same  when  the 
exhaling  surface  appears  almost  dry,  as 
when   it  glistens  with  superfluous  mois- 
ture.    When  the  consumption  of  water  is 
excessive,  it  may  be  allowed  to  percolate 
by  unscrewing  the  cap,  taking  care,  how- 
ever, to  let  no  drops  fall.*     Leslie  on  Heat 
and  Moisture. 

ATMOSPHERE.      See  AIR  (ATMOSPHERI- 
CAL). 

*  ATOMIC  THEORY.    See  EQUIVALENTS 
(CHEMICAL).* 

*  ATROPIA.     A   new   vegetable  alkali, 
extracted  by  Dr.  Brands 8  from  the  .iiropa 


ATT 


ATT 


belladonna,  or  deadly  nightshade.  It  is 
white,  brilliant,  crystallizes  in  long  nee- 
dles, is  tasteless,  and  little  soluble  in  wa- 
ter or  alcohol.  It  resists  a  moderate  heat. 
"With  acids,  it  forms  regular  salts,  and  is 
capable  of  neutralizing  a  considerable  pro- 
portion of  acid.  Sulphate  of  atropia  is 
composed  of, 

Sulphuric  acid,  36.52    5.00 
Atropia,  38.93    5.33 

Water,  24.55 

100.00.* 

ATTRACTION.  The  instances  of  attrac- 
tion which  are  exhibited  by  the  phenome- 
na around  us,  are  exceedingly  numerous, 
and  continually  present  themselves  to  our 
observation.  The  effect  of  gravity,  which 
causes  the  weight  of  bodies,  is  so  universal, 
that  we  can  scarcely  form  an  idea  how  the 
universe  could  subsist  without  it.  Other 
attractions,  such  as  those  of  magnetism 
and  electricity,  are  likewise  observable  ; 
and  every  experiment  in  chemistry  tends 
to  show,  that  bodies  are  composed  of  va- 
rious principles  or  substances,  which  ad- 
here to  each  other  with  various  degrees 
of  force,  and  may  be  separated  by  known 
methods.  It  is  a  question  among  philo- 
sophers, whether  all  the  attractions  which 
obtain  between  bodies  be  referable  to  one 
general  cause  modified  by  circumstances ; 
or  whether  various  original  and  distinct 
causes  act  upon  the  particles  of  bodies  at 
one  and  the  same  time.  The  philosophers 
at  the  beginning  of  the  present  century 
were  di-posed  to  consider  the  several  at- 
tractions as  essentially  different,  because 
the  laws  of  their  action  differ  from  each 
other;  but  the  moderns  appear  disposed 
to  generalize  this  subject,  and  to  consider 
all  the  attractions  which  exist  between 
bodies,  or  at  least  those  which  are  perma- 
nent, as  depending  upon  one  and  the 
same  cause,  whatever  it  may  be,  which  re- 
gulates at  once  the  motions  of  the  im- 
mense bodies  that  circulate  through  the 
celestial  spaces,  and  those  minute  parti- 
cles that  are  transferred  from  one  combi- 
nation to  another  in  the  operations  of  che- 
mistry. The  earlier  philosophers  ob- 
served, for  example,  that  the  attraction  of 
gravitation  acts  upon  bodies  with  a  force 
which  is  inversely  as  the  squares  of  the 
distances ;  and  from  mathematical  deduc- 
tion they  have  inferred,  that  the  law  of  at- 
traction between  the  particles  themselves 
follows  the  same  ratio;  but  when  their 
observations  were  applied  to  bodies  very 
near  each  other,  or  in  contact,  an  adhesion 
took  place,  which  is  found  to  be  much 
greater  than  could  be  deduced  from  that 
law  applied  to  the  centres  of  gravity. 
Hence  they  concluded,  that  the  cohesive 
attraction  is  governed  by  a  much  higher 
ratio,  and  probably  the  cubes  of  the  dis- 


tances. The  moderns,  on  the  contrary, 
among  whom  are  Bergmann,  Guyton-Mor- 
veau,  and  others,  have  remarked,  that 
these  deductions  are  too  general,  because, 
for  the  most  part,  drawn  from  the  conside- 
ration of  spherical  bodies,  which  admit  of 
no  contact  but  such  as  is  indefinitely  small, 
and  exert  the  same  powers  on  each  other, 
whichever  side  may  be  obverted.  They 
remark,  likewise,  that  the  consequence 
depending  on  the  sum  of  the  attractions 
in  bodies  not  spherical,  and  at  minute 
distances  from  each  other,  will  not  follow 
the  inverted  ratio  of  the  square  of  the  dis- 
tance taken  from  any  point  assumed  as 
the  centre  of  gravity,  admitting  the  parti- 
cles to  be  governed  by  that  law  ;  but  that 
it  will  greatly  differ,  according  to  the  sides 
of  the  solid  which  are  presented  to  each 
other,  and  their  respective  distances ;  in- 
somuch that  the  attractions  of  certain  par- 
ticles indefinitely  near  each  other  will  be 
indefinitely  increased,  though  the  ratio  of 
the  powers  acting  upon  the  remoter  parti- 
cles may  continue  nearly  the  same. 

This  doctrine,  which  however  requires 
to  be  much  more  strictly  examined  by  the 
application  of  mathematical  principles, 
obviously  points  to  a  variety  of  interesting 
consequences.  The  polarity  of  particles, 
or  their  disposition  to  present  themselves 
in  their  approach  to  each  other  in  certain 
aspects,  though  it  has  been  treated  as  a 
chimerical  notion  by  a  few  writers,  is  one 
of  the  first  of  these  results. 

These  are  speculations,  which,  with  re- 
gard to  the  present  state  of  chemistry, 
stand  in  much  the  same  situation  as  the 
theory  of  gravity,  which  is  minutely  de- 
scribed in  Plutarch,  did  with  regard  to  as- 
tronomy before  the  time  of  Newton.  As 
the  celestial  phenomena  were  formerly  ar- 
ranged from  observation  merely,  but  are 
now  computed  from  the  physical  cause, 
gravitation;  so,  at  present,  chemistry  is 
the  science  of  matter  of  fact  duly  arranged, 
without  the  assistance  of  any  extensive 
theory  immediately  deduced  from  the  fi- 
gures, volumes,  densities,  or  mutual  ac- 
tions of  the  particles  of  bodies.  What  it 
may  hereafter  be,  must  depend  on  the 
ability  and  research  of  future  chemists; 
but  at  present  we  must  dismiss  this  remo- 
ter part  of  theory,  to  attend  more  imme- 
diately to  the  facts. 

That  the  parts  of  bodies  do  attract  each 
other,  is  evident  from  that  adhesion  which 
produces  solidity,  and  requires  a  certain 
force  to  overcome  it.  For  the  sake  of  per- 
spicuity, the  various  effects  of  attraction 
have  been  considered  as  different  kinds  of 
affinity  or  powers.  That  power  which 
physical  writers  call  the  attraction  of  co- 
hesion, is  generally  called  the  attraction 
of  aggregation  by  chemists.  Aggregation 
is  considered  as  the  adhesion  of  parts  of 


ATT 


ATT 


th«  same  kind.  Thus  a  number  of  pieces 
of  brimstone  united  by  fusion,  form  an  ag- 
gregate, the  parts  of  which  may  be  sepa- 
rated again  by  mechanical  means.  These 
parts  have  been  called  integrant  parts ; 
that  is  to  say,  the  minutest  parts  into 
which  a  body  can  be  divided,  either  really 
or  by  the  imagination,  so  as  not  to  change 
its  nature,  are  called  integrant  parts. 
Thus,  if  sulphur  and  an  alkali  be  combined 
together,  and  form  liver  of  sulphur,  we 
may  conceive  the  mass  to  be  divided  and 
subdivided  to  an  extreme  degree,  until  at 
length  the  mass  consists  of  merely  a  par- 
ticle of  brimstone  and  a  paricle  of  alkali. 
This  then  is  an  integrant  part ;  and  if  it  be 
divided  further,  the  effect  which  chemists 
call  decomposition  will  take  place;  and 
the  particles  consisting  no  longer  of  liver 
of  sulphur,  but  of  sulphur  alone,  and  al- 
kali alone,  will  be  what  chemists  call  com- 
ponent parts  or  principles. 

The  union  of  bodies  in  a  gross  way  is 
called  mixture.  Thus  sand  and  an  alkali 
may  be  mixed  together.  But  when  the 
very  minute  parts  of  a  body  unite  with 
those  of  another  so  intimately  as  to  form  a 
body,  which  has  properties  different  from 
those  of  either  of  them,  the  union  is  called 
combination,  or  composition.  Thus,  if 
sand  and  an  alkali  be  exposed  to  a  strong 
heat,  the  minute  parts  of  the  mixture  com- 
bine, and  form  glass. 

The  earlier  chemists  were  very  desirous 
of  ascertaining  the  first  principles,  or  ele- 
ments of  bodies ;  and  they  distinguished 
by  this  name  such  substances  as  their  art 
was  incapable  of  rendering  more  simple. 
They  seem  however  to  have  overlooked 
the  obvious  circumstance,  that  the  limits 
of  art  are  not  the  limits  of  nature.  At  pre- 
sent we  hear  little  concerning  elements. 
Those  substances  which  we  have  not 
hitherto  been  able  to  analyze,  or  which,  if 
decomposed,  have  hitherto  eluded  the  ob- 
servation of  chemists,  are  indeed  con- 
sidered as  simple  substances  relative  to 
the  present  state  of  our  knowledge,  but 
in  no  other  respect ;  for  a  variety  of  ex- 
periments give  us  reason  to  hope,  that 
future  enquiries  may  elucidate  their  na- 
ture and  composition.  Some  writers,  cal- 
ling these  simple  substances  by  the  name 
of  Primary  Principles,  have  distinguished 
compounds  of  these  by  the  name  of  Se- 
condary Principles,  which  they  suppose 
to  enter  again  into  combinations  without 
decomposition  or  change.  It  must  be 
confessed,  nevertheless,  that  no  means 
have  yet  been  devised  to  show  whether 
any  such  subordination  of  principles  ex- 
ists. We  may  indeed  discover  that  a  com- 
pound body  consists  of  three  or  more  prin- 
ciples; but  whether  two  of  these  be  pre- 
viously united,  so  as  to  form  a  simple  sub- 
stance with  relation  to  the  third,  or  what 


in  other  respects  may  be  their  arrange- 
ment, we  do  not  know.  That  it  does  ex- 
ist, however,  seems  clear  by  making  com- 
binations  in  varied  orders.  Thus  a  weak 
solution  of  alkali  will  not  dissolve  oil ;  but 
a  combination  of  oil  and  alkali  will  not 
separate  by  the  addition  of  water.  The 
alkali  therefore  adheres  to  that  with  which 
it  was  first  combined.  See  also  the  article 
VEGETABLES. 

If  two  solid  bodies,  disposed  to  combine 
together,  be  brought  into  contact  with 
each  other,  the  particles  which  touch  will 
combine,  and  form  a  compound ;  and  if 
the  temperature  at  which  this  new  com- 
pound assumes  the  fluid  form  be  higher 
than  the  temperature  of  the  experiment, 
the  process  will  go  no  further,  because 
this  new  compound  being  interposed  be- 
tween the  two  bodies,  will  prevent  their 
further  access  to  each  other ;  but  if,  on 
the  contrary,  the  freezing  point  of  the 
compound  be  lower  than  this  temperature, 
liquefaction  will  ensue ;  and  the  fluid  par- 
ticles being  at  liberty  to  arrange  them- 
selves according  to  the  law  of  their  at- 
tractions, the  process  will  go  on,  and  the 
whole  mass  will  gradually  be  converted 
into  a  new  compound  in  the  fluid  state. 
An  instance  of  this  may  be  exhibited  by 
mixing  common  salt  and  perfectly  dry 
pounded  ice  together.  The  crystals  of 
the  salt  alone  will  not  liquefy  unless  very 
much  heated  ;  the  crystals  of  the  water, 
that  is  to  say,  the  ice,  will  not  liquefy  un- 
less heated  as  high  as  thirty-two  degrees 
of  Fahrenheit ;  and  we  have  of  course 
supposed  the  temperature  of  the  experi- 
ment to  be  lower  than  this,  because  our 
water  is  in  the  solid  state.  Now  it  is  a 
well  known  fact,  that  brine,  or  the  satu- 
rated solution  of  sea  salt  in  water,  cannot 
be  frozen  unless  it  be  cooled  thirty-eight 
degrees  lower  than  the  freezing  point  of 
pure  water.  It  follows  then,  that,  if  the 
temperature  of  the  experiment  be  higher 
than  this,  the  first  combinations  of  salt  and 
ice  will  produce  a  fluid  brine,  and  the 
combination  will  proceed  until  the  tem- 
perature of  the  mass  has  gradually  sunk 
as  low  as  the  freezing  point  of  brine  ;  af- 
ter which  it  would  cease,  if  it  were  not 
that  surrounding  bodies  continually  tend 
to  raise, the  temperature.  And  according- 
ly it  is  found  by  experiment,  that,  if  the 
ice  and  the  salt  be  previously  cooled  be- 
low the  temperature  of  freezing  brine, 
the  combination  and  liquefaction  will  not 
take  place.  See  CALORIC. 

The  instances  in  which  solid  bodies  thus 
combine  together  not  being  very  nume- 
rous, and  the  fluidity  which  ensues  imme- 
diately after  the  commencement  of  this 
kind  of  experiment,  have  induced  several 
chemists  to  consider  fluidity  in  one  or 
both  of  the  bodies  applied  to  each  other, 


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to  be  a  necessary  circumstance,  in  order 
that  they  may  produce  chemical  action 
upon  each  other.  Corpora  non  agunt  nisi 
sint  fluida. 

If  one  of  two  bodies  applied  to  each 
other  be  fluid  at  the  temperature  of  the 
experiment,  its  parts  will  successively 
unite  with  the  parts  of  the  solid,  which 
will  by  that  means  be  suspended  in  the 
fluid,  and  disappear.  Such  a  fluid  is  called 
a  solvent  or  menstruum;  and  the  solid 
body  is  said  to  be  dissolved. 

Some  substances  unite  tog-ether  in  all 
proportions.  In  this  way  the  acids  unite 
vith  water.  But  there  are  likewise  many 
substances  which  cannot  be  dissolved  in  a 
fluid,  at  a  settled  temperature,  in  any 
quantity  .beyond  a  certain  proportion. 
Thus,  water  will  dissolve  only  about  one- 
third  of  its  weight  of  common  salt ;  and 
if  more  salt  be  added,  it  will  remain  so- 
lid. A  fluid  which  holds  in  solution  as 
much  of  any  substance  as  it  can  dissolve, 
is  said  to  be  saturated  with  it.  But  satu- 
ration with  one  substance  is  so  far  from 
preventing1  a  fluid  from  dissolving  another 
body,  that  it  very  frequently  happens, 
that  the  solvent  power  of  the  compound 
exceeds  that  of  the  original  fluid  itself. 
Chemists  likewise  use  the  word  saturation 
in  another  sense ;  in  which  it  denotes, 
such  a  union  of  two  bodies  as  produces  a 
compound  the  most  remote  in  its  proper- 
ties from  the  properties  of  the  component 
parts  themselves.  In  combinations  wkere 
one  of  the  principles  predominates,  the  one 
is  said  to  be  supersaturated,  and  the  other 
principle  is  said  to  be  subsaturated. 

Heat  in  general  increases  the  solvent 
power  of  fluids,  probably  by  preventing1 
part  of  the  dissolved  substance  from  con- 
gealing, or  assuming  the  solid  form. 

It  often  happens,  that  bodies  which  have 
no  tendency  to  unite  are  made  to  combine 
together  by  means  of  a  third,  which  is 
then  called  the  medium.  Thus,  water  and 
fat  oils  are  made  to  unite  by  the  medium 
of  an  alkali,  in  the  combination  called 
soap.  Some  writers,  who  seem  desirous 
of  multiplying  terms,  call  this  tendency  to 
unite  the  affinity  of  intermedium.  This  case 
has  likewise  been  called  disposing  affinity  ; 
but  Berthollet  more  properly  styles  it  re- 
ciprocal affinity.  He  likewise  distinguish- 
es affinity  into  elementary,  when  it  is  be- 
tween the  elementary  parts  of  bodies ; 
and  resulting,  when  it  is  to  a  compound 
only,  and  would  not  take  place  with  the 
elements  of  that  compound. 

It  very  frequently  happens,  on  the  con- 
trary, that  the  tendency  of  two  bodies  to 
unite,  or  remain  in  combination  together, 
is  weakened  or  destroved  by  the  addition 
of  a  third.  Thus,  alcohol  unites  with  wa- 
ter in  such  a  manner  as  to  separate  most 
salts  from  it.  A  striking1  instance  of  this 


is  seen  in  a  saturated  or  strong  solution  of 
nitre  in  water,  if  to  this  there  be  added 
an  equal  measure  of  alcohol,  the  greater 
part  of  the  nitre  instantly  falls  down. 
Thus  magnesia  is  separated  from  a  solu- 
tion of  Epsom  salt,  by  the  addition  of  an 
alkali,  which  combines  with  the  sulphuric 
acid,  and  separates  the  earth.  The  prin- 
ciple which  falls  down  is  said  to  be  pre- 
cipitated, and  in  many  instances  is  called 
a  precipitate.  Some  modern  chemists  use 
the  term  precipitation  in  a  more  extended, 
and  rather  forced  sense;  for  they  apply  it 
to  all  substances  thus  separated.  In  this 
enunciation,  therefore,  they  would  say, 
that  potash  precipitates  soda  from  a  solu- 
tion of  common  salt,  though  no  visible 
separation  or  precipitation  takes  place ; 
for  the  soda,  when  disengaged  from  its 
acid,  is  still  suspended  in  the  water  by 
reason  of  its  solubility. 

From  a  great  number  of  facts  of  this  na- 
ture, it  is  clearly  ascertained,  not  as  a  pro- 
bable hypothesis,  but  as  simple  matter  of 
fact,  that  some  bodies  have  a  stronger  ten- 
dency to  unite  than  others  ;  and  that  the 
union  of  any  substance  with  another  will 
exclude,  or  separate,  a  third  substance, 
which  might  have  been  previously  united 
with  one  of  them ;  excepting  only  in  those 
cases  wherein  the  new  compound  has  a 
tendency  to  unite  with  that  third  sub- 
stance, and  form  a  triple  compound.  Tins 
preference  of  uniting,  which  a  given  sub- 
stance is  found  to  exhibit  with  regard  to 
other  bodies,  is  by  an  easy  metaphor  call- 
ed elective  attraction,  and  is  subject  to  a 
variety  of  cases,  according  to  the  number 
and  the  powers  of  the  principles  which  are 
respectively  presented  to  each  other.  The 
cases  which  have  been  most  frequently 
observed  by  chemists,  are  those  called  sim- 
ple elective  attractions,  and  double  elec- 
tive attractions. 

When  a  simple  substance  is  presented 
or  applied  to  another  substance  compoun- 
ded of  two  principles,  and  unites  with  one 
of  these  two  principles  so  as  to  separate 
or  exclude  the  other,  this  effect  is  said  to 
be  produced  by  simple  elective  attrac- 
tion. 

It  may  be  doubted  whether  any  of  our 
operations  have  been  carried  to  this  de- 
gree of  simplicity.  All  the  chemical  prin- 
ciples we  are  acquainted  with  are  simple 
only  with  respect  to  our  power  of  decom- 
posing them ;  and  the  daily  discoveries  of 
our  contemporaries  tend  to  decompose 
those  substances,  which  chemists  a  few 
years  ago  considered  as  simple.  Without 
insisting,  however,  upon  this  difficulty,  we 
may  observe,  that  water  is  concerned  in 
all  the  operations  which  are  called  humid, 
and  beyond  a  doubt  modifies  all  the  effects 
of  such  bodies  as  are  suspended  in  it;  and 
the  variationsk  of  temperature,  whether 


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AIT 


arising  from  an  actual  igneous  fluid,  or 
from  a  mere  modification  of  the  parts  of 
bodies,  also  tend  greatly  to  disturb  the  ef- 
fects of  elective  attraction.  These  causes 
render  it  difficult  to  point  out  an  example 
of  simple  elective  attraction,  which  may 
in  strictness  be  reckoned  as  such. 

Double  elective  attraction  takes  place 
when  two  bodies,  each  consisting  of  two 
principles,  are  presented  to  each  other, 
and  mutually  exchange  a  principle  of  each ; 
by  which  means  two  new  bodies,  or  com- 
pounds, are  produced,  of  a  different  na- 
ture from  the  original  compounds. 

Under  the  same  limitations  as  were 
pointed  out  in  speaking  of  simple  elective 
attraction,  we  may  offer  instances  of  dou- 
ble elective  attraction.  Let  oxide  of  mer- 
cury be  dissolved  to  saturation  in  the  ni- 
tric acid,  the  water  will  then  contain  ni- 
trate of  mercury.  Again,  let  potash  be 
dissolved  to  saturation  in  the  sulphuric 
acid,  and  the  result  will  be  a  solution  of 
sulphate  of  potash.  If  mercury  were  ad- 
ded to  the  latter  solution,  it  would  indeed 
tend  to  unite  with  the  acid,  but  would  pro- 
duce no  decomposition ;  because  the  elec- 
tive attraction  of  the  acid  to  the  alkali  is 
the  strongest.  So  likewise,  if  the  nitric 
acid  alone  be  added  to  it,  its  tendency  to 
unite  with  the  alkali,  strong  as  it  is,  will 
not  effect  any  change,  because  the  alkali 
is  already  in  combination  with  a  stronger 
acid.  But  if  the  nitrate  of  mercury  be 
added  to  the  solution  of  sulphate  of  pot- 
ash, a  change  of  principles  will  take  place, 
the  sulphuric  acid  will  quit  the  alkali,  and 
unite  with  the  mercury,  while  the  nitric 
acid  combines  with  the  alkali ;  and  these 
two  new  salts,  namely,  nitrate  of  potash, 
and  sulphate  of  mercury,  may  be  obtained 
separately  by  crystallization. 

The  most  remarkable  circumstance  in 
this  process  is,  that  the  joint  effects  of  the 
attractions  of  the  sulphuric  acid  to  mercu- 
ry, and  the  nitric  acid  to  alkali,  prove  to 
be  stronger  than  the  sum  of  the  attractions 
between  the  sulphuric  acid  and  the  alkali, 
and  between  the  nitrous  acid  and  the  mer- 
cury ;  for,  if  the  sum  of  these  two  last  had 
not  been  weaker,  the  original  combinations 
would  not  have  been  broken,  f 

f  The  influence  of  insolubility  and  of 
gravity  is  here  too  much  overlooked.  It 
is  a  general  law,  that  when  compounds  are 
mixed,  new  combinations  will  take  place 
between  those  substances,  which,  when 
united,  are  most  insoluble.  The  mercury 
is  of  itself  perfectly  insoluble,  and  it  is 
many  times  heavier  than  potash  or  nitric 
acid.  The  sulphuric  acid  is  much  heavier 
than  the  nitric,  and  forms  with  mercury 
an  insoluble  salt.  Hence  the  superior 
affinity  of  the  nitric  acid  and  potash  to 
water,  as  well  as  gravitation,  tends  to  pre- 
cipitate the  sulphate  of  mercury. 


Mr.  KIrwan,  who  first,  in  the  year  1782, 
considered  this  subject  with  that  attention, 
it  deserves,  called  the  affinities  which  tend 
to  preserve  the  original  combinations,  the 
quiescent  affinities.  He  distinguished  the 
affinities  or  attractions,  which  tend  to  pro- 
duce a  change  of  principles,  by  the  name 
of  the  divellent  affinities. 

Some  eminent  chemists  are  disposed  to 
consider  as  effects  of  double  affinities, 
those  changes  of  principles  only,  which 
would  not  have  taken  place  without  the 
assistance  of  a  fourth  principle.  Thus, 
the  mutual  decomposition  of  sulphate  of 
soda  and  nitrate  of  potash,  in  which  the 
alkalis  are  changed,  and  sulphate  of  potash 
and  nitrate  of  soda  are  produced,  is  not 
considered  by  them  as  an  instance  of  dou- 
ble decomposition  ;  because  the  nitre 
would  have  been  decomposed  by  simple 
elective  attraction,  upon  the  addition  of 
the  acid  only. 

There  are  various  circumstances  which 
modify  the  effects  of  elective  attraction, 
and  have  from  time  to  time  misled  che- 
mists in  their  deductions.  The  chief  of 
these  is  the  temperature,  which,  acting 
differently  upon  the  several  parts  of  com- 
pounded bodies,  seldom  fails  to  alter,  and 
frequently  reverses  the  effects  of  the  af- 
finities. Thus,  if  alcohol  be  added  to  a 
solution  of  nitrate  of  potash,  it  unites  with 
the  water,  and  precipitates  the  salt  at  a 
common  temperature.  But  if  the  tempe- 
rature be  raised,  the  alcohol  rises  on  ac- 
count of  its  volatility,  and  the  salt  is  again 
dissolved.  Thus  again,  if  sulphuric  acid 
be  added,  in  a  common  temperature,  to  a 
combination  of  phosphoric  acid  and  lime, 
it  will  decompose  the  salt,  and  disengage 
the  phosphoric  acid ;  but  if  this  same  mix- 
ture of  these  principles  be  exposed  to  a 
considerable  heat,  the  sulphuric  acid  will 
have  its  attraction  to  the  lime  so  much  di- 
minished, that  it  will  rise,  and  give  place 
again  to  the  phosphoric,  which  will  com- 
bine with  the  lime.  Again,  mercury  kept 
in  a  degree  of  heat  very  nearly  equal  to 
volatilizing  it  will  absorb  oxygen,  and  be- 
come converted  into  the  red  oxide  for- 
merly called  precipitate  per  se  ,•  but  if  the 
heat  be  augmented  still  more,  the  oxygen 
will  assume  the  elastic  state,  and  fly  off, 
leaving  the  mercury  in  its  original  state. 
Numberless  instances  of  the  like  nature 
continually  present  themselves  to  the  ob- 
servation of  chemists,  which  are  sufficient 
to  establish  the  conclusion,  that  the  elec- 
tive attractions  are  not  constant  but  at  one 
and  the  same  temperature. 

Many  philosophers  are  of  opinion,  that 
the  variations  produced  by  change  of  tem- 
perature arise  from  the  elective  attraction 
of  the  matter  of  heat  itself.  But  there 
are  no  decisive  experiments  either  in  con- 
firmation or  refutation  of  this  hypothesis. 

If  we  except  the  operation  of  heat, 


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which  really  produces  a  change  in  the 
elective  attractions,  we  shall  find,  that 
most  of  the  other  difficulties  attending  this 
subject  arise  from  the  imperfect  state  of 
chemical  science.  If  to  a  compound  of 
two  principles  a  third  be  aclclecl,  the  effect 
of  this  must  necessarily  be  different  ac- 
cording to  its  quantity,  and  likewise  ac- 
cording to  the  state  of  saturation  of  the 
two  principles  of  the  compounded  body. 
If  the  third  principle  which  is  added  be  in 
excess,  it  may  dissolve  and  suspend  the 
compound  which  may  be  newly  lormed, 
and  likewise  that  which  might  have  been 
precipitated.  The  metallic  solutions,  de- 
composed by  the  addition  of  an  alkali,  af- 
ford no  precipitate  in  various  cases  when 
the  alkali  is  in  excess ;  because  this  ex- 
cess dissolves  the  precipitate,  which  would 
else  have  fallen  down.  If,  on  the  other 
hand,  one  of  the  two  principles  of  the 
compound  body  be  in  excess,  the  addition 
of  a  third  substance  may  combine  with  that 
excess,  and  leave  a  neutral  substance,  ex- 
hibiting very  different  properties  from  the 
former.  Thus,  if  cream  oi  tartar,  which  is 
a  salt  of  difficult  solubility,  consisting  of 
potash  united  to  an  excess  of  the  acid  of 
tartar,  be  dissolved  in  water,  and  chalk  be 
added,  the  excess  unites  with  part  of  the 
lime  of  the  chalk,  and  forms  a  scarcely  so- 
luble salt;  and  the  neutral  compound, 
which  remains  after  the  privation  of  this 
excess  of  acid,  is  a  very  soluble  salt,  great- 
ly differing  in  taste  and  properties  from 
the  cream  of  tartar.  The  metals  and  the 
acids  likewise  afford  various  phenomena, 
according  to  their  degree  of  oxidation.  A 
determinate  oxidation  is  in  general  neces- 
sary for  the  solution  of  metals  in  acids ; 
and  the  acids  themselves  act  very  differ- 
ently, accordingly  as  they  are  more  or  less 
acidified.  Thus,  the  nitrous  acid  gives 
place  to  acids  which  are  weaker  than  the 
nitric  acid  :  the  sulphurous  acid  gives 
place  to  acids  greatly  inferior  in  attractive 
power  or  affinity  to  the  sulphuric  acid.  The 
deception  arising  from  effects  of  this  na- 
ture is  in  a  great  measure  produced  by 
the  want  of  discrimination  on  the  part  of 
chemical  philosophers ;  it  being  evident, 
that  the  properties  of  any  compound  sub- 
stance depend  as  much  upon  the  propor- 
tion of  its  ingredients,  as  upon  their  re- 
spective nature. 

The  presence  and  quantity  of  water  is 
probably  of  more  consequence  than  is  yet 
supposed.  Thus,  bismuth  is  dissolved  in 
nitrous  acid,  but  falls  when  the  water  is 
much  in  quantity.  The  same  is  true  of 
antimony.  Hibaucout  has  shown  the  last 
(Annales  de  Chimie,  TV.  122.)  in  alum, 
and  it  is  likely  that  the  fact  is  more  com- 
mon than  is  suspected.  Whether  the  at- 
traction and  strength,  as  to  quantity  in 
saturation, be  not  variable  by  the  presence 


or  absence  of  water,  must  be  referred  to 
experiment. 

The  power  of  double  elective  attrac- 
tions too,  is  disturbed  by  this  circumstance. 
If  muriate  of  lime  be  added  to  a  solution 
of  carbonate  of  soda,  they  are  both  decom- 
posed, and  the  results  are  muriate  of  soda 
and  carbonate  of  lime.  But  if  lime  and 
muriate  of  soda  be  mixed  with  just  water 
sufficient  to  make  them  into  a  paste,  and 
this  be  exposed  to  the  action  of  carbonic 
acid  gas,  a  saline  efflorescence  consisting 
of  carbonate  of  soda  will  be  formed  on  the 
surface,  and  the  bottom  of  the  vessel  will 
be  occupied  by  muriate  of  lime  in  a  state 
of  deliquescence. 

M.  Berthollet  made  a  great  number  of 
experiments,  from  which  he  deduced  the 
following  law  : — that  in  elective  attrac- 
tions the  power  exerted  is  not  in  the  ratio 
of  the  affinity  simply,  but  in  a  ratio  com- 
pounded of  the  force  of  affinity  and  the 
quantity  of  the  agent;  so  that  quantity 
may  compensate  for  weaker  affinity.  Thus 
an  acid  which  has,  a  weaker  affinity  than 
another  for  a  given  base,  if  it  be  employed 
in  a  certain  quantity,  is  capable  of  taking 
part  of  that  base  from  the  acid  which  has 
a  stronger  affinity  for  it ;  so  that  the  base 
will  be  divided  between  them  in  the  com- 
pound ratio  of  their  affinity  and  quantity. 
This  division  of  one  substance  between 
two  others,  for  which  it  has  different  af- 
finities, always  takes  place,  according  to 
him,  when  three  such  are  present  under 
circumstances  in  which  they  can  mutually 
act  on  each  other.  And  hence  it  is,  that 
the  force  of  affinity  acts  most  powerfully, 
when  two  sub  -tances-  first  come  into  con- 
tact, and  continues  to  decrease  in  power 
as  either  approaches  the  point  of  satura- 
tion. For  the  same  reason  it  is  so  diffi- 
cult to  separate  the  last  portions  of  any 
substance  adhering  to  another.  Hence, 
if  the  doctrine  laid  down  by  M.  Berthollet 
be  true,  to  its  utmost  extent,  it  must  be 
impossible  ever  to  free  a  compound  com- 
pletely from  any  one  of  its  constituent 
parts  by  the  agency  of  elective  attraction  ; 
so  that  all  our  best  established  analyses 
are  more  or  less  inaccurate. 

The  solubility  or  insolubility  of  princi- 
ples, at  the  temperature  of  any  experi- 
ment, has  likewise  tended  to  mislead 
chemists,  who  have  deduced  consequen- 
ces from  the  first  effects  of  their  experi- 
ments. It  is  evident,  that  many  separations 
may  ensue  without  precipitation ;  because 
this  circumstance  does  not  take  place  un- 
less the  separated  principle  be  insoluble, 
or  nearly  so.  The  soda  cannot  be  preci- 
pitated from  a  solution  of  sulphate  of  soda, 
by  the  addition  of  potash,  because  of  its 
great  solubility  ;  but,  on  the  contrary,  the 
new  compound  itself,  or  sulphate  of  pot- 
ash, which  is  much  less  soluble,  may  fall 


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down,  if  there  be  not  enough  water  pre- 
sent to  suspend  it.  No  certain  knowledge 
ean  therefore  be  derived  from  the  appear- 
ance or  the  want  of  precipitation,  unless 
the  products  be  carefully  examined.  In 
some  instances  all  the  products  remain 
suspended,  and  in  others  they  all  fall 
down,  as  may  be  instanced  in  the  decom- 
position of  sulphate  of  iron  by  lime.  Here 
the  acid  unites  with  the  lime,  and  forms 
sulphate  of  lime,  which  is  scarcely  at  all 
soluble ;  and  the  still  less  soluble  oxide 
of  iron,  which  was  disengaged,  falls  down 
along  with  it. 

Many  instances  present  themselves,  in 
which  decomposition  does  not  take  place, 
but  a  sort  of  equilibrium  of  affinity  is  per- 
ceived. Thus,  soda,  added  to  the  super- 
tartrate  of  potash,  forms  a  triple  salt  by 
•ombining  with  its  excess  of  acid.  So 
likewise  ammonia  combines  with  a  por- 
tion of  the  acid  of  muriate  of  mercury, 
and  forms  the  triple  compound  formerly 
distinguished  by  the  barbarous  name  of 
sal  ale mb roth. 

When  we  reflect  maturely  upon  all  the 
circumstances  enumerated,  or  slightly 
touched  upon,  in  the  foregoing  pages,  we 
may  form  some  idea  of  the  extensive  field 
of  research,  which  yet  remains  to  be  ex 
plored  by  chemists.  If  it  were  possible  to 
procure  simple  substances,  and  combine 
two  together,  and  to  this  combination  of 
two  to  add  one  more  of  the  other  simple 
substances,  the  result  of  the  experiment 
•would  in  many  cases  determine,  by  the 
exclusion  of  one  of  the  three,  that  its  af- 
finity to  either  of  the  remaining-  two  was 
less  than  that  between  those  two  respec- 
tively. In  this  way  it  would  be  ascertain- 
ed, in  the  progress  of  experimental  in- 
quiry, that  the  simple  attractions  of  a  se- 
ries of  substances  were  gradually  increas- 
ing or  diminishing  in  strength.  Thus,  am- 
monia separates  alumina  from  the  sulphu- 
ric acid ;  magnesia,  in  like  manner,  sepa- 
rates the  ammonia  ;  lime  predominates,  in 
the  strength  of  affinity,  over  magnesia,  as 
appears  by  its  separating  this  last  earth  ; 
the  soda  separates  the  lime,  and  itself 
gives  place  to  the  potash ;  and,  lastly, 
potash  yields  its  acid  to  barytes.  The  sim- 
ple elective  attractions  of  these  several 
substances  to  sulphuric  acid,  are  therefore 
in  the  inverted  order  of  their  effects: 
barytes  is  the  strongest ;  and  this  is  suc- 
ceeded regularly  by  potash,  soda,  lime, 
magnesia,  ammonia,  and  alumina.  It  is  evi- 
dent, that  results  of  this  nature,  being 
tabulated,  as  was  first  done  by  the  cele- 
brated Geoffroy,  and  afterwards  by  Berg- 
Tnann,  must  afford  a  valuable  mass  of  che- 
mical knowledge.  It  must  be  remarked, 
however,  that  these  results  merely  indi- 
cfate,  that  the  powers  are  greater  or  less 
than  each  other ;  but  how  much  greater 
or  less  is  not  determined,  either  absolute- 
Vou.  i,  {25} 


ly  or  relatively.  Tables  of  this  nature  can- 
not therefore  inform  us  of  the  etiects 
which  may  take  place  in  the  way  of  dou- 
ble affinity,  for  want  of  the  numerical  re- 
lations between  the  attracting  powers. 
Thus,  when  we  are  in  possession  of  the. 
order  of  the  simple  elective  attractions 
between  the  sulphuric  acid  and  a  series  of 
substances,  and  also  between  the  nitrous 
acid  and  the  same  substances;  and  when, 
in  addition  to  this,  the  respective  powers 
of  each  of  the  acids  upon  every  one  of  the 
substances  singly  taken,  are  known,  so  far 
as  to  determine  which  will  displace  the 
other ;  yet  we  cannot  thence  foretell  the 
result  of  applying  two  combinations  to 
each  other,  each  containing  an  acid  united 
with  one  of  the  number  of  simple  substan- 
ces. Or,  more  concisely,  a  table  of  simple 
elective  attractions  can  be  of  no  use  to 
determine  the  effects  of  double  elective 
attraction,  unless  the  absolute  power  of 
the  attractions  be  expressed  by  number 
instead  of  their  order  merely. 

*  It  has  been  often  remarked,  that  the 
action  of  a  substance  is  diminished  in  pro- 
portion as  it  approaches  to  a  state  of  satu- 
ration ;  and  this  diminution  of  power  has 
been  employed  to  explain  several  chemi- 
cal|f)henomena.  It  is  likewise  known,  that 
the  resistance  found  in  expelling  a  sub- 
stance from  the  last  portions  of  a  combi- 
nation, either  by  affinity  or  heat,  is  much 
greater  than  at  the  commencement  of  the 
decomposition,  and  sometimes  such,  that 
its  entire  decomposition  cannot  be  effec- 
ted. Thus  the  black  oxide  of  manganese 
exposed  to  heat  will  part  with  only  a  cer- 
tain definite  quantity  of  its  oxygen.  No 
degree  of  heat  can  expel  the  whole. 

According  to  Berthollet,  when  two  sub- 
stances  are  in  competition  to  combine 
with  a  third,  each  of  them  obtains  a  de- 
gree of  saturation  proportionate  to  its  af- 
finity multiplied  by  its  quantity,  a  product, 
which  he  denominates  mass.  The  subject 
of  the  combination  divides  its  action  in 
proportion  to  the  masses,  and  by  varying 
the  latter,  this  illustrious  chemist  thinks, 
that  the  results  also  will  be  varied.  The 
following  are  the  forces  which  he  regards 
as  exercising  a  great  influence  upon  che- 
mical combinations  and  phenomena,  by 
concurring  with  or  opposing  the  mutual 
affinity  of  the  substances  brought  into  ac  - 
tion.  1.  The  action  of  solvents,  or  the  af- 
finity which  they  exert  according  to  their 
proportion.  Thus,  if  into  a  very  dilute  so- 
lution of  muriate  of  lime,  a  solution  of  sul- 
phate of  soda  be  poured,  no  precipitate 
of  sulphate  of  lime  will  happen,  though 
the  quantity  of  the  solvent  water  be  lesjs 
than  is  necessary  to  dissolve  the  calcare* 
ous  sulphate.  If  the  same  two  saline  solu^ 
tions  be  mixed  with  less  water,  the  sul- 
phate of  lime  will  fall  in  a  few  seconds,  or 
a  few  minutes,  according  to 


ATT 


ATT 


of  the  mingled  solutions.  2.  The  force  of 
cohesion,  which  is  the  effect  of  the  mutu- 
al affinity  of  the  particles  of  a  substance 
or  combination.  Hence  we  can  easily  see 
why  a  solution  of  pure  potash,  which  so 
readily  dissolves  pulverulent  alumina,  has 
no  effect  on  alumina  concreted  and  con- 
densed in  the  oriental  gems.  The  lowest 
red  heat  kindles  charcoal,  or  determines 
its  combination  with  atmospherical  oxy- 
gen ;  but  a  much  higher  temperature  is 
requisite  to  burn  the  same  carbonaceous 
matter,  more  densely  aggregated  in  the 
diamond.  3.  Elasticity,  whether  natural  or 
produced  by  heat;  which  has,by  some,been 
considered  as  the  affinity  of  caloric,  (f  1) 
Of  the  influence  of  this  power  a  fine  illus- 
tration is  afforded  by  muriate  of  lime  and 
carbonate  of  ammonia.  When  a  solution 
of  the  latter  salt  is  poured  into  one  of  the 
former,  a  double  decomposition  instantly 
takes  place  :  carbonate  of  lime  falls  to  the 
bottom  in  powder,  and  muriate  of  ammo- 
nia floats  above.  Let  this  liquid  mixture 
be  boiled  for  some  time ;  exhalation  of 
ammoniacal  gas  will  be  perceived  by  the 
nostrils,  and  the  carbonate  of  lime  will  be 
redissolved  ;  as  may  be  proved  by  the  fur- 
ther addition  of  carbonate  of  ammonia,  (f  2) 
This  will  cause  an  earthy  precipitate^rom 
the  liquid,  which  prior  to  ebullition  was 
merely  muriate  of  ammonia.  4.  Efflores- 
cence, a  power  which  acts  only  under 
very  rare  circumstances.  It  is  exemplified 
in  the  natron  lakes  of  Egypt  ;  on  the  mar- 
gin of  which,  according  to  Berthollet,  car- 
bonate of  lime  decomposes  muriate  of  so- 
da, in  consequence  of  the  efflorescing 
property  of  the  resulting  carbonate.  5. 
Gravity  likewise  exerts  its  influence,  par- 
ticularly when  it  produces  the  compres- 
sion of  elastic  fluids;  but  it  may  always 
without  inconvenience  be  confounded 
with  the  force  of  cohesion. 

M.  Berthollet  thinks,  that  as  the  tables 
of  affinity  have  all  been  constructed  upon 
the  supposition,  that  substances  possess 
different  degrees  of  affinity,  which  pro- 

(fl)  This  is  obscure.  Elasticity,  as  an  an- 
tagonist of  chemical  affinity,  seems  always 
to  result  from  calorific  repulsion.  Par- 
ticles evidently  arrange  themselves  of 
choice  in  certain  angles,  from  which  they 
may  be  made  to  deviate,  to  a  certain  ex- 
tent, in  obedience  to  exterior  force ;  and 
yet  they  regain  their  figure,  as  soon  as 
unconstrained.  Perhaps  this  is  what  the 
author  means  by  natural  elasticity.  For 
"  affinity  of  caloric"  we  ought  probably  to 
read  effects  of  caloric. 

(|2)  It  is  not  the  carbonate  of  lime,  but 
the  lime  of  the  carbonate,  that  is  redissolv- 
ed. I  question  if  the  "  exhalation"  be  not 
carbonate  of  ammonia,  instead  of  ammonia- 
cal gas* 


duce  the  decompositions  and  combinations 
that  are  formed,  independently  of  the  pro- 
portions and  other  conditions  which  con- 
tribute to  the  results  ;  these  tables  are  cal- 
culated only  to  give  a  false  idea  of  the  de- 
grees of  chemical  action  of  the  substances 
arranged  in  them.  "  The  denomination 
of  elective  affinity,"  says  he,  "  is  in  itself 
erroneous,  since  it  supposes  the  union  of 
one  entire  substance  with  another,  in  pre- 
ference to  a  third,  while  there  is  only  a 
division  of  action,  subject  to  other  chemi- 
cal conditions."  The  force  of  cohesion, 
which  was  formerly  considered  merely  as 
an  obstacle  to  solution,  limits  not  only  the 
quantities  of  substances  which  may  be 
brought  into  action  in  a  liquid,  and  conse- 
quently modifies  the  conditions  of  the  sa- 
turation which  follows ;  but  it  is  the  pow- 
er which  causes  the  precipitations  and 
crystallizations  that  take  place,  and  deter- 
mines the  proportions  of  such  combina- 
tions as  are  made  by  quitting  the  liquid ; 
it  is  this  force  which  sometimes  even  pro- 
duces the  separation  of  a  substance,  with- 
out its  forming  any  combination  -with 
another  substance,  as  has  been  remarked 
in  metallic  precipitations.  Elasticity  acts 
by  producing  effects  opposite  to  those  of 
cohesion,  and  which  consists  either  in 
withdrawing  some  substances  from  the  ac- 
tion of  others  in  a  liquid,  or  in  diminishing 
the  proportion  which  exists  within  the 
sphere  of  activity;  but  when  all  the  sub- 
stances are  in  the  elastic  state,  their  ac- 
tion is  subjected  to  the  same  conditions. 
If  tables  were  formed  which  would  repre- 
sent the  disposition  to  insolubility  or  vo- 
latility, in  the  different  combinations,  they 
would  serve  to  explain  a  great  number  of 
combinations  which  take  their  origin  from 
the  mixture  of  different  substances,  and 
from  the  influence  of  heat.  These  con- 
siderations need  not  prevent  us,  says 
Berthollet,  from  using  the  term  affinity  to 
denote  the  whole  chemical  power  of  a 
body  exerted  in  a  given  situation,  even  by 
its  present  constitution,  its  proportion,  or 
even  by  the  concurrence  of  other  affini- 
ties ;  but  we  must  avoid  considering  this 
power  as  a  constant  force,  which  produces 
compositions  and  decompositions.  All 
substances,  according  to  him,  exert  a  mu- 
tual action  during  the  time  they  are  in 
the  liquid  state ;  so  that  in  a  solution,  for 
example,  of  sulphate  of  potash  and  muri- 
ate of  soda,  these  two  salts  are  not  distinct, 
while  there  is  no  cause  to  determine  the 
separation  from  their  combination;  but 
there  exists  in  this  liquid,  sulphuric  acid, 
muriatic  acid,  soda,  and  potash.  In  like 
manner,  when  the  proper  quantity  of  car- 
bonate of  potash  is  added  to  muriate  of 
soda,  the  mingled  solution  does  not  con- 
sist of  carbonate  of  soda  and  muriate  of 
potash,  resulting  from  complex  affinity, 
but  contains  simply  muriatic  and  carbonic 


ATT 


ATT 


acids  with  potash  and  soda,  in  quadruple 
union  and  saturation.  It  is  the  crystalli- 
zing property  of  the  soda  carbonate, 
which,  after  due  evaporation,  determines 
the  definite  decomposition,  and  not  any 
power  of  elective  attraction.  Or  gene- 
rally, when  one  substance  separates  from 
a  combination  by  the  introduction  of  an- 
other, it  is  not  merely  from  being-  sup- 
planted by  the  superior  affinity  of  an  an- 
tagonist, but  because  its  intrinsic  tenden- 
cy to  the  solid  or  gaseous  form  educes  it 
from  its  former  associate.  There  is  cer- 
tainly much  truth  in  the  proposition  of 
Berthollet. 

But  with  regard  to  the  indefinite  parti- 
tion of  a  base  between  two  rival  acids, 
and  of  an  acid  between  two  rival  bases,  a 
doctrine  which  that  profound  philosopher 
laboured  to  establish  by  a  wide  experi- 
mental induction,  many  facts  of  an  irre- 
concileable  nature  occur.  Sir  II.  Davy 
has  remarked  with  his  usual  good  judg- 
ment, that  were  this  proposition  correct, 
it  is  evident  that  there  could  be  scarcely 
any  definite  proportions ;  a  salt  crystalli- 
zing in  a  strong  alkaline  solution  would 
be  strongly  alkaline ;  in  a  weak  one  less 
alkaline ;  while  in  an  acid  solution  it 
would  be  acid.  But  this  does  not  seem 
to  be  the  case.  In  combinations  of  gaseous 
bodies,  whose  constitution  gives  their  par- 
ticles perfect  freedom  of  motion,  the  pro- 
portions are  definite  and  unchangeable, 
however  we  may  change  the  proportions 
of  the  aeriform  mixture.  And  in  all  solid 
compounds  that  have  been  accurately  ex- 
amined, in  which  there  is  no  chance  of 
mechanical  mixture,  the  same  law  seems 
to  prevail.  Different  bodies  may  indeed 
be  dissolved  in  different  menstrua  in  very 
various  proportions,  but  the  result  maybe 
regarded  as  a  mixture  of  different  solu- 
tions, rather  than  a  combination.  With 
regard  to  glasses  and  metallic  alloys,  ad- 
duced by  Berthollet,  it  is  sufficient  to 
know  that  the  points  of  fusion  of  alkali, 
glass,  and  oxides  of  lead  and  tin,  are  so 
near  each  other,  that  transparent  mixtures 
of  them  may  be  formed.  The  attractive 
power  of  matter  is  undoubtedly  general, 
but  in  the  formation  of  aggregates,  cer- 
tain definite  arrangements  take  place. 
Bergmann  observed  long  ago,  that  when 
nitric  acid  was  digested  on  sulphate  of 
potash,  a  portion  of  nitre  was  formed,  in 
apparent  contradiction  to  the  superior  af- 
finity which  he  had  assigned  to  sulphuric 
acid  for  the  potash.  But  he  also  gave 
what  appears  to  be  a  satisfactory  explana- 
tion of  this  seeming  anomaly,  which  Ber- 
thollet has  adduced  in  support  of  his  views 
of  indefinite  and  universal  partition. 

Sulphuric  acid  tends  to  combine  in  two 
distinct  but  definite  proportions  with  pot- 
ash, forming  the  neutral  sulphate  and  the 
bisulphate,  Nitric  acid  may  therefore  ab- 


stract from  the  neutral  salt,  that  portio.n 
of  potash  which  it  should  lose  to  pass  into 
the  acidulous  salt;  but  it  will  not  deprive 
it  of  any  more.  Hence  this  very  example 
is  decidedly  adverse  to  the  indefinite 
combinations  and  successive  partitions 
taught  by  Berthollet.  The  above  decom- 
position resolves  itself  evidently,  there- 
fore, into  a  case  of  double  affinity.  That  a 
large  quantity  of  pure  potash  can  separate 
a  little  sulphuric  acid  from  the  sulphate 
of  barytes,  has  been  stated  by  Berthollet ; 
but  it  is  a  circumstance  difficult  to  demon- 
strate. If  the  operation  be  conducted 
with  access  of  air,  then  carbonate  of  pot- 
ash is  readily  formed,  and  a  well  known 
double  affinity  comes  into  play,  viz.  that 
of  barytes  for  carbonic  acid  on  one  hand, 
and  of  sulphuric  acid  for  potash  on  the 
other.  Supposing  the  agency  of  carbon- 
ic acid  to  be  excluded,  then  are  we  to 
believe  that  the  potash  having  become  a 
soluble  sulphate,  exists  in  liquid  union 
with  pure  barytes  ?  See  M.  Dulong's  ex- 
periments further  on. 

When  M.  Berthollet  separated  a  little 
potash  from  sulphuric  acid  by  soda,  he 
merely  formed  a  little  bisulphate  of  pot- 
ash, while  the  free  potash  united  to  the 
water  and  alcohol,  for  which  it  has  a 
strong  affinity,  and  sulphate  of  soda  was 
also  formed.  This,  therefore,  is  a  very  in- 
telligible case  of  compound  attraction. 
According  to  M.  Berthollet,  whenever  an 
earth  is  precipitated  from  a  saline  com- 
bination, by  an  alkali,  it  should  carry  down 
with  it  a  portion  of  its  acid  associate.  But 
sulphate  of  magnesia  acted  on  by  potash, 
yields  an  earthy  precipitate,  which,  after 
proper  washing,  betrays  the  presence  of 
no  retained  sulphuric  acid.  The  neutral 
salts  of  soda  and  potash  part  with  none 
of  their  acid  to  magnesia,  by  the  longest 
digestion  in  their  solutions.  If  on  the 
tartrate  of  lime,  or  oxalate  of  lead,  the 
portion  of  sulphuric  acid  adequate  to 
saturate  these  respective  bases  be  poured, 
entire  decomposition  will  be  effected 
without  any  partition  whatever.  Now, 
sulphate  of  lime,  which  is  the  result  in 
the  first  case,  being  actually  a  much  more 
soluble  salt  than  the  tartrate,  we  should 
expect  a  portion  of  the  latter  to  resist  de- 
composition by  the  aid  of  its  cohesive 
force.  A  plate  of  iron  plunged  into  a  so- 
lution of  sulphate  of  copper,  separates  the 
whole  of  the  latter  metal.  An  equally 
absolute  decomposition  is  effected  by 
zinc  on  the  saline  solutions  of  lead  and 
tin.  The  sum  total  of  oxygen  and  acid  is 
here  transferred  to  the  decomposing  body, 
without  any  partition  whatever. 

We  have  already  observed,  that  sul- 
phate of  barytes  digested  in  a  hot  solution 
of  carbonate  of  potash,  gives  birth  to  a 
portion  of  carbonate  of  barytes  and  sul- 
phate of  potash.  But  by  M.  Dulong's  ex- 


ATT 


ATT 


periment,  the  reverse  decomposition  is 
possible,  viz.  carbonate  of  barytes  being- 
digested  in  solution  of  sulphate  of  potash, 
we  obtain  sulphate  of  barytes  and  carbo- 
nate of  potash.  Are  we  hence  to  infer,  that 
Sulphate  of  barytes  and  carbonate  of  potash 
having-  for  some  time  amused  the  operator 
by  the  production  of  an  alkaline  sulphate 
and  earthy  carbonate,  will  change  their 
mood,  and  retracing-  their  steps,  restore 
things  to  their  pristine  condition ;  and  thus 
in  alternate  oscillation  for  ever  ? 

If  chlorine  gas  be  made  to  act  on  the 
oxides  of  mercury,  tin,  or  antimony,  it 
will  unite  to  the  metallic  base,  and  dis- 
place every  particle  of  the  oxygen.  Now, 
the  resulting  chlorides  cannot  owe  their 
purity  to  any  superiority  of  cohesive 
force  which  they  possess  over  the  oxides, 
which,  on  the  contrary,  are  both  denser 
and  more  fixed  than  the  new  compounds. 
Finally,  if  25  parts  of  pure  magnesia  mix- 
ed with  35.6  of  dry  lime,  be  digested  in 
85  parts  of  nitric  acid,  sp.  gr.  1.500,  dilu- 
ted with  water,  we  shall  find  that  the 
whole  lime  will  be  dissolved,  but  not  a 
particle  of  the  magnesia.  On  decanting 
the  neutral  calca-eous  nitrate,  washing 
and  drying  the  earthy  residuum,  we  shall 
procure  the  25  parts  of  magnesia  un- 
changed. 

We  are,  therefore,  entitled  to  affirm, 
that  affinity  is  elective,  acting  in  the  dif- 
ferent chemical  bodies  with  gradations  of 
attractive  force,  liable  however  to  be 
modified,  as  we  have  shown  in  the  case  of 
muriate  of  lime  and  carbonate  of  ammo- 
nia, by  temperature,  and  other  adventi- 
tious powers. 

Decompositions  which  cannot  be  pro- 
duced by  single  attractions,  may  be  effect- 
ed by  double  affinity ;  and  that,  we  may 
expect  with  the  greater  certainty,  a  pri- 
ori, if  one  of  the  two  resulting  compounds 
of  the  double  interchange,  naturally  ex- 
ists in  the  solid  or  aeriform  state.  And  if 
the  one  resulting  compound  be  solid  and 
the  other  gaseous,  then  decomposition 
will  be  certain  and  complete.  This  ap- 
plies with  equal  force  to  single  affinities, 
or  decompositions.  Thus  when  sulphuric 
acid  and  muriate  of  lime  in  due  propor- 
tions are  exposed  to  heat,  a  perfect  de- 
composition is  accomplished,  and  pure 
sulphate  of  lime  and  muriatic  acid  gas  are 
produced.  But  when  the  various  mixed 
ingredients  remain  in  solution,  it  is  then 
reasonable  to  think  with  Berthollet,  that 
a  reciprocal  attraction  pervades  the  whole, 
modifying  its  nature  and  properties.  Thus 
solution  of  sulphate  of  copper  is  blue, 
that  of  muriate  of  copper  is  green.  Now, 
if  into  a  solution  of  the  former  salt,  we 
pour  muriatic  acid,  we  shall  observe  this 
robbing  the  sulphuric  acid  of  a  quantity  of 
the  cupreous  oxide,  proportional  to  its 
mass;  for  the  more  muriatic  acid  we  add, 


the  greener  will  the  liquid  become.  But 
if,  by  concentration,  the  sulphate  of  cop- 
per be  suffered  to  crystallize,  the  pheno- 
mena change ;  a  new  force,  that  ot  crv  stal- 
lization,  is  superaclded,  which  aids  the  af- 
finity of  the  sulphuric  acid,  and  decides 
the  decomposition.  The  surplus  of  each 
of  these  acids  is  employed  in  counterba- 
lancing the  surplus  of  its  antagonist,  and 
need  not  be  considered  as  combined  with 
the  copper.  Here,  however,  we  verge  on 
the  obscure  and  unproductive  domain  of 
chemical  metaphysics,  a  region  in  which 
a  late  respectable  systematist  delighted  to 
expatiate. 

M.  Bethollet  estimates  the  attractive 
forces  or  affinities  of  bodies  of  the  same 
class,  to  be  inversely  as  their  saturating 
quantities.  Thus,  among  acids,  50  parts 
of  real  sulphuric,  will  saturate  as  much 
potash  or  soda  as  67£  of  real  nitric,  and  as 
27  TJ  of  carbonic.  Thus  too,  21i  of  ammo- 
nia will  saturate  as  much  acid  as  25  of 
magnesia,  35 A  of  lime,  and  59£  of  potash. 
Hence  he  infers  'hat  the  carbonic  acid  is 
endowed  with  a  higher  affinity  ihan  the 
sulphuric ;  and  this,  than  the  nitric.  The 
same  proposition  applies  to  ammonia, 
magnesia,  lime  and  potash.  But  in  direct 
hostility  to  this  doctrine,  we  have  seen 
lime  exercise  a  greater  affinity  for  the 
acids  than  magnesia.  And  though  M. 
Berthollet  has  ingeniously  sought  to  ex- 
plain away  the  difficulty  about  potash,  am- 
monia, and  carbonic  acid,  by  referring  to 
the  solid  or  gaseous  results  of  their  action ; 
yet  it  is  hard  to  conceive  of  solidity  opera- 
ting in  producing  an  effect,  before  solidity 
exists,  and  of  elasticity  opera  ing  while 
the  substance  is  solid  or  liquid.  On  this 
point  a  good  syllogism  has  been  offered 
by  SirH.  Davy.  "The  action,"  says  this 
profound  chemist,  "between  the  consti- 
tuents of  a  compound  must  be  mutual. 
Sulphuric  acid,  there  is  every  reason  to 
believe,  has  as  much  attraction  for  barytes, 
as  barytes  has  for  sulphuric  acid,  and  ba- 
rytes is  the  alkaline  substance  of  which 
the  largest  quantity  is  required  to  satu- 
rate sulphuric  acid;  therefore,  on  M.  Ber- 
thollet's  view,  it  has  the  weakest  affinity 
for  that  acid ;  but  less  sulphuric  acid  satu- 
rates this  substance  than  any  other  earthy 
or  alkaline  body.  Therefore,  according 
to  M.  Berthollet,  sulphuric  acid  has  a 
stronger  affinity  for  barytes  than  for  any 
other  substance ;  which  is  contradictory." 

In  the  table  of  chemical  equivalents  at 
the  end  of  the  Dictionary,  will  be  found 
a  view  of  the  definite  proportions  in 
which  the  various  chemical  bodies  com- 
bine, referred  to  their  primary  or  lowest 
numerical  terms,  vulgarly  called  the 
\veigJits  of  the  atoms. 

Mr.  Higgins,  the  real  author  of  the 
Atomic  Theory,  in  first  promulgating  its 
principles  in  his  Comparative  View  of  tl*e 


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Phlogistic  and  Antiphlogistic  Hypotheses, 
connected  their  exposition  with  general 
views  of  the  relative  forces  of  affinity 
among  the  combining  particles.  These 
forces  he  illustrates  by  diagrams,  to  which 
I  have  adverted,  in  the  article  EQ.UIVA- 
XENTS  (CHEMICAL).  This  joint  considera- 
tion of  combining/97'ce1  and  combining  ra- 
tio, .:as  been  neglected  by  subsequent  wri- 
ters ,  A  hence,  Mr.  Higg'ins  says,  "  The 
atomic  doctrine  has  been  applied  by  me 
in  abtruse  and  difficult  researches.  Its  ap- 
plet, jn  by  Mr.  Dalton,  has  been  in  a  ge 
nerui  and  popular  way;  andii  is  from  these 
circumstances  alone,  that  it  gained  the 
name  of  Daltcn's  Theory." 

Since  the  chemical  statics  appeared, 
perhaps  no  chemist  has  contributed  so 
jnany  important  facts  to  the  docrrines  of 
affinity  as  M.  Dulong.  His  admirable  in- 
quiries concerning  the  mutual  decompo- 
sition of  soluble  and  insoluble  salts,  were 
presented  to  the  National  Institute,  and 
afterwards  published  in  the  Annales  de 
Chimie,  torn.  82  ;  from  which  they  were 
translated  into  the  -5th  and  36th  volumes 
of  Nicholson's  Journal,  and  an  abstract  of 
them  was  given  in  the  41st  vol.  of  the 
Phil.  Mag.  Notwithstanding  such  means 
of  notoriety,  it  is  amusing  to  observe  so 
unwearied  a  compiler  as  Dr.  Thomson, 
recently  appropriating  to  his  friend  Mr. 
Phillips,  the  discovery  of  a  fact  observed 
and  recorded  years  before  by  M.  Dulong; 
and  treating  as  an  anomaly,  what  the 
French  philosopher  had  shown  to  be  none, 
but  had  referred  with  equal  sagacity  and 
industry  to  general  principles. 

After  the  labours  ofBergmannandBer- 
thollet,  chemistry  seemed  to  leave  little 
further  to  be  desired,  relative  to  the  mu- 
tual decomposition  of  soluble  salts.  But 
the  insoluble  salts  are  likewise  susceptible 
of  exchanging  their  principles  with  a 
great  number  of  the  soluble  salts.  ''This 
class  of  phenomena,"  says  M.  Dulong, 
"  though  almost  as  numerous  as  that  which 
embraces  the  soluble  salts,  and  capable  of 


lions  which  would  be  requisite  to  asceiv 
tain  them. 

M.  Dulong  found  by  experiment,  that 
all  the  insoluble  salts  are  decomposable 
by  the  carbonate  of  potash  or  the  carbo- 
nate of  soda,  and  in  some  instances  with 
curious  phenomena.  When  sulphate  of 
barytes,  phosphate  of  barytes,  or  oxalate 
of  lime,  is  boiled  with  solution  of  bicarbo- 
nate, or  carbonate  of  potash,  a  considera- 
ble pan  of  the  insoluble  sulphate  is  con- 
stantly transformed  into  a  carbonate  of  the 
same  base  ;  but  on  reaching  a  certain  li- 
mit, the  decomposition  stopped,  although 
there  remained  sometimes  a  very  conside- 
rable quantity  of  the  soluble  carbonate  not 
decomposed.  M.  Dulong  convinced  him- 
self, that  the  different  degrees  of  concen- 
tration of  the  alkaline  solution,  produced 
but  very  slight  variations  in  the  results  of 
this  decomposition.  He  took  10  grammes 
of  dry  subcarbonate  of  potash,  and  7.66, 
being  their  equivalent  proportion,  of  dry 
subcarbonate  of  soda;  quantities  contain- 
ing each  3.07  grammes  of  carbonic  acid. 
They  were  separately  dissolved  in  250 
grammes  of  water,  and  each  solution  was 
kept  in  ebullition  for  two  hours,  on  8 
grammes  of  the  sulphate  of  barytes.  On 
analyzing  the  two  residues,  it  was  found 
that  the  potash  experiment  yielded  2.185 
grammes,  and  the  soda  only  1.833;  or  in 
the  proportion  of  6  to  5.  Is  this  difference 
to  be  ascribed  to  the  difference  in  the  at- 
tractive forces  of  the  two  alkalis ;  to  the 
more  sparing  solubility,  or  greater  attrac- 
tive force  of  the  sulphate  of  potash ;  or 
to  both  causes  conjointly  ? 

Since  the  alkaline  carbonates  lose  their 
decomposing  agency  when  a  certain  pro- 
portion of  the  alkaline  sulphate  is  formed, 
M.  Dulong  tried  to  ascertain  the  limits  by 
the  following  experiment:  7  grammes  of 
sulphate  of  potash,  with  6  of  subcarbo- 
nate, dissolved  in  250  of  water,  were  boil- 
ed with  the  sulphate  of  barytes  for  several 
hours,  without  the  least  trace  of  decompo- 
sition being  evinced.  The  supernatant  li- 


po 

< 


affording  new  resources  to   analysis,  has    quid,  filtered,  and  boiled  on  carbonate  of 

-i barytes,  produced  a  considerable  quantity 

of  sulphate ;  but  ceased  acting  before  this 
sulphate  of  potash  was  exhausted.  The 
same  phenomena  were  obtained  with  car- 
bonate and  sulphate  of  soda.  "  Lastly, 
the  sulphate  of  potash  and  the  sulphate  of 
soda  alone,  and  perfectly  neutral,  re-acted 
likewise  upon  the  carbonate  of  barytes, 
and  produced  on  one  part,  sulphate  of 
barytes,  but  on  the  other  the  subcarbonate 
of  potash  or  soda  which  remained  in  solu- 
tion, together  with  the  portion  of  the  sul- 
phate which  resisted  the  decomposition. 
20  grammes  of  crystallized  sulphate  of  .so- 


il ot  yet  been  examined  in  a  general  man- 
ner." 

The  action  of  the  soluble  carbonates  on 
the  insoluble  salts,  is  the  only  one  which 
had  been  at  all  studied.  Thus  carbonates 
of  potash  and  soda  in  solution,  had  been 
employed  conveniently  to  decompose  sul- 
phate of  barytes.  M.  Dulong  had  an  op- 
portunity in  some  particular  researches,  to 

bserve  a  considerably  extensive  number 
facts,  relating  to  the  mutual  decompo- 
sition of  the  soluble  and  insoluble  salts, 
and  endeavoured,  he  says,  to  determine 
the  general  cause  of  these  phenomena, 
and  the  method  of  foreseeing  their  results, 
without  being  obliged  to  retain  by  an  ef- 
fort of  memory,  of  which  few  persons 
Would  be  capable,  all  the  direct  observa- 


da,  and  10  grammes  of  sulphate  of  potash, 
were  separately  dissolved  in  260  of  water, 
Each  solution  was  boiled  for  2  hours  on 
20  grains  of  carbonate  of  barytes.  The 


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sulphate  of  soda  produced  10.17  gr.  of 
sulphate  of  barytes,  and  the  sulphate  of 
potash  9.87."  Had  108  of  sulphate  of 
potash  been  employed,  which  is  the  true 
equivalent  of  200  sulphate  of  soda  in  crys- 
tals, a  somewhat  larger  product  would 
have  been  obtained  than  9.87.  This  ex- 
periment, however,  is  most  satisfactory 
with  regard  to  the  amount  of  decomposi- 
tion. The  mutual  action  of  the  insoluble 
carbonates,  with  the  soluble  salts,  whose 
acids  form,  with  the  bases  of  these  carbo- 
nates, insoluble  salts,  is  equally  general 
with  that  of  the  soluble  carbonates  on  the 
insoluble  salts.  The  following  is  M.  Du- 
long's  table  of  results : 


Carbonate  of  Earytes. 

Carbo- 
nate of 
Stron- 

tiuu- 

Cnrbo-l 
nate  of 
Lime. 

0 
0 
0 
Id. 

Id. 
Id. 
Id. 
Id. 
Id. 

Id. 

Id. 
Id. 
Id. 
Id. 
Id. 
Id 

Car  bo- 
mteof 
Lead. 

Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 

Sulphate  of  Potash 
Soda 

Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 
Id. 

Phosphate  of  Soda 

Sulphite  of  Potash 
Phosphite  of  Potash 
Soda 

Borate  of  Soda 
Arseniate  of  Potash 
•  •  Soda 

Oxalate  of  Potash 
Ammonia 
Fluate  of  Soda 
Chromate  of  Potash 

All  those  salts  which  have  ammonia  for 
their  base,  are  completely  decomposed  by 
the  insoluble  carbonates  found  in  the  same 
column.  The  new  insoluble  salt  replaces 
the  carbonate  which  is  decomposed,  and 
the  carbonate  of  ammonia  flies  off'.  Hence, 
if  a  sufficient  quantity  of  insoluble  carbo- 
nate be  present,  the  liquid  will  become 
pure  water. 

When  the  soluble  salt  has  an  insoluble 
base,  the  decomposition  does  not  meet 
with  any  obstacle,  but  continues  until  the 
liquid  becomes  mere  water.  Thus,  solu- 
tion of  sulphate  of  magnesia,  boiled  with 
carbonate  of  barytes,  will  be  resolved  into 
an  insoluble  carbonate  and  sulphate,  pro- 
vided enough  of  carbonate  of  barytes  be 
present.  Otherwise  a  portion  of  the  mag- 
nesian  carbonate  being  dissolved  in  its 
own  sulphate,  gives  alkaline  properties  to 
the  solution. 

If  the  base  be  metallic,  it  almost  always 
forms  a  salt  with  excess  of  oxide,  which 
being  insoluble,  precipitates. 

The  general  inferences  of  M.  Dulong's 
inquiries  are  the  following:  1.  That  all 
the  insoluble  salts  are  decomposed  by  the 


subcarbonates  of  potash  or  soda,  but  that 
a  mutual  exchange  of  the  principles  of 
these  salts  cannot  in  any  case  be  complete- 
ly made ;  or  in  other  words,  that  the  de- 
composition of  the  subcarbonates  is  only 
partial.  2.  That  all  the  soluble  salts,  of 
which  the  acid  forms,  with  the  base  of  the 
insoluble  carbonates,  an  insoluble  salt, 
are  decomposed  by  these  carbonates,  un- 
til the  decomposition  has  reached  a  certain 
limit  which  it  cannot  pass. 

When  a  soluble  subcarbonate  acts  on  an 
insoluble  salt,  in  proportion  as  the  carbonic 
acid  is  precipitated  on  the  base  of  the  in- 
soluble salt,  it  is  replaced  in  the  solution 
by  a  quantity  of  another  acid,  capable  of 
completely  neutralizing  the  alkali.  Thus, 
during  the  whole  course  of  the  decompo- 
sition, fresh  quantities  of  neutral  salt  re- 
place the  corresponding  quantities  of  an 
imperfectly  saturated  alkaline  compound; 
and  if  we  view  the  excess  of  alkaline  pow- 
er in  the  undecomposed  subcarbonate,  or 
its  unbalanced  capacity  of  saturation,  as 
acting  upon  both  acids,  it  is  evident  that 
in  proportion  as  the  decomposition  ad- 
vances, the  liquid  approaches  more  and 
more  to  the  neutral  state.  In  the  inverse 
experiment,  a  contrary  change  supervenes. 
Each  portion  of  the  acid  of  the  soluble  salt, 
(sulphate  of  soda  for  example),  which  is 
precipitated  on  the  base  of  the  insoluble 
carbonate,  is  replaced  by  a  quantity  of 
carbonic  acid,  which  forms  with  the  cor- 
responding base,  an  alkaline  subcarbo- 
nate ;  and  the  more  of  the  first  acid  is  pre- 
cipitated upon  the  earthy  base,  the  more 
subcarbonate  the  liquid  contains,  and  the 
further  does  its  state  recede  from  neutrali- 
zation. This  consideration  seems  to  lead 
directly  to  the  following  theory  of  these 
decompositions. 

It  is  known,  says  M.  Dulong,  that  all  the 
salts,  even  those  which  possess  the  great- 
est cohesion,  yield  to  caustic  potash  or  so- 
da, a  more  or  less  considerable  portion  of 
their  acid,  according  to  circumstances. 
Now  the  alkaline  subcarbonates  may  be 
considered  as  weak  alkalis,  which  may 
take  from  all  the  insoluble  salts  a  small 
quantity  of  their  acids.  This  effect  would 
soon  he  limited  if  the  alkali  were  pure,  in 
consequence  of  the  resistance  offered  by 
the  pure  and  soluble  base.  But  the  latter 
meeting  in  the  liquid,  an  acid  with  which 
it  can  form  an  insoluble  salt,  unites  with  it, 
and  thus  re-establishes  the  primitive  con- 
ditions of  the  experiment.  The  same  ef- 
fects are  produced  successively  on  new 
portions  of  the  bodies,  till  the  degree  of 
saturation  of  the  liquid  is  in  equilibrium 
with  the  cohesive  force  of  the  insoluble 
salt,  so  that  the  feebler  this  resistance  may 
be,  the  more  progress  the  decomposition 
will  make.  And  again,  when  an  insoluble 
carbonate  is  in  contact  with  a  neutral  solu- 
ble salt,  the  base  of  the  carbonate  will  tend 


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to  take  part  of  the  acid  of  the  neutral  salt ; 
and  if,  from  this  union,  an  insoluble  salt  can 
result,  the  force  of  cohesion  peculiar  to 
this  compound,  will  determine  the  forma- 
tion. The  carbonic  acid,  released  from 
the  attraction  of  the  earthy  base  by  the 
fixed  acid,  instantly  attaches  itself  to  the 
surrounding1  alkali,  forming1  a  subcarbo- 
nate  which  replaces  the  decomposed  neu- 
tral salt.  The  precipitation  of  the  fixed 
acid  on  the  insoluble  carbonate,  and  the 
absorption  of  carbonic  acid  by  the  liquid 
continues,  until  the  alkalinity  thereby  de- 
veloped, becomes  so  strong1  as  to  resist 
the  precipitation  of  the  acid;  thus  forming 
a  counterpoise  to  the  force  by  which  that 
precipitation  was  accomplished.  All  ac- 
tion then  ceases,  so  that  the  mere  cohesion 
the  insoluble  salt  possesses,  the  greater 
will  be  the  proportion  of  acid  taken  from 
the  soluble  salt. 

When  the  carbonate  of  potash  can  no 
longer  decompose  the  sulphate  of  barytes, 
the  carbonic  acid  which  remains  in  the  so- 
lution, is  to  the  sulphuric  acid  nearly  in 
the  ratio  of  3  to  1 ;  and  when  the  sulphate 
of  potash  can  no  longer  act  upon  the  car- 
bonate of  barytes,  these  two  acids  are 
nearly  in  the  ratio  of  3  to  2 ;  whence  it 
follows,  that  the  first  liquor  is  much  more 
alkaline  than  the  second. 

It  is  easy  to  account  for  this  difference 
by  examining  the  conditions  of  the  equili- 
brium established  in  the  two  cases.  When 
the  sulphate  of  potash  no  longer  decom- 
poses the  carbonate  of  barytes,  it  is  be- 
cause the  excess  of  alkali,  developed  in 
the  liquid,  forms  a  counterpoise  to  the 
power  with  which  sulphate  of  barytes 
tends  to  be  produced  in  these  circumstan- 
ces. And  when  the  subcarbonate  of  pot- 
ash can  no  longer  decompose  the  sulphate 
of  barytes,  it  is  because  there  is  not  such 
an  excess  of  alkali  in  the  liquid,  as  is  capa- 
ble of  overcoming  the  cohesion  and  attrac- 
tion between  the  elements  of  that  salt. 
Now  we  know,  that  it  requires  a  greater 
force  to  overcome  an  existing  attractive 
power,  than  to  maintain  the  quiescent  con- 
dition. Therefore  the  subcarbonate  of 
potash  ought  to  cease  to  decompose  the 
sulphate  of  barytes,  before  the  sulphuric 
and  carbonic  acids  are  in  the  same  rela- 
tion in  which  they  are  found,  when  the 
equilibrium  is  established  by  the  inverse 
experiment.  Hence  we  see,  that  a  mix- 
ture of  sulphate  and  subcarbonate  of  pot- 
ash, in  which  the  proportions  of  their  two 
acids  shall  be  within  the  limits  pointed 
out,  will  have  no  action  either  on  the  sul- 
phate or  carbonate  of  barytes.  For  the 
other  insoluble  salts,  there  will  be  other 
relations  of  quantity ;  but  there  is  always 
a  certain  interval,  more  or  less  considera- 
ble, between  their  limits.  The  mutual 
action  of  sulphate  of  soda  and  carbonate 
of  b.arytes  is  almost  in&tsntaneons,  It  is 


sufficient  to  pour  a  boiling  hot  solution  of 
the  sulphate,  on  the  carbonate  placed  on 
a  filter,  in  order  that  more  than  three- 
fourths  of  the  sulphuric  acid  be  precipi- 
tated, and  replaced  by  a  corresponding 
quantity  of  carbonic  acid. 

In  the  first  part  of  the  Philosophical 
Transactions  for  1809,  we  have  tables  of 
elective  attractions  by  Dr.  Thomas  Young, 
a  philosopher  of  the  very  first  rank,  whom 
the  late  ingenious  Dr.  Wells  pronounced 
the  most  learned  man  in  England.  These 
have  been  unaccountably  overlooked  by 
our  different  systematic  writers,  though 
they  are,  both  in  accuracy  and  ingenuity, 
far  superior  to  the  tables  which,  with  un- 
varying routine  of  typography,  are  copied 
into  their  compilations,  I  conceive  it  will 
be  doing  an  essential  service  to  chemical 
students,  to  lay  before  them  the  tables  of 
lH^  Young,  accompanied  with  his  admira- 
ble remarks  on  the  sequences  of  double 
decompositions. 

Attempts  have  been  made,  by  several 
chemists,  to  obtain  a  series  of  numbers, 
capable  of  representing  the  mutual  attrac- 
tive forces  of  the  component  parts  of  dif- 
ferent salts  ;  but  these  attempts  have 
hitherto  been  confined  within  narrow  li- 
mits, and  have  indeed  been  so  hastily 
abandoned,  that  some  very  important  con- 
sequences, which  necessarily  follow  from 
the  general  principle  of  a  numerical  re- 
presentation, seem  to  have  been  entirely 
overlooked.  It  appears  that  nearly  all  the 
phenomena  of  the  mutual  actions  of  a  hun- 
dred different  salts  may  be  correctly  re- 
presented by  a  hundred  numbers,  while, 
in  the  usual  manner  of  relating  every  case 
as  a,  different  experiment,  above  two  thou- 
sand separate  articles  would  be  required. 

Having  been  engaged  in  the  collection 
of  a  few  of  the  principal  facts  relating  to 
chemistry  and  pharmacy,  Dr.  Young  was 
induced  to  attempt  the  investigation  of  a 
series  of  these  numbers  ;  and  he  has  suc- 
ceeded in  obtaining  such  as  appear  to 
agree  sufficiently  well  with  all  the  cases 
of  double  decompositions  which  are  fully 
established,  the  exceptions  not  exceeding 
twenty,  out  of  about  twelve  hundred  cases 
enumerated  by  Fourcroy.  The  same  num- 
bers agree  in  general  with  the  order  of 
simple  elective  attractions,  as  usually  lai«l 
down  by  chemical  authors ;  but  it  was  of 
so  much  less  importance  to  accommodate 
them  to  these,  that  he  has  not  been  very 
solicitous  to  avoid  a  few  inconsistencies  in 
this  respect ;  especially  as  many  of  the  ba- 
ses of  the  calculation  remain  uncertain? 
and  as  the  common  tables  of  simple  elec- 
tive attractions  arc  certainly  imperfect,  if 
they  are  considered  as  indicating  the  order 
of  the  independent  attractive  forces  of  the 
substances  concerned.  Although  it  can- 
not be  expected  that  these  numbers  should 
be  aceurata  measures  of  the  forces  which 


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they  represent,  yet  they  may  be  supposed 
to  be  tolerable  approximations  to  such 
measures  ;  at  least,  if  any  two  of  them  are 
nearly  in  the  true  proportion,  it  is  proba- 
ble that  the  rest  cannot  deviate  very  far 
from  it :  thus,  if  the  attractive  force  of  the 
phosphoric  acid  for  potash  is  about  eight- 
tenths  of  that  of  the  sulphuric  acid  for 
barytes,  that  of  the  phosphoric  acid  for 
barytes  must  be  about  nine-tenths  as  great. 
But  they  are  calculated  only  to  agree  with 
a  certain  number  of  phenomena,  an<f  will 
probably  require  many  alterations,  as  well 
as  additions,  when  all  other  similar  phe- 
nomena shall  have  been  accurately  inves- 
tigated. 

"There  must  be  a  sequence,"  says  Dr. 
Young-,  "  in  the  simple  elective  attrac- 
tions. For  example,  there  must  be  an 
error  in  the  common  tables  of  elective  at- 
tractions, in  which  magnesia  stands  atl§ve 
ammonia  under  the  sulphuric  acid,  and  be- 
low it  under  the  phosphoric ;  and  the 
phosphoric  acid  stands  above  the  sulphuric 
under  magnesia,  and  below  it  under  am- 
monia ;  since  such  an  arrangement  im- 
plies that  the  order  of  the  attractive  forces 
is  this:  phosphate  of  magnesia,  sulphate 
of  magnesia,  sulphate  of  ammonia,  phos- 
phate of  ammonia,  and  again  phosphate  of 
magnesia ;  which  forms  a  circle,  and  not  a 
sequence.  We  must  therefore  either 
place  magnesia  above  ammonia  under  the 
phosphoric  acid,  or  the  phosphoric  acid 
below  the  sulphuric  under  magnesia;  or 
we  must  abandon  the  principle  of  a  nume- 
rical representation  in  this  particular  case. 

"  In  the  second  place,  there  must  be  an 
agreement  between  the  simple  and  dou- 
ble elective  attractions.  Thus,  if  the  flu- 
oric acid  stands  above  the  nitric  under  ba- 
rita,  and  below  it  under  lime,  the  fluate  of 
barita  cannot  decompose  the  nitrate  of 
lime,  since  the  previous  attractions  of  these 
two  salts  are  respectively  greater  than  the 
divellent  attractions  of  the  nitrate  of  barita 
and  the  fluate  of  lime.  Probably,  there- 
fore, we  ought  to  place  the  fluoric  acid 
below  the  nitric  under  barita  ;  and  we  may 
suppose,  that  when  the  fluoric  acid  has 
appeared  to  form  a  precipitate  with  the 
nitrate  of  barita,  there  has  been  some  fal- 
lacy in  the  experiment. 

"The  third  proposition  is  somewhat  less 
obvious,  but  perhaps  of  greater  utility  : 
there  mustbe  a  continued  sequence  in  the 
order  of  double  elective  attractions ;  that 
is,  between  any  two  acids  we  may  place 
the  different  bases  in  such  an  order,  that 
any  two  salts,  resulting  from  their  union, 
shall  always  decompose  each  other,  un- 
less each  acid  be  united  to  the  base  near- 
est to  it ;  for  example,  sulphuric  acid,  ba- 
rita, potash,  soda,  ammonia,  strontia,  mag- 
nesia, glucina,  alumina,  zirconia,  lime, 
phosphoric  acid.  The  sulphate  of  potash 
decomposes  the  phosphate  of  barita,  be- 


cause the  difference  of  the  attractions  of* 
barita  for  the  sulphuric  and  phosphoric 
acids  is  greater  than  the  difference  of  the 
similar  attractions  of  potash ;  and  in  the 
same  manner,  the  difference  of  the  attrac- 
tions of  potash  is  greater  than  that  of  the 
attractions  of  soda  ;  consequently  the  dif- 
ference of  the  attractions  of  barita  must 
be  much  greater  than  that  of  the  aitrac- 
tions  of  soda,  and  the  sulphate  of  soda 
must  decompose  the  phosphate  of  barita ; 
and  in  the  same  manner  it  may  be  shown, 
that  eacli  base  must  preserve  its  relations 
of  priority  or  posteriority  to  every  other 
in  the  series.  It  is  also  obvious,  that,  for 
similar  reasons,  the  acids  may  be  arranged 
in  a  continued  sequence  between  the  dif- 
ferent bases  ;  and  when  all  the  decompo- 
sitions of  a  certain  number  of  salts  have 
been  investigated,  we  may  form  two  cor- 
responding tables,  one  of  the  sequences  of 
the  buses  with  the  acids,  and  another  of 
those  of  the  acids  with  the  different  bases; 
and  if  either  or  both  of  the  tables  are  im- 
perfect, their  deficiencies  may  often  be 
supplied,  and  their  errors  corrected  by  a 
repeated  comparison  with  each  other." 

In  the  table  of  simple  elective  attrac- 
tions, he  has  retained  the  usual  order  of 
the  different  substances ;  inserting  again 
in  parentheses  such  of  them  as  require  to 
be  transposed,  in  order  to  avoid  inconse- 
quences in  the  simple  attractions  :  He  has 
attached  to  each  combination  marked  with 
an  asterisk  the  number  deduced  from  the 
double  decompositions,  as  expressive  of 
its  attractive  force;  and  where  the  num- 
ber is  inconsistent  with  the  corrected  or- 
der of  the  simple  elective  attractions,  he 
has  enclosed  it  in  a  parenthesis.  Such 
an  apparent  inconsistency  may  perhaps 
in  some  cases  be  unavoidable,  as  it  is  pos- 
sible that  the  different  proportions  of  the 
masses  concerned  in  the  operations  of  sim- 
ple and  compound  decomposition  may 
sometimes  cause  a  real  difference  in  the 
comparative  magnitude  of  the  attractive 
forces.  Those  numbers  to  which  no  aste- 
risk is  affixed,  are  merely  inserted  by  in- 
terpolation, and  they  can  only  be  so  far 
employed  for  determining  the  mutual  ac- 
tions of  the  salts  to  which  they  belong,  as 
the  results  which  they  indicate  would  fol- 
low from  the  comparison  of  any  other 
numbers,  intermediate  to  the  nearest  of 
those  which  are  more  correctly  determi- 
ned. He  was  not  able  to  obtain  a  suffi- 
cient number  of  facts  relating  to  the  me- 
tallic salts,  to  enable  him  to  comprehend 
many  of  them  in  the  tables. 

He  thought  it  necessary  to  make  some 
alterations  "in  the  orthography  generally 
adopted  by  chemists,  not  from  a  want  of 
deference  to  their  individual  authority, 
but  because  it  appeared  to  him  that  there 
are  certain  rules  of  etymology,  which  no 
modern  author  has  a  right  to  set  aside. 


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[26] 


ATT 


ATT 


TABLE  II.  BY  DR.  YOUNG. 


CITRIC 

ACID. 

NITRIC  AND  MURIATIC  ACIDS. 

Barita 

Potash 

Barita 

Potash 

Barita  (10) 

Potash 

Soda 

Potash 

Soda 

Potash 

Soda 

Ammonia 

Soda 

Ammonia 

Soda 

Stroutia 

Magnesia 

Ammonia 

Magnesia 

Ammonia 

Lime 

Glycina 

Magnesia 

Glycina 

Magnesia 

Magnesia  (7) 

Alumina 

Glycina 

Alumina 

Glycina 

Ammonia  (7) 

Zirconia  (8) 

Alumina 

Zirconia 

Alumina 

Glycina 

Barita 

Zirconia 

Barita 

Zirconia 

Alumina 

Strontia 

Strontia  (9) 

Strontia 

Strontia 

Zirconia 

Lime 

Lime 

Lime 

Lime 

MURIATIC 

PHOSPHORIC 

FLUORIC 

SULPHUROUS 

BORACIC 

Potash 

Soda 

Barita  (10) 

Ammonia  (7,11) 

Magnesia  (7) 

Strontia 

Lime 

Glycina 

Alumina 

Zirconia 

CAKBOSIC. 


(7.)  A  triple  salt  is  formed.  (8.)  Fourcroy  says,  that  the  muriate  of  zirconia  decom- 
poses the  phosphates  of  barita  and  strontia.  (9.)  According  to  Fourcroy's  account, 
the  fluate  of  strontia  decomposes  the  muriates  of  ammonia,  and  of  all  the  bases  below 
it ;  but  he  says  in  another  part  of  the  same  volume,  that  the  fluate  of  strontia  is  an  un- 
known salt.  (10.)  According  to  Fourcroy's  account  of  these  combinations,  barita 
should  stand  immediately  below  ammonia  in  both  of  these  columns.  (11.)  With  heat, 
the  carbonate  of  lime  decomposes  the  muriate  of  ammonia, 


PHOSPHORIC  ACID. 


Bariia 

Lime 

Barita                 Potash 

Barita 

Lime 

Barita 

Lime                  Soda 

Lime 

Potash 

Potash 

Potash               Barita 

Potash 

Soda 

Soda 

Soda                  Lime  (13) 

Soda 

Strontia 

Strontia 

Strontia             Strontia 

Strontia 

Magnesia 

Magnesia 

Ammonia(12)  Ammonia 

Magnesia 

Ammonia 

Ammonia 

Magnesia           Magnesia 

Glycina  ? 

Glycina 

Glycina 

Glycina              Glycina 

Alumina 

Alumina 

Alumina 

Alumina            Alumina 

Zirconia 

Zirconia 

Zirconia 

Zirconia             Zirconia 

FLUORIC 

SULPHUROUS 

BORACIC             CARBONIC 

(PHOSPHOROUS) 

(12.)  According  to  Fourcroy,  the  phosphate  of  ammonia  decomposes  the  borate  of 
magnesia.  (13.)  Fourcroy  says,  that  the  carbonate  of  lime  decomposes  the  phos- 
phates of  potash  and  of  soda, 

FLUORIC  ACID. 


Lime 

Lime 

Potash 

Potash 

Barita 

Soda 

Soda 

Strontia 

Lime 

Magnesia 

Potash 

Barita 

Ammonia 

Soda 

Strontia 

Glycina 

Ammonia 

Ammonia  (14) 

Alumina 

Magnesia 

Magnesia 

Zirconia 

Glycina 

Glycina 

Strontia 

Alumina 

Alumina 

Barita 

Zirconia 

Zirconia 

SULPHUROUS 

BOUACIC 

CARBONIC 

(14.)  According  to  Fourcroy,  the  carbonate  of  ammonia  decomposes  the  fluates  of 
arita  and  strontia. 


ATT 


ATT 


DR.  YOUNG'S  SECOND  TABLE— (CONCLUDED.) 
SULPHUROUS  ACID.  BORACIC  ACID. 


Barita 

Potash 

Lime 

Zirconia                Potash 

Strom  ia 

Soda 

Strontia 

Alumina                 Soda 

Potash 

Barita  (15.) 

Barita 

Glycina                 Lime 

Soda 

Strontia 

Zirconia 

Ammonia              Barita 

Ammonia 

Ammonia 

Alumina 

Magnesia               Strontia 

Magnesia 

Lime 

Glycina 

Strontia                 Magnesia 

Lime 

Magnesia 

Magnesia 

Soda                        Ammonia 

Glycina 

Glycina 

Ammonia 

Potash                    Glycina 

Alumina 

Alumina 

Soda 

Barita                     Alumina 

Zirconiu 

Zirconia 

Potash 

Lime                      Zirconia 

BOIIACIC 

CARBONIC 

(NITROUS) 

(PHOSPHOROUS  ?)   CARBOXIC 

(15.)  Fourcroy  says,  that  the  sulphite  of  barita  decomposes  the  carbonate  of  ammonia. 


ITT.  Jl  Table  of  the  Sequences  oftkeJlcids  with  different  Jhises,  by  Dr.  Yotrxa. 


MAG- 
NESIA. 

rs   B 

N  C 
M  P 
P  F 
F  SS 

ss  s 

B  N 
C  M 

AM 


The  comparative  use  of  this  Table  maybe  understood  from  an  example:  If  we  sup- 
pose that  the  nitrate  of  barita  decomposes  the  borate  of  ammonia,  we  must  place  the 
boracic  acid  above  the  nitric,  between  barita  and  ammonia  in  this  Table,  and  conse- 

3uently  barita  below  ammonia,  between  the  fluoric  and  boracic  in  the  former:  hence 
le  boracic  and  fluoric  acids  must  also  be  transposed  between  barita  and  strontia,  and 
between  barita  and  potash  ;  or  if  we  place  the  fluoric  still  higher  than  the  boracic  in 
the  first  instance,  we  must  place  barita  below  ammonia  between  the  nitric  and  fluoric 
acids,  where  indeed  it  is  not  impossible  that  it  ought  to  stand. 


BAIIITA. 

STRONTIA. 

LIME. 

POTASH 

SODA 

Sulphuric    S     C     S 

S     C     S     P    S 

C     P     P     P 

MAGN,=AMM. 

Nitric          N     S     P 

N    SS   P     S    P 

P     F     F     F 

GLYCINA 

Muriatic      M    P  SS 

M   F  SS  SS  SS 

F    B     B    SS 

ALUMINA 

Phosphoric  SS  SS  N 

SS  P    F     F    F 

B    SS     C     S 

ZIRCONIA 

Sulphurous  P     N  M 

C     B    B    B     B 

SS    S    SS  B 

Each  with  every 

Fluoric         C     M   F 

B     S     C    C     N 

S      C     S     N 

subsequent  base 

Boracic        B     F    B 

F    M   N    N   M 

M    N    N    M 

in  this  order, 

Carbonic       F     B    C 

P     N    M    M    C 

N     M    M    C 

STRONTIA    LMPTMG 

LM    PT  MG    AM  GL 

PT    MG    AM    GL 

SD  AM 

SD                      At 

SI)                        AL 

GL 

zn 

ZR 

AL 

ZB 

ATT 


ATT 


IV.  JL  Numerical  Table  of  Elective  Attractions,  by  Dr.  YOUNG. 


BARITA. 

STRONTTA.                     POTASH. 

SODA.          LIME. 

Sulphuric  acid  1000*  Sulphuric  acid  903*  Sulphuric  acid  894*  885*  Oxalic  acid  960 

Oxalic 

950    Phosphoric 

827*  Nitric 

812*  804*  Sulphuric    868* 

Succmic 

930     Oxalic 

825     Muriatic 

804*  797*  Tartaric       867 

Fluoric 

Tartaric 

757    Phosphoric 

801*  795*  Suceinic      866 

Phosphoric 

906*  Fluoric 

Suberic  ? 

745    740    Phosphoric  865* 

Mucic 

900    Nitric 

754*  Fluoric 

671*  666*  Mucic          860 

Nitric 

849*  Muriatic 

748*  Oxalic 

650    645    Nitric           741* 

Muriatic 

840*   (Succmic) 

740    Tartaric 

616    611    Muriatic      736* 

Suberic 

800     (Fluoric) 

*  703    Arsenic 

614    609    Suberic       735 

Citric 

Snccinic 

Suceinic 

612    607    Fluoric        734* 

Tartaric 

760    Citric? 

618     Citric 

610    605    Arsenic       733£ 

Arsenic 

733  £  Lactic 

603     Lactic 

609    6U4    Lactic          732 

(Citric) 

730     Sulphurous 

527*   Benzoic 

608    603    Citric           731 

Lactic 

729    Acetic 

Sulphurous 

488*  484*  Malic            700 

(Fluoric) 

706*  Arsenic 

(733|)  Acetic 

486    482    Benzoie       590 

Benzoic 

597    Boracic 

513*   Mucic 

484    480    Acetic 

Acetic 

594    (Acetic) 

480     Boracic 

482*  479*  Boracic        537* 

Soracic 

(515)*  Nitrous? 

4.  »0     Nitrous 

440    437    Sulphurous  516* 

Sulphurous 

592*  Carbonic 

419*  Carbonic 

306*  304*  (Acetic)       470 

Nitrous 

450 

Prussic 

300    298    Nitrous        425 

Carbonic 

420* 

Carbonic      423* 

Pruss'c 

400 

Prussic        290 

MAGNESIA 

AMMONIA.                      GLYCINA 

?             ALUMINA.  ZIRCONIA? 

Oxalic  acid 

820     Sulphuric  acid 

808*      Sulphuric  acid    718*        709*          700* 

Phosphoric 

Nitric 

731*      Nitric 

642*         634*           626 

Su  phuric 

810*  Muriatic 

729*      Muriatic 

639*         6S2*           625* 

(Phosphoric) 

736*  Phosphoric 

728*      Oxalic 

600          594            588 

Fluoric 

Suberic  ? 

720        Arsenic 

580          575            570 

Arsenic 

733     Fluoric 

613*      Suberic  ? 

535          530            525 

Mucic 

732^  Oxalic 

611        Fluoric 

534*         529*           524* 

Snccinic 

732|  Tartaric 

609        Tartaric 

520          515            510 

Nitric 

732*  Arsenic 

607        Suceinic 

510          505            500 

Muriatic 

728*  Suceinic 

605        Mucic 

425          420            415 

Suberic  ? 

700    Citric 

603        Citric 

415          410            405 

(Fluoric) 

620*  Lactic 

601        Phosphoric 

(648)*     (642)*      (636)* 

Tartaric 

618     Benzoic 

599        Lactic 

410          405            400 

Citric 

615     Sulphurous 

433*      Benzoic 

400          395            390 

Malic  ? 

600?   Acetic 

432        Acetic 

395          391            387 

Lactic 

575    Mucic 

431        Boracic 

388*        385*          382* 

Benzoic 

560     Boracic 

430*      Sulphurous 

355*        351*           347* 

Acetic 

Nitrous 

400        Nitrous 

340          338            332 

Boracic 

459*  Carbonic 

339*      Carbonic 

325*        323*           321* 

Sulphurous 

439*  Prussic 

270       Prussic 

260          258           256 

(Acetic) 

430 

Nitrous 

410 

Carbonic 

366* 

Pruasic 

280 

SULPHURIC. 

NITRIC. 

Barita 

1000* 

Barita 

Strontia 

903* 

Potash 

Potash 

894* 

Soda           ! 

Soda 

885* 

Strontia      I 

Lime 

868* 

Lime           ' 

Magnesia 

810* 

Magnesia 

Ammonia 

808* 

Ammonia 

Glycina 

718* 

Glycina 

Itria 

712 

Alumina      i 

Alumina 

709* 

Zireonia 

Zireonia 

700* 

Acids. 

MURIATIC. 

849*    Barita  840* 

812*    Potash  804* 

804*    Soda  797* 

754*     Strontla  748* 

741*    Lime  736* 

732*     Ammonia  729* 

731*     Magnesia  728* 

642*     Glycina  639* 

634*    Alumina  632* 

626*    Zireonia  625* 


PHOSPHORIC. 
Barita  906* 
Strontia  827* 
Lime  (865)* 
Potash  801* 
Soda  795* 

Ammonia  (728)* 
Magnesia  736* 
Glycina  648* 
Alumina  642* 
Zireonia  636* 


AT 


ATT 


FLTTORIC. 

OXALIC.         TARTARIC.    ARSENIC. 

TuSTGSTIir. 

Lime           734* 

Lime          960 

867 

Lime          733| 

Lime 

Barita          706* 

Barira        930 

760 

Barita         733  1 

Barita 

Strontia        703* 

Strontia    825 

757 

Strontia     733  1 

Strontia 

Magnesia  (620)* 

Magnesia  820 

618 

Magnesia  733 

Magnesia 

Potash         671* 

Potash       650 

616 

Potash        614 

Potash 

Soda             666* 

Soda          645 

611 

Soda           609 

Soda 

Ammonia     613* 

Ammonia  611 

609 

Ammonia  607 

Ammonia 

Glycina         5>4* 

Glycina?   600 

520 

Glycina      580 

Glycina 

Alumina       529* 

Alumina    51'4 

515 

Alumina     575 

AHn:*^ia 

Zirconia       524* 

Zirconia  ?  588 

510 

Zirconia     570 

^tfOoaia 

SUCCINIC. 

SUBERIC. 

CAMPHORIC. 

CITRIC. 

Barita         930 

Barita          800 

Lime 

Lime           731 

Lime           866 

Potash        745 

Potash 

Barita          730 

Strontia?    740 

Soda           740 

Soda 

Strontia       618 

(Magnesia)732£ 

Lime           735 

Barita 

Magnesia     615 

Potash        612 

Ammonia   720 

Ammonia 

Potash         610 

Soda           607 

Magnesia    700 

Glycina  ? 

Soda            605 

Ammonia    605 

Gl>cina?     5;,5? 

Alumina 

Ammonia     603 

Magnesia 

Alumina     530 

Zirconia  ? 

Glycina  ?     415  ? 

Glycina  ?     510 

Zirconia?    525? 

Magnesia 

Alumina      410 

Alumina      505 

Zirconia      405 

Zirconia?   500 

LACTIC. 

BENZOIC. 

SULPHUROUS. 

ACETIC. 

Barita         729 

White  oxide  of 

Barita          592* 

Barita          594 

Potash        609 

arsenic 

Lime          516* 

Potash        486 

Soda           604 

Potash        608 

Potash        488* 

Soda            482 

Strontia      603 

Soda           603 

Soda           484* 

Strontia       480 

Lime          (732) 

Ammonia  599 

Strontia   (527)* 

Lime            470 

Ammonia    601 

Barita         597 

Magnesia    439* 

Ammonia    432 

Magnesia    575 

Lime          590 

Ammonia   433* 

Magnesia    430 

Metallic  oxides 

Magnesia    560 

Glycina       355* 

Metallic  oxides 

Glycina       410 

Glycina?    400? 

Alumina      351* 

Glycina      395 

Alumina     405 

Alumina     395 

Zirconia     347* 

Alumina     391 

Zirconia      400 

Zirconia?    390? 

Zirconia     387 

Mucic  ? 

BORACIC. 

NITROUS  ? 

PHOSPHOROUS, 

Barita         900 

Lime           537* 

Barita         450 

Lime 

Lime           860 

Barita          515* 

Potash        440 

Barita 

Potash        484 

Strontia      513* 

Soda           437 

Strontia 

Soda           480 

•Mo§fiesia(459)* 

Strontia      430 

Potash 

Ammonia   431 

Potash        482* 

Lime          425 

Soda 

Glycina      425 

Soda            479* 

Magnesia    410 

Magnesia  ? 

Alumina     420 

Ammonia    430* 

Ammonia    400 

Ammonia 

Zirconia     415 

Glycina       388* 

Glycina       340 

Glycina 

Alumina     385* 

Alumina      336 

Alumina 

Zirconia      382* 

Zirconia     332 

Zirconia 

CARBOKIC. 

PRUSSIC. 

Barita 

420* 

Barita           400 

Strontia 

419* 

Strontia 

Lime 

(423)* 

Potash         300 

Potash  ? 

306* 

Soda             298 

Soda 

304* 

Lime            290 

Magnesia  (366)* 

Magnesia     280 

Ammonia 

339* 

Ammonia     270 

Glycina 

325* 

Glycina?      260 

Alumina 

323* 

Alumina  ?     258 

Zirconia 

331* 

Zirconia  ?     256 

ATT 


ATT 


TABLES 

OF 

SIMPLE   ELECTIVE   ATTRACTIONS, 
FROM  BERGMANN. 

I.— WATER  AND  COMBUSTIBLE  SUBSTANCES 

IN  THE  HUMID  WAY. 


WATER. 

SULPHUR. 

SALINE 
SULPIIUUKTS. 

ALCOHOL. 

ETHER. 

Potash 

Oxygen 

Oxygen 

Water 

Alcohol 

Soda 

Molybdic  oxide 

Oxide  of  gold 

Ether 

Volatile  oils 

Ammonia 

and  acid 

silver 

Volatile  oils 

Water 

Deliquescent 

Oxide  of  lead 

mercury 

Ammonia 

Sulphur 

salts 

tin 

arsenic 

Fixed  alkali 

Alcohol 

silver 

antimony 

Alkaline     sul- 

Carbonate   of 

mercury 

bismuth 

phurets 

ammonia 

arsenic 

copper 

Sulphur 

Ether 

antimony 

tin 

Muriates 

Sulphuric  acid 
Non-deliques- 

iron 
Potash 

lead 
nickel 

Phosphoric  acic 

cent  salts 

Soda 
Barytes 

cobalt 
manganese 
iron 

FAT  OILS. 

VOLATILE   OILS. 

Lime 

Other  metallic 

Barytes? 

Ether 

Magnesia 

oxides 

Strontian  ? 

Alcohol 

Phosphorus 

Carbon 

Lime 

Fat  oils 

Fat  oils 

Water 

Metallic  oxides 

Fixed  alkalis 

Ammonia 
Ether 

Hydrogen? 

Alcohol 
Ether 

Ethel- 
Volatile  oils 
Fixed  alkalis 

Sulphur 
Phosphorus 

Ammonia 

Sulphur 

IN  THE  DRY  WAY. 

Phosphorus 

SULPHURETTED 

Oxygen 

Manganese 

Potash 

Iron 

Barytes 

Soda 

Copper 

Potash 

Ton 

Tin 

Soda 

Copper 

Lead 

Lime 

rin 

Silver 

Ammonia 

Lead 

Gold 

Magnesia 

Silver 

Antimony 

Zircon 

Cobalt 

Cobalt 

Nickel 

Nickel 

j  Bismuth 

Bismuth 

Antimony 

Mercury 

Mercury 

Arsenic 

(Arsenic 

Carbon  ? 

Uranium  ? 

Molybdena 

Tellurium 

ATT 


ATT 


TABLE  OF  SIMPLE  ELECTIVE  ATTRACTIONS. 

II._ OXYGHEN  AND  METALS. 

IN  THE  HUMID  WAY. 


OXIDE  OF 

OXIDE  OF 

OXIDE  OF 

OXIDE  OF 

OXIDE  OF^ 

OXYGEK. 

GOLD. 

SILVER. 

PLATINA. 

MERCURT. 

LEAD. 

Zinc 

Acids,  gallic 

Acids,  gallic 

Acids,  gallic 

Acids,  gallic 

Acids,  gallic 

Iron 

muriatic 

muriatic 

muriatic 

muriatic 

sulphuric 

Tin 

nitric 

oxalic 

nitric 

oxalic 

mucic 

Antimony 

sulphuric 

sulphuric 

sulphuric 

succinic 

oxalic 

Arsenic 

arsenic 

mucic 

arsenic 

phospho- 

arsenic 

Lead 

fluoric 

phospho- 

fluoric 

ric 

tartaric 

Bismuth 

tartaric 

ric 

tartaric 

sulphuric 

phospho- 

Copper 

phospho- 

sulphu- 

phospho- 

mucic 

ric 

Platinum 

ric 

rous 

ric 

tartaric 

muriatic 

Mercury 

acetic 

nitric 

oxalic 

citric 

sulphu- 

("Palladium 

sebacic 

arsenic 

citric 

malic 

rous 

J  Rhodium 

prussic 

fluoric 

acetic 

sulphu- 

suberic 

j  Iridium 

?ixed  alkalis 

tartaric 

succinic 

rous 

nitric 

^Osmium 

Ammona 

citric 

prussic 

nitric 

fluoric 

Silver 

Sulphuretted 

succinic 

carbonic 

fluoric 

citric 

Gold 

hydrogen 

acetic 

Ammonia 

acetic 

malic 

prussic 

benzoic 

succinic 

carbonic 

boracic 

acetic 

Ammonia 

prussic 

benzoic 

carbonic 

boracic 

Ammonia 

prussic 

carbonic 

IV           J       11        1  "  « 

IN  THE  DRY  WAY. 

r  ixed  alkalis 
Fat  oils 

Ammonia 

GOLD. 

SiLVEK. 

PLATINA. 

MERCURY. 

LEAD. 

Titanium 

Mercury 

Lead 

Arsenic 

Gold 

Gold 

Manganese 

Copper 

Copper 

Gold 

Silver 

Silver 

Zinc 

Silver 

Mercury 

Copper 

rMatina 

Copper 

Iron 

Lead 

Bismuth 

Tin 

Lead 

Mercury 

Tin 

Bismuth 

Tin 

Bismuth 

Tin 

Bismuth 

Uranium 

Tin 

Gold 

Zinc 

Zinc 

Tin 

Molybdena 

Antimony 

Antimony 

Antimony 

Bismuth 

Antimony 

'Tungsten 
Cobalt 

Iron 
Platina 

Iron 

Manganese 

Nickel 
Cobalt 

Hopper 
Antimony 

Platina 
Arsenic 

Antimony 

Zinc 

Zinc 

Manganese 

Arsenic 

Zinc 

Nickel 

Nickel 

Arsenic 

Iron 

Iron 

Nickel 

Arsenic 

Arsenic 

Nickel 

Lead 

Alkaline  sul- 

Iron 

Chromium 

Cobalt 

Platina 

Silver 

phurets 

Alkaline  sul- 

Bismuth 
Lead 

Manganese 
Alkaline  sul- 

Alkaline  sul 
phurets 

Mercury 
Alkaline  sul 

Sulphur 

phurets 
Sulphur 

Copper 
Tellurium 

phurets 

phurets 

Platinum 

Mercury 

Silver 

Gold 

Hydrogen 

Carbon 

Boron 
Phosphorus 
Sulphur 
Azote 

The  column  under  oxygen  is  divided  into  two  parts.     The  first  exliibits 
the  order  in  which  the  metals  precipitate  one  another  from  acid  solutions  ; 
the  second,  according  to  Vauquelin,  shows  the  affinities  of  the  metals  for 
oxygen,  represented  by  the  difficulty  with  which  their  oxides  are  decompo- 
sed bvheat.     It  is  different  from  Berqrmann's  column. 

Chlorine 

*                                                     & 

ATT 


ATT 


TABLE  OP  SIMPLE  ELECTIVE  ATTRACTIONS. 

METALS— (CONTINUED). 

IN  THE  HUMID  WAY. 


OXIDE  OF 

OXIDE  OF 

OXIDE  OF 

OXIDE  OF 

OXIDE  or 

OXIDE  OF 

COPPER. 

IHOTV. 

Tw. 

BISMUTH. 

NlCKE',. 

ARSEMC. 

Acids,  gallic 
oxalic 

Acids,  gallic 
oxalic 

Acids,  gallic 
tartaric 

Acids,  oxalic 
arsenic 

Acids,  oxalic 
muriatic 

Acids,  gallic 
muriatic 

tartaric 

tartaric 

muriatic 

tartaric 

sulphuric 

oxalic 

muriatic 

campho- 

sulphuric 

phospho- 

tartaric 

sulphuric 

sulphuric 

ric 

oxalic 

ric 

nitric 

nitric 

mucic 

sulphuric 

arsenic 

sulphuric 

sebacic 

sebacic 

nitric 

mucic 

phospho- 

muriatic 

phospho- 

tartaric 

arsenic 

muriatic 

ric 

nitric 

ric 

phospho- 

phospho- 

nitric 

nitric 

fluoric 

fluoric 

ric 

ric 

phospho- 

succinic 

mucic 

mucic 

fluoric 

succinic 

ric 

fluoric 

succinic 

Succinic 

mucic 

fluoric 

arsenic 

mucic 

ci  ric 

citric 

succinic 

citric 

fluoric 

citric 

acetic 

acetic 

citric 

acetic 

succinic 

acetic 

prussic 

arsenic 

arsenic 

boracic 

citric 

boracic 

carbonic 

boracic 

acetic 

prussic 

acetic 

prussic 

Ammonia 

prussic 

prussic 

carbonic 

boracic 

Potash 

carbonic 

Fixed  ni  kalis 

Potash 

prassic 

Soda 

Ammonia 

Ammonia 

Soda 

carbonic 

Ammonia 

Fat  oils 

Ammonia 

Water 

Compound 

salts 

Fat  oils 

=sr 

IN  THE  DRY  WAY. 

T™. 

BISMUTH. 

NICKEL. 

ABSEMC. 

Gold 

Nickel 

Zinc 

Lead 

Iron 

Nickel 

Silver 

Cobalt 

Mercury 

Silver 

Cobalt 

Cobalt 

Iron 
Arsenic 
Manganese 
Zinc 

Manganese 
Arsenic 
Copper 
Gold 

Copper 
Antimony 
Gold 
silver 

Gold 
Mercury 
Antimony 
Tin 

Arsenic 
Copper 
Gold 
Tin 

Copper 
Iron 
Silver 
Tin 

Antimony 
Platina 

Silver 
Tin 

Lead 
Iron 

Copper 
Platina 

Antimony 
Platina 

Lead 
Gold 

Tin 
Lead 

Antimony 
Platina 

Manganese 
Nickel 

Nickel 
Iron 

Bismuth 
Lead 

Platina 
Zinc 

Nickel 
Bismuth 
Cobalt 
Mercury 
Alkaline  sul- 
phurets 

Bismuth 
Lead 
Alkaline  sul- 
phurets 
Sulphur 

Arsenic 
Platina 
Bismuth 
Cobalt 
Alkaline  sul- 
phurets 

Zinc 
Alkaline  sul- 
phurets 
Sulphur 

Silver 
Zinc 
Alkaline  sul- 
Shurets 
phur 

Antimony 
Alkaline  sul- 
phurets 
Sulphur 

Sulphur 

Sulphur 

ATT 


ATT 


TABLE  OF  SIMPLE  ELECTIVE  ATTRACTIONS. 
METALS— -(CONCLUDED.) 


IX  THE  HUMID  WAY. 


OXIDE  OF 

OXIUE  OF 

OXUIE  OF 

OXIDE  OF 

OXIJJE  OF 

OXIDE  OF 

COBAi.T. 

ZlKC, 

ANTIMONY. 

MANGANESE. 

TELLURIUM. 

TITANIUM. 

Acids,  oxalic 

Acids,  gallic 

Acids,  gallic 

Acids,  oxalic 

Acids,  nitric 

Acids,  sulphu- 

muriatic 

oxalic 

muriatic 

tartaric 

nitro-mu- 

ric 

sulphuric 

sulphuric 

benzoic 

citric 

riatic 

nitric 

tartaric 

muriatic 

oxalic 

fluoric 

sulphuric 

muriatic 

nitric       ', 

mucic 

sulphuric 

phospho- 

Sulphur 

prussic 

phospho- 

nitric 

nitri« 

ric 

Alkalis 

ric 

tartaric 

tartaric 

nitric 

Mercury 

fluoric 

phospho- 

mucic 

sulphuric 

muclc 

ric 

phospho- 

muriatic 

~ 

succinic 

citric 

ric 

arsenic 

OXIDE  OP 

citric 

succinic 

citric 

acetic 

URANIUM. 

acetic 
arsenic 

fluoric 
arsenic 

succinic 
fluoric 

prussic 
carbonic 

Acids,  sulphu- 

boracic 

acetic 

arsenic 

ric 

prussic 

boracic 

acetic 

nitro-mu- 

carbonic 

prussic 

boracic 

riatic 

Ammonia 

carbonic 
Fixed  alkalis 

prussic 
carbonic 

muriatic 
nitric 

Ammonia 

Sulphur 

phospho- 

Fixed alkalis 

ric 

Ammonia 

acetic 

gallic 

prussic 
carbonic 

IN  THE  DRY  WAY. 

Sulphur 

COBALT. 

ZINC. 

ANTIMONY. 

MANGANESE. 

TJELLIBIUM. 

Iron 

Copper 

ron 

Hopper 

Mercury 

Nickel 

Antimony 

Copper 

Iron 

Sulphur 

Arsenic 

Tin 

Tin 

Gold 

Copper 

Mercury 

^ead 

Silver 

Gold 

Silver 

Nickel 

Tin 

Platina 

Gold 

Silver 

Alkaline  sul- 

Tin 

Cobalt 

Bismuth 

phurets 

Antimony 

Arsenic 

Zinc 

Zinc 

Platina 

Sold 

Alkaline  sul- 

Bismuth 

Platina 

phurets 

Lead 

Mercury 

Sulphur 

Nickel 

Arsenic 

Iron 

Cobalt 

Alkaline  sul- 

phurcts 

Sulphur 

ATT 


ATT 


SCHEMES  OF  DOUBLE  AFFINITIES  IN  THE  HUMID  \VAY, 


TSulphuric 

acid 
Sulphate 

of       <(      50 
Magnesia    | 

Fluoric 
\_Magnesia      acid 

^    -    "    - 


£ 

Aneni-    Oxygen*} 

^         Oxygen 


ous 
acid    1 


> 
l^ArsenicJ  J 

Arsenic  acid 


acid 


Sulphuret 
oi  lime 


Sulphate  of  lime 


"Lime      54  Sulphuric 
acid 


^Sulphur 


Nitre 


Nitrate  of 
lime 


"Nitric 
acid 

44 

Sulphuric 
^Lime    54        acid 


Sulphate  of  lime 
Acetate  of  potash 

26   Acetic 
acid 


Sulphupet 
of  potash 


Sulphate 
ofpot- 


^Sulphur 
v ^ 

Muriate  of  potash 

"Potash     32  Muriatic 
acid 


62 


-f   23 

54 


85 


Sulphu- 
j-ic  acid    86        Limo_ 


Sulphate  of  lime 


Muriate 
^of  lime 


"Potash    58    Nitric  "\ 

fPotash    62  Sulphu-^ 

Sulphate 
of  pot-     ^ 

«"                          «icl 

62                          iKitrate 
fofleaa 

ric  acid 
Muriate  j 
of  pot-   -^      32         -j-  54  =  86 

Bul- 

-phute  of 

ash 

• 

frsll 

lime 

Sulphuric     Oxide  of  { 

1  Muriatic  £? 

„    acid              lead    J 

L    acid      85      Limej 

Sulphate  of  lead 

Nitrate  of  ammonia 

Nitrate  of  soda 

r           —  -^ 
'Ammo-    38     Nitric~) 

"Soda               Nitric  " 

nia                 ucid 

acid 

Sulphate 

Nitrate 

of  am-     s 

46                            Vof  mer- 

Com-      < 

>N5trate 

moiiia 

cury 

mon  salt 

of  silver 

Sulphuric    Oxide  of 

Muriatic 

acid         mercury., 

acid               Silver^ 

V-                                                          J 

^  j 

Sulphate  of  mercury 

Muriate  of  silver 

AUR 


AX1 


*  AtreiTE.     Pyroxene   of  Haiiy.    This 
mineral  is  for  the  most  part  crystallized  in 
small  six  or  eight-sided  prisms,  with  dihe- 
dral summits.     It  is  found  also  in  grains. 
Its  colours  are  green,  brown,  and  black. 
Internal  luster  shining.    Uneven  fracture. 
Translucent.    Easily  broken.  It  Scratches 
g-lass.     Sp.  gr.  3.3.     Melts  into  a  black 
enamel.       Its  composition  according  to 
Klaproth,  is  48  silica,  24  lime,  12  oxide  of 
iron,  8.75  magnesia,  5  alumina,  1  manga- 
nese   It  is  met  with  among  volcanic  rocks 
but  is  supposed  to  have  existed  prior  to 
the    eruption,   and  ejection  of  the  lava. 
Larg*   crystals  of  it  are  also  found  in  ba- 
salt, of  a  finer  green  and  more  brilliant 
than  those  found  in  lavas.     It  occurs  with 
olivin   in  the  basalt  of  Teesdale ;  in  the 
trap  rocks  round  Edinburgh ;  and  in  seve- 
ral of  the  Hebrides. 

Sahlite  and  coccolite  are  considered  to 
be  varieties  of  augite.* 

AUKUM  FUL^II*  ANS.    See  FcMiiTfATTjrG. 

*  AUHUM  GUAPHICUM.  See  OiiEsof  Gold* 
AURCM  Musivtnvr,  or  MOSAICUM.  A  com- 
bination of  tin  and  sulphur,  which  is  thus 
made  :    Melt  12  ounces  of  tin,  and  add  to 
it  three  ounces  of  mercury ;  triturate  this 
amalgam  with  seven  ounces  of  sulphur 
and  three  of  muriate  of  ammonia.    Put 
the  powder  into  a  matrass,  bedded  rather 
deep  in  sand,  and  keep  it  for  several  hours 
in  a  gentle  heat ;  which  is  afterward  to  be 
raised,  and  continued  for  several  hours 
longer.    If  the  heat  have  been  moderate 
and  not  continued  too  long,  the  golden- 
coloured  scaly  porous  mass,  called  aimim 
Tnusivum,  will  be  found  at  the  bottom  of 
the  vessel ;  but  if  it  have  been  too  strong, 
the  aurum  musivum  fuses  to  a  black  mass 
of  a  striated  texture.    This  process  is  thus 
explained  :  As  the  heat  increases,  the  tin, 
by  stronger  affinity,  seizes  and  combines 
with  the  muriatic  acid  of  the  muriate  of 
ammonia;  while  the  alkali  of  that  salt, 
combining  with  a  portion  of  the  sulphur, 
flies  off  in  the  form  of  a  sulphuret.     The 
combination  of  tin  and  muriatic  acid  sub- 
limes ;  and  is  found  adhering  to  the  sides 
ofthemalrass.  The  mercury  which  served 
to  divide  the  tin,  combines  with  part  of  the 
sulphur,  and  forms  cinnabar,  which  also 
sublimes  ;    and  the   remaining  sulphur, 
with  the  remaining  tin  forms  the  aurum 
musivum,  which   occupies  the  lower  part 
of  the  vessel.    It  must  be  admitted,  how- 
ever, that  this  explanation  does  not  in- 
dicate the  reasons  why  such  an  indirect 
and  complicated  process  should  be  re- 
quired to  form  a  simple  combination  of 
tin  and  sulphur. 

It  does  not  appear  that  the  proportions 
of  the  materials  require  to  be  strictly  at- 
tended to.  The  process  of  the  Marquis 
<le  Bullion,  as  described  by  Chaptal  in  his 
Elements  of  Chemistry,  consists  in  amal- 


gamating eight  ounces  of  tin  with  eight 
ounces  of  mercury,  and  mixing  this  with 
six  ounces  of  sulphur,  and  four  of  muri- 
ate of  ammonia.  This  mixture  is  to  be 
exposed  for  three  hours  on  a  sand  heat 
sufficient  to  render  the  bottom  of  the  ma- 
trass obscurely  red-hot.  But  Chaptal  him- 
self found,  that  if  the  matrass  containing 
the  mixture  were  exposed  to  a  naked  fire 
and  violently  heated,  the  mixture  took  fire 
and  a  sublimate  was  formed  in  the  neck  of 
the  matrass,  consisting  of  the  most  beau- 
tiful  aurum  musivum  in  large  hexagonal 
plates. 

Aurum  musivum  has  no  taste,  though 
some  specimens  exhibit  a  sulphureous 
smell.  It  is  not  soluble  in  water,  acids,  or 
alkaline  solutions.  Hut  in  the  dry  way  it 
forms  a  yellow  sulphuret,  soluble  in  water. 
It  deflagrates  with  nitre.  Bergmann  men- 
tions a  native  aurum  musivum  from  Sibe- 
ria, containing  tin,  sulphur,  and  a  small  pro- 
portion of  copper. 

Aurum  musivum  is  used  as  a  pigment 
for  giving  a  golden  colour  to  small  statue 
or  plaster  figures.  It  is  likewise  said  to 
be  mixed  with  melted  glass  to  imitate  la- 
pis lazuli. 

*  Mosaic  gold  is  composed  of  100  tin-f- 
56.25  sulphur,  by  Dr.  John  Davy;  and  of 
100  tin  -f-  52.3  sulphur,  by  Professor  Ber- 
zelius ;  the  mean  of  which,  or  100  +  54.2 
is  probably  correct.     It  will  then  consist 
of  1  prime  of  tin  =  7.375  +  2  sulphur^ 
4.<V 

*  AvANTtrniNE.  A  variety  of  quartz  rock 
containing  mica  spangles.  The  most  beau- 
tiful comes  from  Spain,  but  Dr.  M'Cullocli 
found  specimens  at  Glen  Fernat  in  Scot- 
land, which,  when  polished,   were  equal 
in  beauty  to  any  of  the  foreign.  The  most 
usual  colour  of  the  base  of  avanturine  is 
brown,  or  reddish -brown,  enclosing  gold- 
en coloured  spangles.* 

*  AXE-STOSE.      A  subspecies    of  jade, 
from  which  it  differs  in  not  being  of  so 
light  a  green,  and  in  having  a  somewhat 
slaty  texture.     The  natives  of  New  Zea- 
land work  it  into  hatchets.     It  is  found 
in  Corsica,  Switzerland,    Saxony,  and  on 
the  banks  of  the  river  Amazons,  whence 
it  has  been  called  Amazonian  stone.    Its 
constituents  are  silica  50.5,  magnesia  31, 
alumina  10,  oxide  of  iron  5.5,  water  2.75, 
oxide  of  chromium  0.05.* 

*  AXINITE,  or  THmiEnsTOKE.  This 
mineral  is  sometimes  massive,  but  most, 
usually  crystallized.  The  crystals  resem- 
ble an  axe  in  the  form  and  sharpness  of 
their  edges;  being  flat  rhomboidal  pa- 
rallelopipeds,  with  two  of  the  opposite 
edges  wanting,  and  a  small  face  instead  of 
each.  They  are  translucent,  and  of  a  vio- 
let colour,  whence  called  violet  schorl. 
They  become  electric  by  heat.  The  usual 
colour  is  clove-brown.  Lustre  splendent. 


AZU 


AZU 


Hard,  but  yields  to  the  file,  and  easily 
broken.  Sp.  gr.  3.25.  It  froths  like  zeo- 
lite before  the  blow-pipe,  melting-  into  a 
black  enamel,  or  a  dark  green  glass.  Ac- 
cording- to  Vauquelin's  analysis,  it  con- 
tains 44  silica,  18  alumina,  19  lirne,  14  ox- 
ide of  iron,  and  4  oxide  of  manganese.  It 
is  found  in  beds  at  Thum  in  Saxony;  in 
Killas  at  Botallack  near  the  Land's-end, 
Cornwall ;  and  at  Trewellard  in  that  neigh- 
bourhood.* 

AZOTE.     See  GAS  (NITROGEN). 

*  AZURE-STONE,  or  LAPIS  LAZULI.  This 
massive  mineral  is  of  a  fine  azure  blue  co- 
lour. Lustre  glistening.  Fine  grained 
uneven  fracture.  Scratches  glass,  but 
scarcely  strikes  fire  with  steel.  Opaque, 
or  translucent  on  the  very  edges.  Easily 
broken.  Sp.  grav.  2.85.  In  a  very  strong- 
heat  it  intumesces,  and  melts  into  a  yel- 
lowish-black mass.  After  calcination  it 
forms  a  jelly  with  acids.  It  consists  of  46 
silica,  28  lime,  14.5  alumina,  3  oxide  of 
iron,  6.5  sulphate  of  lime,  and  2.  water, 
according  to  Klaproth.  Hut  by  a  later 
and  most  interesting  research  of  MM.  Cle- 
ment and  Desormes,  lapis  lazuli  appears 
to  be  composed  of  34  silica,  33  alumina,  3 
sulphur,  and  22  soda.  (Ann.  de  Chimie, 
torn.  57.)  In  this  analysis,  however,  a 
loss  of  eight  per  cent  was  experienced. 
These  distinguished  chemists  consider  the 
above  ingredients  essential,  and  the  2.4  of 
lime  and  1.5  of  iron,  which  they  have  oc- 
casionally met  with,  as  accidental.  It  is 
from  azure-stone  that  the  beautiful  and  un- 


changeable blue  colour  ultramarine  is  p?^V 
pared.  The  finest  specimens  are  brought 
from  China,  Persia,  and  Great  Bucharia. 
They  are  made  red-hot  in  the  fire,  and 
thrown  into  water  to  render  them  easily 
pulverizable.  They  are  then  reduced  to 
a  fine  powder,  and  intimately  combined 
with  a  varnish,  formed  of  rosin,  wax,  and 
boiled  linseed  oil.  This  pasty  mixture  is> 
put  into  a  linen  cloth,  and  repeatedly 
kneaded  with  hot  water :  the  first  wateiv 
which  is  usually  dirty,  is  thrown  away  ; 
the  second  gives  a  blue  of  the  first  quality  ; 
and  the  third  yields  one  of  less  value.  The 
process  is  founded  on  the  property  which 
the  colouring  matter  of  azure-stone  has  of 
adhering  less  firmly  to  the  resinous  cement, 
th an  the  foreign  matter  with  which  it  is 
associated.  \Vhen  azure-stone  has  its  co- 
lour altered  by  a  moderate  heat,  it  is  reck- 
oned bad.  Messrs.  Clement  and  Desormes 
consider  the  extraction  of  ultramarine  as 
a  species  of  saponification.* 

*  AZUUITB,  the  LAZULITE  of  Werner  and 
Haiiy.  This  mineral  is  often  found  in 
oblique  quadrangular  crystals  of  a  fine 
blue  colour.  It  is  translucent  only  on  the 
edges,  brittle, and  nearly  as  hard  as  quartz. 
"When  massive,  it  is  either  in  grains,  or 
bits  like  a  hazel  nut.  It  occurs  imbedded 
in  mica  slate.  Its  lustre  is  vitreous.  Its 
constituents  are  66  alumina,  18  magnesia, 
10  silica,  2.5  oxide  of  iron,  2  lime.  It  oc- 
curs in  Vorau  in  Stiria  in  a  gangue  o£ 
2uartz ;  but  the  finest  specimens 
•om  the  bishopric  of  Salzburg,* 


B 


BALANCE.  The  beginning  and  end  of 
every  exact  chemical  process  consists 
in  weighing1.  With  imperfect  instruments 
this  operation  will  be  tedious  and  inaccu- 
rate; but  with  a  good  balance,  the  result 
will  be  satisfactory;  and  much  time,  which 
is  so  precious  in  experimental  researches, 
will  be  saved. 

The  balance  is  a  lever,  the  axis  of  mo- 
tion of  which  is  formed  with  an  edge  like 
that  of  a  knife;  and  the  two  dishes  at  its  ex- 
tremities are  hung  upon  edges  of  the  same 
kind.  These  edges  are  first  made  sharp, 
and  then  rounded  with  a  fine  hone,  or  a 
piece  of  buff  leather.  The  excellence  of  the 
instrument  depends,  in  a  great  measure, 
on  the  regular  form  of  this  rounded  part. 
When  the  lever  is  considered  as  a  mere 
line,  the  two  tmter  edges  are  called  points 
of  suspension,  and  the  inner  the  fulcrum. 
The  points  of  suspension  are  supposed  to 
be  at  equal  distances  from  the  fulcrum,  and 
to  be  pressed  with  equal  weights  when 
loaded. 

1.  If  the  fulcrum  be  placed  in  the  centre 
of  gravity  of  the  beam,  and  the  three  ed- 
ges lie  all  in  the  same  right  line,  the  bal- 
ance will  have  no  tendency  to  one  position 
more  than  another,  but  will  rest  in  any  po- 
sition it  may  be  placed  in,  whether   the 
scales  be  on  or  off,  empty  or  loaded. 

2.  If  the  centre  of  gravity  of  the  beam, 
when  level,  be  immediately  above  the  ful- 
crum, it  will  overset  by  the  smallest  action; 
that  is,  the  end  which  is  lowest  will  descend: 
and  it  will  do  this  with  more  swiftness, 
the  higher  the  centre  of  gravity,  and  the 
less  the  points  of  suspension  are  loaded. 

3.  But  if  the  centre  of  gravity  of  the 
beam  be  immediately  below  the  fulcrum, 
the  beam  will  not  rest  in  any  position  but 
when  level:  and,  if  disturbed  from  this  po- 
sition, and  then  left  at  liberty,  it  will  vi- 
brate, and  at  last  come  to  rest  on  the  level. 
Its  vibrations  will  be  quicker,  and  its  ho- 
rizontal tendency  stronger,  the  lower  the 
centre  of  gravity,  and  the  less  the  weights 
upon  the  points  of  suspension. 

4.  If  the  fulcrum  be  below  the  line  join- 
ing the  points  of  suspension,  and  these  be 
loaded,  the  beam  will  overset,  unless  pre- 
vented by  the  weight  of  the  beam  tending 
to  produce  a  horizontal  position,  as  in  §  3. 
In  this  last  case,  small  weights  will  equili- 
brate, as  in  §  3.;  a  certain  exact  weight  will 
rest  in  any  position  of  the  beam,  as  in  §  1.; 
and  all  greater  weights  will  cause  the  beam 
to  overset,  as  in  §  2.  Many  scales  are  often 
made  this  way,  and  will  overset  with  any 
considerable  load. 

•5.  If  the  fulcrum  be  above  the  line  join- 
ing the  points  of  suspension,  the  beam  will 
come  to  the  horizontal  position,  unless  pre- 
vented by  its  own  weight,  as  in  §  2.  If  the 
centre  of  gravity  of  the  beam  be  nearly  in 


the  fulcrum,  all  the  vibrations  of  the  loaded 
beam  will  be  made  in  times  nearly  equal, 
unless  the  weights  be  very  small,  when 
they  will  be  slower.  The  vibrations  of 
balances  are  quicker,  and  the  horizontal 
tendency  stronger,  the  higher  the  fulcrum. 

6.  If  the  arms  of  a  balance  be  unequal, 
the  weights  in  equipoise  will  be  unequal  in 
the  same  proportion.  It  is  a  severe  check 
upon  a  workman  to  keep  the  arms  equal, 
while  he  is  making  the  other  adjustments 
in  a  strong  and  inflexible  beam. 

7.  The  equality  of  the  arms  of  a  balance 
is  of  use,  in  scientific  pursuits,  chiefly  in 
making  weights   by  bisection.  A  balance 
with  unequal  arms  will  weigh  as  accurately 
as  another  of  the  same  workmanship  with, 
equal  arms,  provided  the  standard  weight 
itself  be  first  counterpoised,  then  taken  out 
of  the  scale,  and  the  tiling  to  be  weighed 
be  put  into  the  scale,  and  adjusted  against 
the   counterpoise;    or   when    proportional 
quantities  only  are  considered,  as  in  che- 
mical and  in  other  philosophical  experi- 
ments, the  bodies  and  products  under  exa- 
mination   may    be    weighed    against   the 
weights,   taking  care    always  to  put  the 
weights    into  the  same    scale.    For   then, 
though  the  bodies  may  not  be,  really  equal 
to  the  weights,  yet  their  proportions  among 
each  other  may  be  the  same  as  if  they  had 
been  accurately  so. 

8.  But  though  the  equality  of  the  arms 
may  be  well  dispensed  with,  yet  it  is  indis- 
pensably   necessary,    that    their    relative 
lengths,  whatever  they  may  be,  should  con- 
tinue invariable.  For  this  purpose,  it  is  ne- 
cessary, either  that  the  three  edges  be  all 
truly  parallel,  or  that  the  points  of  suspen- 
sion and  support  should  be  always  in  the 
same  part  of  the  edge.  This  last  requisite 
is  the  most  easily  obtained. 

The  balances  made  in  London  are  usual- 
ly constructed  in  such  a  manner,  that  the 
bearing  parts  form  notches  in  the  other 
parts  of  the  edges;  so  that  the  scales  being 
set  to  vibrate,  ail  the  parts  naturally  fail 
into  the  same  bearing.  The  balances  made 
in  the  country  have  the  fulcrum  edge 
straight,  and  confined  to  one  constant  bear- 
ing by  two  side  plates.  But  the  points  of 
suspension  are  referred  to  notches  in  the 
edges,  like  the  London  balances.  The  bal- 
ances here  mentioned,  which  come  from 
the  country,  are  enclosed  in  a  small  iron 
japanned  box;  and  are  to  be  met  with  at 
the  Birmingham  and  Sheffield  warehouses, 
though  less  frequently  than  some  years  ago; 
because  a  pocket  contrivance  for  weighing 
guineas  and  half-guineas  has  got  posses- 
sion of  the  market.  They  are,  in  general, 
well  made  and  adjusted,  turn  with  the 
twentieth  of  a  grain  when  empty,  and  will 
sensibly  show  the  tenth  of  a  grain, ^with  an 
ounce  in  each  scale.  Their  price  is  from 
22 


BAL 


BAL 


'five  shillings  to  half  a  guinea;  but  those 
which  are  under  seven  shillings  have  not 
their  edges  hardened,  and  consequently  are 
not  durable.  This  may  be  ascertained  by 
the  purchaser,  by  passing1  the  point  of  a 
penknife  across  the  small  piece  which  goes 
through  one  of  the  end  boxes:  if  it  makes 
any  mark  or  impression,  the  part  is  soft. 

9.  If  a  beam  be  adjusted  so  as  to  have  no 
tendency  to  any  one  position,  as  in  §  1.  and 
the  scales  be  equally  loaded;  then,  if  a  small 
weight  be  added  in  one  of  the  scalesfthat 
balance  will  turn,  and  the  points  of  suspen- 
sion will  move  with  an  accelerated  motion, 
similar  to  that  of  falling  bodies,   but    as 
much  slower,  in  proportion,  very  nearly,  as 
the  added  weight  is  less  than  the  whole 
weight  borne  by  the  fulcrum. 

10.  The  stronger  the  tendency  to  a  hori- 
zontal  position    in    any    balance,   or   the 
quicker  its  vibrations,  §§  3.  5.  the  greater 
additional  weight  will  be  required  to  cause 
it  to  turn,  or  incline  to  any  given  angle.  No 
balance,  therefore,  can  turn  so  quick  as  the 
motion  deduced  in  §  9.  Such  a  balance  as 
is  there  described,  if  it  were  to  turn  with 
the  ten-thousandth  part  of  the  weight,  would 
move  at  quickest  ten  thousand  times  slower 
than  falling  bodies;  that  is,  the  dish  contain- 
ing the  weight,  instead  of  falling  through 
sixteen  feet  in  a  second  of  time,  would  fall 
through  only  two  hundred  parts  of  an  inch, 
and  it  would  require  four  seconds  to  move 
through  one-third  part  of  an  inch;  conse- 
quently all  accurate  weighing  must  be  slow. 
If  the  indexes  of  two  balances  be  of  equal 
lengths,  that  index  which  is  connected  with 
the  shorter  balance  will  move  proportional- 
ly quicker  than  the  other.  Long-  beams  are 
the    most   in   request,    because   they    are 
thought  to  have  less  friction;  this  is  doubt- 
ful; but  the  quicker  angular  motion,  greater 
strength,  and  less  weight  of  a  short  balance, 
are  certainly  advantages. 

11.  Very  delicate  balances  are  not  only 
useful  in  nice  experiments,  but  are  likewise 
much  more  expeditious  than  others  in  com- 
mon weighing.  If  a  pair  of  scales  with  a 
certain  load  be  barely  sensible  to  one-tenth 
of  a  grain,  it  will  require  a  considerable 
time  to  ascertain  the  weight  to  that  degree 
of  accuracy,  because  the  turn  must  be  ob- 
served several  times  over,  and  is  very  small. 
But  if  no  greater  accuracy  were  required, 
and  scales  were  used,  which  would  turn 
with  the  hundredth  of  a  grain,  a  tenth  of 
a  grain,  more  or  less,  would  make  so  great 
a  difference  in  the  turn,  that  it  would  be 
seen  immediately. 

12.  If  a  balance  be  found  to  turn  with  a 
certain  addition,  and  is  not  moved  by  any 
smaller  weight,  a  greater  sensibility  may  be 
given  to  that  balance,  by  producing  a  tre- 
mulous motion  in  its  parts.  Thus,  if  the 
edge  of  a  blunt  saw,  a  file,  or  other  similar 


instrument,  be  drawn  along  any  part  of  the 
case  or  support  of  a  balance,  it  will  pro- 
duce a  jarring,  which  will  diminish  the 
friction  on  the  moving  parts  so  much,  that 
the  turn  will  be  evident  with  one-third  or 
one-fourth  of  the  addition  that  would  else 
have  been  required.  In  this  way,  a  beam 
which  would  barely  turn  by  the  addition 
of  one-tenth  of  a  grain,  will  turn  with  one- 
thirtieth  or  fortieth  of  a  grain. 

13.  A  balance,  the  horizontal  tendency 
of  which  depends  only  on  its  own  weight, 
as  in  §  3.  will  turn  with  the  same  addition, 
whatever  may  be  the  load;  except  so  far  as 
a  greater  load  will  produce  a  greater  fric- 
tion. 

14.  But  a  balance,  the  horizontal  tenden- 
cy of  which  depends  only  on  the  elevation 
of  the  fulcrum,  as  in  §  5.  will  be  less  sen- 
sible the  greater  the  load;  and  the  addition 
requisite  to  produce  an  equal  turn  will  be 
in  proportion  to  the  load  itself. 

15.  In  order  to  regulate  the  horizontal 
tendency  in  some  beams,  the  fulcrum  is 
placed  below  the  points  of  suspension,  as 
in  §  4.  and  a  sliding  weight  is  put  upon  the 
cock  or  index,  by  means  of  which  the  centre 
of  gravity  may  be  raised  or  depressed.  This 
is  a  useful  contrivance. 

16.  Weights  are  made  by  a  subdivision 
of  a  standard  weight.  If  the  weight  be  con- 
tinually halved,  it  will  produce  the  common 
pile,    which   is    the  smallest  number  for 
weighing  between    its  extremes,  without 
placing  any  weight  in  the  scale  with  the 
body  under  examination.  Granulated  lead 
is  a  very  convenient  substance  to  be  used 
in  this  operation  of  halving,  which,  how- 
ever, is  very  tedious.  The  readiest  way  to 
subdivide  small  weights,  consists  in  weigh- 
ing a  certain  quantity  of  small  wire,  and 
afterward  cutting  it  into  such  parts,  by 
measure,  as  are  desired;  or  the  wire  may 
be  wrapped  close  round  two  pins,  and  then 
cut  asunder  with  a  knife.  By  this  means  it 
will  be   divided  into   a  great  number  of 
equal  lengths,  or  small  rings.  The  wire 
ought  to  be  so  thin,  as  that  one  of  these 
rings  may  barely  produce  a  sensible  effect 
on  the  beam.  If  any  quantity  (as,  for  ex- 
ample, a  grain)  of  these  rings  be  weighed, 
and  the  number  then  reckoned,  the  grain 
may  be  subdivided  in  any  proportion,  by  di- 
viding that  number,  and  makingthe  weights 
equal  to  as  many  of  the  rings  as  the  quo- 
tient of  the  division  denotes.  Then,  if  750 
of  the  rings  amounted  to  a  grain,  and  it 
were  required  to  divide  the  grain  decimally, 
downwards,  9-10ths  would  be  equal  to  675 
rings,  8-10ths  would  be  equal  to  600  rings, 
7-lUlhs  to  525  rings,  Sic.  Small  weights  may 
be  made  of  thin  leaf  brass.  Jewellers'  foil 
is  a  good  material  for  weights  below  1-lOth 
of  a  grain,  as  low  as  to  l-100th  of  a  grain; 
and  all  lower  quantities  may  be  either  esti- 


EAL 


BAL 


mated  by  the  position  of  the  index,  or 
shown  by  actually  counting-  the  rings  of 
wire,  the  value  of  which  has  been  deter- 
mined. 

17.  In  philosophical  experiments,  it  will 
be  found  very  convenient  to  admit  no  more 
than  one  dimension  of  weight.  The  grain  is 
of  that  magnitude  as  to  deserve  the  pre- 
ference. With  regard  to  the  number  of 
weights  the  chemists  ought  to  be  provided 
with,  writers  have  differed  according  to 
their  habits  and  views.  Mathematicians 
have  computed  the  least  possible  number, 
with  which  all  weights  within  certain  lim- 
its might  be  ascertained;  but  their  deter- 
mination is  of  little  use.  Because,  with  so 
small  a  number,  it  must  often  happen,  that 
the  scales  will  be  heavily  loaded  with 
weights  on  each  side,  put  in  with  a  view 
only  to  determine  the  difference  between 
them.  It  is  not  the  least  possible  number  of 
weights  which  it  is  necessary  an  operator 
should  buy  to  effect  his  purpose,  that  we 
ought  to  inquire  after,  but  the  most  con- 
venient number  for  ascertaining  his  in- 
quiries with  accuracy  and  expedition.  The 
error  of  adjustment  is  the  least  possible, 
when  only  one  weight  is  in  the  scale;  that 
is,  a  single  weight  of  five  grains  is  twice 
as  likely  to  be  true,  as  two  weights,  one  of 
three,  and  the  other  of  two  grains,  put  into 
the  dish  to  supply  the  place  of  the  single 
five;  because  each  of  these  last  has  its  own 
probability  of  error  in  adjustment.  But 
since  it  is  as  inconsistent  with  convenience 
to  provide  a  single  weight,  as  it  would  be 
to  have  a  single  character  for  every  num- 
ber; and  as  we  have  nine  characters,  which 
•we  use  in  rotation,  to  express  higher  values 
according  to  their  position,  it  will  be  found 
very  serviceable  to  make  the  set  of  weights 
correspond  with  our  numerical  system. 
This  directs  us  to  the  set  of  weights  as 
follows:  1000  grains,  900  g.  800  g.  700  g. 
600  g.  500  g.  400  g.  300  g.  200  g.  100  g. 
90  g.  80  g.  70  g.  60  g.  50  g.  40  g.  30  g. 
20  g.  10  g.  9  g.  8  g.  7  g.  6  g.  5  g.  4  g. 
3  g.  2  g.  1  g.  T9o  g.  TV  g-  T7o  g-  T6o  g- 
T5o  g-  T4o  g«  To  g-  T2o  §'  To  g-  Tfo  g- 
T£O-  g'  T£O  g-  ToTT  g'  T£O  g'  TOO  g- 
TW  g'  T¥o  g-  TW  g-  With  these  the 
philosopher  will  always  have  the  same 
number  of  weights  in  his  scales,  as  there 
are  figures  in  the  number  expressing  the 
weights  in  grains. 

Thus  742  5  grains  will  be  weighed  by 
the  weights  700,  40,  2,  and  5-lOths. 

I  shall  conclude  this  chapter  with  an  ac- 
count of  some  balances  I  have  seen  or 
heard  of,  and  annex  a  table  of  the  corres- 
pondence of  weights  of  different  countries. 

Muschenbroek,  in  his  Cours  de  Physique, 
(French  translation,  Paris,  1769),  torn.  ii. 
p  247.  says,  he  used  un  ocular  balance  of 


great  accuracy,  which  turned  (trebuchoit) 
with  -L  of  a  grain.  The  substances  he 
weighed  were  between  200  and  300  grains. 
His  balance  therefore  weighed tothe  ygiJ^o" 
part  of  the  whole;  and  would  ascertain  such 
weights  truly  to  four  places  of  figures. 

In  the  Philosophical  Transactions,  vol. 
Ixvi.  p.  509.  mention  is  made  of  two  accu- 
rate balances  of  Mr.  Bolton;  and  it  is  said 
that  one  would  weigh  a  pound,  and  turn 
with  TIQ.  of  a  grain.  This,  if  the  pound  be 
avoirdupois,  is  700-QO  of  the  weight;  and 
shews  that  the  balance  could  be  well  depend- 
ed on  to  four  places  of  figures,  and  probably 
to  five.  The  other  weighed  half  an  ounce, 
and  turned  with  -fa  of  a  grain.  This  is 

2T¥o o-  of  the  weight. 

In  the  same  volume,  p.  511.  a  balance  of 
Mr.  Read's  is  mentioned,  which  readily 
turned  with  less  than  one  pennyweight, 
\vhen  loaded  with  55  pounds,  before  the 
Royal  Society;  but  very  distinctly  turned 
with  four  grains,  when  tried  more  patiently. 
This  is  about  -g-g-^Q-o  Part  °^  ^le  weight; 
and  therefore  this  balance  may  be  depend- 
ed on  to  five  places  of  figures. 

Also,  page  576.  a  balance  of  Mr.  White- 
hurst's  weighs  one  pennyweight,  and  is  sen- 
sibly affected  with  -^Vo  of  a  grain.  This 
is4ird-oo  Part  of  the  weight. 

I  have  a  pair  of  scales  of  the  common 
construction,  §  8.  made  expressly  for  me  by 
a  skilful  workman  in  London.  With  1200 
grains  in  each  scale,  it  turns  with  -f$  of  a 
grain.  This  is  •B-^-0-0-  of  the  whole;  and 
therefore  about  this  weight  may  be  known 
to  five  places  of  figures.  The  proportional 
delicacy  is  less  in  greater  weights.  The 
beam  will  weigh  near  a  pound  troy;  and 
when  the  scales  are  empty,  it  is  affected  by 
__i__  of  a  grain.  On  the  whole,  it  may  be 
usefully  applied  to  determine  all  weights  be- 
tween 100  grains  and  4000  grains  to  four 
places  of  figures. 

A  balance  belonging  to  Mr.  Alchorne  of 
the  Mint  in  London,  is.  mentioned,  vol. 
Ixxvii.  p.  205.  of  the  Philosophical  Transac- 
tions. It  is  true  to  3  grains  with  15  Ib.  an 
end.  If  these  were  avoirdupois  pounds,  the 
weight  is  known  to  j-g-^0-^  part,  or  to  four 
places  of  figures,  or  barely  five. 

A  balance,  (made  by  Ramsden,  and  turn- 
ing on  points  instead  of  edges)  in  the  pos- 
session of  Dr.  George  Fordyce,  is  mentioned 
in  the  seventy-fifth  volume  of  the  Philoso- 
phical Transactions.  With  a  load  of  four 
or  five  ounces,  a  difference  of  one  division 
in  the  index  was  made  by  T6Vo  of  a  £ranl- 
This  is  -g-g-jVo-or  part  of  the  weight,  and 
consequently  this  beam  will  ascertain  such 
weights  to  five  places  of  figures,  beside  an 
estimate  figure, 


BAL 


BAL 


I  have  seen  a  strong-  balance  in  the  pos- 
session of  my  friend  Mr.  Magellan,  of  the 
kind  mentioned  in  §  15.  which  would  bear 
several  pounds,  and  showed  -JLof  a  grain, 
with  one  pound  an  end.  This  is  7(y-g-06  of 
the  weight,  and  answers  to  five  figures.  But 
I  think  it  would  have  done  more  by  a  more 
patient  trial  than  I  had  time  to  make. 

The  Royal  Society's  balance,  which  was 
lately  made  by  Itamsden,  turns  on  steel 
edges,  upon  planes  of  polished  crystal  I 
was  assured,  that  it  ascertained  a  weight  to 
the  seven-millionth  part.  1  was  not  present 
at  this  trial,  which  must  have  required  great 
care  and  patience,  as  the  point  of  suspension 
could  not  have  moved  over  much  more  than 
the  T|~g-  of  an  inch  in  the  first  half  minute; 
but,  from  some  trials  which  I  saw,  I  think  it 
probable  that  it  may  be  used  in  general 
practice  to  determine  weights  to  five  places 
and  better. 

From  this  account  of  balances,  the  stu- 
dent may  form  a  proper  estimate  of  the 
value  of  those  tables  of  specific  gravities, 
which  are  carried  to  five,  six,  and  even 
seven  places  of  figures,  and  likewise  of  the 
theoretical  deductions  in  chemistry,  that 
depend  on  a  supposed  accuracy  in  weighing, 
which  practice  does  not  authorise.  In  gene- 
ral, where  weights  are  given  to  five  places 
of  figures,  the  last  figure  is  an  estimate,  or 
guess  figure;  and  where  they  are  carried 


farther,  it  may  be  taken  for  granted,  tbat 
the  author  deceives  either  intentionally,  or 
from  want  of  skill  in  reducing  his  weights 
to  fractional  expressions,  or  otherwise. 

The  most  exact  standard  weights  were 
procured,  by  means  of  the  ambassadors  of 
France,  resident  in  various  places;  and  these 
were  compared  by  Mons.  Tillet  with  the 
standard  mark  in  the  pile  preserved  in  the 
Gourde Monnoies  de Paris.  His  experiments 
were  made  with  an  exact  balance  made  to 
weigh  one  marc,  and  sensible  to  one  quarter 
of  a  grain.  Now,  as  the  marc  contains 
18432  quarter  grains,  it  follows  that  this 
balance  was  a  good  one,  and  would  exhibit 
proportions  to  four  places,  and  a  guess 
figure.  The  results  are  contained  in  the  fol- 
lowing table,  extracted  from  Mons.  Tillet's 
excellent  paper  in  the  Memoirs  of  the 
Royal  Academy  of  Sciences  for  the  year 
1767-  I  have  added  the  two  last  Columns, 
which  show  the  number  of  French  and 
English  grains  contained  in  the  compound 
quantities  against  which  they  stand.  The 
English  grains  are  computed  to  one-tenth 
of  a  grain,  although  the  accuracy  of  weigh- 
ing came  no  nearer  than  about  two-tenths. 

The  weights  of  the  kilogramme,  gramme, 
decigramme,  and  centigramme,  which  are 
now  frequently  occurring  in  the  French  che- 
mical writers,  are  added  at  the  bottom  of  this 
table,  according  to  their  respective  values. 


Table  of  the  Weights  of  different  Countries. 


Place  and  Denomination  of  Weights. 

Berlin.  The  marc  of  16  loths,  -     -     -     - 

Berne.  Goldsmiths'   weight  of  8  ounces, 

Berne,  Pound  of  16  ounces,  for  merchan- 
dise,       ----._ 
The  common  pound  varies  very  consi- 
derably in  other  towns  of  the'canton. 

Berne.  Apothecaries'  weight  of  8  ounces, 

JBonn.         ..... 

Brussels.  The  marc,  or  original  troyes  wt. 

Cologn.  The  marc  of  16  loths, 

Constantinople.  The  cheki,  or  100  drachms, 

Copenhagen.  Goldsmiths'  weight,  comO 
monly  supposed  equal  to  the  marc  > 
of  Cologn,  j 

Copenhagen.  Merchants'  \veight  of  16  loths, 

Dantzic    weight,    commonly   supposed  ^ 
equal  to  the  marc  of  Cologn, 

Florence.  The  pound  (anciently  used  bv"J 
the  Romans), 

Genoa.  The  peso  sottile, 

Genoa.  The  peso  grosso,         - 

Hamburgh  weight,  commonly  supposed  > 
equal  to  the  Cologn  marc, 

Hamburgh.  Another  weight,         .  . 

Liege.  The  Brussels  marc  used;  but  the  7 
weight  proved, 

.  The  marc,  or  half  pound,     .      . 


marc. 

OS. 

7 

gros. 
o 

grains. 
16 

F.  grains. 
4408 

E.  grains. 
3616.3 

1 

— 

$ 

4 

4648 

5813.2 

2 

1 

i 

6 

9834 

8067.7 

__ 

7 

5* 

26 

4454 

3654. 

— 

7 

5 

6| 

4398£ 

3608.6 

1 

— 

— 

21 

4629 

3797.6 

— 

7 

5 

11 

4403 

3612.2 

1 

2 

3 

28 

6004 

4925.6 

— 

7 

5* 

WJ 

44381 

3641.2 

1 

— 

1 

22$ 

4702$ 

3857.9 

—  • 

7 

5 

3* 

95| 

3606. 

1 

3 

i 

20 

6392 

5244. 

1 

2 

2i 

30 

5970 

4897.7 

1 

2 

3 

5 

5981 

4906.7 

— 

7 

5 

n 

4399| 

3609.4 

— 

7 

7 

23 

4559 

3f40.2 

1 

— 

— 

24 

4632 

3800.1 

7 

3£ 

kA 

o4 

4318 

3542.4 

BAI- 


KAL 


Place  and  Denomination  of  Weights. 
London.  The  pound  troy,        ... 
London.  The  pound  avoirdupois,      - 
Lucca.  The  pound,         -         -         • 
Madrid.  The  marc  royal  of  Castile, 
Malta.  The  pound,         - 
Manheim.  (The  Cologn  marc), 
Milan.  The  marc,         .... 
Milan.  The  libra  grossa, 
Munich.  (The  Cologn  marc), 
Naples.  The  pound  of  12  ounces, 
Ratisbon.  The  weight  for  gold:  of  128  crowns 
Ratisbon.  The  weight   for  ducats:  of  647 
ducats,  5 

Ratisbon.  The  marc  of  8  ounces, 
Ratisbon.  The  pound  of  16  ounces,    -     - 
Rome.  The  pound  of  12  ounces, 
Stockholm.  The  pound  of  2  marcs,     -     - 
Stuttgard.  (The  Cologn  marc), 
Turin.  The  marc  of  8  ounces, 

At  Turin  they  have  also  a  pound  of  12 

of  the  above  ounces.  But,  in  their 

apothecaries*  pound  of  12  ounces, 

the  ounce  is  one-sixth  lighter. 

Warsaw.  The  pound,      - 

Venice.  The  libra  grossa  of  12  ounces, 

Venice,  The  peso  sottile  of  12  ounces, 

In  the  pounds  dependent  on  Venice,  the 

pound  differs  considerably  in  each. 
Vienna.  The  marc  of  commerce,    - 
Vienna.  The  marc  of  money, 
England.  The  grain,      -         ... 
France.  The  grain,          .... 
The  kilogramme,       ... 
The  gramme, 

The  decigramme,       ... 
The  centigramme,     ... 


See  TABLES  of  WEIGHTS  and  MEASURED  in  the  Appendix. 


•ware.  02.  gros.  grains.  F.  grains.  E.  grains. 

1 

4 

H 

1 

7021 

5760. 

1 

6 

6i 

6 

8538 

7004.5 

1 

3 

23 

63  5  9£ 

5217. 

— 

7 

4 

8* 

4328 

3550.7 

1 

2 

2£ 

21 

5961 

4890.4 

_ 

7 

5 

10 

4402 

3611.5 

__ 

7 

5 

33i 

4425 

3660.2 

3 

—  . 

7^ 

__ 

14364^ 

11784. 

7 

5 

11 

4403i 

3612.3 

1 

2 

si 

27$ 

6039 

4954.3 

1 

6. 

24 

8088 

6635.3 

— 

7 

2 

32 

4208 

3452.3 

1 

__ 

___ 

24 

4632 

3800.1 

2 

2 

4* 

6 

10698 

8776.5 

1 

3 

* 

14 

6386 

5239. 

1 

5 

7 

8 

8000 

6563.1 



7 

5 

11| 

4403| 

3612.6 

1 

~~" 

22i 

4630* 

3799. 

1 

5 

2 

12 

7644 

6271. 

1 

7 

89895 

7374.5 

1 

1 

6i 

24 

5676 

4656.5 

1 

1 

1 

16 

5272 

4325. 

1 

1 

1 

26 

5282 

4333.3 

__ 

___ 

— 



1.21895 

1. 

_„ 

— 

— 



1. 

0.82039 

4 

— 

5 

35  |  18827.15 

15445.5 

_ 

— 

— 

_ 

18.827 

15.445 

— 

— 

— 

1.8827 

1.5445 

— 

— 

— 

.18827 

.15445 

*  The  commissioners,  appointed  by  the 
British  government  for  considering  the  sub- 
ject of  weights  and  measures,  gave  in  their 
first  report  on  the  24th  June  1819.  The  fol- 
lowing is  the  substance  of  it : 

"  1.  With  respect  to  the  actual  magnitude 
of  the  standards  of  length,  the  commis- 
sioners are  of  opinion,  that  there  is  no  suffi- 
cient reason  for  altering  those  generally 
employed,  as  there  is  no  practical  advan- 
tage in  having  a  quantity  commensurable  to 
any  original  quantity  existing,  or  which  may 
be  imagined  to  exist,  in  nature,  except  as 
affording  some  little  encouragement  to  its 
common  adoption  by  neighbouring  nations. 

"  2.  The  subdivisions  of  weights  and 
measures  at  present  employed  in  this  coun- 
try, appear  to  be  far  more  convenient  for 
practical  purposes  than  the  decimal  scale. 
The  power  of  expressing  a  third,  a  fourth, 
and  a  sixth  of  a  foot  in  inches,  without  a 
fraction,  is  a  peculiar  advantage  in  the  duo- 
decimal scale;  and  for  the  operation  of 
weighing  and  of  measuring  capacities,  the 


continual  division  by  two,  renders  it  practi- 
cable to  make  up  any  given  quantity  with 
the  smallest  possible  numberof  weights  and 
measures,  and  is  far  preferable  in  this  res- 
pect to  any  decimal  scale.  The  commis- 
sioners therefore  recommend,  that  all  the 
multiples  and  subdivisions  of  the  standard 
to  be  adopted,  should  retain  the  same  re- 
lative  proportions  to  each  other  as  are  at 
present  in  general  use. 

"  3.  That  the  standard  yard  should  be  that 
employed  by  Gen.  Roy  in  the  measurement 
of  a  base  on  Hounslow  Heath,  as  a  founda- 
tion of  the  great  trigonometrical  survey. 

"  4.  That  in  case  this  standard  should  be 
lost  or  impaired,  it  shall  be  declared,  that 
the  length  of  a  pendulum,  vibrating  seconds 
of  mean  solar  time  in  London,  on  the  level 
of  the  sea,  and  in  a  vacuum,  is  39.1372  in- 
ches of  the  standard  scale,  and  that  the 
length  of  the  French  metre,  as  the  10  mil- 
lionth part  of  the  quadrantal  arc  of  the 
meridian,  has  been  found  equal  to  39.3694 
inches. 


BAL 


BAR 


"  5.  That  10  ounces  troy,  or  4800  grains, 
should  be  declared  equal  to  the  weight  of 

19  cubic  inches  of  distilled  water,  at  the 
temperature  of  50°,  and  that  one  pound 
avoirdupois   must  contain    7000  of  these 
grains. 

"  6.  That  the  standard  ale  and  corn  gal- 
lon should  contain  exactly  ten  pounds  avoir- 
dupois of  distilled  water  at  62°  Fahr.  being 
nearly  equal  to  277.2  cubic  inches,  and 
agreeing  with  the  standard  pint  in  the  Ex- 
chequer, which  is  found  to  contain  exactly 

20  ounces  of  water.  The  customary  ale  gal- 
lon contains  282  cubic  inches,  and  the  Win- 
chester corn  gallon  269,  or  according  to 
other  statutes  272i  cubic  inches;  so  that  no 
inconvenience  can  possibly  be  felt  from  the 
introduction  of  a  new  gallon  of  277.2  inches. 
The  commissioners  have  not  decided  upon 


the  propriety  of  abolishing  entirely  the  use 
of  the  wine  gallon." 

The  following  elegantly  simple  relations 
of  weight  and  measure  were  suggested  by 
Dr.  Wollaston,  in  his  examination  before 
the  committee;  and  it  is  to  be  hoped  they 
will  be  adopted  in  the  national  system: 

"There  is  one  standard  of  capacity  that 
would  be  particularly  advantageous,  because 
it  would  bear  simple  proportions  to  the  mea- 
sures now  in  use,  so  that  one  of  the  great 
inconveniences  arising  from  change  of  the 
standard  would  be  obviated,  by  the  facility 
of  making  many  necessary  computations 
without  reference  to  tables. 

"  If  the  gallon  measure  be  defined  to  be 
that  which  contains  10  Ibs.  of  water  at  564° 
F.;  then,  since  the  cubic  foot  of  water 
weighs  1000  oz.  at  56£°, 


|  pint   =  10  oz.  =    T^Q-     cubic  foot  =  17.28  inches. 
Pint       =  20  oz.  =     34.56  inches. 
Bushel  =  80  Ib.  =  2211.84 

And  the  simple  proportions  above  alluded  to  will  be  found  as  follows: 


The  gallon  of  10  Ib. 

Also, 

The  pint  of  H  Ib. 
Bushel  of  80  Ib. 
A  cylinder  of  18£  in.  diam. 
Ditto         18| 


Cubic  Inches. 
276.48  X  If  = 


=    276.48  X  Tiz-  = 

3    = 


282.01 
230.40 

34.56  X  3     =     103.68 
2211.84  X  ||  =  2150.40 
X  8     =  2208.9J 
X  8.0105 


282  beer  gallon. 
231  wine  gallon. 
103.4  Stirlg.jug. 
2150,42  Winch,  bush. 
Approximate  bush. 
221.184  new  bush. 


"  The  following  mode  of  defining  the  standards  of  length,  weight,  and  capacity,  is 
submitted  to  the  committee  on  weights  and  measures,  as  the  most  distinct  answer  to 
their  inquiries: 

On     r     1     f  36  '     1       ^  *s  such,  that  a  pendulum  of  39.13  inches,  vibrates  seconds 

is  such,  that  one  cubic  foot  of  water  at  56^°,  weighs  1000  oz. 

such»  that  700°  grains  =  1  Pound  (avoirdupois). 

rv          n          r  0    .   ,     7  maV  be  such  as  to  contain  10  pounds  of  distilled  water  at  the 
One  gallon,  of  8  pints,  temperature  of  56^°  Fahr.  with  great  convenience." 


Captain  Kater  has  lately  made  a  small 
correction  on  his  first  determination  of  the 
length  of  the  pendulum  vibrating  seconds 
in  the  latitude  of  London.  Instead  of 
39  13860  inches,  as  given  in  the  Ph.  Trans, 
for  1818,  he  has  made  it  39.13929  inches 
of  Sir  Geo.  Shuckburgh's  standard  scale. 
Mr.  Watts,  in  the  5th  number  of  the  Edin- 
burgh Philosophical  Journal,  makes  it  = 
39.138666  of  the  above  scale,  or  = 
39.13724D5  of  General  Roy's  scale,  at  Cap- 
tain Rater's  temperature  of  62°  Fahr.  and 
0.9941  of  a  metre.*  ' 

*  BAIKALITE.  See  TREMOLITE,  AS- 
BESTIFORM.* 

BALAS,  or  BALAIS  RUBY.      See  SPI- 

NELLE. 

B  A  L  LOO  N.  Receivers  of  a  spherical  form 
are  called  balloons. 


BALLOON.     See  AEROSTATICS. 

*  BALSAMS,  are  vegetable  juices,  either 
liquid,    or   which    spontaneously    become 
concrete,  consisting  of  a  substance  of  a  re- 
sinous nature,  combined  with  ben  zoic  acid, 
or  which  are  capable  of  affording  benzoic 
acid,  by  being  heated  alone,  or  with  water. 
They  are  insoluble  in  water,  but  readily 
dissolve  in  alcohol  and  ether.     The  liquid 
balsams  are  ccpaiva,  opobalsam,  Peru,  sty- 
rax,  tolu;  the'concrete  are  benzoin, dragon's 
blood,  and  storax;  which  see.* 

BALSAM   OF    SULPHUR.  A   solution  of 
sulphur  in  oil. 

*  BALDWIN'S  PHOSPHORUS.  Ignited  ni- 
trate of  lime.* 

*  BARIUM.   The  metallic  basis  of  the 
earth  barytes  has  been  called  barium  by  its 
discoverer,  Sir  H.  Davy.  Take  pure  barytes, 


EAR 


BAB 


make  it  into  a  paste  with  water,  and  put  this 
on  a  plate  of  platinum.  Make  a  cavity  in  the 
middle  of  the  barytes,  into  which  a  globule 
of  mercury  is  to  be  placed.  Touch  the  glob- 
ule with  the  negative  wire  and  the  platinum 
with  the  positive  wire,  of  a  voltaic  battery  of 
about  100  pairs  of  plates  in  good  action.  In  a 
short  time  an  amalgam  will  be  formed,  con- 
sisting of  mercury  and  barium.  This  amal- 
gam must  be  introduced  into  a  little  bent 
tube,  made  of  glass  free  from  lead,  sealed  at 
one  end,  which  being  filled  with  the  vapour 
of  naphtha,  is  then  to  be  hermetically  sealed 
at  the  other  end.  Heat  must  be  applied  to 
the  recurved  end  of  the  tube,  where  the 
amalgam  lies.  The  mercury  will  distil  over, 
while  the  barium  will  remain. 

This  metal  is  of  a  dark  grey  colour,  with 
a  lustre  inferior  to  that  of  cast-iron.  It  is  fu- 
sible at  a  red  heat.  Its  density  is  superior 
to  that  of  sulphuric  acid;  for  though  sur- 
rounded with  globules  of  gas,  it  sinks  im- 
mediately in  that  liquid.  When  exposed  to 
air,  it  instantly  becomes  covered  with  a 
crust  of  barytes;  and  when  gently  heated  in 
air,  burns  with  a  deep  red  light.  It  efferves- 
ces violently  in  water,  converting  this  li- 
quid into  a  solution  of  barytes.  Sir  H.  Davy 
thinks  it  probable  that  barium  may  be  pro- 
cured by  chemical  as  well  as  electrical  de- 
composition. When  chloride  of  barium,  or 
even  the  dry  earth,  ignited  to  whiteness,  is 
exposed  to  the  vapour  of  potassium,  a  dark 
grey  substance  is  found  diffused  through 
the  barytes  or  the  chloride,  not  volatile, 
which  effervesces  copiously  in  water,  and 
possesses  a  metallic  appearance,  which  dis- 
appears in  the  air.  The  potassium,  by  being 
thus  transmitted,  is  converted  into  potash. 
From  indirect  experiments,  Sir  H.Davy  was 
inclined  to  consider  barytes  as  composed  of 
89.7  barium  4-  10,3  oxygen  =  100.  This 
would  make  the  prime  equivalent  of  barium 
8.7,  and  that  of  barytes  9.7,  compared  to 
that  of  oxygen  1.0;  a  determination  probably 
very  exact.  Dr.  Clark  of  Cambridge,  by  ex- 
posing dry  nitrate  of  barytes  on  charcoal,  to 
the  intense  heat  of  the  condensed  hydroxy- 
gen  flame,  observed  metallic  globules  in  the 
midst  of  the  boiling  fluid,  and  the  charcoal 
was  found  to  be  studded  over  with  innumer- 
able globules  of  a  pure  metal  of  the  most 
brilliant  lustre  and  whiteness.  On  letting 
these  globules  fall  from  the  charcoal  into 
water,  hydrogen  was  evolved  in  a  continued 
stream.  When  the  globules  are  plunged  in 
naphtha,  they  retain  their  brilliancy  but 
for  a  few  days. 

Barium  combines  with  oxygen  in  two 
proportions  forming1,  1st,  barytes,  and  2d, 
the  deutoxide  of  barium. 

Pure  barytes  is  best  obtained  by  igniting 
in  a  covered  crucible,  the  pure  crystallized 
nitrate  of  barytes.  It  is  procured  in  the  state 
of  hydrate,  by  adding  caustic  potash  or  soda 


to  a  solution  of  the  muriate  or  nitrate.  And 
barytes,  slightly  coloured  with  charcoal, 
may  be  obtained  by  strongly  igniting  the 
carbonate  and  charcoal  mixed  together  in 
fine  powder.  Barytes  obtained  from  the  ig- 
nited nitrate  is  of  a  whitish-grey  colour; 
more  caustic  than  strontites,  or  perhaps 
even  lime.  It  renders  the  syrup  of  violets 
green,  and  the  infusion  of  turmeric  red.  Its 
specific  gravity  by  Fourcroy  is  4.  W  hen 
water  in  small  quantity  is  poured  on  the  dry 
earth,  it  slakes  like  quicklime,  but  perhaps 
with  evolution  of  more  heat.  When  swal- 
lowed it  acts  as  a  violent  poison.  It  is  des- 
titute of  smell. 

When  pure  barytes  is  exposed,  in  a  porce- 
lain tube,  at  a  heat  verging  on  ignition,  to  a 
stream  of  dry  oxygen  gas,  it  absorbs  the  gas 
rapidly,  and  passes  to  the  state  of  deutoxide 
of  barium.  But  when  it  is  calcined  in  con- 
tact with  atmospheric  air,  we  obtain  at 
first  this  deutoxide  and  carbonate  of  bary- 
tes; the  former  of  which  passes  very  slowly 
into  the  latter,  by  absorption  of  carbonic 
acid  from  the  atmosphere. 

The  deutoxide  of  barium  is  of  a  greenish- 
grey  colour;  it  is  caustic,  renders  the  syrup 
of  violets  green,  and  is  not.  decomposable  by 
heat  or  light.  The  voltaic  pile  reduces  it. 
Exposed  at  a  moderate  heat  to  carbonic 
acid,  it  absorbs  it,  emitting  oxygen,  and  be- 
coming carbonate  of  barytes.  The  deutoxide 
is  probably  decomposed  by  sulphuretted  hy- 
drogen at  ordinary  temperatures.  Aided  by 
heat,  almost  all  combustible  bodies,  as  well 
as  many  metals,  decompose  it.  The  action  of 
hydrogen  is  accompanied  with  remarkable 
phenomena.  At  about  592°  F.  the  absorption 
of  this  gas  commences;  but  at  a  heat  ap- 
proaching to  redness  it  is  exceedingly  ra- 
pid, attended  with  luminous  jets  proceed- 
ing from  the  surface  of  the  deutoxide.  Al- 
though much  water  be  formed,  none  of  it 
appears  on  the  sides  of  the.  vessel.  It  is  all 
retained  in  combination  with  the  protoxide, 
which  in  consequence  becomes  a  hydrate, 
and  thus  acquires  the  property  of  fusing 
easily.  By  heating  a  certain  quantity  of  ba- 
rytes with  an  excess  of  oxygen  in  a  small 
curved  tube  standing  over  mercury,  M. 
Thenard  ascertained,  that  in  the  deutoxide 
the  quantity  of  the  oxygen  is  the  double  of 
that  in  the  protoxide.  Hence  the  former 
will  consist  of  8.7  barium  -f-  2  oxygen  = 
10.7  for  its  prime  equivalent.  From  the  fa- 
cility with  which  the  protoxide  passes  into 
the  deutoxide,  we  may  conceive  that  the 
former  may  frequently  contain  a  proportion 
of  the  latter,  to  which  cause  may  be  as- 
cribed in  some  degree  the  discrepancies 
among  chemists,  in  estimating  the  equiva- 
lent of  barytes. 

Wrater  at  50°  F.  dissolves  one-twentieth 
of  its  weight  of  barytes,  and  at  212°  about 
one-half  of  its  weight;  though  M.  Thenard 


BAH 


BAS 


in  a  table,  has  stated  it  at  only  one-tenth.  As 
the  solution  cools,  hexagonal  prisms,  termi- 
nated at  each  extremity  with  a  four-sided 
pyramid,  form.  These  crystals  are  often 
attached  to  one  another,  so  as  to  imitate  the 
leaves  of  fern.  Sometimes  they  are  deposit- 
ed in  cubes.  They  contain  about  53  per  cent 
of  water,  or  20  prime  proportions.  The  su- 
pernatant liquid  is  barytes  water.  It  is  co- 
lourless, acrid,  and  caustic.  It  acts  power- 
fully on  the  vegetable  purples  and  yell«wrs. 
Exposed  to  the  air,  it  attracts  carbonic  acid, 
and  the  dissolved  barytes  is  converted  into 
carbonate,  which  falls  down  in  insoluble 
crusts.  It  appears  from  the  experiments  of 
M.  Berthollet,  that  heat  alone  cannot  de- 
prive the  crystallized  hydrate  of  its  wa- 
ter. After  exposure  to  a  red  heat,  when  it 
ftises  like  potash,  a  proportion  of  water  re- 
mains in  combination.  This  quantity  is  a 
prime  equivalent  =  1.125,  to  9.7  of  barytes. 
•—The  ignited  hydrate  is  a  solid  of  a  whi- 
tish-grey colour,  caustic,  and  very  dense. 
It  fuses  at  a  heat  a  little  under  a  cherry 
red;  is  fixed  in  the  fire;  attracts,  but  slowly, 
carbonic  acid  from  the  atmosphcre.lt  yields 
earburetted  hydrogen  and  carbonate  of 
barytes  when  heated  along  with  charcoal, 
provided  this  be  not  in  excess. 

Sulphur  combines  with  barytes,  when 
they  are  mixed  together,  and  heated  in  a 
crucible.  The  same  compound  is  more  eco- 
nomically obtained  by  igniting  a  mixture  of 
sulphate  of  barytes  and  charcoal  in  fine 
powder.  This  sulphuret  is  of  a  reddish- 
yellow  colour,  and  when  dry  without  smell. 
When  this  substance  is  put  into  hot  water, 
a  powerful  action  is  manifested.  The  water 
is  decomposed,  and  two  new  products  are 
formed;  namely,  hydrosulphuret,  and  hy- 
droguretted  sulphuret  of  barytes,  The  first 
crystallizes  as  the  liquid  cools,  the  second 
remains  dissolved.  The  hydrosulphuret  is  a 
compound  of  9.7  of  barytes  with  2.125  sul- 
phuretted hydrogen.  Its  crystals  should  be 
quickly  separated  by  filtration,  and  dried 
by  pressure  between  the  folds  of  porous  pa- 
per. They  are  white  scales,  have  a  silky 
lustre,  are  soluble  in  water,  and  yield  a  so- 
lution having  a  greenish  tinge.  Its  taste  is 
acrid,  sulphureous,  and  when  mixed  with 
the  hydroguretted  sulphuret,  eminently 
corrosive.  It  rapidly  attracts  oxygen  from 
the  atmosphere,  and  is  converted  into  the 
sulphate  of  barytes.  The  hydroguretted  sul- 
phuret is  a  compound  of  9.70  barytes  with 
4.125  bisulphuretted  hydrogen;  but  con- 
taminated with  sulphite  and  hyposulphite 
in  unknown  proportions.  The  dry  sulphuret 
consists  probably  of  2  sulphur  -j-  9-7  bary- 
tes. The  readiest  way  of  obtaining  barytes 
water  is  to  boil  the  solution  of  the  sulphuret 
with  deutoxide  of  copper,  which  seizes  the 
sulphur,  while  the  hydrogen  flies  oft',  and 
the  barytes  remains  dissolved. 


Phosphuret  of  barytes  may  be  easily 
formed  by  exposing  the  constituents  to- 
gether to  heat  in  a  glass  tube.  Their  reci- 
procal action  is  so  intense  as  to  cause  igni- 
tion. Like  phosphuret  of  lime,  it  decom- 
poses water,  and  c:\uses  rhe  disengagement 
of  phosphuretted  hydrogen  gas,  which 
spontaneously  inflames  with  contact  of  uir. 
When  sulphur  is  made  to  act  on  the  deu- 
toxide  of  barytes,  sulphuric  acid  is  formed, 
which  unites  to  a  portion  of  the  earth  into 
a  sulphate. 

The  salts  of  barytes  are  white,  and  more 
or  less  transparent.  All  the  soluble  sulphates 
cause  in  the  soluble  salts  of  barytes,  a  preci- 
pitate insoluble  in  nitric  acid.  They  are  all 
poisonous  except  the  sulphate;  and  hence 
the  proper  counter-poison  is  dilute  sulphu- 
ric acid  for  the  carbonate,  and  sulphate  of 
soda  for  the  soluble  salts  of  barytes.  An  ac- 
count has  been  given  of  the  moit  useful  of 
these  salts  under  the  respective  acids. 
What  remains  of  any  consequence  will  be 
found  in  the  table  of  SALTS.  For  some  in- 
teresting facts  on  the  decomposition  of  the 
sulphate  and  carbonate,  see  ATTRACTION. 
When  the  object  is  merely  to  procure  ba- 
rytes or  the  sulphuret,  form  the  powdered 
carbonate  or  sulphate  into  a  paste  with 
lamp  black  and  coal  tar,  and  subject  to 
strong  ignition  in  a  covered  crucible.* 

BARBADOES  TAR.  See  PETROLEUM. 

BARii.LA,or  BARILLOR. The  term  given 
in  commerce  to  the  impure  soda  imported 
from  Spain  and  the  Levant.  It  is  made  by 
burning  to  ashes  different  plants  that  grow 
on  the  sea-shore,  chiefly  of  the  genus  sal- 
sola,  and  is  brought  to  us  in  hard  porous 
masses,  of  a  speckled  brown  colour. 

Kelp,  a  still  more  impure  alkali  made  in 
this  country  by  burning  various  sea  weeds, 
is  sometimes  called  ^British  barilla.  See 
SODA. 

BAROLITE.    Carbonate  of  barytes. 

*  B ARRAS.  The  resinous  incrustation  on 
the  wounds  made  in  fir  trees.  It  is  also 
called  galipot.* 

BARYTES.    See  BARIUM. 

*  BASALT.  Occurs  in  amorphous  mas. 
ses,  columnar,  amygdaloidal,  and  vesicular. 
Its  colours  are  greyish-black,  ash-grey,  and 
raven-black.  Massive.  Dull  lustre.  Granular 
structure.  Fracture  uneven  or  conchoidal 
Concretions,  columnar,  globular,  or  tabular 
It  is  opaque,  yields  to  the  knife,  but  not 
easily  frangible.  Streak  light  ash-grey.  Sp 
grav.  3.  Melts  into  a  black  glass.  It  is  fotinc 
in  beds  and  veins  in  granite  and  mica  slate 
the  old  red  sandstone,  limestone,  and  coa 
formations.  It  is  distributed  over  the  whole 
world;  but  nowhere  is  met  with  in  greate; 
variety  than  in  Scotland. The  German  basal 
is  supposed  to  be  a  watery  deposite;  anc 
that  of  France  to  be  of  volcanic  origin.* 

The  most  remarkable  is  the  columnar  ba 


BAS 


BAT 


suites,  which  form  immense  masses,  com- 
posed  of  columns  thirty,  forty,  or  more  feet 
in  height,  and  of  enormous  thickness.  Nay, 
those  at  Fairhead  are  two  hundred  and  fif- 
ty feet  high.  These  constitute  some  of  the 
most  astonishing  scenes  in  nature,  for  the 
immensity  and  regularity  of  their  parts. 
The  coast  of  Antrim  in  Ireland,  for  the 
space  of  three  miles  in  length,  exhibits  a 
very  magnificent  variety  of  columnar  cliffs; 
and  the  Giant's  Causeway  consists  of  a 
point  of  that  coast  formed  of  similar  co- 
lumns, and  projecting  into  the  sea,  upon  a 
descent  for  several  hundred  feet.  These  co- 
lumns are,  for  the  most  part,  hexagonal,  and 
fit  very  accurately  together;  but  most  fre- 
quently not  adherent  to  each  other,  though 
water  cannot  penetrate  between  them.  And 
the  basaltic  appearances  on  the  Hebrides 
Islands  on  the  coast  of  Scotland,  as  de- 
scribed by  Sir  Joseph  Banks,  who  visited 
them  in  1772,  are  upon  a  scale  very  strik- 
ing for  their  vastness  and  variety. 

An  extensive  field  of  inquiry  is  here  offer- 
ed to  the  geological  philosopher,  in  his  at- 
tempts to  ascertain  the  alterations  to  which 
the  globe  has  been  subjected.  The  inquiries 
of  the  chemist  equally  co-operate  in  these 
researches,  and  tend  likewise  to  show  to 
what  useful  purposes  this  andother  substan- 
ces may  be  applied.  Bergmann  found  that 
the  component  parts  of  various  specimens 
of  basaltes  were,  at  a  medium  52  parts  silex, 
15  alumina,  8  carbonate  of  lime,  and  25 
iron.  The  differences  seem,  however,  to  be 
considerable;  for  Faujas  de  St.  Fond  gives 
these  proportions:  46  silex,  30  alumina,  10 
lime,  6  magnesia,  and  8  iron.  The  amor- 
phous basaltes,  known  by  the  name  of  row- 
ley  rag,  the  ferrilite  of  Kirwan,  of  the  sped-  , 
fie  gravity  of  2.748,  afforded  Dr.  Withering 
47.5  of  silex,  32.5  of  alumina,  and  20  of  iron, 
at  a  very  low  degree  of  oxidation  probably. 
Dr.  Kennedy,  in  his  analysis  of  the  basaltes 
of  Staffa,  gives  the  following  as  its  compo- 
nent parts:  silex  48,  alumina  16,  oxide  of 
iron  16,  lime  9,  soda  4,  muriatic  acid  1,  wa- 
ter and  volatile  parts  5.  Klaproth  gives  for 
the  analysis  of  the  prismatic  basaltes  of  Ha- 
senberg:  silex  44.5,  alumina  16.75,  oxide  of 
iron  20,  lime  9.5,  magnesia  2.25,  oxide  of 
manganese  0.12,  soda  2.60,  water  2.  On  a 
subsequent  analysis,  with  a  view  to  detect 
the  existence  of  muriatic  acid,  he  found 
slight  indications  of  it,  but  it  was  in  an  ex- 
tremely minute  proportion. 

*  Sir  James  Hall  and  Mr.  Gregory  Watt 
have  both  proved,  by  admirably  conducted 
experiments,  that  basalt  when  fused  into  a 
perfect  glass  will  resume  the  stony  struc- 
ture by  slow  cooling;  and  hence  have  endea- 
voured to  show,  that  the  earthy  structure 
affords  no  argument  against  the  igneous 
formation  of  basalt  in  the  terrestrial  globe.* 

Basraltes,  when  calcined  and  pulverized,  is 


said  to  be  a  good  substitute  for  puzzolana 
in  the  composition  of  mortar,  giving  it  the 
property  of  hardening  under  water.  Wine 
bottles  have  likewise  been  manufactured 
with  it,- but  there  appears  to  be  some  nicety 
requisite  in  the  management  to  ensure  suc- 
cess. Mr.  Castelveil,  who  heated  his  furnace 
with  wood,  added  soda  to  the  basaltes  to 
render  it  more  fusible;  while  Mr.  Giral,  who 
used  pit  coal,  found  it  necessary  to  mix  with 
his  basaltes  a  very  refractory  sand.  The  best 
mode  probably  would  be  to  choose  basaltes 
of  a  close  fine  grain  and  uniform  texture, 
and  to  employ  it  alone,  taking  care  to  regu- 
late the  heat  properly;  for  if  this  be  carried 
too  high,  it  will  drop  from  the  iron  almost 
like  water. 

*  BASALTIC  HORNBLENDE.  It  usually 
occurs  in  opaque  six-sided  single  crystals, 
which     sometimes    act   on   the   magnetic 
needle.  It  is  imbedded  in  basalt  or  wacke. 
Colour  velvet  black.  Lustre  vitreous.  Scrat- 
ches glass.  Sp.  gr.  3.25.  Fuses  with  difficulty 
into  a  black  glass.  It  consists  of  47  silica, 
26  alumina,  8  lime,  2  magnesia,  15  iron,  and 
0.5  water.  It  is  found  in  the  basalt  of  Ar- 
thur's Seat,  in  that  of  Fifeshire,  and  in  the 
Isles  of  Mull,  Canna,  Kigg,  and  Sfcy.  It  is 
found  also  in  the  basaltic  and  floetz  trap- 
rocks  of  England,  Ireland,  Saxony,  Bohemia, 
Silesia,  Bavaria,  Hungary,  Spain,  Italy,  and 
France.* 

*  BASANITE.    See  FLINTY  SLATE.* 

*  BASE  or  BASIS.  A  chemical  term  usu- 
ally applied  to  alkalis,  earths,  and  metallic 
oxides,  in  their  relations  to  the  acids  and 
salts.  It  is  sometimes  also  applied  to  the 
particular  constituents  of  an  acid  or  oxide, 
on  the  supposition  that  the  substance  com- 
bined with  the  oxygen,  &.c.  is  the  basis  of 
the  compound  to  which  it  owes  its  particu- 
lar qualities.  This  notion  seems  unphiloso- 
phical,  as  these  qualities  depend  as  much 
on  the  state  of  combination  as  on  the  nature 
of  the  constituent.* 

BATH.  The  heat  communicated  from 
bodies  in  combustion  must  necessarily  vary 
according  to  circumstances;  and  this  varia- 
tion not  only  influences  the  results  of  opera- 
tions, but  in  many  instances  endangers  the 
vessels,  especially  if  they  be  made  of  glass. 
Among  the  several  methods  of  obviating 
this  inconvenience,  one  of  the  most  usual 
consists  in  interposing  a  quantity  of  sand, 
or  other  matter  between  the  fire  and  the 
vessel  intended  to  be  heated.  The  sand  bath 
and  the  water  bath  are  most  commonly  used; 
the  latter  of  which  was  called  Balneum  Ma- 
riae  by  the  elder  chemists.  A  bath  of  steam 
may,  in  some  instances,  be  found  preferable 
to  the  water  bath.  Some  chemists  have  pro- 
posed baths  of  melted  lead,  of  tin,  and  of 
other  fusible  substances.  These  may  per- 
haps be  found  advantageous  in  a  few  pecu- 
liar operations,  in  which  the  intelligent  ope- 
23 


BEE 


BEE 


rator  must  indeed  be  left  to  his  own  sa- 
gacity. 

*  A  considerably  greater  heat  may  be 
given  to  the  water  bath  by  dissolving  vari- 
ous salts  in  it.  Tims  a  saturated  solution  of 
common  salt  boils  at  225°.3,  or  13°.3  Fahr. 
above  the  boiling  point  of  water.  By  using 
solution  of  muriate  of  lime,  a  bath  of  any 
temperature  from  212  to  252°  may  be  con- 
veniently  obtained.* 

BDELLIUM.  A  gum  resin,  supposed^)  be 
of  African  origin.  The  best  bdellium  is  of  a 
yellowish  brown,  or  dark  brown  colour,  ac- 
cording to  its  age;  unctuous  to  the  touch, 
brittle,  but  soon  softening,  and  growing 
tough  betwixt  the  fingers;  in  some  degree 
transparent,  not  unlike  myrrh;  of  a  bitterish 
taste,  and  a  moderately  strong  smell.  It 
does  not  easily  take  flame,  and,  when  set  on 
fire,  soon  goes  out.  In  burning  it  sputters  a 
little,  owing  to  its  aqueous  humidity.  *  Its 
sp.  gruv.  is  1.371.  Alcohol  dissolves  about 
three-fifths  of  bdellium,  leaving  a  mixture 
of  gum  and  cerasin.  Its  constituents,  accord- 
ing to  Pelletier,  are  59  resin,  9-2  gum,  30.6 
cerasin,  1.2  volatile  oil  and  loss.* 

*  BEAN.  The  seed  of  the  vicia  faba,  a 
small  esculent  bean,  which  becomes  black 
as  it  ripens,  has  been  analyzed  by  Einholf. 
He  found  3840  parts  to  consist  of  600  vo- 
latile matter,  386  skins,  610  fibrous  starchy 
matter,  1312  starch,  417  vegeto-animal  mat- 
ter, 31  albumen,  136  extractive,  soluble  in 
alcohol,   177  gummy  matter,   37£   earthy 
phosphate,  133^  loss.  Fourcroy  and  Vau- 
quelin  found  its  incinerated  ashes  to  contain 
the  phosphates  of  lime,  magnesia,  potash, 
and  iron,  with  uncombined  potash.  They 
found  no  sugar  in  this  bean.  Kidney  beans, 
the  seeds  of  the  phaseolus  -vnlgans,  yielded 
to  Einholf  288  skins,  425  fibrous  starchy 
matter,  1380  starch,  799  vegeto-animal  mat- 
ter, not  quite  free  from  starch,  131  extrac- 
tive, 52  albumen,  with  some  vegeto-animal 
matter,  744  mucilage,  and  21  loss  in  3840.* 

*  BEE.  The  venom  of  the  bee  according 
to  Fontana,  bears  a  close  resemblance  to 
that  of  the  viper.  It  is  contained  in  a  small 
vesicle,  and  has  a  hot  and  acrid  taste,  like 
that  of  the  scorpion.* 

BEER  is  the  wine  of  grain.  Malt  is  usu- 
ally made  of  barley.  The  grain  is  steeped 
for  two  or  three  days  in  water  until  it  swells, 
becomes  somewhat  tender,  and  tinges  the 
water  of  a  bright  reddish-brown  color.  The 
water  being  then  drained  away,  the  barley 
is  spread  about  two  feet  thick  upon  a  floor, 
where  it  heats  spontaneously,  and  begins  to 
grow,  by  first  shooting  out  the  radicle.  In 
this  state  the  germination  is  stopped  by 
spreading  it  thinner,  and  turning  it  over  for 
two  days;f  after  which  it  is  again  made  into 

•J- The  time  varies  very  much  with  the 
weather,  and  is  never  so  short  as  two  days. 


a  heap,  and  suffered  to  become  sensibly  hot, 
which  usually  happens  in  little  more  than 
a  day.  Lastly,  it  is  conveyed  to  the  kiln, 
where,  by  a  gradual  and  low  heat,  it  is  ren- 
dered dry  and  crisp.  This  is  malt;  and  its 
qualities  diifer  according  as  it  is  more  or 
less  soaked, drained, germinated, dried, and 
baked.  In  this,  as  in  other  manufactories, 
the  intelligent  operators  often  make  a  mys- 
tery of  their  processes  from  views  of  pro- 
fit; and  others  pretend  to  peculiar  secrets 
who  really  possess  none. 

Indian  corn,  and  probably  all  large  grain, 
requires  to  be  suffered  to  grow  into  the 
blade,  as  well  as  root,  before  it  is  fit  to  be 
made  into  malt.  For  this  purpose  it  is 
buried  about  two  or  three  inches  deep  in 
the  ground,  and  covered  with  loose  earth; 
and  in  ten  or  twelve  days  it  springs  up.  In 
this  state  it  is  taken  up  and  washed,  or 
fanned,  to  clear  it  from  its  dirt;  and  then 
dried  in  the  kiln  for  use. 

*  Barley,  by  being  converted  into  malt, 
becomes  one-fifth  lighter,  or  20  per  cent; 
12  of  which  are  owing  to  kiln  drying,  1.5 
are  carried  off  by  the  steep-water,  3  dis- 
sipated on  the  floor,  3  lost  in  cleaning  the 
roots,  and  0.5  waste  or  loss.* 

The  degree  of  heat  to  which  the  malt  is 
exposed  in  this  process,  gradually  changes 
its  colour  from  very  pale  to  actual  black- 
ness, as  it  simply  dries  it,  or  converts  it  to 
charcoal. 

The  colour  of  the  malt  not  only  affects 
the  colour  of  the  liquor  brewed  from  it; 
but,  in  consequence  of  the  chemical  opera- 
tion, of  the  heat  applied,  on  the  principles 
that  are  developed  in  the  grain  during  the 
process  of  malting,  materially  alters  the 
quality  of  the  beer,  especially  with  regard 


The  perfection  of  the  process  is  judged 
of,  by  the  length  of  the  roots  and  the  germ; 
of  the  latter  especially.  When  this  has 
passed  two-thirds  of  the  length  of  the 
grain,  it  is  time  to  check  the  vegetation. 
Heaping  it  up  is  unnecessary.  If  allowed 
to  lie  in  heaps  so  long  as  to  heat  much, 
the  malt  would  be  injured.  The  drying 
cannot  be  well  effected  by  heat  in  a  close 
vessel.  A  current  of  dry  air  is  the  desi- 
deratum. I  have  seen  malt  made  by  dry 
air  at  the  heat  of  90  degrees.  Our  summer 
sun  would  answer.  Greater  heat  gives 
more  colour  and  stronger  flavour,  but  less 
strength  to  the  wort.  Neither  Indian  corn 
nor  rice  are  improved  by  malting,  for 
the  purpose  of  fermentation.  Those  grains 
only  are  improved  by  it,  which  have  the 
germ  to  pass  internally  from  one  end  to 
the  other  before  coming  out.  One-third 
raw  Indian  corn  meal,  ground  up  with  two- 
thirds  malt,  gives  more  strength  than  all 
malt. 


BEE 


BEE 


to  the  properties  of  becoming  fit  for  drink- 
ing1 and  growing-  fine. 

Beer  is  made  from  maltpreviously  ground, 
or  cut  to  pieces  by  a  mill.  This  is  placed  in 
a  tun,  or  tub  with  a  false  bottom;  hot  water 
is  poured  upon  it,  and  the  whole  stirred 
about  with  a  proper  instrument.  The  tem- 
perature of  the  water  in  this  operation,  cal- 
led Mashing,  must  not  be  equal  to  boiling; 
for,  in  that  case,  the  malt  would  be  convert- 
ed into  a  paste,  from  which  the  impregna- 
ted water  could  not  be  separated.  This  is 
called  Setting.f  1  After  the  infusion  has  re- 
mained for  some  time  upon  the  malt,  it  is 
drawn  off,  and  is  then  distinguished  by  the 
name  of  Sweet  Wort.  By  one  or  more  sub- 
sequent infusions  of  water,  a  quantity  of 
weaker  wort  is  made,  which  is  either  added 
to  the  foregoing,  or  kept  apart,  according 
to  the  intention  of  the  operator.  The  wort 
is  then  boiled  with  hops,  which  gives  it  an 
aromatic  bitter  taste,  and  is  supposedf2  to 
render  it  less  liable  to  be  spoiled  in  keep- 
ing; after  which  it  is  cooled  in  shallow 
vessels,  and  suffered  to  ferment,|3  with  the 

fl  The  temperature  should  never  be 
above  180  degrees  of  Fahrenheit. 

f  2  It  is  well  known,  that  other  things  be- 
ing equal,  the  liquor  keeps  in  proportion 
to  the  quantity  of  hops.  Fresh  beer  may 
have  from  a  pound  to  a  pound  and  a  half 
to  a  barrel  of  32  gallons.  June  beer,  two 
pounds  and  a  half:  beer  for  the  month  of 
August,  three  pounds;  and  for  a  second 
summer,  three  and  an  half.  For  India  voy- 
ages, four  pounds. 

f3  It  ought  not  to  ferment  in  shallow  ves- 
sels, but  in  vessels  of  a  cubical  or  deep 
cylindrical  form.  The  fermentation  should 
be  commenced  not  lower  than  fifty-eight 
nor  higher  than  sixty-six  F.  The  smaller 
the  fermenting  tun  and  the  colder  the  wea- 
ther, the  warmer  the  wort  should  be,  and 
vice  versa.  The  fall  of  the  head  resulting 
from  the  loss  of  the  viscidity,  which  ena- 
bles it  to  confine  the  carbonic  acid,  is  the 
most  obvious  mark  to  determine  when  the 
fermentation  should  stop.  The  hydrome- 
ter or  saccharometer  affords  a  better  mean 
of  judging,  since  the  same  degree  of  at- 
tenuation takes  place  in  all  infusions  over 
a  certain  strength,  or  22  Ibs.  to  the  London 
barrel,  according  to  instruments  made  in 
that  city.  From  15  to  17  pounds  to  the  bar- 
rel of  diminution  will  generally  be  observ- 
ed. The  fermentation  is  then  to  be  stop- 
ped, by  allowing  the  liquor  to  run  into 
smaller  vessels  of  about  sixty  gallons,  and 
in  these  it  becomes  depurated  by  the  yeast, 
which,  evolved  by  the  fermentation,  entan- 
gles the  carbonic  acid,  and  is  brought  to 
the  top  of  the  beer  by  it,  so  as  to  roll  out 
at  the  bung:  this  is  called  cleansing. 


addition  of  a  proper  quantity  of  yeast.  The 
fermented  liquor  is  beer;  and  differs  great- 
ly in  its  quality,  according  to  the  nature  of 
the  grain,  the  malting,  the  mashing,  the 
quantity,  and  kind  of  the  hops  and  the  yeast, 
the  purity  or  admixtures  of  the  water  made 
use  of,  the  temperature  and  vicissitudes 
of  the  weather,  &c. 

Beside  the  various  qualities  of  malt  li- 
quors of  a  similar  kind,  there  are  certain 
leading  features  by  which  they  are  distin- 
guished, and  classed  under  different  names, 
and  to  produce  which,  different  modes  of 
management  must  be  pursued.  The  princi- 
pal distinctions  are  into  beer,  properly  so 
called;  ale;  table  or  small  beer;  and  porter, 
which  is  commonly  termed  beer  in  London. 
Beer  is  a  strong,  fine,  and  thin  liquor;  the 
greater  part  of  the  mucilage  having  been  se- 
parated by  boiling  the  wort  longer  than  for 
ale,  and  carrying  the  fermentation  farther, 
so  as  to  convert  the  saccharine  matter  into 
alcohol.  A^e  is  of  a  more  sirupy  consistence, 
and  sweeter  taste;  more  of  the  mucilage  be- 
ing retained  in  it,  and  the  fermentation  not 
having  been  carried  so  far  as  to  decompose 
all  the  sugar .f  Small  beer,  as  its  name  im- 
plies, is  a  weaker  liquor;  and  is  made,  either 
by  adding  a  large  portion  of  water  to  the 
malt,  or  by  mashing  with  a  fresh  quantity 
of  water  what  is  left  after  the  beer  or  ale 
wort  is  drawn  off.  Porter  was  probably 
made  originally  from  very  high  dried  malt; 
but  it  is  said,  that  its  peculiar  flavour  can- 
not be  imparted  by  malt  and  hops  alone. 

*Mr.  Brande  obtained  the  folio  wing  quan- 
tities of  alcohol  from  100  parts  of  different 
species  of  beers.  Burton  ale,  8.88,  Edin- 
burgh ale,  6.2,  Dorchester  ale,  5.56;  the 
average  being  =  6.87.  Brown  stout,  6.8, 
London  porter  (average)  4.2,  London  small 
beer,  (average)  1.28.* 

As  long  ago  as  the  reign  of  Queen  Anne, 
brewers  were  forbid  to  mix  sugar,  honey, 
Guinea  pepper,  essentia  bina,  cocculus  in- 
dicus,  or  any  other  unwholesome  ingredi- 
ent, in  beer,  under  a  certain  penalty;  from 
which  we  may  infer,  that  such  at  least  was 
the  practice  of  some;  and  writers,  who  pro- 
fess to  discuss  the  secrets  of  the  trade, 
mention  most  of  these  and  some  other  arti- 
cles as  essentially  necessary.  The  essentia 
bina  is  sugar  boiled  down  to  a  dark  colour, 
and  empyreumatic  flavour.  Broom  tops, 
wormwood,  and  other  bitter  plants,  were 
formerly  used  to  render  beer  fit  for  keep- 
ing, before  hops  were  introduced  into  this 

f  There  is  no  essential  difference  be- 
tween the  mode  of  brewing  ale  and  beer. 
The  colour  and  flavour  of  the  malt  is 
the  principal  ground  of  distinction.  Keep- 
ing ale  is  boiled  longer  than  fresh  beer. 
The  more  sirupy  consistence  is  in  conse- 
quence of  more  malt  being  used. 


BEE 


BEN 


country;   but  now   are  prohibited   to  be 
used  in  beer  made  for  sale. 

*  By  the  present  law  of  this  country, 
nothing  is  allowed  to  enter  into  the  com- 
position of  beer,  except  malt  and  hops. 
Quassia  and  wormwood  are  often  fraudu- 
lently introduced;  both  of  which  are  ea- 
sily discoverable  by  their  nauseous  bitter 
taste.  They  form  a  beer  which  does  not 
preserve  so  well  as  hop  beer.  Sulphate  of 
iron,  alum,  and  salt,  are  often  added  by 
the  publicans,  under  the  name  of  beer-hfdd- 
ing>  to  impart  a  frothing  property  to  beer, 
when  it  is  poured  out  of  one  vessel  into 
another.  Molasses  and  extract  of  gentian 
root  are  added  with  the  same  view.  Cap- 
sicum, grains  of  paradise,  ginger  root,  co- 
riander seed,  and  orange  peel,  are  also  em- 
ployed to  give  pungency  and  flavour  to 
weak  or  bad  beer.  The  following  is  a  list 
of  some  of  the  unlawful  substances  seized 
at  different  breweries,  and  brewers'  drug- 
gists' laboratories,  in  London,  as  copied 
from  the  minutes  of  the  committee  of  the 
House  of  Commons.  Coculus  indicus,  mul- 
tum,  (an  extract  of  the  cocculus),  colour- 
ing, honey,  hartshorn  shavings,  Spanish 
juice,  orange  powder,  ginger,  grains  of 
paradise,  quassia,  liquorice,  caraway  seeds, 
copperas,  capsicum,  mixed  drugs.  Sulphu- 
ric acid  is  very  frequently  added  to  bring 
beer  forward,  or  make  it  hard,  giving  new 
beer  instantly  the  taste  of  what  is  18 
months  old.  According  to  Mr.  Accum,  the 
present  entire  beer  of  the  London  brewer 
is  composed  of  all  the  waste  and  spoiled 
beer  of  the  publicans,  the  bottoms  of  butts, 
the  leavings  of  the  pots,  the  drippings  of 
the  machines  for  drawing  the  beer,  the 
remnants  of  beer  that  lay  in  the  leaden 
pipes  of  the  brewery,  with  a  portion  of 
brown  stout,  bottling  beer,  and  mild  beer. 
He  says  that  opium,  tobacco,  nux  vomica, 
and  extract  of  poppies,  have  likewise  been 
used  to  adulterate  beer.  For  an  account  of 
the  poisonous  qualities  of  the  cocculus  in- 
dicus,  see  PICROTOXIA,  and  for  those  of 
nux  vomica,  see  STRYCHNIA.  By  evapo- 
rating a  portion  of  beer  to  dryness,  and  ig- 
niting the  residuum  with  chlorate  of  pot- 
ash, the  iron  of  the  copperas  will  be  pro- 
cured in  an  insoluble  oxide.  Muriate  of 
barytes  will  throw  down  an  abundant  pre- 
cipitate from  beer  contaminated  with  sul- 
phuric acid  or  copperas^  which  precipitate 
may  be  collected,  dried,  and  ignited.  It 
Will  be  insoluble  in  nitric  acid.* 

Beer  appears  to  have  been  of  ancient 
vse,  as  Tacitus  mentions  it  among  the 
Germans,  and  has  been  usually  supposed 
to  have  been  peculiar  to  the  northern  na- 
tions: but  the  ancient  Egyptians,  whose 
country  was  not  adapted  to  the  culture  of 
the  grape,  had  also  contrived  this  substi- 
tute for  wine;  and  Mr.  Park  has  found  the 


art  of  making  malt,  and  brewing  from  it 
very  good  beer,  among  the  negroes  in  the 
interior  parts  of  Africa. 

BEET.  The  root  of  the  beet  affords  a 
considerable  quantity  of  sugar,  and  has 
lately  been  cultivated  for  the  purpose  of 
extracting  it  to  some  extent  in  Germany. 
See  SUGAR.  It  is  likewise  said,  that  if  beet 
roots  be  dried  in  the  same  manner  as  malt, 
after  the  greater  part  of  their  juice  is 
pressed  out,  very  good  beer  may  be  made 
from  them. 

*BELLMETAL.  See  COPPER.* 

*  BELLMETAL  ORE.  See  ORES  OF  TIN.* 

BEN  (OIL  OF).  This  is  obtained  from 
the  ben  nut,  by  simple  pressure.  It  is  re- 
markable for  its  not  growing  rancid  in  keep- 
ing, or  at  least  not  until  it  has  stood  for  a 
number  of  years;  and  on  this  account  it  is 
used  in  extracting  the  aromatic  principle 
of  such  odoriferous  flowers  as  yield  little 
or  no  essential  oil  in  distillation. 

*BENZOIC  ACID.  See  ACID  (BEN- 
ZOIC).* 

BENZOIN  OR  BENJAMIN.  The  tree 
which  produces  Benzoin  is  a  native  of  the 
East  Indies,  particularly  of  the  island  Siam 
and  Sumatra.^  The  juice  exudes  from  in- 
cisions, in  the  form  of  a  thick  white  bal- 
sam. If  collected  as  soon  as  it  has  grown 
somewhat  solid,  it  proves  internally  white 
like  almond,  and  hence  it  is  called  Ben- 
zoe  Amygdaloides;  if  suffered  to  lie  long 
exposed  to  the  sun  and  air,  it  changes 
more  and  more  to  a  brownish,  and  at  last 
to  a  quite  reddish-brown  colour. 

This  resin  is  moderately  hard  and  brit- 
tle, and  yields  an  agreeable  smell  when 
rubbed  or  warmed.  When  chewed,  it  im- 
presses a  slight  sweetness  on  the  palate. 
It  is  totally  soluble  in  alcohol;  from  which, 
like  other  resins,  it  may  be  precipitated 
by  the  addition  of  water.  Its  specific  gra- 
vity is  1.092. 

The  white  opaque  fluid  thus  obtained 
lias  been  called  Lac  Virginale;  and  is  still 
sold,  with  other  fragrant  additions,  by  per- 
fumers, as  a  cosmetic.  Boiling  water  sepa- 
rates the  peculiar  acid  of  benzoin. 

The  products  Mr.  Brande  obtained  by 
distillation  were,  from  a  hundred  grains, 
ben  zoic  acid  9  grains,  acidulated  watev 
5.5,  butyraceous  and  empyreumatic  oil  60, 
brittle  coal  22,  and  a  mixture  of  carburet- 
ted  hydrogen  and  carbonic  acid  gas,  com- 
puted at  3.5.  On  treating  the  empyreuma- 
tic oil  with  water,  however,  5  grains  more 
of  acid  were  extracted,  making  14  in  the 
whole. 

*  From  1500  grains  of  benzoin,  Bucholz 

$  Consult  the  Philosophical  Transactions, 
vol.  Ixxvii.  page  307,  for  a  botanical  de- 
scription and  drawing  of  the  tree,  by  Dry- 
ander. 


BE/, 


BIL 


obtained  1250  of  resin,  187  benzole  acid,  25 
of  a  substance  similar  to  balsam  of  Peru,  8 
of  an  aromatic  substance  soluble  in  water 
and  alcohol,  and  30  of  woody  fibres  and  im- 
purities. 

Ether,  sulphuric  and  acetic  acids,  dis- 
solve benzoin;  so  do  solutions  of  potash  and 
soda.  Nitric  acid  acts  violently  on  it,  and  a 
portion  of  artificial  tannin  is  formed.  Am 
inonia  dissolves  it  sparingly.* 

*  BERGMANNITE.  A  massive  mineral  of 
a  greenish,  greyish-white,  or  reddish  co- 
lour. Lustre  intermediate  between  pearly 
and  resinous.  Fracture  fibrous,  passing  into 
line  grained,  uneven.  Slightly  translucent  on 
the  edges.  Scratches  felspar.  Fuses  into  a 
transparent  glass,  or  a  semi-transparent  ena- 
mel. It  is  found  at  Frederickswarn  in  Nor- 
way, in  quartz  and  in  felspar.* 

*  BERYL.  This  precious  mineralj  is  most 
commonly  green,  of  various  shades,  passing 
into  honey-yellow,  and  sky-blue.  It  is  crys- 
tallized in  hexahedral  prisms  deeply  striat- 
ed longitudinally,  or  in  6  or  12  sided  prisms, 
terminated  by  a  6  sided  pyramid,  whose 
summit  is  replaced.  It  is  harder  than  the 
emerald,  but  more  readily  yields  to  cleav- 
age. Its  sp.  grav.  is  2.7.  Its  lustre  is  vitre- 
ous. It  is  transparent,  and  sometimes  only 
translucent.  It  consists  by  Vauquelin  of  68 
silica,  15  alumina,  14  glucina,  1  oxide  of 
iron,  2  lime.  Berzelius  found  in  it  a  truce  of 
oxide  of  tantalum.  It  occurs  in  veins  tra- 
versing granite  in  Daouria;  in  the  Altaic 
chain  in  Siberia;  near  Limoges  in  France; 
in  Saxony;  Brazil;  at  Kinloch  liaimoch,  and 
Cairngorm,  Aberdeenshire,  Scotland;  above 
Dundrum,  in  the  county  of  Dublin,  and  near 
Cronebane,  county  of  Wicklow,  in  Ireland. 
It  differs  from  emerald  in  hardness  and  co- 
lour. It  has  been  called  aqua  marine,  and 
greenish-yellow  emerald.  It  is  electric  by 
friction  and  not  by  heat.* 

*  BEZ.OAR.  This  name,  which  is  derived 
from  a  Persian  word  implying  an  antidote 
to  poison,  was  given  to  a  concretion  found 
in  the  stomach  of  an  animal  of  the  goat  kind, 
which  was  once  very  highly  valued  for  this 
imaginary  quality,  and  has  thence  been  ex- 
tended to  ail  concretions  found  in  animals. 

These  are  of  eight  kinds,  according  to 
Fourcroy,  Vauquelin,  and  Berthollet.  1.  Su- 
perphosphate of  lime,  which  forms  concre- 
tions in  the  intestines  of  many  mammalia.  2. 
Phosphate  of  magnesia,  semi-transparent 
and  yellowish,  and  of  sp.  grav.  £.160.  3. 
Phosphate  of  ammonia  and  magnesia.  A 
concretion  of  a  grey  or  brown  colour,  com- 
posed of  radiations  from  a  centre.  It  is  found 
in  the  intestines  of  herbiverous  animals,  the 
elephant,  horse,  &c.  4.  Biliary,  colour  red- 

•j-  Beryl  is  not  always  precious,  and  even 
when  transparent,  as  in  the  form  of  aqua 
Tsarina,  has  little  value. 


dish-brown,  found  frequently  in  the  intes- 
tines and  gall  bladder  of  oxen,  and  used  by 
painters  for  an  orange-yellow  pigment.  It  is 
inspissated  bile  5.  Resinous.  The  oriental 
bezoars,  procured  from  unknown  animals, 
belongto  tbis  class  of  concretions.  They  con- 
sist of  concentric  layers,  are  fusible,  com- 
bustible, smooth,  soft,  and  finely  polished. 
They  are  composed  of  bile  and  resin.  6. 
Fungous,  consisting  of  pieces  of  the  boletus 
igniarius,  swallowed  by  the  animal.  7.  Hairy. 
8.  Ligniform.  Three  bezoars  sent  to  Bona- 
parte by  the  king  of  Persia,  were  found  by 
Berthollet  to  be  nothing  but  woody  fibre 
agglomerated.* 

BlHYDROGURET       OF      CARBON.        See 

CARBURETTED  HYDROGEN. 

BlHYDROGURET  OF  PHOSPHORUS.    See 

PHOSPHURETTED  HYDROGEN. 

*BILDSTEIN,  AGALMATOLITE,  or  Fi- 
GURESTONE.  A  massive  mineral,  with 
sometimes  an  imperfectly  slaty  structure. 
Colour  gray,  brown,  flesh  red,  and  some- 
times spotted,  or  with  blue  veins.  It  is  trans- 
lucent on  the  edges,  unctuous  to  the  touch, 
and  yields  to  the  nail.  Sp.  grav.  2.8.  It  is 
composed  of  56  silica,  29  alumina,  7  potash, 
2  lime,  1  oxide  of  iron,  and  5  water,  by  Vau- 
quelin. Klaproth  found  in  a  specimen  from 
China,  54.5  silica,  34  alumina,  6.25  potash, 
0.75  oxide  of  iron,  and  4  water.  It  fuses  into 
a  transparent  glass.  M.  Brongniart  calls  it 
steatite  pagodite,  from  its  coining  from  China 
cut  into  grotesque  figures.  It  wants  the 
magnesia,  which  is  a  constant  ingredient  of 
steatites.  It  is  found  at  Naygag  in  Transyl- 
vania, and  Glyder-bach  in  Wales. 

*  BILE.  A  bitter  liquid,  of  a  yellowish  or 
greenish-yellow  colour,  more  or  less  viscid, 
of  a  sp.  gravity  greater  than  that  of  water, 
common  to  a  great  number  of  animals,  the 
peculiar  secretion  of  their  liver.  It  is  the 
prevailing-  opinion  of  physiologists,  that  the 
bile  is  separated  from  the  venous,  and  not 
like  the  other  secretions,  from  the  arterial 
blood.  The  veins  which  receive  the  blood 
distributed  to  the  abdominal  viscera,  unite 
into  a  large  trunk  called  the  vena  portce, 
which  divides  into  two  branches,  that  pene- 
trate into  the  liver,  and  divide  into  innumer- 
able ramifications.  The  last  of  these  termi- 
nate partly  in  the  biliary  ducts,  and  partly 
in  the  hepatic  veins,  which  restore  to  the 
circulation  the  blood  not  needed  for  the 
formation  of  bile.  This  liquid  passes  directly 
into  the  duodenum  by  the  ductns  choledochus, 
when  the  animal  has  no  gall  bladder;  but 
wrhen  it  has  one,  as  more  frequently  hap- 
pens, the  bile  flows  back  into  it  by  the  cys- 
tic duct,  and  remaining  there  for  a  longeF 
or  shorter  time,  experiences  remarkable  al- 
terations. Its  principal  use  seems  to  be,  to 
promote  the  duodenal  digestion,  in  concert 
with  the  pancreatic  juice. 

Boerhaave,  by  an  extravagant  error,  re- 


BIL 


BIR 


garded  the  bile  as  one  of  the  most  putresci- 
ble  fluids;  and  hence  originated  many  hypo- 
thetical and  absurd  theories  on  diseases  and 
their  treatment.  We  shall  follow  the  ar- 
rangement of  M.  Thenard,  in  a  subject 
which  owes  to  him  its  chief  illustration. 

1.  Ox  bile  is  usually  of  a  greenish-yellow 
colour,  rarely  a  deep  green.  By  its  colour 
it  changes  the  blue  of  turnsole  and  violet 
to  a  reddish-yellow.  At  once  very  bitter,  and 
slightly  sweet,  its  taste  is  scarcely  support- 
able. Its  smell,  though  feeble,  is  easy  to 
recognize,  and  approaches  somewhat  to  the 
nauseous  odour  of  certain  fatty  matters 
when  they  are  heated.  Its  specific  gravity 
varies  very  little.  It  is  about  1.026  at  43°  F. 
It  is  sometimes  limpid,  and  at  others  dis- 
turbed with  a  yellow  matter,  from  which  it 
may  be  easily  separated  by  water;  its  con- 
sistence varies  from  that  of  a  thin  mucilage, 
to  viscidity.  Cadet  regarded  it  as  a  kind  of 
soap.  This  opinion  was  first  refuted  by  M. 
Thenard.  According  to  this  able  chemist, 
800  parts  of  ox  bile,  are  composed  of  700 
water,  15  resinous  matter,  69  picromel, 
about  4  of  a  yellow  matter,  4  of  soda,  2 
phosphate  of  soda,  3.5  muriates  of  soda  and 
potash,  0.8  sulphate  of  soda,  1.2  phosphate 
of  lime,  and  a  trace  of  oxide  of  iron.  When 
distilled  to  dry  ness,  it  leaves  from  l-8th  to 
8-9th  of  solid  matter,  which,  urged  with  a 
higher  heat,  is  resolved  into  the  usual  ig- 
neous products  of  animal  analysis;  only  with 
more  oil  and  less  carbonate  of  ammonia. 

Exposed  for  some  time  in  an  open  ves- 
sel, the  bile  gradually  corrupts  and  lets  fall 
a  small  quantity  of  a  yellowish  matter; 
then  its  mucilage  decomposes.  Thus  the 
putrefactive  process  is  very  inactive,  and 
the  odour  it  exhales  is  not  insupportable, 
but  in  some  cases  has  been  thought  to  re- 
semble that  of  musk.  Water  and  alcohol 
combine  in  all  proportions  with  bile.  When 
a  very  little  acid  is  poured  into  bile,  it  be- 
comes slightly  turbid,  and  reddens  litmus; 
when  more  is  added,  the  precipitate  aug- 
ments, particularly  if  sulphuric  acid  be  em- 
ployed. It  is  formed  of  a  yellow  animal  mat- 
ter, with  very  little  resin.  Potash  and  soda 
increase  the  thinness  and  transparency  of 
bile.  Acetate  of  lead  precipitates  the  yel- 
low matter  and  the  sulphuric  and  phospho- 
ric acids  of  the  bile.  The  solution  of  the  sub- 
acetate  precipitates  not  only  these  bodies, 
but  also  the  picromel  and  the  muriatic  acid, 
all  combined  with  the  oxide  of  lead.  The  a- 
cetic  acid  remains  in  the  liquid  united  to  the 
soda.  The  greater  number  of  fatty  substan- 
ces  are  capable  of  being  dissolved  by  bile. 
This  property,  which  made  it  be  considered 
a  soap,  is  owing  to  the  soda,  and  to  the  tri- 
ple compound  of  soda,  resin,  and  picromel 
Scourers  sometimes  prefer  it  to  soap,  for 
cleansing  woollen.  The  bile  of  the  calf,  the 
•dog,  and  the  sheep,  is  similar  to  that  of  the 


ox.  The  bile  of  the  sow  contains  no  picro- 
mel. It  is  merely  a  soda-resinous  soap.  Hu- 
man bile  is  peculiar.  It  varies  in  colour, 
sometimes  being  green,  generally  yellow- 
ish-brown, occasionally  almost  colourless. 
Its  taste  is  not  very  bitter.  In  the  gall  blad- 
der it  is  seldom  limpid,  containing  often, 
like  that  of  the  ox,  a  certain  quantity  of 
yellow  matter  in  suspension.  At  times  this 
is  in  such  quantity,  as  to  render  the  bile 
somewhat  grumous.  Filtered  and  boiled,  it 
becomes  very  turbid,  and  diffuses  the  odour 
of  white  of  egg.  When  evaporated  to  dry- 
ness,  there  results  a  brown  extract,  equal 
in  weight  to  1-1 1th  of  the  bile.  By  calcina- 
tion we  obtain  the  same  salts  as  from  ox 
bile. 

All  the  acids  decompose  human  bile,  and 
occasion  an  abundant  precipitate  of  albu- 
men and  resin,  which  are  easily  separable 
by  alcohol.  One  part  of  nitric  acid,  'sp. 
grav.  1.210,  saturates  100  of  bile.  On  pour- 
ing into  it  a  solution  of  sugar  of  lead,  it  is 
changed  into  a  liquid  of  a  light  yellow  co- 
lour, in  which  no  picromel  can  be  found, 
and  which  contains  only  acetate  of  soda, 
and  some  traces  of  animal  matter.  Human 
bile  appears  hence  to  be  formed,  by  The- 
nard, in  1100  parts;  of  1000  water;  from  2 
to  10  yellow  insoluble  matter;  42  albumen; 
41  resin;  .5.6  soda:  and  45  phosphates  of  so- 
da and  lime,  sulphate  of  soda,  muriate  of 
soda  and  oxide  of  iron.  But  by  Berzelius, 
its  constituents  are  in  1000  parts:  908.4 
water;  80  picromel;  3  albumen;  4.1  soda; 
0.1  phosphate  of  lime;  3.4  common  salt, 
and  1.  phosphate  of  soda,  with  some  phos- 
phate of  lime.* 

BIRDLIME.  The  best  birdlime  is  made 
of  the  middle  bark  of  the  holly,  boiled  se- 
ven or  eight  hours  in  water,  till  it  is  soft 
and  tender;  then  laid  in  heaps  in  pits  in 
the  ground  and  covered  witli  stones,  the 
water  being  previously  drained  from  it; 
and  in  this  state  left  for  two  or  three  weeks 
to  ferment  till  it  is  reduced  to  a  kind  of 
mucilage.  This  being  taken  from  the  pit  is 
pounded  in  a  mortar  to  a  paste,  washed  in 
river  water,  and  kneaded,  till  it  is  freed 
from  extraneous  matters.  In  this  state  it  is 
left  four  or  five  days  in  earthen  vessels,  to 
ferment  and  purify  itself,  when  it  is  fit  for 
use. 

It  may  likewise  be  obtained  from  the 
misleto,  the  viburnum  lantana,  young 
shoots  of  elder,  and  other  vegetable  sub- 
stances. 

It  is  sometimes  adulterated  with  turpen- 
tine, oil,  vinegar,  and  other  matters. 

Good  birdlime  is  of  a  greenish  colour 
and  sour  flavour;  gluey,  stringy,  and  tena- 
cious; and  in  smell  resembling  linseed  oil. 
By  exposure  to  the  air  it  becomes  dry  and 
brittle,  so  that  it  may  be  powdered;  but  its 
viscidity  is  restored  "by  wetting  it.  It  red- 


BIS 


BIS 


dens  tincture  of  litmus.  Exposed  to  a  gen- 
tie  heat  it  liquefies  slightly,  swells  in  bub- 
bles, becomes  grumous,  emits  a  smell  re- 
sembling that  of  animal  oils,  grows  brown, 
but  recovers  its  properties  on  cooling,  if 
not  heated  too  much..  With  a  greater  heat 
it  burns,  giving  out  a  brisk  flame  and  much 
smoke.  The  residuum  contains  sulphate 
and  muriate  of  potash,  carbonate  of  lime 
and  alumina,  with  a  small  portion  of  iron 

BISMUTH  is  a  metal  of  a  yellowish  or 
reddish-white  colour,  little  subject  to 
change  in  the  air.f  It  is  somewhat  harder 
than  lead,  and  is  scarely,  if  at  all,  mallea- 
ble; being  easily  broken,  and  even  reduced 
to  powder,  by  the  hammer.  The  internal 
face,  or  place  of  fracture,  exhibits  large 
shining  plates,  disposed  in  a  variety  of  po- 
sitions; thin  pieces  are  considerably  sono- 
rous. At  a  temperature  of  480°  Fahrenheit, 
it  melts;  and  its  surface  becomes  covered 
with  a  greenish-grey,  or  brown  oxide.  A 
stronger  heat  ignites  it,  and  causes  it  to 
burn  with  a  small  blue  flame;  at  the  same 
time  that  a  yellowish  oxide,  known  by  the 
name  of  flowers  of  bismuth,  is  driven  up. 
This  oxide  appears  to  rise  in  consequence 
of  the  combustion;  for  it  is  very  fixed,  and 
runs  into  a  greenish  glass  when  exposed  to 
heat  alone. 

*  This  oxide  consists  of  100  metal  -f- 
11.275  oxygen,  whence  its  prime  equiva- 
lent will  be  9.87,  and  that  of  the  metal  it- 
self 8.87.  The  specific  gravity  of  the  me- 
tal is  9.85.* 

Bismuth,  urged  by  a  strong  heat  in  a 
closed  vessel,  sublimes  entire,  and  crystal- 
lizes very  distinctly  when  gradually  cooled 

The  sulphuric  acid  has  a  slight  action 
upon  bismuth,  when  it  is  concentrated  and 
boiling.  Sulphurous  acid  gas  is  exhaled, 
and  part  of  the  bismuth  is  converted  into 
a  white  oxide.  A  small  portion  combines 
with  the  sulphuric  acid,  and  affords  a  de- 
liquescent salt  in  the  form  of  small  needles. 

The  nitric  acid  dissolves  bismuth  with 
the  greatest  rapidity  and  violence;  at  the 
same  time  that  much  heat  is  extricated,  and 
a  large  quantity  of  nitric  oxide  escapes. 
The  solution,  when  saturated,  affords  crys- 
tals as  it  cools;  the  salt  detonates  weakly, 
and  leaves  a  yellow  oxide  behind,  which 
effloresces  in  the  air.  Upon  dissolving  this 
salt  in  water,  it  renders  that  fluid  of  a 
milky  white,  and  lets  fall  an  oxide  of  the 
same  colour. 

The  nitric  solution  of  bismuth  exhibits 
the  same  property  when  diluted  with  wa- 
ter, most  of  the  metal  falling  down  in  the 
form  of  a  white  oxide,  called  magistery  of 
bismuth.  This  precipitation  of  the  nitric 
solution,  by  the  addition  of  water,  is  the 

f  It  is  more  properly  tin  or  silver-white 
-with  a  blush  of  red, 


criterion  by  which  bismuth  is  distinguished 
from  most  other  metals.  The  magistery  or 
oxide  is  a  very  white  and  subtile  powder: 
when  prepared  by  the  addition  of  a  large 
quantity  of  water,  it  is  used  as  a  paint  for 
the  complexion,  and  is  thought  gradually 
to  impair  the  skin.  The  liberal  use  of  any 
paint  for  the  skin  seems  indeed  likely  to  do 
this;  but  there  is  reason  to  suspect,  from 
the  resemblance  between  the  general  pro- 
perties of  lead  and  bismuth,  that  the  oxide 
ot  this  metal  may  be  attended  with  effects 
similar  to  those  which  the  oxides  of  lead 
are  known  to  produce.  If  a  small  portion  of 
muriatic  acid  be  mixed  with  the  nitric,  and 
the  precipitated  oxide  be  washed  with  but 
a  small  quantity  of  cold  water,  it  will  ap- 
pear in  minute  scales  of  a  pearly  lustre, 
constituting  the  pearl  potuder  of  perfumers. 
These  paints  are  liable  to  be  turned  black 
by  sulphuretted  hydrogen  gas. 

The  muriatic  acid  does  not  readily  act 
upon  bismuth. 

*  When  bismuth  is  exposed  to  chlorine 
gas  it  takes  fire,  and  is  converted  into  a 
chloride,  which,  formerly  prepared  by  heat- 
ing the  metal  with  corrosive  sublimate,  was 
called  butter  of  bismuth.  The  chloride  is 
of  a  grayish-white  colour,  a  granular  tex- 
ture, and  is  opaque.  It  is  fixed  at  a  red  heat. 
According  to  Dr.  John  Davy,  it  is  composed 
of  33.6  chlorine,  +  66.4  bismuth,  =  100; 
or  in  equivalent  numbers,  of  4.45  chlorine, 
-f-  b.87  bismuth,  =  13.32.  When  iodine  and 
bismuth  are  heated  together,  they  readily 
form  an  iodide  of  an  orange-yellow  colour, 
insoluble  in  water,  but  easily  dissolved  in 
potash  ley.* 

Alkalis  likewise  precipitate  its  oxide;  but 
not  of  so  beautiful  a  white  colour  as  that 
afforded  by  the  affusion  of  pure  water. 

The  gallic  acid  precipitates  bismuth  of  a 
greenish-yellow,  as  ferroprussiate  of  potash 
does  of  a  yellowish  colour. 

*  There  appears  to  be  two  sulphurets, 
the  first  a  compound  of  100  bismuth  to  22.34 
sulphur;  the  second  of  100  to  46  5;  the  se- 
cond is  a  bisulphuret.* 

This  metal  unites  with  most  metallic 
substances,  and  renders  them  in  general 
more  fusible.  When  calcined  with  the  im- 
perfect metals,  its  glass  dissolves  them, 
and  produces  the  same  effect  as  lead  in 
cupellation;  in  which  process  it  is  even 
said  to  be  preferable  to  lead. 

Bismuth  is  used  in  the  composition  of 
pewter,  in  the  fabrication  of  printers'  tvpes, 
and  in  various  other  metallic  mixtures. 
With  an  equal  weight  of  lead,  it  forms  a 
brilliant  white  alloy,  much  harder  than 
lead,  and  more  malleable  than  bismuth, 
though  not  ductile;  and  if  the  proportion 
of  lead  be  increased,  it  is  rendered  still 
more  malleable.  Eight  parts  of  bismuth, 
five  of  lead,  and  three  of  tin,  constitute 


BIT 


BIT 


tfoe  fusible  metal,  sometimes  called  New- 
ton's; from  its  discoverer,  which  melts  at 
the  heat  of  boiling  water,  and  may  be  fused 
over  a  candle  in  a  piece  of  stiff  paper 
without  burning  the  paper.  One  part  of 
bismuth,  with  five  of  lead,  and  three  of 
tin,  forms  plumbers'  solder.  It  forms  the 
basis  of  a  sympathetic  ink.  The  oxide  of 
bismuth,  precipitated  by  potash  from  ni- 
tric acid,  has  been  recommended  in  spas- 
modic disorders  of  the  stomach,  and  given 
in  doses  of  four  grains  four  times  a  day. 
A  writer  in  the  Jena  Journal  says  he  has 
known  the  dose  carried  gradually  to  one 
scruple  without  injury. 

Bismuth  is  easily  separable,  in  the  dry 
way,  from  its  ores,  on  account  of  its  great 
fusibility.  It  is  usual,  in  the  processes  at 
large,  to  throw  the  bismuth  ore  into  a  fire 
of  wood;  beneath  which  a  hole  is  made  in 
the  ground  to  receive  the  metal,  and  de- 
fend it  from  oxidation.  The  same  process 
may  be  imitated  in  the  small  way,  in  the 
examination  of  the  ores  of  this  metal;  no- 
thing more  being  necessary,  than  to  expose 
it  to  a  moderate  heat  in  a  crucible,  with  a 
quantity  of  reducing  flux;  taking  care,  at 
the  same  time,  to  perform  the  operation  as 
speedily  as  possible,  that  the  bismuth  may 
be  neither  oxidized  nor  volatilized. 

BISTRE.  A  brown  pigment,  consisting 
of  the  finer  parts  of  wood  soot,  separated 
from  the  grosser  by  washing.  The  soot  of 
the  beech  is  said  to  make  the  best. 

*  BITTER  PRINCIPLE,  of  which  there 
are  several  varieties. 

When  nitric  acid  is  digested  on  silk,  in- 
digo, or  white  willow,  a  substance  of  a 
deep  yellow  colour,  and  an  intensely  bitter 
taste,  is  formed.  It  dyes  a  permanent  yel- 
low. It  crystallizes,  in  oblong  plates,  and 
saturates  alkalis,  like  an  acid,  producing 
crystallizable  salts.  That  with  potash,  is 
in  yellow  prisms.  They  are  bitter,  per- 
manent in  the  air,  and  less  soluble  than 
the  insulated  bitter  principle.  On  hot  char- 
coal they  deflagrate.  When  struck  smart- 
ly on  an  anvil,  they  detonate  with  much 
violence,  and  with  emission  of  a  purple 
light.  Ammonia  deepens  the  colour  of  the 
bitter  principle  solution,  and  forms  a  salt 
in  yellow  spiculae.  It  unites  also  with  the 
alkaline  earths  and  metallic  oxides.  M. 
Chevreul  considers  it  a  compound  of  nitric 
acid,  with  a  peculiar  substance  of  an  oily 
nature.  Quassia,  cocculus  Indicus,  daphne 
Alpina,  coffee,  squills,  colocynth,  and  bry- 
ony,  as  well  as  many  other  medicinal  plants, 
yield  bitter  principles,  peculiarly  modified.* 

BITTERN.  The  mother  waterwhich  re- 
mains after  the  crystallization  of  common- 
salt  in  sea  water,  or  the  water  of  salt  springs. 
It  abounds  with  sulphate  and  muriate  of 
magnesia,  to  which  its  bitterness  is  owing. 
See  WATER  (SEA). 


*  BlTTERSPAR,  Or  RHOMBSPAR.      ThJ9 

mineral  crystallizes  in  rhomboids,  which 
were  confounded  with  those  of  calcareous 
spar,  till  Dr.  Wollaston  applied  his  admi- 
rable reflecting  goniometer,  and  proved 
the  peculiarity  of  the  angles  in  bitterspar, 
which  are  106°  15',  and  73°  45'.  Its  colour 
is  grayish  or  yellow,  with  a  somewhat  pear- 
ly lustre.  It  is  brittle,  semi-transparent, 
splendent,  and  harder  than  calcareous  spar. 
Fracture  straight  foliated  with  a  threefold 
cleavage.  Its  sp.  gr.  is  2.88.  It  consists  of 
from  68  to  73  carbonate  of  lime,  25  carbo- 
nate of  magnesia,  and  2  oxide  of  manga- 
nese. It  is  usually  imbedded  in  serpentine, 
chlorite  or  steatite;  and  is  found  in  the  Ty- 
rol, Salzburg,  and  Dauphiny.  In  Scotland, 
on  the  borders  of  Loch  Lomond  in  the  chlo- 
rite slate,  and  near  Newton-Stewart  in  Gal- 
loway; as  also  in  the  Isle  of  Mann.  It  bears 
the  same  relation  to  dolomite  and  magne- 
sian  limestone,  that  calcareous  spar  does 
to  common  limestone.* 

BITUMEN.  This  term  includes  a  consi- 
derable range  of  inflammable  mineral  sub- 
stances, burning  with  flame  in  the  open  air. 
They  are  of  different  consistency,  from  a 
thin  fluid  to  a  solid;  but  the  solids  are  for 
the  most  part  liquefiable  at  a  moderate 
heat.  The  fluid  are,  1.  Naphtha;  a  fine, 
white,  thin,  fragrant,  colourless  oil,  which 
issues  out  of  white,  yellow,  or  black  clays 
in  Persia  and  Media.  This  is  highly  in- 
flammable, and  is  decomposed  by  distilla- 
tion. It  dissolves  resins,  and  the  essential 
oils  of  thyme  and  lavender;  but  is  not  it- 
self soluble  either  in  alcohol  or  ether.  It  is 
the  lightest  of  all  the  dense  fluids,  its  spe- 
cific gravity  being  0.708.  2.  Petroleum, 
which  is  a  yellow,  reddish,  brown,  green- 
ish, or  blackish  oil,  found  dropping  from 
rocks,  or  issuing  from  the  earth,  in  the 
duchy  of  Modena,  and  in  various  other 
parts  of  Europe  and  Asia.  This  likewise  is 
insoluble  in  alcohol,  and  seems  to  consist 
of  naphtha,  thickened  by  exposure  to  the 
atmosphere.  It  contains  a  portion  of  the 
succinic  acid.  3.  Barbadoes  tar,  which  is  a 
viscid,  brown,  or  black  inflammable  sub- 
stance, insoluble  in  alcohol,  and  contain- 
ing the  succinic  acid.  This  appears  to  be 
the  mineral  oil  in  its  third  state  of  altera- 
tion. The  solid  are,  1.  Asphaltum,  mineral 
pitch,  of  which  there  are  three  varieties: 
the  cohesive;  the  semi-compact,  maltha; 
the  compact,  or  asphaltum.  These  are 
smooth,  more  or  less  hard  or  brittle,  in- 
flammable substances,  which  melt  easily, 
and  burn  without  leaving  any  or  but  little 
ashes,  if  they  be  pure.  They  are  slightly 
and  partially  acted  on  by  alcohol  and  ether. 
2.  Mineral  tallow,  which  is  a  white  sub- 
stance of  the  consistence  of  tallow,  and  as 
greasy,  although  more  brittle.  It  was  found 
in  the  sea  on  the  coasts  of  Finland,  in  the 


BLA 


BLE 


year  1736;  and  is  also  met  with  in  some 
rocky  parts  of  Persia.  It  is  nearly  one-fifth 
lighter  than  tallow;  burns  with  a  blue  flame, 
and  a  smell  of  grease,  leaving  a  black  viscid 
matter  behind,  which  is  more  difficultly  con- 
sumed. 3.  Elastic  bitumen,  or  mineral 
caoutchouc,  of  which  there  are  two  vari- 
eties. Beside  these,  there  are  other  bitumi- 
nous substances,  as  jet  and  amber,  which 
approach  the  harder  bitumens  in  their  na- 
ture; and  all  the  varieties  of  pit-coal,  and 
the  bituminous  schistus,  or  shale,  which, 
contain  more  or  less  of  bitumen  in  their 
composition.  See  the  different  kinds  of  bi- 
uimcn  and  bituminous  substances,  in  their 
respective  places  in  the  order  of  the  alpha- 
bet. 

|  There  are  no  two  substances  more  op- 
posite in  their  habitudes  with  caloric,  than 
carbon  and  hydrogen.  The  last  is,  of  all 
ponderable  substances,  the  most  volatile; 
and,  per  se,  probably  the  most  incondensi- 
ble.  Charcoal,  on  the  other  hand,  cannot 
even  be  fused,  much  less  volatilized,  per 
se.  It  has,  perhaps,  of  all  substances,  the 
least  disposition  to  combine  with  caloric. 
Hence,  in  the  combinations  of  hydrogen 
and  carbon,  we  find  a  gradation  of  proper- 
ties from  substances,  fixed  like  anthracite, 
to  naphtha,  or  inflammable  matter,  almost 
as  volatile  as  air,  accordingly  as  the  carbon 
or  hydrogen  predominates  in  the  com- 
pound. 

The  distillation  of  rosin  yields,  besides 
carburetted  hydrogen,  a  species  of  petro- 
leum; and  this  by  rectification  yields  an 
essential  oil,  like  oil  of  tar,  and  afterwards 
some  heavier  and  less  volatile  products, 
some  of  which  though  white  at  first  turn 
black  by  keeping. 

In  like  manner,  mineral  bitumens  and 
bituminous  coals  yield  petroleum,  and  vol- 
atile oil.  A  quantity  of  acetic  acid  comes 
over  in  combination  with  the  petroleum  of 
rosin,  and  is  retained  till  the  heat  is  con- 
siderable. It  is  then  evolved  with  explosive 
violence.f 

*  BITUMINOUS  LIMESTONE  is  of  a  la- 
mellar structure;  susceptible  of  polishing; 
emits  an  unpleasant  smell  when  rubbed, 
and  has  a  brown  or  black  colour.  Heat  con- 
verts it  into  quicklime.  It  contains  8.8  alu- 
mina; 0.6  silica;  0.6  bitumen;  and  89.75  car- 
bonate of  lime.  It  is  found  near  Bristol,  and 
in  Galway  in  Ireland.  The  Dalmatian  is  so 
charged  with  bitumen  that  it  may  be  cut 
like  soap,  and  is  used  for  building  houses. 
When  the  walls  are  reared,  fire  is  applied 
to  them  and  they  burn  white.* 

*  BLACK  CHALK.  This   mineral  has  a 
bluish-black  colour;  a  slaty  texture;  soils 
the  fingers,  and  is  meagre  to  the  touch.  It 
contains  about  64  silica,  11  alumina,  11  car- 
bon, with  a  little  iron  and  water.  It  is  found 
in  primitive  mountains,  and  also  sometimes 

VOL.  I. 


near  coal  formations.  It  occurs  in  CaernaiN 
vonshire,  and  in  the  Island  of  Isla.* 

BLACK  JACK.  The  miners  distinguish 
blende,  or  mock  lead,  by  this  name.  It  is 
an  ore  of  zinc. 

BLACK  LEAD.     See  PLUMBAGO. 

BLACK  WADD.  One  of  the  ores  of 
manganese, 

*  BLEACHING.  The  chemical  art  by 
which  the  various  articles  used  for  clothing 
are  deprived  of  their  natural  dark  colour 
and  rendered  white. 

The  colouring  principle  of  silk  is  un- 
doubtedly resinous.  Hence,  M.  Baume  pro- 
posed the  following  process,  as  the  best 
mode  of  bleaching  it.  On  six  pounds  of  yel- 
low raw  silk,  disposed  in  an  earthen  pot, 
48  pounds  of  alcohol,  sp.  gr.  0.867,  mixed 
with  12  oz.  muriatic  acid,  sp.  gr.  1.100,  are 
to  be  poured.  After  a  day's  digestion,  the 
liquid  passes  from  a  fine  green  colour  to  a 
dusky  brown.  The  silk  is  then  to  be  drain* 
ed,  and  washed  with  alcohol.  A  second  in.? 
fusion  with  the  above  acidulated  alcohol  19 
then  made,  for  four  or  six  days,  after  which 
the  silk  is  drained  and  washed  with  alcohol. 
The  spirit  may  be  recovered  by  saturating 
the  mingled  acid  with  alkali  or  lime,  and 
distilling.  M.  Baume"  says,  that  silk  may 
thus  be  made  to  rival  or  surpass  in  white- 
ness and  lustre,  the  finest  specimens  from 
Nankin.  But  the  ordinary  method  of  bleach- 
ing silk  is  the  following:* — The  silk,  being 
still  raw,  is  put  into  a  bag  of  thin  linen, 
and  thrown  into  a  vessel  of  boiling  river 
water,  in  which  has  been  dissolved  gopd 
Genoa  or  Toulon  soap. 

After  the  silk  has  boiled  two  or  three 
hours  in  that  water,  the  bag  being  frequent- 
ly turned,  it  is  taken  out  to  be  beaten,  and 
is  then  washed  in  cold  water.  When  it  has 
been  thus  thorougly  washed  and  beaten, 
they  wring  it  slightly,  and  put  it  for  the 
second  time  into  the  boiling  vessel,  filled 
with  cold  water,  mixed  with  soap  and  a, 
little  "indigo;  which  gives  it  that  bluish, 
cast  commonly  observed  in  white  silk. 

When  the  silk  is  taken  out  of  this  se. 
cond  water,  they  wring  it  hard  with  a  wood- 
en peg,  to  press  out  all  the  water  and  soapj 
after  which  they  shake  it  to  untwist  it,  an4 
separate  the  threads.  Then  they  suspend  it 
in  a  kind  of  stove  constructed  for  that  pur- 
pose, where  they  burn  sulphur;  the  vapour 
of  which  gives  the  last  degree  of  white- 
ness to  the  silk. 

The  method  of  bleaching  woollen  stuffs.— 
There  are  three  ways  of  doing  this.  The 
first  is  with  water  and  soap;  the  second 
with  the  vapour  of  sulphur;  and  the  third 
with  chalk,  indigo,  and  the  vapour  of  sul- 
phur. 

Bleaching  ivith  soap  and  •water.* — After  thft 
stuffs  are  taken  out  of  the  fuller's  niijl, 
24 


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they  are  put  into  soap  and  water,  a  little 
warm,  in  which  they  are  again  worked  by 
the  strength  of  the  arms  over  a  wooden 
bench:  this  finishes  giving  them  the  white- 
ning which  the  fuller's  mill  had  only  be- 
gun.  When  they  have  been  sufficiently 
worked  with  the  hands,  they  are  washed 
in  clear  water  and  put  to  dry. 

This  method  of  bleaching  woollen  stuffs 
is  called  the  Natural  Method. 

JBleaching  with   sulphur. They  J>egin 

with  washing  and  cleansing  the  stuffs  tho- 
roughly in  river  water;  then  they  put  them 
to  dry  upon  poles  or  perches.  When  they 
are  half  dry,  they  stretch  them  out  in  a 
very  close  stove,  in  which  they  burn  sul- 
phur; the  vapour  of  which  diffusing  itself, 
adheres  by  degrees  to  the  whole  stuff,  and 
gives  it  a  fine  whitening;  this  is  commonly 
called  Bleaching  by  the  Flower,  or  Bleach- 
ing of  Paris,  because  they  use  this  method 
in  that  city  more  than  any  where  else. 

*  The  colouring  matter  of  linen  and  cot- 
ton is  also  probably  resinous;  at  least  the 
experiments  of  Mr.  Kirwan  on  alkaline  lix- 
ivia saturated  with  the  dark  colouring  mat- 
ter, lead  to  that  conclusion.  By  neutralizing 
the  alkali  with  dilute  muriatic  acid,  a  pre- 
cipitate resembling  lac  was  obtained,  solu- 
ble in  alcohol,  in  solutions  of  alkalis,  and 
alkaline  sulphurets. 

The  first  step  towards  freeing  vegetable 
yarn  or  cloth  from  their  native  colour,  is 
fermentation.  The  raw  goods  are  put  into 
a  large  wooden  tub,  with  a  quantity  of  used 
alkaline  lixivium,  in  an  acescent  state,  heat- 
ed to  about  the  hundredth  degree  of  Fahr. 
It  would  be  better  to  use  some  uncolouied 
fermentable  matter,  such  as  soured  bran  or 
potato  paste,  along  with  clean  warm  water. 
In  a  short  time,  an  intestine  motion  arises, 
air  bubbles  escape,  and  the  goods  swell, 
raising  up  the  loaded  board  which  is  used 
to  press  them  into  the  liquor.  At  the  end  of 
from  18  to  48  hours,  according  to  the  quali- 
ty of  the  stuffs,  the  fermentation  ceases, 
when  the  goods  are  to  be  immediately  with- 
drawn and  washed.  Much  advantage  may  be 
derived  by  the  skilful  bleacher,  from  con- 
ducting the  acetous  fermentation  complete- 
ly to  a  close,  without  incurring  the  risk  of 
injuring  the  fibre,  by  the  putrefactive  fer- 
mentation. 

The  goods  are  next  exposed  to  the  ac- 
tion of  hot  alkaline  lixivia,  by  bucking  or 
boiling,  or  both.  The  former  operation  con- 
sists in  pouring  boiling  hot  ley  on  the  cloth 
placed  in  a  tub;  after  a  short  time  drawing 
off  the  cool  liquid  below,  and  replacing  it 
above,  by  hot  lixivium.  The  most  conveni- 
ent arrangement  of  apparatus  is  the  follow- 
ing:—Into  the  mouth  of  an  egg-shaped  iron 
boiler,  the  bottom  of  a  large  tub  is  fixed 
air  tight.  The  tub  is  furnished  with  a  false 
bottom  pierced  with  holes,  a  few  inches 


above  the  real  bottom.  In  the  latter,  a  valve 
is  placed,  opening  downwards,  but  which 
may  be  readily  closed,  by  the  upwards 
pressure  of  steam.  From  the  side  of  the 
iron  boiler,  a  little  above  its  bottom,  a  pipe 
issues,  which,  turning  at  right  angles  up. 
wards,  rises  parallel  to  the  outside  of  the 
bucking  tub,  to  a  foot  or  two  above  its 
summit.  The  vertical  part  of  this  pipe 
forms  the  cylinder  of  a  sucking  pump,  and 
has  a  piston  and  rod  adapted  to  it.  At  a  few 
inches  above  the  level  of  the  mouth  of  the 
tub,  the  vertical  pipe  sends  off  a  lateral 
branch,  which  terminates  in  a  bent-down 
nozzle,  over  a  hole  in  the  centre  of  the  lid 
of  the  tub.  Under  the  nozzle  and  immedi- 
ately within  the  lid,  is  a  metallic  circular 
disc.  The  boiler  being  charged  with  lixiv- 
ium, and  the  tub  with  the  washed  goods, 
a  moderate  fire  is  kindled.  At  the  same 
time,  the  pump  is  set  a-going,  either  by 
the  hand  of  a  workman  or  by  machinery. 
Thus,  the  lixivium  in  its  progressively 
heating  state,  is  made  to  circulate  conti- 
nually down  through  ,the  stuffs.  But  when 
it  finally  attains  the  boiling  temperature, 
the  piston  rod  and  piston  are  removed,  and 
the  pressure  of  the  included  steam  alone, 
forces  the  liquid  up  the  vertical  pipe,  and 
along  the  horizontal  one  in  an  uninterrupt- 
ed stream.  The  valve  at  the  bottom  of  the 
tub,  yielding  to  the  accumulated  weight  of 
the  liquid,  opens  from  time  to  time,  and  re- 
places the  lixivium  in  the  boiler. 

This  most  ingenious  self-acting  appara- 
tus, was  invented  by  Mr.  John  Laurie  of 
Glasgow;  and  a  representation  of  it  accom- 
panies Mr.  Ramsay's  excellent  article, 
Bleaching,  in  the  Edinburgh  Encyclopaedia. 
By  its  means,  labour  is  spared,  the  negli- 
gence of  servants  is  guarded  against,  and 
fully  one-fourth  of  alkali  saved. 

It  is  of  great  consequence  to  heat  the 
liquid  very  slowly  at  first.  Hasty  boiling  is 
incompatible  with  good  bleaching.  When 
the  ley  seems  to  be  impregnated  with  co- 
louring matter,  the  fire  is  lowered,  and  the 
liquid  drawn  off  by  a  stop-cock;  at  the  same 
time  that  water,  at  first  hot  and  then  cold, 
is  run  in  at  top,  to  separate  all  the  dark 
coloured  lixivium.  The  goods  are  then 
taken  out  and  well  washed,  either  by  the 
hand  with  the  wash  stocks,  or  by  the  rota- 
tory wooden  wheel  with  hollow  compart- 
ments, called  the  dash  wheel.  The  strength 
of  the  alkaline  lixivium  is  varied  by  diffe- 
rent bleachers.  A  solution  of  potash,  ren- 
dered caustic  by  lime,  of  the  specific  gra- 
vity 1.014,  or  containing  a  little  more  than 
1  per  cent  of  pure  potash,  is  used  by  many 
bleachers.  The  Irish  bleachers  use  barilla- 
lixivium  chiefly,  and  of  inferior  alkaline 
power.  The  routine  of  operations  may  be 
conveniently  presented  in  a  tabular  form. 

A  parcel  of  goods  consists  of  360  pieces 


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of  those  linens  which  are  called  Britannias. 
Each  piece  is  35  yards  long,  weighing  on 
an  average,  10  pounds.  Hence,  the  weight 
of  the  whole  is  3600  pounds  avoirdupois. 
These  linens  are  first  washed,  and  then  sub- 
jected to  the  acetous  fermentation,  as  above 
described.  They  then  undergo  the  follow- 
ing1 operations: — 

1.  Bucked    with    60   Ibs.   pearl    ashes, 
washed  and  exposed  on  the  field. 

2.  do.  with  80  Ibs.     do.         do.     do. 

3.  do.  90      potashes     do.     do. 

4.  do.  80  do.         do.     do. 

5.  do.  80  do.         do.     do. 

6.  do.  50  do.         do.     do. 

7.  do.  70  do.        do.     do. 

8.  do.  70  do.         do.     do. 

9.  Soured  one  night  in  dilute  sulphuric 
acid. 

10.  Bucked   with    50   Ibs.   pearl  ashes, 
washed  and  exposed. 

11.  Immersed  in  the  oxymuriate  of  pot- 
ash for  12  hours. 

12.  Boiled   with    30   Ibs.   pearl    ashes, 
washed  and  exposed. 

13.  do.  30       do.     do.     do. 
13.  Soured  and  washed. 

The  linens  are  then  taken  to  the  rubbing 
board,  and  well  rubbed  with  a  strong  lather 
of  black  soap,  after  which  they  are  well 
washed  in  pure  spring  water.  At  this  pe- 
riod they  are  carefully  examined,  and  those 
which  are  fully  bleached  are  laid  aside  to 
be  blued  and  made  up  for  the  market. 
Those  which  are  not  fully  white,  are  re- 
turned to  be  boiled  and  steeped  in  the  oxy- 
muriate of  potash,  and  soured  until  they 
are  fully  white.  By  the  above  process,  690 
Ibs.  of  commercial  alkali  are  used  in  bleach- 
ing 360  pieces  of  linen,  each  measuring  35 
yards.  Hence,  the  expenditure  of  alkali 
would  be  a  little  under  2  Ibs.  a-piece,  were 
it  not  that  some  part  of  the  above  linens 
may  not  be  thoroughly  whitened.  It  will, 
therefore,  be  a  fair  average,  to  allow  2  Ibs. 
for  each  piece  of  such  goods. 

On  the  above  process  we  may  remark, 
thatmany  enlightened  bleachers  have  found 
it  advantageous  to  apply  the  souring  at  a 
more  early  period,  as  well  as  the  oxy muri- 
atic solution.  According  to  Dr.  Stephen- 
son,  in  his  elaborate  paper  on  the  linen  and 
hempen  manufactures,  published  by  the 
Belfast  Literary  Society,  10  noggins,  or 
quarter  pints  of  oil  of  vitriol,  are  sufficient 
to  make  200  gallons  of  souring.  This  gives 
the  proportion,  by  measure,  of  640  water 
to  1  of  acid.  Mr.  Parkes,  in  describing  the 
bleaching  of  calicoes  in  his  Chemical  Es- 
says, says,  that,  throughout  Lancashire, 
one  measure  of  sulphuric  acid  is  used  with 
46  of  water,  or  one  pound  of  the  acid  to  25 
pounds  of  water;  and  he  states,  that  a  sci- 
entific calico  printer  in  Scotland  makes  his 


sours  to  have  the  specific  gravity  1.0254  at 
110°  of  Fahrenheit;  which  dilute  acid  con- 
tains at  least  l-25th  of  oil  of  vitriol.  Five 
or  six  hours'  immersion  is  employed. 

In  a  note  Mr.  Parkes  adds,  that  in  bleach- 
ing common  goods,  and  such  as  are  not  de- 
signed for  the  best  printing,  the  specific 
gravity  of  the  sours  is  varied  from  1.0146 
to  1.0238,  if  taken  at  the  atmospheric  tem- 
perature. Most  bleachers  use  the  strongest 
alkaline  lixiviums  at  first,  and  the  weaker 
afterwards.  As  to  the  strength  of  the  oxy- 
muriatic  steeps,  as  the  bleacher  terms 
them,  it  is  difficult  to  give  certain  data, 
from  the  variableness  of  the  chlorides  of 
potash  and  lime. 

Mr.  Parkes,  in  giving  the  process  of  the 
Scotch  bleacher,  says,  that  after  the  ca- 
licoes have  been  singed,  steeped,  and 
squeezed,  they  are  boiled  four  successive 
times,  for  10  or  12  hours  each,  in  a  solu- 
tion of  caustic  potash  of  a  specific  gravity 
from  1.0127  to  1.0156,  and  washed  tho- 
roughly between  each  boiling.  "  They  are 
then  immersed  in  a  solution  of  the  oxymu- 
riate of  potash,  originally  of  the  strength 
of  1.0625,  and  afterwards  reduced  with  24 
times  its  measure  of  water.  In  this  pre- 
paration they  are  suffered  to  remain  12 
hours."  Dr.  Stephenson  says,  that,  for 
coarse  linens,  the  steep  is  made  by  dissolv- 
ing 1  Ib.  of  oxymuriate  of  lime  in  3  gallons 
of  water,  and  afterwards  diluting  with  25 
additional  gallons.  The  ordinary  specific 
gravity  of  the  oxymuriate  of  lime  steeps, 
by  Mr.  Ramsay,  is  1.005.  But  from  these 
data,  little  can  be  learned;  because  oxymu- 
riate of  lime  is  always  more  or  less  mixed 
with  common  muriate  of  lime,  or  chloride 
of  calcium,  a  little  of  which  has  a  great  ef- 
fect on  the  hydrometric  indications.  The 
period  of  immersion  is  10  or  12  hours. 
Many  bleachers  employ  gentle  and  long 
continued  boiling  without  bucking1.  The 
operation  of  souring  was  long  ago  effected 
by  butter  milk,  but  it  is  more  safely  and 
advantageously  performed  by  the  dilute 
sulphuric  acid  uniformly  combined  with 
the  water  by  much  agitation. 

Mr.  Tennent's  ingenious  mode  of  uniting 
chlorine  with  pulverulent  lime,  was  one 
of  the  greatest  improvements  in  practical 
bleaching.  When  this  chloride  is  well  pre- 
pared and  properly  applied,  it  will  not  in- 
jure the  most  delicate  muslin.  Magnesia 
has  been  suggested  as  a  substitute  for  lime, 
but  the  high  price  of  this  alkaline  earth, 
must  be  a  bar  to  its  general  employment. 
The  muriate  of  lime  solution  resulting 
from  the  action  of  unbleached  cloth  on  that 
of  the  oxymuriate,  if  too  strong,  or  too 
long  applied,  would  weaken  the  texture  of 
cloth,  as  Sir  H.  Davy  has  shown.  But  the 
bleacher  is  on  his  guard  against  this  acci- 
dent; and  the  process  of  souring,'  which 


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follows  most  commonly  the  oxymuriatic 
ateep,  thoroughly  removes  the  adhering 
particles  of  lime. 

Mr.  Parkes  informs  us,  that  calicoes  for 
madder  work,  or  resist  work,  or  for  the  fine 
pale  blue  dipping,  cannot  without  injury 
be  bleached  with  oxy muriate  of  lime.  They 
require,  he  says,  oxymuriate  of  potash.  I 
believe  this  to  be  a  mistake.  Test  liquors 
made  by  dissolving  indigo  in  sulphuric  acid, 
and  then  diluting  the  sulphate  with  water, 
or  with  infusion  of  cochineal,  are  employed 
to  measure  the  blanching  power  of  the  oxy- 
muriatic or  chloridic  solutions.  But  they 
are  all  more  or  less  uncertain,  from  the 
changeableness  of  these  colouring  matters. 
I  have  met  with  indigo  of  apparently  ex- 
cellent quality,  of  which  four  parts  were 
required  to  saturate  the  same  weight  of 
oxymuriate  of  lime,  as  was  saturated  by 
three  parts  of  another  indigo.  Such  colour- 
ed liquors,  however,  though  they  give  no 
absolute  measure  of  chlorine,  afford  useful 
means  of  comparison  to  the  bleacher. 

Some  writers  have  recommended  lime 
fend  sulphuret  of  lime  as  detergent  substan- 
fces  instead  of  alkali;  but  1  believe  no  prac- 
tical bleacher  of  respectability  would  trust 
to  them.  Lime  should  always  be  employed, 
however,  to  make  the  alkalis  caustic;  in 
which  state  their  detergent  powers  are 
greatly  increased. 

The  coarser  kinds  of  muslin  are  bleached 
by  steeping,  washing,  and  then  boiling  them 
in  a  weak  solution  of  pot  and  pearl  ashes. 
They  are  next  washed,  and  afterwards 
boiled  in  soap  alone,  and  then  soured  in 
very  dilute  sulphuric  acid.  After  being 
washed  from  the  sour,  they  are  boiled  with 
soap,  washed,  and  immersed  in  the  solu- 
tion of  chloride  of  lime  or  potash.  The  boil- 
ing in  soap,  and  immersion  in  the  oxymu- 
riate, is  repeated,  until  the  muslin  is  of  a 
pure  white  colour.  It  is  finally  soured  and 
washed  in  pure  spring  water.  The  same  se- 
ries of  operations  is  used  in  bleaching  fine 
muslins^  only  soap  is  used  in  the  boilings 
commonly  to  the  exclusion  of  pearl  ash. 
Fast  coloured  cottons  are  bleached  in  the 
following  way: — After  the  starch  or  dress- 
ing is  well  removed  by  cold  water,  they 
are  gently  boiled  with  soap,  washed,  and 
immersed  in  a  moderately  strong  solution 
of  oxymuriate  of  potash.  This  process  is 
repeated  till  the  white  parttfof  the  cloth 
are  sufficiently  pure.  They  an  then  soured 
in  dilute  sulphuric  acid.  If  these  operations 
be  well  conducted,  the  colours,  instead  of 
being  impaired,  will  be  greatly  improved, 
having  acquired  a  delicacy  of  tint  which 
ho  other  process  can  impart. 

After  immersing  cloth  or  yarn  in  alka- 
line ley,  if  it  be  exposed  to  the  action  of 
steam  heated  to  222°,  in  a  strong  vessel, 
it  will  be  in  a  great  measure  bleached* 


This  operation  is  admirably  adapted  to 
the  cleansing  of  hospital  linen. 

The  following  is  the  practice  followed  by 
a  very  skilful  bleacher  of  muslins  near 
Glasgow. 

"  In  fermenting  muslin  goods,  Mre  sur- 
round them  with  our  spent  leys  from  the 
temperature  of  100°  to  150°  F.  according  ' 
to  the  weather,  and  allow  them  to  ferment 
for  36  hours.  In  boiling  112  Ibs.  =  112 
pieces  of  yard-wide  muslin,  we  use  6  or  7 
Ibs.  of  ashes,  and  2  Ibs.  of  soft  soap,  in  360 
gallons  of  water,  and  allow  them  to  boi!  for 
6  hours;  then  wash  them,  and  boil  them 
again,  with  5  Ibs.  of  ashes,  and  2  Ibs.  of  soft 
soap,  in  the  same  quantity  of  water,  and  al- 
low them  to  boil  3  hours;  then  wash  them 
with  water,  and  immerse  them  into  the  so- 
lution of  oxymuriate  of  lime,  at  5  on  the  test 
tube,  and  allow  them  to  remain  from  6  to 
12  hours;  next  wash  them,  and  immerse 
them  into  diluted  sulphuric  acid  at  the  spe- 
cific gravity  of  3£  on  Twaddle's  hydrome- 
ter =  1.0175,  and  allow  them  to  remain  an 
hour.  They  are  now  well  washed,  and  boil- 
ed with  2jt  Ibs.  of  ashes,  and  2  Ibs.  of  soap, 
for  half  an  hour;  afterwards  washed  and 
immersed  into  the  oxymuriate  of  lime  as 
before,  at  the  strength  of  3  on  the  test  tube, 
which  is  stronger  than  the  former,  and  al- 
lowed to  remain  for  6  hours.  They  are  again 
washed  and  immersed  into  diluted  sul- 
phuric acid  at  the  specific  gravity  of  3  on 
Twaddle's  hydrometer  =  1.015.  If  the 
goods  be  strong,  they  will  require  another 
boil,  steep,  and  sour.  At  any  rate,  the  sul- 
phuric acid  is  well  washed  out  before  they 
receive  the  finishing  operation  with  starch. 
"  With  regard  to  the  lime,  which  some 
use  instead  of  alkali,  immediately  after  fer- 
menting, the  same  weight  of  it  is  employed 
as  of  ashes.  The  goods  are  allowed  to  boil 
in  it  for  15  minutes,  but  not  longer,  other- 
wise the  lime  will  injure  the  fabric." 

The  alkali  may  be  recovered  from  the 
brown  lixivia,  by  evaporating  them  to  dry- 
ness  and  gentle  ignition  of  the  residuum. 
But,  in  most  situations,  the  expense  of  fuel 
would  exceed  the  value  of  the  recovered 
alkuli.  A  simpler  mode  is  to  boil  the  foul 
lixivium  with  quicklime,  and  a  little  pipe- 
clay and  bullock's  blood.  After  skimming* 
and  subsidence,  a  tolerably  pure  ley  is  ob- 
tained.* 

Under  the  head  of  chlorine,  we  have  de- 
scribed the  preparation  of  this  article;  and 
the  chief  circumstances  respecting  it  to  be 
noticed  here  is  the  apparatus,  which  must 
be  on  an  extensive  scale,  and  adapted  to 
the  purpose  of  immersing  and  agitating  the 
goods  to  be  bleached.  The  process  of  dis- 
tillation may  be  performed  in  a  large  leaden 
alembic,  ,§•£•,  Plate  I.  fig.  1.  supported  by 
an  iron  trevetj^  in  an  iron  boiler  e.  This  is 
heated  by  a  furnace  6,  of  which  o  is  the 


BLE 


BLO 


ashhole,  c  the  place  for  introducing  the  fuel; 
d  is  the  handle  of  a  stopper  of  burnt  clay, 
for  regulating  the  draught.  To  the  top  of 
the  alembic  is  fitted  a  leaden  cover  i,  which 
is  luted  on,  and  has  three  perforations:  one 
for  the  curved  glass  or  leaden  funnel  /i, 
through  which  the  sulphuric  acid  is  to  be 
poured  in;  one  in  the  centre  for  the  agita- 
tor k,  made  of  iron  coated  with  lead;  and 
the  third  for  the  leaden  tube  I,  three  inches 
in  diameter  internally,  through  which  the 
gas  is  conveyed  into  the  tubulated  leaden 
receiver  m.  To  prevent  the  agitator  from 
reaching  to  the  bottom  of  the  alembic,  it  is 
furnished  with  a  conical  leaden  collar, 
adapted  to  a  conical  projection  round  the 
hole  in  the  centre  of  the  cover,  to  which  it 
becomes  so  closely  fitted  by  means  of  its 
rotatory  motion,  as  to  prevent  the  escape 
of  the  gas.  The  tube  /,  passing  through  the 
aperture  m,  to  the  bottom  of  the  interme- 
diate receiver  nearly,  which  is  two-thirds 
full  of  water,  deposites  there  the  little  sul- 
phuric acid  that  may  arise;  while  the  chlo- 
rine gas  passes  through  the  tube  n  into  the 
wooden  condenser  o  o.  The  agitator  />, 
turned  by  its  handle  t,  serves  to  accelerate 
the  combination  of  the  gas  with  the  alkali, 
to  which  the  horizontal  pieces  g  qt  pro- 
jecting from  the  inside,  like  wise  contribute. 
The  cover  of  this  receiver  has  a  sloping 
groove  r,  to  fit  close  on  its  edge,  which  is 
bevelled  on  each  side;  and  a  cock  s  serves 
to  draw  off  the  liquor.  Mr.  Tennent's  chlo- 
ride of  lime  has  nearly  superseded  that 
plan. 

The  rags  or  other  materials  for  making 
paper  may  be  bleached  in  a  similar  man- 
ner: but  it  is  best  to  reduce  them  first  to 
the  state  of  pulp,  as  then  the  acid  acts 
more  uniformly  upon  the  whole  substance. 

For  bleaching  old  paper:  Boil  your  print- 
ed paper  for  an  instant  in  a  solution  of 
caustic  soda.  That  from  kelp  maybe  used. 
Steep  it  in  soap-suds,  and  then  wash  it; 
after  which  it  may  be  reduced  to  pulp. 
The  soap  muy  be  omitted  without  much 
inconvenience.  For  old  written  paper  to  be 
worked  up  again:  Steep  it  in  water  acidu- 
lated with  sulphuric  acid,  and  then  wash  it 
well  before  it  is  taken  to  the  mill.  If  the 
water  he  heated  it  will  be  more  effectual. 
To  bleach  printed  paper,  without  destroy- 
ing its  texture:  Steep  the  leaves  in  a  caus- 
tic solution  of  soda,  either  hot  or  cold, 
and  then  in  a  solution  of  soap.  Arrange 
them  alternately  between  cloths,  as  paper- 
makers  do  thin  sheets  of  paper  when  de- 
livered from  the  form,  and  subject  them  to 
the  press.  If  one  operation  do  not  render 
them  sufficiently  white,  it  may  be  repeated 
as  often  as  necessary.  To  bleach  old  writ^ 
ten  paper,  without  destroying  its  texture: 
Steep  the  paper  in  water  acidulated  with 
sulphuric  acid,  either  hot  or  cold,  and  then 


in  a  solution  of  oxygenated  muriatic  acid; 
after  which  immerse  it  in  water,  that  none 
of  the  acid  may  remain  behind.  This  paper, 
when  pressed  and  dried,  will  be  fit  for  use 
as  before. 

BLENDE.  An  ore  of  zinc. 
BLOOD.  The  fluid  which  first  presents 
itself  to  observation,  when  the  parts  of  liv- 
ing animals  are  divided  or  destroyed,  is 
the  blood,  which  circulates  with  conside- 
rable velocity  through  vessels,  called  veins 
and  arteries,  distributed  into  every  part  of 
the  system. 

Recent  blood  is  uniformly  fluid,  and  of 
a  saline  taste.  Under  the  microscope,  it  ap- 
pears to  be  composed  of  a  prodigious  num- 
ber of  red  globules,  swimming  in  a  trans- 
parent fluid.  After  standing  for  a  short 
time,  its  parts  separate  into  a  thick  red 
matter,  or  crassamentum,  and  a  fluid  call- 
ed serum.  If  it  be  agitated  till  cold,  it 
continues  fluid;  but  a  consistent  polypous 
matter  adheres  to  the  stirrer,  which  by  re- 
peated ablutions  with  water  becomes  white, 
and  has  a  fibrous  appearance;  the  crassa- 
mentum becomes  white  and  fibrous  by  the 
same  treatment.  If  blood  be  received  from 
the  vein  into  warm  water,  a  similar  fila- 
mentous matter  subsides,  while  the  other 
parts  are  dissolved.  Alkalis  prevent  the 
blood  from  coagulating;  acids,  on  the  con- 
trary, accelerate  that  effect.  In  the  latter 
case,  the  fluid  is  found  to  contain  neutral 
salts,  consisting  of  the  acid  itself,  united 
with  soda,  which  consequently  must  exist 
in  the  blood,  probably  in  a  disengaged  state. 
Alcohol  coagulates  blood.  On  the  water 
bath,  blood  affords  an  aqueous  fluid,  neither 
acid  nor  alkaline,  but  of  a  faint  smell,  and 
easily  becoming  putrid.  A  stronger  heat 
gradually  dries  it,  and  at  the  same  time 
reduces  it  to  a  mass  of  about  one-eighth  of 
its  original  weight 

*  Blood  usually  consists  of  about  3  parts 
serum  to  one  of  cruor.  The  serum  is  of  a 
pale  greenish-yellow  colour.  Its  specific 
gravity  is  about  1.029,  while  that  of  blood 
itself  is  1.053.  It  changes  sirup  of  violets 
to  a  green,  from  its  containing  free  soda. 
At  156°  serum  coagulates,  and  resembles 
boiled  white  of  egg.  When  this  coagu- 
lated albumen  is  squeezed,  a  muddy  fluid 
exudes,  which  has  been  called  the  sero- 
sity.  According  to  Berzelius,  1000  parts 
of  the  scrum  of  bullock's  blood  consist  of 
905.  water,  79.99  albumen,  6.175  lactate  of 
soda  and  extractive  matter,  2.565  muriates 
of  soda  and  potash,  1.52  soda  and  animal 
matter,  and  4.75  loss.  1000  parts  of  serum 
of  human  blood  consist,  by  the  same  che- 
mist, of  905  water,  80  albumen,  6  muriates 
of  potash  and  soda,  4  lactate  of  soda  with 
animal  matter,  and  4.1  of  soda,  and  phos- 
phate of  soda  with  animal  matter.  There 
is  no  gelatin  in  serum. 


BLO 

The  cruor  has  a  specific  gravity  of  about 
1.245.  By  making-  a  stream  of  water  flow 
upon  it  till  the  water  runs  off  colourless,  it 
is  separated  into  insoluble  fibrin,  and  the 
soluble  colouring  matter.  A  little  albumen 
has  also  been  found  in  cruor.  The  propor- 
tions of  the  former  two,  are  64  colouring- 
matter,  and  36  fibrin  in  100.  To  obtain  the 
colouring-  matter  pure,  we  mix  the  cruor 
with  4  parts  of  oil  of  vitriol  previously  di- 
luted with  8  parts  of  water,  and  expose  the 
mixture  to  a  heat  of  about  160  degree?  for 
5  or  6  hours.  Filter  the  liquid  while  hot, 
and  wash  the  residue  with  a  few  ounces  of 
hot  water.  Evaporate  the  liquid  to  one-half, 
and  add  ammonia,  till  the  acid  be  almost, 
but  not  entirely  saturated.  The  colouring- 
matter  falls.  Decant  the  supernatant  liquid, 
filter  and  wash  the  residuum,  from  the 
whole  of  the  sulphate  of  ammonia.  When 
it  is  well  drained,  remove  it  with  a  platina 
blade,  and  dry  it  in  a  capsule. 

When  solid,  it  appears  of  a  black  colour, 
but  becomes  wine-red  by  diffusion  through 
water,  in  which,  however,  it  is  not  soluble. 
It  has  neither  taste  nor  smell.  Alcohol  and 
ether  convert  it  into  an  unpleasant  smell- 
ing- kind  of  adipocere.  It  is  soluble  both  in 
alkalis  and  acids.  It  approaches  to  fibrin  in 
its  constitution,  and  contains  iron  in  a  pe- 
culiar state,  -3-  of  a  per  cent  of  the  oxide 
of  which  may  be  extracted  from  it  by  cal- 
cination. The  incinerated  colouring-  matter 
weig-hs  l-80th  of  the  whole;  and  these 
ashes  consist  of  50  oxide  of  iron,  7.5  sub- 
phosphate  of  iron,  6  phosphate  of  lime, 
with  traces  of  magnesia,  20  pure  lime,  16.5 
carbonic  acid  and  loss;  or  the  two  latter  in- 
gredients may  be  reckoned  32  carbonate  of 
lime.  Berzelius  imagines  that  none  of  these 
bodies  existed  in  the  colouring-  matter,  but 
only  their  bases,  iron,  phosphorus,  calcium, 
carbon,  &c.  and  that  they  were  formed  dur- 
ing the  incineration.  From  the  albumen  of 
blood,  the  same  proportion  of  ashes  may 
be  obtained,  but  no  iron. 

No  good  explanation  has  yet  been  given 
of  the  change  of  colour  which  blood  un- 
dergoes from  exposure  to  oxygen,  and 
other  gases.  Under  the  exhausted  receiver, 
carbonic  acid  gas  is  disengaged  from  it. 
The  blood  of  the  foetus  is  darker  coloured 
than  that  of  the  adult;  it  has  no  fibrin,  and 
no  phosphoric  acid.  The  buffy  coat  of  in- 
flamed blood  is  fibrin;  from  which  the  co- 
louring matter  has  precipitated  by  the 
greater  liquidity  or  slowness  of  coagula- 
tion produced  by  the  disease.  The  serum 
of  such  blood  does  not  yield  consistent  al- 
bumen by  heat.  In  diabetes  mellitus,  when 
the  urine,  of  the  patient  is  loaded  with  su- 
gar, the  serum  of  the  blood  assumes  the 
appearance  of  whey,  according  to  Drs.  Rol- 
lo  and  Dobson;  but  Dr.  Wollaston  has 
proved  that  it  contains  no  sugar.* 


BLO 

Dr.  Carbonel  of  Barcelona  has  employed 
serum  of  blood  on  an  extensive  scale  in 
painting.  Mixed  with  powdered  quicklime 
or  slaked  lime,  to  a  proper  consistence,  it 
is  easily  applied  on  wood,  to  which  it  thus 
gives  a  coating  of  a  stone  colour,  that  dries 
quickly,  without  any  bad  smell,  and  resists 
the  action  of  sun"  and  rain.  The  wood 
should  be  first  covered  with  a  coating  of 
plaster;  the  composition  must  be  mixed  as 
it  is  used,  and  the  serum  must  not  be  stale. 
It  may  be  used  too  as  a  cement  for  water- 
pipes,  and  for  stones  for  building  under 
water. 

*  BLOODSTONE.     See  CALCEDONY.* 
BLOW-PIPE.  This  simple  instrument  will 

be  described  under  the  article  LABORA- 
TORY. 

*  We  shall  here  present  our  readers  first 
with  an  abstract  of  Assessor  Calm's  late 
valuable  treatise  on  the  common  blow-pipe, 
and  shall  afterwards  give   an  account  of 
Dr.    Clark's  very  interesting  experiments 
with  the  oxyhydrogen  blow-pipe-* 

The  substance  to  be  submitted  to  the 
action  of  the  blow-pipe  must  be  placed  on 
a  piece  of  charcoal,  or  in  a  small  spoon  of 
platina,  gold,  or  silver;  or,  according  to 
Saussure,  a  plate  of  cyanite  may  sometimes 
be  used.  Charcoal  from  the  pine  is  to  be 
preferred,  which  should  be  well  ignited 
and  dried,  that  it  may  not  crack.  The  sides, 
not  the  ends,  of  the  fibres  must  be  used, 
otherwise  the  substance  to  be  fused  spreads 
about,  and  a  round  bead  will  not  be  form- 
ed. A  small  hole  is  to  be  made  in  the  char- 
coal, which  is  best  done  by  a  slip  of  plate  iron 
bent  longitudinally.  Into  this  hole  the  sub- 
stance to  be  examined  must  be  put  in  very 
small  quantity;  if  a  very  intense  heat  is  to 
be  used,  it  should  not  exceed  the  size  of 
half  a  peppercorn. 

The  metallic  spoons  are  used  when  the 
substance  to  be  examined  is  intended  to  be 
exposed  to  the  action  of  heat  only,  and 
might  undergo  some  change  by  immediate 
contact  with  the  charcoal.  When  the  spoon 
is  used,  the  flame  of  the  blow-pipe  should 
be  directed  to  that  part  of  it  which  con- 
tains the  substance  under  examination,  and 
not  be  immediately  applied  to  the  substance 
itself.  The  handle  of  the  spoon  may  be  in- 
serted into  a  piece  of  charcoal:  and  if  a 
very  intense  heat  is  required,  the  bowl  of 
the  spoon  may  be  adapted  to  a  hole  in  the 
charcoal.  Small  portions  may  be  taken  up 
by  platina  forceps.  Salts  and  volatile  sub- 
stances are  to  be  heated  in  a  glass  tube 
closed  at  one  end,  and  enlarged  according 
to  circumstances,  so  as  to  form  a  small  ma- 
trass. 

When  the  alteration  which  the  substance 
undergoes  by  the  mere  action  of  heat  has 
been  observed,  it  will  be  necessary  to  exa- 
mine what  further  change  takes  place  when 


BLO 


BLO 


when  it  is  melted  with  various  fluxes,  and 
how  far  it  is  capable  of  reduction  to  the 
metallic  state. 
These  fluxes  are, 

1.  Microcosmic  salt;  a  compound  of  phos- 
phoric acid,  soda,  and  ammonia. 

2.  Subcarbonate  of  soda,  which  must  be 
free  from  all  impurity,  and  especially  from 
sulphuric  acid,  as  this  will  be  decomposed, 
and  sulphuret  of  soda  will  be  formed,  which 
will  dissolve  the  metals  we  wish  to  reduce, 
and  produce  a  bead  of  coloured  glass  with 
substances  that  would  otherwise  give  a  co- 
lourless one. 

3.  Borax,  which   should   be  first  freed 
from  its  water  of  crystallization. 

These  are  kept  powdered  in  small  phials; 
and  when  used,  a  sufficient  quantity  may 
be  taken  up  by  the  moistened  point  of  a 
knife •  the  moisture  causes  the  particles  to 
cohere,  and  prevents  their  being  blown 
away  when  placed  on  the  charcoal.  The 
flux  must  then  be  melted  to  a  clear  bead, 
and  the  substance  to  be  examined  placed 
upon  it.  It  is  then  to  be  submitted  to  the 
action,  first  of  the  exterior,  and  afterwards 
of  the  interior  flame,  and  the  following  cir- 
cumstances to  be  carefully  observed: — 

1.  Whether  the  substance  is   dissolved; 
and,  if  so, 

2.  Whether  with  or  without    efferves- 
cence, which  would  be  occasioned  by  the 
liberation    of    carbonic    acid,    sulphurous 
acid,  oxygen,  gaseous  oxide  of  carbon,  &c. 

3.  The  transparency  and   colour  of  the 
glass  while  cooling. 

4.  The  same  circumstances  after  cooling. 

5.  The  nature  of  the  glass  formed  by  the 
exterior  flame,  and 

6.  By  the  interior  flame. 

7.  The  various  relations  to  each  of  the 
fluxes. 

It  must  be  observed  that  soda  will  not 
form  a  bead  on  charcoal,  but  with  a  cer- 
tain degree  of  heat  will  be  absorbed.  When, 
therefore,  a  substance  is  to  be  fused  with 
soda,  this  flux  must  be  added  in  very  small 
quantities,  and  a  very  moderate  heat  used 
at  first,  by  which  means  a  combination  will 
take  place,  and  the  soda  will  not  be  ab- 
sorbed. If  too  large  a  quantity  of  soda  has 
been  added  at  first,  and  it  has  consequently 
been  absorbed,  a  more  intense  heat  will 
cause  it  to  return  to  the  surface  of  the 
charcoal,  and  it  will  then  enter  into  com- 
bination. 

Some  minerals  combine  readily  with 
only  very  small  portions  of  soda,  biit  melt 
with  difficulty  if  more  be  added,  and  are 
absolutely  infusible  with  a  larger  quantity: 
and  when  the  substance  has  no  affinity  for 
this  flux,  it  is  absorbed  by  the  charcoal, 
and  no  combination  ensues. 


When  the  mineral  or  the  soda  contains 
sulphur  or  sulphuric  acid,  the  glass  ac- 
quires a  deep  yellow  colour,  which  by  the 
light  of  a  lamp  appears  red,  and  as  if  pro- 
duced by  copper. 

If  the  glass  bead  becomes  opaque  as  it 
cools,  so  as  to  render  the  colour  indistinct 
it  should  be  broken,  and  a  part  of  it  mixed 
with  more  of  the  flux,  until  the  colour  be- 
comes more  pure  and  distinct.  To  render 
the  colour  more  perceptible,  the  bead  may 
be  either  compressed  before  it  cools,  or 
drawn  out  to  a  thread. 

When  it  is  intended  to  oxidate  more 
highly  a  metallic  oxide  contained  in  a  vi- 
trified compound  with  any  of  the  fluxes, 
the  glass  is  first  heated  by  a  strong  flame, 
and  when  melted  is  to  be  gradually  with- 
drawn from  the  point  of  the  blue  flame. 
This  operation  may  be  repeated  several 
times,  permitting  the  glass  sometimes  to 
cool,  and  using  a  jet  of  large  aperture  with 
the  blow-pipe. 

The  reduction  of  metals  is  effected  in  the 
following  manner:  The  glass  bead,  formed 
after  the  manner  already  pointed  out,  is  to 
be  kept  in  a  state  of  fusion  on  the  charcoal 
as  long  as  it  remains  on  the  surface,  and  is 
not  absorbed,  that  the  metallic  particles 
may  collect  themselves  into  a  globule.  It  is 
then  to  be  fused  with  an  additional  quantity 
of  soda,  which  will  be  absorbed  by  the  char- 
coal, and  the  spot  where  the  absorption  has 
taken  place  is  to  be  strongly  ignited  by  a 
tube  with  a  small  aperture.  By  continuing 
this  ignition,  the  portion  of  metal  which 
was  not  previously  reduced  will  now  be 
brought  to  a  metallic  state;  and  the  process 
may  be  assisted  by  placing  the  bead  in  a 
smoky  flame,  so  as  to  cover  it  with  soot 
that  is  not  easily  blown  off. 

The  greatest  part  of  the  beads  which 
contain  metals  are  frequently  covered  with 
a  metallic  splendour,  which  is  most  easily 
produced  by  a  gentle,  fluttering,  smoky 
flame,  when  the  more  intense  heat  has 
ceased.  With  a  moderate  heat  the  metallic 
surface  remains;  and  by  a  little  practice  it 
may  generally  be  known  whether  the  sub- 
stance under  examination  contains  a  metal 
or  not.  But  it  must  be  observed,  that  the 
glass  of  borax  sometimes  assumes  exter- 
nally a  metallic  splendour. 

When  the  charcoal  is  cold,  that  part  im- 
pregnated with  the  fused  mass  should  be 
taken  out  with  a  knife,  and  ground  with 
distilled  water  in  a  crystal,  or  what  is  much 
better,  an  agate  mortar.  The  soda  will  be 
dissolved;  the  charcoal  will  float,  arid  may 
be  poured  off;  and  the  metallic  particles 
will  remain  in  the  water,  and  may  be  exa- 
mined. In  this  manner  most  of  the  metals 
may  be  reduced. 


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Helations  of  the  Earths  and  Metallic  Oxides 
before  the  Blo-w-pipe. 

I.  THE   EARTHS. 

JBarytes,  when  containing  water,  melts 
and  spreads  on  the  charcoal.  Combined 
with  sulphuric  acid,  it  is  converted,  in  the 
interior  flame,  into  a  sulphuret,  and  is  ab- 
sorbed by  the  charcoal,  with  effervescence, 
which  continues  as  long  as  it  is  exposed  to 
the  action  of  the  instrument. 

Strontites.  Tf  combined  with  carbonic  acid, 
and  held  in  small  thin  plates  with  platina 
forceps  in  the  interior  flame,  the  carbonic 
acid  is  driven  off;  and  on  the  side  of  the 
plate  farthest  from  the  lamp,  a  red  flame 
is  seen  sometimes  edged  with  green,  and 
scarcely  perceptible  but  by  the  flame  of  a 
lamp.  Sulphate  of  strontites  is  reduced  in 
the  interior  flame  to  a  sulphuret.  Dissolve 
this  in  a  drop  of  muriatic  acid,  add  a  drop 
.of  alcohol,  and  dip  a  small  bit  of  stick  in 
the  solution;  it  will  burn  with  a  fine  red 
flame. 

Lime.  The  carbonate  is  easily  rendered 
caustic  by  heat;  it  evolves  heat  on  being 
moistened,  and  is  afterwards  infusible  be- 
fore the  blow-pipe.  The  sulphate  is  easily 
reduced  to  sulphuret,  and  possesses,  be- 
sides, the  property  of  combining  with  fluor 
at  a  moderate  heat,  forming  a  clear  glass, 
The  fluor  should  be  rather  in  excess. 

Magnesia  produces,  like  tbe  strontites, 
an  intense  brightness  in  the  flame  of  the 
blow-pipe.  A  drop  of  solution  of  cobalt  be- 
ing added  to  it,  and  it  being  then  dried 
and  strongly  ignited,  a  faint  reddish  colour 
like  flesh  is  produced,  which,  however,  is 
scarcely  visible  by  the  light  of  a  lamp.  And 
magnesia  may  by  this  process  be  detected 
in  compound  bodies,  if  they  do  not  contain 
much  metallic  matter,  or  a  proportion  of 
alumina  exceeding  the  magnesia.  Some  in- 
ference as  to  the  quantity  of  the  magnesia 
may  be  drawn  from  the  intensity  of  the  co- 
lour produced. 

All  these  alkaline  earths,  when  pure,  are 
readily  fusible  in  combination  with  the 
fluxes  into  a  clear,  colourless  glass,  with- 
out effervescence;  but  on  adding  a  further 
quantity  of  the  earth,  the  glass  becomes 
opaque. 

Alumina  combines  more  slowly  with  the 
fluxes  than  the  preceding  earths  do,  and 
forms  a  clear  glass,  which  does  not  become 
opaque.  But  the  most  striking  character  of 
alumina  is  the  bright  blue  colour  it  ac- 
quires from  the  addition  of  a  drop  of  ni- 
trate of  cobalt,  after  having  been  dried  and 
ignited  for  some  time.  And  its  presence 
may  be  detected  in  this  manner  in  com- 
pound minerals,  where  the  metallic  sub- 
stances are  not  in  great  proportion,  or  the 
quantity  of  magnesia  large.  Alumina  may 
be  thus  detected  in  the  agalmatoUtc. 


II.  THE  METALLIC  OXIDES. 

Arsenic  flies  off  accompanied  by  its  cha- 
racteristic smell,  resembling  garlic.  When 
larger  pieces  of  white  arsenic  are  heated 
on  a  piece  of  ignited  charcoal,  no  smell  is 
perceived.  To  produce  this  effect  the  white 
oxide  must  be  reduced,  by  being  mixed 
with  powdered  charcoal.  If  arsenic  is  held 
in  solution;  it  may  be  discovered  by  dip- 
ping into  the  solution  a  piece  of  pure  and 
well-burned  charcoal,  which  is  afterwards 
to  be  dried  and  ignited. 

Chrome.  Its  green  oxide,  the  form  in 
which  it  most  commonly  occurs,  and  to 
which  it  is  reduced  by  heating  in  the  com- 
mon  air,  exhibits  the  following  properties: 
it  is  fusible  with  microcosmic  saltt  in  the  in- 
terior  flame,  into  a  glass  which  at  the  in- 
stant of  its  removal  from  the  flame,  is  of  a 
violent  hue,  approaching  more  to  the  dark 
blue  or  red,  according  to  the  proportion  of 
chrome.  After  cooling,  the  glass  is  bluish- 
green,  but  less  blue  than  the  copper  glass. 
In  the  exterior  flame  the  colour  becomes 
brighter,  and  less  blue,  than  the  former. 
With  borax  it  forms  a  bright  yellowish,  or 
yellow-red  glass,  in  the  exterior  flame;  and 
in  the  interior  flame,  this  becomes  darker 
and  greener,  or  bluish-green.  The  reduc- 
tion with  soda  has  not  been  examined. 

Molybdic  acid  melts  by  itself  upon  the 
charcoal  with  ebullition,  and  is  absorbed. 
In  a  platina  spoon  it  emits  white  fumes, 
and  is  reduced  in  the  interior  flame  to  mo- 
lybdous  acid,  which  is  blue;  but  in  the  ex- 
terior flame  it  is  again  oxidated,  and  be- 
comes white.  With  microcosmic  salt,  in  the 
exterior  flame,  a  small  proportion  of  the 
acid  gives  a  green  glass,  which  by  gradual 
additions  of  the  acid  passes  through  yel- 
low-green to  reddish,  brownish,  and  hya- 
cinth-brown, with  a  slight  tinge  of  green. 
In  the  interior  flame  the  colour  passes  from 
yellow-green,  through  yellow-brown  and 
brown-red,  to  black;  and  if  the  proportion 
of  acid  be  large,  it  acquires  a  metallic  lus- 
tre, like  the  sulphuret,  which  sometimes 
remains  after  the  glass  has  cooled.  Molyb- 
dic acid  is  but  little  dissolved  by  borax.  In 
the  exterior  flame  the  glass  acquires  a  gray- 
yellow  colour.  In  the  interior  flame,  a  quan- 
tity of  black  particles  is  precipitated  from 
the  clear  glass,  and  leaves  it  almost  colour- 
less when  the  quantity  of  molybdenum  is 
small,  and  blackish  when  the  proportion  is 
larger.  If  to  a  glass  formed  of  this  acid  and 
microcosmic  salt  a  little  borax  be  added, 
and  the  mixture  fused  in  the  exterior  flame, 
the  colour  becomes  instantly  reddish- 
brown;  in  the  interior  flame  the  black  par- 
ticles are  also  separated,  but  in  smaller 
quantity.  By  long  continued  heat  the  co- 
lour of  the  glass  is  diminished,  and  it  ap- 
pears yellower  by  the  light  of  a  lair.n  than 


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by  day -light.  This  acid  is  not  reduced  by 
soda  in  the  interior  flame. 

Tungstic  acid  becomes  upon  the  char- 
coal  at  first  brownish-yellow,  is  then  re- 
duced to  a  brown  oxide,  and  lastly  becomes 
black  without  melting-  or  smoking-.  With 
microcosmic  salt  it  forms  in  the  interior  flame 
a  pure  blue  glass,  without  any  violet  ting-e; 
in  the  exterior  flame  this  colour  disappears, 
and  re-appears  again  in  the  interior.  With 
borax,  in  the  internal  flame,  and  in  small 
proportions  it  forms  a  colourless  gl-.ss, 
which,  by  increasing  the  proportion  of  the 
acid,  becomes  dirty  gray,  and  then  red- 
dish  By  long  exposure  to  the  external 
flame  it  becomes  transparent, but  as  it  cools 
it  becomes  muddy,  whitish,  and  changea- 
ble into  red  when  seen  by  day-light.  It  is 
not  reduced. 

Oxide  of  Tantalum  undergoes  no  change 
by  itself,  but  is  readily  fused  with  micro- 
cosmic  salt  and  with  borax,  into  a  clear  co- 
lourless glass,  from  which  the  oxide  may 
be  precipitated  by  heating  and  cooling  it 
alternately.  The  glass  then  becomes  opaque, 
and  the  oxide  is  not  reduced. 

Oxide  of  Titanium  becomes  yellowish 
when  ignited  in  a  spoon,  and  upon  charcoal 
dark  brown.  With  microcosmic  salt  it  gives 
in  the  interior  flame  a  fine  violet-coloured 
glass,  with  more  of  blue  than  that  from 
manganese.  In  the  exterior  flame  this  co- 
lour disappears.  With  borax  it  g-ives  a  dirty 
hyacinth  colour.  Its  combinations  with  so- 
da have  not  been  examined. 

Oxide  of  Cerium  becomes  red-brown  when 
ignited.  When  the  proportion  is  small  it 
forms  with  the  fluxes  a  clear  colourless 
glass,  which  by  increasing  the  proportion  of 
oxide  becomes  yellowish -green  while  hot. 
With  microcosmic  salt,  if  heated  a  long  time 
in  the  internal  flame,  it  gives  a  clear  co- 
lourless glass.  With  borax,  under  similar 
circumstances,  it  gives  a  faint  yellow-green 
glass  while  warm,  but  colourless  when  cold. 
Exposed  again  for  some  time  to  the  exter. 
nal  flame,  it  becomes  reddish-yellow,  which 
colour  it  partly  retains  when  cold.  If  two 
transparent  beads  of  the  compound  with 
mici'ocosmic  salt  and  with  borax  be  fused 
together,  the  triple  compound  becomes 
opaque  and  white.  Flies  off  by  reduction. 

Oxide  of  Uranium.  The  yellow  oxide  by 
ignition  becomes  green  or  greenish  brown. 
With  microcosmic  salt  in  the  interior  flame 
it  forms  a  clear  yellow  glass,  the  colour  of 
which  becomes  more  intense  when  cold.  If 
long  exposed  to  the  exterior  flame,  and  fre- 
quently cooled,  it  gives  a  pale  yellowish 
red-brown  glass,  which  becomes  greenish 
as  it  cools.  With  borax  in  the  interior  flame 
a  clear,  colourless,  or  faintly  green  glass, 
is  formed,  containing  black  particles,  which 
appear  to  be  the  metal  in  its  lowest  state  of 
oxidation.  In  the  exterior  flame  this  black 
VOL.  I, 


matter  is  dissolved  if  the  quantity  be  not 
too  great,  and  the  glass  becomes  bright 
yellowish -green,  and  after  further  oxida- 
tion yellowish-brown.  If  brought  again  into 
the  interior  flame,  the  colour  gradually 
changes  to  green,  and  the  black  matter  is 
again  precipitated,  but  no  farther  reduc- 
tion takes  place. 

Oxide  of  Manganese  gives  with  microcos- 
mic salt  in  the  exterior  flame  a  fine  amethyst 
colour,  which  disappears  in  the  interior 
flame.  With  borax  it  gives  a  yellowish  hya- 
cinth red  glass. 

When  the  manganese,  from  its  combina- 
tion with  iron,  or  any  other  cause,  does  not 
produce  a  sufficiently  intense  colour  in  the 
glass,  a  little  nitre  may  be  added  to  it  while 
in  a  state  of  fusion,  and  the  glass  then  be- 
comes dark  violet  while  hot,  and  reddish 
violet  when  cool:  is  not  reduced. 

Oxide  of  Tellurium,  when  gently  heated, 
becomes  first  yellow, then  light  red,  and  af- 
terwards black.  It  melts  and  is  absorbed 
by  the  charcoal,  and  is  reduced  with  a 
slight  detonation,  a  greenish  flame,  and  a 
smell  of  horse-raddish.  JWicrocosmic  salt 
dissolves  it  without  being  coloured. 

Oxide  of  Antimony  is  partly  reduced  in 
the  exterior  flame,  and  spreads  a  white 
smoke  on  the  charcoal.  In  the  interior  flame 
it  is  readily  reduced  by  itself,  and  with  so- 
da. With  microcosmic  salt  and  with  borax 
it  forms  a  hyacinth-coloured  glass.  Metal- 
lic antimony,  when  ignited  on  charcoal,  and 
remaining  untouched,  becomes  covered 
with  radiating  acicular  crystals  of  white 
oxide.  Sulphuret  of  antimony  melts  on 
charcoal,  and  is  absorbed. 

Oxide  of  Bismuth  melts  readily  in  a  spoon 
to  a  brown  glass,  which  becomes  brighter 
as  it  cools.  With  microcosmic  salt  it  forms 
a  gray-yellow  glass,  which  loses  its  trans- 
parency, and  becomes  pale,  when  cool. 
Add  a  further  proportion  of  oxide,  and  it 
becomes  opaque.  With  borax  it  forms  a 
gray  glass,  which  decrepitates  in  the  inte- 
rior flame,  and  the  metal  is  reduced  and 
volatilized.  It  is  most  readily  reduced  by 
itself  on  charcoal. 

Oxide  of  Zinc  becomes  yellow  when 
heated,  but  whitens  as  it  cools.  A  small 
proportion  forms  with  microcosmic  salt  and 
with  borax  a  clear  glass,  which  becomes 
opaque  on  increasing  the  quantity  of  oxide. 
A  drop  of  nitrate  of  cobalt  being  added  to 
the  oxide,  and  dried  and  ignited,  it  be- 
comes green.  With  soda  in  the  interior 
flame  it  is  reduced,  and  burns  with  its  cha- 
racteristic flame,  depositing  its  oxide  upon 
the  charcoal.  By  tins  process  zinc  may  be 
easily  detected  even  in  the  automolite. 
Mixed  with  oxide  of  copper,  and  reduced, 
the  zinc  will  be  fixed,  and  brass  be  obtain- 
ed.  But  one  of  the  most  unequivocal  cha. 
racters  of  the  oxide  of  zinc  is  to  dissolve  it 
25 


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in  vinegar,  evaporate  the  solution  to  dry- 
ness,  and  expose  it  to  the  flame  of  a  lamp, 
when  it  will  burn  with  its  peculiar  flame. 

Oxide  of  Iron  produces  with  microcosmic 
salt  or  borax  in  the  exterior  flame,  when 
cold,  a  yellowish  glass,  which  is  blood-red 
while  hot.  The  protoxide  forms  with  these 
fluxes  a  green  glass,  which,  by  increasing 
the  proportion  of  the  metal,  passes  through 
bottle-green  to  black  and  opaque.  The  glass 
from  the  oxide  becomes  green  in  tb*  inte- 
rior flame,  and  is  reduced  to  protoxide,  and 
becomes  attractible  by  the  magnet.  When 
placed  on  the  wick  of  a  candle,  it  burns 
with  the  crackling  noise  peculiar  to  iron. 

Oxide  of  Cobalt  becomes  black  in  the 
exterior,  and  gray  in  the  interior  flame.  A 
small  proportion  forms  with  microcosmic 
salt  and  with  borax  a  blue  glass,  that  with 
borax  being  the  deepest.  By  transmitted 
light  the  glass  is  reddish.  By  farther  addi- 
tions of  the  oxide  it  passes  through  dark 
blue  to  black.  The  metal  may  be  precipita- 
ted from  the  dark  blue  glass  by  inserting  a 
steel  wire  into  the  mass  while  in  fusion.  It 
is  malleable  if  the  oxide  has  been  free  from 
arsenic,  and  may  be  collected  by  the  mag- 
net; and  is  distinguished  from  iron  by  the 
absence  of  any  crackling  sound  when  placed 
on  the  wick  of  a  candle. 

Oxide  of  Nickel  becomes  black  at  the 
extremity  of  the  exterior  flame,  and  in  the 
interior  greenish-gray.  It  is  dissolved  rea- 
dily, and  in  large  quantity,  by  microcosmic 
salt.  The  glass,  while  hot,  is  a  dirty  dark 
red,  which  becomes  paler  and  yellowish  as 
it  cools.  After  the  glass  has  cooled,  it  re- 
quires a  large  addition  of  the  oxide  to  pro- 
duce a-distinct  change  of  colour.  It  is  near- 
ly the  same  in  the  exterior  and  interior 
flame,  being  slightly  reddish  in  the  latter. 
Nitre  added  to  the  bead  makes  it  froth, 
and  it  becomes  red-brown  at  first,  and  af- 
terwards paler.  It  is  easily  fusible  with  bo- 
rax, and  the  colour  resembles  the  preced- 
ing. When  this  glass  is  long  exposed  to  a 
high  degree  of  heat  in  the  interior  flame, 
it  passes  from  reddish  to  blackish  and 
opaque;  then  blackish -gray,  and  translu- 
cent; then  paler  reddish-gray,  and  clearer; 
and,  lastly,  transparent;  and  the  metal  is 
precipitated  in  small  white  metallic  glo- 
bules. The  red  colour  seems  here  to  be  pro- 
duced by  the  entire  fusion  or  solution  of 
the  oxide,  the  black  by  incipient  reduction, 
and  the  gray  by  the  minute  metallic  parti- 
cles before  they  combine  and  form  small 
globules.  When  a  little  soda  is  added  to  the 
glass  formed  with  borax,  the  reduction  is 
more  easily  effected,  and  the  metal  collects 
itself  into  one  single  globule.  When  this 
oxide  contains  iron,  the  glass  retains  its 
own  colour  while  hot,  but  assumes  that  of 
the  iron  as  it  cools. 

Oxide  of  Tin,  in  form  of  hydrate,  and  in 


its  highest  degree  of  purity,  becomes  yel- 
low when  heated,  then  red,  and  when  ap- 
proaching to  ignition,  black.  If  iron  or  lead 
be  mixed  with  it,  the  colour  is  dark  brown 
when  heated.  These  colours  become  yel- 
lowish as  the  substance  cools.  Upon  char- 
coal in  the  interior  flame  it  becomes  and 
continues  white;  and,  if  originally  white  and 
free  from  water,  it  undergoes  no  change  of 
colour  by  heating.  It  is  very  easily  reduced 
without  addition,  but  the  reduction  is  pro- 
moted by  adding  a  drop  of  solution  of  soda 
or  potash. 

Oxide  of  Lead  melts,  and  is  very  quickly 
reduced,  either  without  any  addition,  or 
when  fused  with  microcosmic  salt  or  bo- 
rax. The  glass  not  reduced  is  black. 

Oxide  of  Copper  is  not  altered  by  the  ex- 
terior flame,  but  becomes  protoxide  in  the 
interior.  With  both  microcosmic  salt  and  bo- 
rax it  forms  a  yellow-green  glass  while  hot, 
but  which  becomes  blue-green  as  it  cools. 
When  strongly  heated  in  the  interior  flame, 
it  loses  its  colour,  and  the  metal  is  reduced. 
If  the  quantity  of  oxide  is  so  small  that  the 
green  colour  is  not  perceptible,  its  pre- 
sence may  be  detected  by  the  addition  of 
a  little  tin,  which  occasions  a  reduction  of 
the  oxide  to  protoxide,  and  produces  an 
opaque,  red  glass.  If  the  oxide  has  been 
fused  with  borax,  this  colour  is  longer  pre- 
served; but  if  with  microcosmic  salt,  it  soon 
disappears  by  a  continuance  of  heat. 

The  copper  may  also  be  precipitated 
upon  iron,  but  the  glass  must  be  first  satu- 
rated with  iron.  Alkalis  or  lime  promote 
this  precipitation.  If  the  glass  containing 
copper  be  exposed  to  a  smoky  flame,  the 
copper  is  superficially  reduced,  and  the 
glass  covered  while  hot  with  an  iridescent 
pellicle,  which  is  not  always  permanent  af- 
ter cooling.  It  is  very  easily  reduced  by 
soda.  Salts  of  copper,  when  heated  before 
the  blow-pipe,  give  a  fine  green  flame. 

Oxide  of  Mercury  before  the  blow-pipe 
becomes  black,  and  is  entirely  volatilized. 
In  this  manner  its  adulteration  may  be  dis- 
covered. 

The  other  metals  may  be  reduced  by 
themselves,  and  may  be  known  by  their  own 
peculiar  characters. 

*  Under  the  particular  mineral  species 
their  habitudes  with  the  blow-pipe  are 
given. 

Dr.  Robert  Hare,  Professor  of  Natural 
Philosophy  in  the  University  of  Philadel- 
phia, published,  in  the  first  volume  of 
Bruce's  Mineralogical  Journal,  an  account 
of  very  intense  degrees  of  heat,  which  he 
had  produced  and  directed  on  different  bo- 
dies, by  a  jet  of  flame,  consisting  of  hydro- 
gen and  oxygen  gases,  in  the  proportion 
requisite  for  forming  water.  The  gases 
were  discharged  from  separate  gasometers, 
and  were  brought  in  contact  only  at  a  com- 


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morv  orifice  or  nozzle  of  small  diameter, 
in  which  their  two  tubes  terminated.f 

In  the  first  number  of  the  Journal  of  Sci- 
ence and  Arts,  is  a  description  of  a  blow- 
pipe contrived  by  Mr.  Brooke,  and  exe- 
cuted by  Mr.  Newman,  consisting  of  a 
strong-  iron  box,  with  a  blow-pipe  nozzle 
and  stop-cock,  for  regulating  the  emission 
of  air,  which  had  been  previously  condensed 
into  the  box,  by  means  of  a  syringe  screwed 
into  its  top.  For  this  fine  invention  we  are 
ultimately  indebted  to  Sir  H.  Davy.  John 
George  Children,  Esq.  first  proposed  to  him 
this  application  of  Newman's  apparatus  for 
condensed  air  or  oxygen,  immediately  after 
Sir  H.  had  discovered  that  the  explosion 
from  oxygen  and  hydrogen  would  not  com- 
municate  through  very  small  apertures; 
and  lie  first  tried  the  experiment  himself 
with  a  fine  glass  capillary  tube.  The  flame 
was  not  visible  at  the  end  of  this  tube, 
being  overpowered  by  the  brilliant  star  of 
the  glass  ignited  at  the  aperture. 

Dr.  Clarke,  after  being  informed  by  Sir 
H.  Davy  that  there  would  be  no  danger  of 
explosion  in  burning  the  compressed  gases, 
by  suffering  them  to  pass  through  a  fine 
thermometer  tube,  •£$  of  an  inch  diameter, 
and  three  inches  in  length;  commenced  a 
series  of  experiments,  which  were  attended 
with  most  important  and  striking  results. 
By  the  suggestion  of  Professor  Gumming, 
there  has  been  enclosed  in  the  iron  box,  a 
small  cylinder  of  safety,  about  half  filled 
with  oil,  and  stuffed  at  top  with  fine  wire 
gauze.  The  condensed  gases  must  pass 
from  the  large  chamber  into  this  small 
one,  up  through  the  oil,  and  then  across 
the  gauze,  before  they  can  reach  the  stop- 
cock and  blow-pipe  nozzle.  By  this  means, 
the  dangerous  explosions  which  had  oc- 
curred so  frequently,  as  would  have  deter- 
red a  less  intrepid  experimenter  than  Dr. 
Clarke,  are  now  obviated.  It  is  still,  howe- 
ver, a  prudent  precaution,  to  place  a  wood- 
en screen  between  the  box  and  the  opera- 
tor. The  box  is  about  five  inches  long,  four 
broad,  and  three  deep.  The  syringe  is  join- 
ed to  the  top  of  the  box  by  a  stop-cock. 
Near  the  upper  end  of  the  syringe,  a  screw 
nozzle  is  fixed  in  it  at  right  angles,  to 
which  the  stop-cock  of  a  bladder  contain- 
ing the  mixed  gases  may  be  attached. 
When  we  wish  to  inject  the  gases,  it  is 

f  My  memoir  on  the  supply  and  applica- 
tion of  the  blow-pipe,  in  which  the  fusion 
of  the  pure  earths,  and  volatilization  of  pla- 
tinum, were  first  mentioned  as  practicable, 
was  published  in  a  separate  pamphlet 
twelve  years  before  the  article  on  the  com- 
pound blow-pipe  appeared  in  Bruce's  Jour- 
nal. This  was  a  republication  of  a  paper 
previously  presented  by  Professor  SiUiman 
to  the  Connecticut  Academy  of  Sciences, 


proper  to  draw  the  piston  to  the  top,  be- 
fore  opening  the  lower  stop-cock,  lest  the 
flame  of  the  jet  should  be  sucked  back- 
ward, and  cause  explosion.  It  is  likewise 
necessary  to  see  that  no  little  explosion, 
has  dislodged  the  oil  from  the  safety  cy- 
linder. A  bubbling  noise  is  heard  when  the 
oil  is  present.  A  slight  excess  of  hydrogen 
is  found  to  be  advantageous. 

Platinum  is  not  only  fused  the  instant  it 
is  brought  in  contact  with  the  flame  of  the 
ignited  gases,  but  the  melted  metal  runs 
down  in  drops.  Dr.  Clarke  has  finely  fused 
the  astonishing  quantity  of  half  an  ounce 
at  once,  by  this  jet  of  flame.  In  small  quan- 
tities, it  burns  like  iron  wire.  Palladium 
melted  like  lead.  Pure  lime  becomes  a  wax- 
yellow  vitrification.  A  lambent  purple  flame 
always  accompanies  its  fusion.  The  fusion 
of  magnesia  is  also  attended  with  combus- 
tion. Strontites  fused  with  a  flame,  of  an 
intense  amethystine  colour,  and  after  some 
minutes  there  appeared  a  small  oblong  mass 
of  shining  matter  in  its  centre.  Silex  instant- 
ly melted  into  a  deep  orange -coloured  glass, 
which  was  partly  volatilized.  Alumina  melt- 
ed with  great  rapidity  into  globules  of  a 
yellowish  transparent  glass.  In  these  expe- 
riments, supports  of  charcoal,  platinum  or 
plumbago,  were  used  with  the  same  effect. 
The  alkalis  were  fused  and  volatilized  the 
instant  they  came  in  contact  with  the  flame, 
with  an  evident  appearance  of  combustion. 

The  following  refractory  native  com- 
pounds were  fused.  Rock  crystal,  white 
quartz,  noble  opal,  flint,  calcedony,  Egyp- 
tian jasper,  zircon,  spinelle,  sapphire,  to- 
paz, cymophane,  pycnite,  andalusite,  wa- 
velite,  rubellite,  hyperstene,  cyanite,  talc, 
serpentine,  hyalite,  lazulite,  gadolinite,  leu- 
cite,  apatite,  Peruvian  emerald,  Siberian  be- 
ryl, potstone,  hydrate  of  magnesia,  subsul- 
phate  of  alumina,  pagodite  of  China,  Iceland 
spar,  common  chalk,  Arragonite,  diamond. 

Gold  exposed  on  pipe-clay  to  a  flame,  was 
surrounded  with  a  halo  of  a  lively  rose  co- 
lour, and  soon  volatilized.  Stout  iron  wire 
was  rapidly  burned.  Plumbago  was  fused 
into  a  magnetic  bead.  Red  oxide  of  titani- 
um fused,  with  partial  combustion.  Red 
ferriferous  copper,  blende,  oxides  of  plati- 
num, gray  oxide  of  manganese,  crystalliz- 
ed oxide  of  manganese,  wolfram,  sulphuret 
of  molybdenum,  siliceo-calcareous  titani- 
um, black  oxide  of  cobalt,  pechblende,  si- 
liciferous  oxide  of  cerium,  chromate  of 
iron,  and  ore  of  iridium,  were  all,  except 
the  second  and  last,  reduced  to  the  metal- 
lic state,  with  peculiar,  and  for  the  most 
part,  splendid  phenomena.  Jade,  mica,  ami- 
anthus, asbestus,  melt  like  wax  before  this 
potent  flame. 

But  the  two  most  surprising  of  Dr. 
Clarke's  experiments  were,  the  fusion  of 
the  meteoric  stone  from  1'Aigle,  and  its 


BLO 


BLO 


conversion  into  iron;  and  the  reduction  of 
barium,  from  the  earth  barytes  and  its  salts. 
Some  nitrate  of  barytes,  put  into  a  cavity, 
at  the  end  of  a  stick  of  charcoal,  was  ex- 
posed to  the  ignited  gas.  It  fused  with  ve- 
hement ebullition,  and  metallic  globules 
were  clearly  discernible  in  the  midst  of  the 
boiling  fluid,  suddenly  forming,  and  as  sud- 
denly disappearing.  On  checking  the  flame, 
the  cavity  of  the  charcoal  was  studded  over 
with  innumerable  globules  of  a  metafc  of 
the  most  brilliant  lustre  and  whiteness,  re- 
sembling the  purest  platinum  after  fusion. 
Some  globules  were  detached  and  dropped 
into  naphtha,  where  they  retained  for  some 
time  their  metallic  aspect.  Their  specific 
gravity  was  4.00. 

Dr.  Clarke  fused  together  a  bead  of  ba- 
rium and  one  of  platinum,  each  weighing 
one  grain. The  bronze  coloured  alloy  weigh- 
ed two  grains,  proving  a  real  combination. 
The  alloy  of  barium  and  iron  is  black  and 
brittle.  Barium  is  infusible  before  the  blow- 
pipe, Per  se,-  but  with  borax  it  dissolves 
like  barytes,  with  a  chrysolite  green  co- 
lour, and  disclosing  metallic  lustre  to  the 
file.  The  alloy  of  barium  and  copper  is  of 
a  vermilion  colour.  When  si  lex  is  mixed 
into  a  paste  with  lamp-oil,  and  exposed  on 
a  cavity  of  charcoal  to  the  flame,  it  runs 
readily  into  beads  of  various  colours.  If 
these  be  heated  in  contact  with  iron,  an  al- 
loy of  silicium  and  iron  is  obtained,  which 
discloses  a  metallic  surface  to  the  file.  Mag- 
nesium and  iron  may  be  alloyed  in  the  same 
way. 

By  using  from  two  to  three  volumes  of 
hydrogen  to  one  of  oxygen,  and  directing 
the  flame  on  pure  barytes,  supported  on 
pincers  of  slate,  Dr.  Clarke  has  more  lately 
revived  barium  in  larger  quantities,  so  as 
to  exhibit  its  qualities  for  some  time.  It 
gradually,  however,  passes  again  into  pure 
barytes  Muriate  of  rhodium,  placed  in  a 
charcoal  crucible,  yielded  the  metal  rho- 
dium, brilliant  like  platinum.  It  is  mallea- 
ble on  the  anvil.  Oxide  of  uranium,  from 
Cornwall,  was  also  reduced  to  the  metallic 
state.f 


|  How  far  Dr.  Ure  has  done  me  justice 
in  this  article,  will  be  seen  more  fully  in 
the  strictures  which  I  have  lately  publish- 
ed on  "  Clarke's  gas  blow-pipe,"  in  Silli- 
roan's  Journal,  No.  2,  vol.  2.  fiut  it  may  be 
sufficient  to  subjoin  the  following  article 
translated  into  No.  1,  vol.  3d.  of  the  same 
journal,  from  the  Annalesde  Chirnie  From 
this  it  appears,  that  Dr.  Clarke's  plagia- 
risms are  not  likely  to  receive  the  counte- 
nance in  France,  which  he  has  managed  to 
prof ure  for  them  in  his  own  country. 

"  The  blow-pipe  of  Hare  was  described 
in  the  Annals  of  Chemistry,  (Vol.  45,  p. 
113.)  It  is  supplied  by  two  streams,  one  of 


tVe  shall  conclude  this  ai'ticle  by  the  fol- 
lowing experiment  of  Dr.  Clarke's:  If  you 
take  up  two  pieces  of  lead  foil  and  plati- 

hydrogen  and  the  other  of  oxygen,  which 
do  not  mix  till  the  moment  of  their  com- 
bustion; and  consequently  are  attended  by 
no  kind  of  danger.  This  blow-pipe  is  in  this 
respect  far  preferable  to  that  of  Ne-vman, 
or  rather  of  Brooke,  who  appears  to  have 
been  the  first  inventor,  and  it  is  not  inferior 
to  it,  or  only  in  a  very  slight  degree,  in  in- 
tensity of  heat.  We  can  besides  supply  it 
with  hydrogen  gas  and  oxygen  gas,  com- 
pressed each  in  its  own  reservoir;  but,  if 
we  were  to  judge  of  it  by  the  effects  pro- 
duced by  this  instrument,  and  by  that  of 
Brooke,  there  is  but  little  advantage  in 
having  recourse  to  this  means. 

"  Lavoisier,  as  is  well  known,  by  direct- 
ing oxygen  gas  upon  burning  charcoal,  suc- 
ceeded in  melting  and  volatilizing  some 
substances,  which,  till  that  time,  had  been 
considered  as  infusible  and  fixed.  (Me"m. 
de  1'Acad.  1782  et  1783).  He  melted  alu- 
mine,  and  many  of  its  mixtures;  but  he  did 
not  succeed  in  melting  silex,  barytes,  lime 
and  magnesia. 

"  Mr.  Hare,  by  means  of  his  blow-pipe, 
perfectly  melted  alumine, silex  and  barytes, 
but  with  great  difficulty,  lime  and  magne- 
sia. He  brought  silver  and  gold  to  a  state 
of  ebullition,  and  succeeded,  almost  in- 
stantly, in  volatilizing  completely,  globules 
of  platina  of  more  than  a  line  in  diameter. 
(Ann.  de  Chim.  XLV.  134.  et  LX.  82.) 

"Some  years  Afterwards,  Mr.  Silliman, 
Professor  of  Chemistry  and  Mineralogy, 
who  had  co-operated  in  the  early  experi- 
ments of  Mr.  Hare,  performed  new  ones, 
which  were  published  in  1813,  in  the  first 
volume  of  the  Memoirs  of  the  Connecticut 
Academy  of  Arts  and  Sciences;  we  proceed 
to  give  the  principal  results. 

"  Alumine  was  perfectly  melted  into  a 
milk  white  enamel. 

"  Silex,  into  a  colourless  glass. 
"  Barytes  and  strontian  into   a   grayish 
white  enamel. 

"  Glucine  and  Zircon  were  perfectly  melt- 
ed into  a  white  enamel. 

"  Lime,  prepared  by  the  calcination  of 
Carrara  marble,  was  melted  into  a  per- 
fectly white  and  brilliant  enamel 

"  The  splendor  of  the  light  was  such  that 
the  eye,  when  naked,  and  even  when  pro- 
tected by  deeply  coloured  glasses,  could 
not  sustain  it.  The  lime  was  seen  to  become 
rounded  at  the  angles,  and  gradually  to 
sink  down;  and  in  a  few  seconds,  there  re- 
mained only  a  small  globular  mass. 

"  Magnesia  was  affected  almost  exactly 
as  lime;  the  light  reflected  was  equally  vi- 
vid; ihe  surface  was  melted  into  small  vi- 
treous globules. 


BOL 


num  foil  of  equal  dimensions,  and  roll 
them  together,  and  place  the  roll  upon 
charcoal,  and  direct  the  flame  of  a  candle 
cautiously  towards  the  edges  of  the  roll, 
at  about  a  red  heat,  the  two  metals  will 
combine  with  a  sort  of  explosive  force, 
scattering1  their  melted  particles  off  the 
charcoal,  and  emitting  light  and  heat  in  a 
very  surprising  manner.  Then  there  will 
remain  upon  the  charcoal  a  film  of  glass; 
which  by  further  urging  the  flame  towards 
it,  will  melt  into  a  highly  transparent  glo- 
bule of^  sapphire  blue  colour.  Also,  if  the 
platinum  and  lead  be  placed  beside  each 
other,  as  soon  as  the  platinum  becomes 
heated,  you  will  observe  a  beautiful  play  of 
blue  light  upon  the  surface  of  the  lead,  be- 
coming highly  iridescent  before  it  melts.* 

*  BLUE  (PRUSSIAN).  A  combination  of 
oxide   of  iron   with  an  acid  distinguished 
by  the  name  of  \\\efcrro-prussic.    See  ACID 
(PRUSSIC),  and  IRON.* 

BLUE  (SAXON).  The  best  Saxon  blue  co- 
lour may  be  given  by  the  following  compo- 
sition: 

Mix  one  ounce  of  the  best  powdered  in- 
digo with  four  ounces  of  sulphuric  acid,  in 
a  glass  bottle  or  matrass,  and  digest  it  for 
one  hour  with  the  heat  of  boiling  water, 
shaking  the  mixture  at  different  times: 
then  add  twelve  ounces  of  water  to  it,  and 
stir  the  whole  well,  and  when  grown  cold, 
filter  it. 

Mr.  Poerner  adds  one  ounce  of  good  dry 
potash  at  the  end  of  twenty -four  hours,  and 
lets  this  stand  as  much  longer,  before  he 
dilutes  it  with  water.  The  cloth  should  be 
prepared  with  alum  and  tartar. 

BOG  ORES.     See  ORES  OF  IRON. 

*  BOLE.  A  massive  mineral,  having  a  per- 

"  Platina  was  not  only  melted,  but  vola- 
tilized with  strong  ebullition. 

"  A  great  number  of  minerals,  such  as 
rock  crystal,  chalcedony,  beryl,  Peruvian 
emerald,  peridot  (chrysolite),  amphigene 
(leucite),  disthene  (sappare),  corundum, 
zircon,  spinel-ruby,  &c.  melted  with  the 
greatest  facility. 

"  In  subsequent  experiments,  which  Mr. 
Silliman  has  communicated  to  us,  platina, 
gold,  silver,  and  manv  other  metals  were 
not  only  rapidly  vaporized,  but  entered,  at 
the  same  time,  into  beautiful  and  vivid 
combustion. 

"  Although  the  experiments  of  Mr.  Sil- 
liman date  in  1812,  we  have  thought  that 
they  ought  to  be  known  upon  our  conti- 
nent. They  demonstrate,  on  the  one  hand, 
that  Mr.  Clarke  has  been  anticipated  in 
America,  with  respect  to  the  fusion  of  bo- 
dies in  the  flame  of  hydrogen  and  oxygen; 
— and  on  the  other,  that  the  blow-pipe  of 
Hare  gives  results  almost  perfectly  identi- 
cal with  those  of  Brooke.'* 


BOL 

fectly  conchoidal  fracture,  a  glimmering- 
internal  lustre,  and  a  shining  streak.  Its 
colours  are  yellow-red,  and  brownish-black, 
when  it  is  called  mountain  soap.  It  is  trans- 
lucent, or  opaque.  Soft,  so  as  to  be  easily 
cut,  and  to  yield  to  the  nail.  It  adheres  to 
the  tongue,  has  a  greasy  feel,  and  falls  to 
pieces  in  water.  Sp.  gr.  1.4  to  2.  It  may  be 
polished.  If  it  be  immersed  in  water  after 
it  is  dried,  it  falls  asunder  with  a  crackling1 
noise.  It  occurs  in  wacke  and  basalt,  in  Si* 
lesia,  Hessia,  and  Sienna  in  Italy,  and  also 
in  the  clifts  of  the  Giant's  ( lauseway,  Ire- 
land. The  black  variety  is  found  in  the  trap 
rocks  of  the  Isle  of  Sky.* 

BOLOGNIAN  STONE.  Lemery  reports, 
that  an  Italian  shoemaker,  named  Vincen- 
zo  Casciarolo,  first  discovered  the  phos- 
phoric property  of  the  Bolognian  stone.  It 
is  the  ponderous  spar,  or  native  sulphate 
of  barytes. 

If  it  be  first  heated  to  ignition,  then  finely 
powdered,  and  made  into  a  paste  with  mu- 
cilage; and  this  paste,  divided  into  pieces 
a  quarter  of  an  inch  thick,  and  dried  in  a 
moderate  heat,  be  exposed  to  the  heat  of  a 
wind  furnace,  by  placing  them  loose  in  the 
midst  of  the  charcoal;  a  pyrophorus  will  be 
obtained,  which,  after  a  few  minutes'  ex- 
posure to  the  sun's  rays,  will  give  light 
enough  in  the  dark  to  render  the  figures 
on  the  dial-plate  of  a  watch  visible. 

*  BOLETIC  ACID.     See   ACID    (BOLE- 
TIC)* 

*  BOLETUS.  A  genus  of  mushroom,  of 
which  several  species  have  been  subjected 
to  chemical  examination  by  M.  M.  Bracon- 
not  and  Bouillon  La  Grange. 

1.  Boletus  juglandis,  in  1260  parts,  yield- 
ed, 1118.3  water,  95.68  fungin,   18  animal 
matter  insoluble  in  alcohol,  12  osmazome, 
7.2  vegetable  albumen,  6  fungate  of  potash, 
1.2  adipocere,  1.12  oily  matter,  0.5  sugar 
of  mushrooms,  and  a  trace  of  phosphate  of 
potash. 

2.  Boletus  lands ,  used  on  the  continent 
in  medicine,  under  the  name  of  agaric.   It 
is  in  white,  light  friable  pieces,  of  which 
the  outside  is  like   dark-coloured  leather. 
Its  taste  at  first  sweetish,  soon  passes  into 
bitterness  and  acrimony.  Its  infusion  in  wa- 
ter is  yellowish,  sweet-tasted,  and  reddens 
vegetable  blues.  It  contains  muriate  of  pot- 
ash, sulphate  of  lime,  and  sulphate  of  pot- 
ash. Water  boiled  on  agaric,  becomes  ge- 
latinous on  cooling;  and  if  the  water  be  dis- 
sipated by  evaporation,  ammonia  is  exhaled 
by  the  addition  of  lime.  Resin  of  a  yellow 
colour,  with  a  bitter  sour  taste,  may  be  ex- 
tracted from  it  by  alcohol.  It  yields  ben- 
zoic  acid,  by  Sheele's  process.  The  strong 
acids  act  with  energy  on  agaric,  and  the 
nitric  evolves   oxalic  acid.   Fixed  alkalis 
convert  it  into  a  red  jelly,  which  emits  an 
ammoniacal  smell. 


BON 


EON 


3.  JBoletus  igniarius  is   found  in   most 
countries,  and  particularly  in  the  Highlands 
of  Scotland,  on  the  trunks  of  old  ash  and 
other  trees.  The  French  and  Germans  pre- 
pare it  abundantly  for  making  tinder,  by 
boiling  in  water,  drying,   beating  it,  and 
steeping  it  in  a  solution  of  nitre,  and  again 
drying  it.  In  France  it  is  called  amadou,  in 
this  country  German  tinder.  It  has  been  re- 
commended in  surgery,  for  stopping  hae- 
morrhage from  wounds.  It  imparts  to^wa- 
ter  a  deep  brown  colour,  and  an  astringent 
taste.  The  liquid  consists  of  sulphate  of  lime, 
muriate  of  potash,  and  a  brown  extractive 
matter.  When  the  latter  is  evaporated  to 
dryness,  and  burned,  it  leaves  a  good  deal 
of  potash.  Phosphates  of  lime  and  magne- 
sia, with  some  iron,  are  found  in  the  inso- 
luble matter.  Alkalis  convert  it  with  some 
difficulty  into  a  soapy  liquid,  exhaling  am- 
monia. No  benzoic  acid,  and  little  animal 
matter,  are  found  in  this  boletus. 

4.  Boletus  pseudo-igniarius,  yielded  to  Bra- 
connot,  water,  fungin,  a  sweetish  mucilage, 
boletate  of  potash,  a  yellow  fatty  matter, 
vegetable   albumen,   a  little  phosphate   of 
potash,  acetate  of  potash,  and  fungic  acid 
combined  with  a  base. 

5.  Boletus  viscidus  was  found  by  Bracon- 
not  to  be  composed,  in  a  great  measure,  of 
an  animal  mucus,  which  becomes  cohesive 
by  heat.* 

BONE.  The  bones  of  men  and  quadrupeds 
owe  their  great  firmness  and  solidity  to  a 
considerable  portion  of  the  phosphate  of 
lime  which  they  contain.  When  these  are 
rasped  small,  and  boiled  in  water,  they  af- 
ford gelatinous  matter,  and  a  portion  of  fat 
or  oil,  which  occupied  their  interstices. 

*  Calcined  human  bones,  according  to 
Berzelius,  are  composed,  in  100  parts,  of 
81.9  phosphate  of  lime,  3  fiuate  of  lime,  10 
lime,  1.1  phosphate  of  magnesia,  2  soda,  and 
2  carbonic  acid.  100  parts  of  bones  by  cal- 
cination are  reduced  to  63.  Fourcroy  and 
Vauquelin  found  the  following  to  be  the 
composition  of  100  parts  of  ox  bones:  51 
solid  gelatin,  37.7  phosphate  of  lime,  10  car- 
bonate of  lime,  and  1.3  phosphate  of  magne- 
sia; but  Berzelius  gives  the  following  as 
their  constituents;  33.3  cartilage,  55.35 
phosphate  of  lime,  3  fluate  of  lime,  3.85 
carbonate  of  lime,  2.05  phosphate  of  mag- 
nesia, and  2.45  soda,  with  a  little  common 
salt. 

About  l-30th  of  phosphate  of  magnesia 
was  obtained  from  the  calcined  bones  of 
fowls,  by  Fourcroy  and  Vauquelin.  When 
the  enamel  of  teeth,  rasped  down,  is  dis- 
solved in  muriatic  acid,  it  leaves  no  albu- 
men, like  the  other  bones.  Fourcroy  and 
Vauquelin  state  its  components  to  be,  27.1 
gelatin  and  water,  72.9  phosphate  of  lime. 
Messrs.  Hatchett  and  Pepys  rate  its  compo- 
sition at  78  phosphate  of  lime,  6  carbonate 


of  lime,  and  16  water  and  loss.  Berzelius, 
on  the  other  hand,  found  only  2  per  cent  of 
combustible  matter  in  teeth.  The  teeth  of 
adults,  by  Mr.  Pepys,  consist  of  64  phos- 
phate of  lime,  6  carbonate  of  lime,  20  car- 
tilage, and  10  water  or  loss.  The  fossil 
bones  from  Gibraltar,  are  composed  of  phos- 
phate of  lime  and  carbonate,  like  burnt 
bones.  Much  difference  of  opinion  exists 
with  regard  to  the  existence  of  fluoric  acid 
in  the  teeth  of  animals,  some  of  the  most 
eminent  chemists  taking  opposite  sides  of 
the  question.  It  appears  that  bones  buried 
for  many  centuries,  still  retain  thefr  albu- 
men, with  very  little  diminution  of  its  quan- 
tity.* 

Fourcroy  and  Vauquelin  discovered  phos- 
phate of  magnesia  in  all  the  bones  they  exa- 
mined, except  human  bones.  The  bones  of 
the  horse  and  sheep  afford  about  l-36th  of 
phosphate  of  magnesia;  those  of  fish  nearly 
the  same  quantity  as  those  of  the  ox.  They 
account  for  this  by  observing,  that  phos- 
phate of  magnesia  is  found  in  the  urine  of 
man,  but  not  in  that  of  animals,  though  both 
equally  take  in  a  portion  of  magnesia  with 
their  food. 

The  experiments  of  Mr.  Hatchett  show, 
that  the  membranous  or  cartilaginous  sub- 
stance, which  retains  the  earthy  salts  within 
its  interstices,  and  appears  to  determine  the 
shape  of  the  bone,  is  albumen.  Mr  Hat- 
chett observes,  that  the  enamel  of  tooth  is 
analogous  to  the  porcellanous  shells,  while 
mother  of  pearl  approaches  in  its  nature  to 
true  bone. 

A  curious  phenomenon  with  respect  to 
bones  is  the  circumstance  of  their  acquiring 
a  red  tinge,  when  madder  is  given  to  ani- 
mals with  their  food.  The  bones  of  young 
pigeons  will  thus  be  tinged  of  a  rose  colour 
in  twenty -four  hours,  and  of  a  deep  scarlet 
in  three  days;  but  the  bones  of  adult  ani- 
mals will  be  a  fortnight  in  acquiring  a  rose 
colour.  The  bones  most  remote  from  the 
heart  are  the  longest  in  acquiring  this  tinge. 
Mr.  Gibson  informs  us,  that  extract  of  log- 
wood too,  in  considerable  quantity,  will 
tinge  the  bones  of  young  pigeons  purple.  On 
desisting  from  the  use  of  this  food,  how- 
ever, the  colouring  matter  is  again  taken  up 
into  the  circulation,  and  carried  off,  the 
bones  regaining  their  natural  hue  in  a  short 
time.  It  was  said  by  Du  Hamel,  that  the 
bones  would  become  coloured  and  colour- 
less in  concentric  layers,  if  an  animal  were 
fed  alternately  one  week  with  madder,  and 
one  week  without;  and  hence  he  inferred, 
that  the  bones  were  formed  in  the  same 
manner  as  the  woodv  parts  of  trees.  But  he 
was  mistaken  in  the  fact;  and  indeed  had  it 
been  true,  with  the  inference  he  naturally 
draws  from  it,  the  bones  of  animals  must 
have  been  out  of  all  proportion  larger  than 
they  are  at  present. 


BOR 


BOR 


(  Bones  are  of  extensive  use  in  the  arts.  In 
their  natural  state,  or  dyed  of  various  co- 
lours, they  are  made  into  handles  of  knives 
and  forks,  and  numerous  articles  of  turnery. 
We  have  already  noticed  the  manufacture  of 
volatile  alkali  from  bones,  the  coal  of  which 
forms  bone  black;  or  if  they  be  afterwards 
calcined  to  whiteness  in  the  open  air,  they 
constitute  the  bone  ashes,  of  which  cupels 
are  made,  and  which,  finely  levigated,  are 
used  for  cleaning1  articles  of  paste,  and  some 
other  trinkets,  by  the  name  of  burnt  harts- 
horn. The  shavings  of  hartshorn,  which  is 
a  species  of  bone,  afford  an  elegant  jelly; 
and  the  shavings  of  other  bones,  of  which 
those  of  the  calf  are  the  best,  are  often  em- 
ployed in  their  stead. 

On  this  principle,  Mr.  Proust  has  recom- 
mended an  economical  use  of  bones,  parti- 
cularly with  a  view  to  improve  the  subsis- 
tence of  the  soldier.  He  first  chops  them 
into  small  pieces,  throws  them  into  a  kettle 
of  boiling  water,  and  lets  them  boil  about 
a  quarter  of  an  hour.  When  this  has  stood 
till  it  is  cold,  a  quantity  of  fat,  excellent  for 
culinary  purposes  when  fresh,  and  at  any 
time  fit  for  making  candles,  may  be  taken 
off  the  liquor.  This  in  some  instances 
amounted  to  an  eighth,  and  in  others  even 
to  a  fourth,  of  the  weight  of  the  bones. 
After  this  the  bones  may  be  ground,  and 
boiled  in  eight  or  ten  times  their  weight  of 
water,  of  which  that  already  used  may  form 
a  part,  till  about  half  is  wasted,  when  a  very 
nutritious  jelly  will  be  obtained.  The  boiler 
should  not  be  of  copper,  as  this  metal  is 
easily  dissolved  by  the  jelly;  and  the  cover 
should  fit  very  tight,  so  that  the  heat  may 
be  greater  than  that  of  boiling  water,  but 
not  equal  to  that  of  Papin's  digester,  which 
would  give  it  an  empyreuma.  The  bones 
of  meat  that  have  been  boiled,  are  nearly  as 
productive  as  fresh  bones;  but  Dr.  Young 
found  those  of  meat  that  had  been  roasted 
afforded  no  jelly,  at  least  by  simmering,  or 
gentle  boiling. 

*  BORACIC  ACID.  See  ACID  (BORACIC). 
This  acid  has  been  found  native  on  the 
edges  of  hot  springs,  near  Sapo  in  the  terri- 
tory of  Florence;  also  attached  to  specimens 
from  the  Lipari  Islands,  and  from  Monte 
Kotondo,  to  the  west  of  Sienna.  It  is  in 
small  pearly  scales,  and  also  massive;  fusing 
at  the  flame  of  a  candle  into  a  glassy  glo- 
bule. It  consists,  by  Klaproth's  analysis,  of 
86  boracic  acid,  11  ferruginous  sulphate  of 
manganese,  and  3  sulphate  of  lime.* 

*  BORACITE.  Borate  of  magnesia.  It  is 
found  in  cubic  crystals,  whose  fracture  is 
uneven,  or  imperfectly  conchoidal  Shining 
greasy  lustre;  translucent;   so  hard  as  to 
strike  fire  with  steel;  of  a  yellowish,  gray- 
ish, or  greenish-white.   Sp.  grav.  2.56.   It 
becomes  electric  by  heat;  and  the  diagon- 
ally-opposite solid  angles,  are  in  opposite 


electrical  states.  It  fuses  into  a  yellow  en- 
amel, after  emitting  a  greenish  light. 

Vauquelin's  analysis  gives,  83.4  boracic 
acid,  and  16  6  magnesia.  It  occurs  in  gyp- 
sum in  the  Kalkberg  in  the  duchy  of 
Brunswick,  and  at  Segeberg,  near  Kiel  in 
Holstein.* 

BORAX.  The  origin  of  Borax  was  for  a 
long  time  unknown  in  Europe.  Mr.  Grill 
Abrahamson,  however,  sent  some  to  Swe- 
den in  the  year  1772,  in  a  crystalline  form, 
as  dug  out  of  the  earth  in  Thibet,  where  it 
is  called  Pounnxa,  Mypoun,  and  Houipoun: 
it  is  said  to  have  been  also  found  in  Saxony, 
in  some  coal  pits. 

It  does  not  appear  that  borax  was  known 
to  the  ancients,  their  chrysocolla  being  a 
very  different  substance,  composed  of  the 
rust  of  copper,  triturated  with  urine.  The 
word  borax  is  found  for  the  first  time  in 
the  works  of  Geber. 

Borax  is  not  only  found  in  the  East,  but 
likewise  in  South  America.  Mr.  Anthony 
Carera,  a  physician  established  at  Potosi, 
informs  us,  that  this  salt  is  abundantly  ob- 
tained at  the  mines  of  Riquintipa,  and  those 
in  the  neighbourhood  of  Escapa,  where  it 
is  used  by  the  natives  in  the  fusion  of  cop- 
per ores. 

The  purification  of  borax  by  the  Vene- 
tians and  the  Hollanders,  was  for  a  long 
time  kept  secret.  Chaptal  finds,  after  try- 
ing all  the  processes  in  the  large  way,  that 
the  simplest  method  consists  in  boiling  the 
borax  strongly,  and  for  a  long  time,  with 
water.  This  solution  being  filtered,  affords 
by  evaporation  crystals,  which  are  some- 
what foul,  but  may  be  purified  by  repeat- 
ing the  operation. 

Purified  borax  is  white,  transparent,  ra- 
ther greasy  in  its  fracture,  affecting  the 
form  of  six-sided  prisms,  terminating  in 
three-sided  or  six-sided  pyramids.  Its  taste 
is  styptic;  it  converts  sirup  of  violets  to  a 
green:  and  when  exposed  to  heat,  it  swells 
up,  boils,  loses  its  water  of  crvstalliza- 
tion,  and  becomes  converted  into  a  porous, 
white,  opaque  mass,  commonly  called  Cal- 
cined Borax.  A  stronger  heat  brings  it  into 
a  state  of  quiet  fusion;  but  the  glassy  sub- 
stance thus  afforded,  which  is  transparent, 
and  of  a  greenish-yellow  colour,  is  solu- 
ble  in  water,  and  effloresces  in  the  air.  It 
requires  about  eighteen  times  its  weight 
of  water  to  dissolve  it  at  the  temperature 
of  sixty  degrees  of  Fahrenheit;  but  water 
at  the  boiling  heat  dissolves  three  times 
this  quantity.  Its  component  parts,  accord- 
ing to  Kirwan,  are,  boracic  acid  34,  soda 
17,  water  47-  For  an  account  of  the  neu- 
tral borate  of  soda,  and  other  compounds 
of  this  acid,  see  ACID  (BORACIC). 

Borax  is  used  as  an  excellent  flux  in  clo- 
cimastic  operations.  It  enters  into  the  com- 
position of  reducing  fluxes,  and  is  of  the 


BOV 


BRA 


greatest  use  in  analysis  by  the  blow-pipe. 
It  may  be  applied  with  advantage  in  glass 
manufactories;  for  when  the  fusion  turns 
out  bad,  a  small  quantity  of  borax  re-es- 
tablishes it.  It  is  more  especially  used  in 
soldering;  it  assists  the  fusion  of  the  sol- 
der, causes  it  to  flow,  and  keeps  the  sur- 
face of  the  metals  in  a  soft  or  clean  state, 
which  facilitates  the  operation.  It  is  scarce- 
ly of  any  use  in  medicine.  Its  acid,  called 
Sedative  Salt,  is  used  by  some  physicians; 
and  its  name  sufficiently  indicates  its  sup- 
posed effects.  Mixed  with  shell  lac,  in  the 
proportion  of  one  part  to  five,  it  renders 
the  lac  soluble  by  digestion  in  water  heat- 
ed near  boiling. 

*  BORON.  The  combustible  basis  of  bo- 
racic  acid,  which  see.* 

*  BOTANY  BAY  RESIN   exudes   spon- 
taneously from  the  trunk  of  the  acarois  re- 
sinifera  of  New  Holland,  and  also  from  the 
wounded  bark.  It  soon  solidifies  by  the  sun, 
into  pieces  of  a  3rellow  colour  of  various 
sizes.  It  pulverizes  easily  without  caking; 
nor  does  it  adhere  to  the  teeth  when  chew- 
ed. It  has  a  slightly  sweet  astringent  taste. 
It  melts  at  a  moderate  heat.  When  kindled, 
it  emits  a  white  fragrant  smoke.  It  is  in- 
soluble in  water,  but  imparts  to  it  the  fla- 
vour of  storax.  Out  of  nine  parts,  six  are 
soluble  in  water,  and  astringent  to  the  taste; 
and  two  parts  are  woody  fibre.* 

*  BOTRYOLITE  is  a  mineral  which  oc- 
curs in  mamillary  concretions,  formed  of 
concentric  layers;   and  also  in   botryoidal 
masses,  white  and  earthy.    Its  colour  is 
pearl  and  yellowish -gray,  with  sometimes 
reddish-white  concentric  stripes.  It  has  a 
rough  and  dull  surface,  and  a  pearly  lus- 
tre internally.   Fracture  delicate  stellular 
fibrous.  Translucent  on  the  edges.  Brittle, 
but  moderately  hard.  Sp.  grav.  2.85.  It  is 
composed  of  36  silica,  39.5  boracic  acid, 
13  5  lime,  1  oxide  of  iron,  6.5  water.  It 
froths  and  fuses  before  the  blow-pipe  into 
a  white  glass.  It  is  found  in  a  bed  of  gneiss, 
near  Arendahl  in  Norway.  It  is  regarded 
by  some  as  a  variety  of  Datholite.* 

*BOURNONITE.  Anantimonial  sulphuret 
of  lead.* 

BOVEY  COAL.  This  is  of  a  brown  or 
brownish-black  colour;  and  lamellar  tex- 
ture; the  laminze  are  frequently  flexible 
when  first  dug,  though  generally  they 
harden  when  exposed  to  the  air.  It  con- 
sists of  wood  penetrated  with  petroleum 
or  bitumen,  and  frequently  contains  py- 
rites, alum,  and  vitriol;  its  ashes  afford  a 
small  quantity  of  fixed  alkali,  according  to 
the  German  chemists;  but  according  to  Mr. 
Mills,  they  contain  none.  By  distillation  it 
yields  an  ill-smelling  liquor,  mixed  with 
volatile  alkali  and  oil,  part  of  which  is  so- 
luble in  alcohol,  and  part  insoluble,  being 
of  a  mineral  nature. 


It  is  found  in  England,  France,  Italy, 
Switzerland,  Germany,  Iceland,  &c. 

*  BOYLE'S  FUMING  LIQUOR.  Hydro- 
guretted  sulphuret  of  ammonia.* 

BRAIN  OF  ANIMALS.  The  brain  has  long- 
been  known  to  anatomists;  but  it  is  only  of 
late  years  that  chemists  have  paid  it  any  at- 
tention. It  is  a  soft  white  substance,  of  a 
pulpy  saponaceous  feel,  and  little  or  no 
smell.  Exposed  to  a  gentle  heat,  it  loses 
moisture,  shrinks  to  about  a  fourth  of  its 
original  bulk,  and  becomes  a  tenacious 
mass  of  a  greenish-brown  colour.  When 
completely  dried,  it  becomes  solid,  and  fri- 
able like  old  cheese.  Exposed  to  a  strong 
heat,  it  gives  out  ammonia,  swells  up, 
melts  into  a  black  pitchy  mass,  takes  fire, 
burns  with  much  flame  and  a  thick  pun- 
gent smoke,  and  leaves  a  coal  difficult  of 
incineration. 

In  its  natural  state,  or  moderately  dried, 
it  readily  forms  an  emulsion  by  trituration 
with  water,  and  is  not  separated  by  filtra- 
tion. This  solution  lathers  like  soap-suds, 
but  does  not  turn  vegetable  blue  colours 
green.  Heat  throws  down  the  dissolved 
brain  in  a  flocculent  form,  and  leaves  an  al- 
kaline phosphate  in  solution.  Acids  se- 
parate a  white  coagulum  from  it;  and  form 
salts  with  bases  of  lime,  soda,  and  ammo- 
nia. Alcohol  too  coagulates  it. 

Caustic  fixed  alkalis  act  very  powerfully 
on  brain  even  cold,  evolving  much  ammo- 
nia and  caloric.  With  heat  they  unite  with 
it  into  a  saponaceous  substance. 

The  action  of  alcohol  on  brain  is  most 
remarkable.  When  Fourcroy  treated  it  four 
times  in  succession  with  twice  its  weight 
of  well  rectified  alcohol,  boiling  it  a  quarter 
of  an  hour  each  time,  in  a  long-necked  ma- 
trass with  a  grooved  stopple,  the  three  first 
portions  of  alcohol,  decanted  boiling  depo- 
sited by  cooling  brilliant  laminae  of  a  yel- 
lowish-white colour,  diminishing  in  quan- 
tity each  time  The  fourth  deposited  very 
little.  The  cerebral  matter  had  lost  5-8ths 
of  its  weight;  and  by  the  spontaneous  de- 
position, and  the  subsequent  evaporation 
of  the  alcohol,  half  of  this  was  recovered 
in  needly  crystals,  large  scales,  or  granu- 
lated matter.  The  other  half  was  lost  by 
volatilization.  This  crystallized  substance, 
of  a  fatty  appearance,  was  agglutinated  in- 
to a  paste  under  the  finger;  but  did  not 
melt  at  the  heat  of  boiling  water,  being 
merely  softened.  At  a  higher  temperature 
it  suddenly  acquired  a  blackish-yellow  co- 
lour, and  exhaled  during  fusion  an  em- 
pyreumatic  and  ammoniacal  smell.  This 
shows  that  it  is  not  analogous  to  sperma- 
ceti, or  to  adipocere;  but  it  seems  more  to 
resemble  the  fat  lamellated  crystals  con- 
tained in  some  biliary  calculi,  which,  how- 
ever, do  not  soften  at  a  heat  of  234°  F.  or 
become  ammoniacal  and  empyreumatic  at 


BRA 


BRA 


this  temperature,  as  the  crystalline  cere- 
bral oil  does. 

A  portion  of  this  concrete  oil,  separated 
from  the  alcohol  by  evaporation  in  the  sun, 
formed  a  granulated  pellicle  on  its  surface, 
of  a  consistence  resembling-  that  of  soft 
soap.  It  was  of  a  yellower  colour  than  the 
former,  and  had  a  marked  smell  of  animal 
extract,  and  a  perceptible  saline  taste.  It 
was  diffusible  in  water,  gave  it  a  milky  ap- 
pearance, reddened  litmus  paper,  and  did 
not  become  really  oily,  or  fusible  after  the 
manner  of  an  oil,  till  it  had  given  out  am- 
monia, and  deposited  carbon,  by  the  action 
of  fire  or  caustic  alkalis. 

A  similar  action  of  alcohol  on  the  brain, 
nerves,  and  spinal  marrow,  is  observed  af- 
ter long1  maceration  in  it  cold,  when  they 
are  kept  as  anatomical  preparations. 

*  Vauquelin  analyzed  the  brain  and  found 
the  following-  constituents  in  100  parts:  80 
water,  4.53  white  fatty  matter,  0.7  reddish 
fatty  matter,  7.  albumen,  1.12  osmuzome, 
1.5  phosphorus,  5.15  acids,  salts,  and  sul- 
phur. The  medulla  oblongata  and  nerves 
have  the  same  chemical  composition.* 

The  spontaneous  change  that  brain  un- 
dergoes in  certain  situations,  has  already 
been  noticed  under  the  article  AD  IPO- 
CERE. 

BRANDY.  This  well  known  fluid  is  the 
spirit  distilled  from  wine.  The  greatest 
quantities  are  made  in  Languedoc,  where 
this  manufacture,  upon  the  whole  so  perni- 
cious to  society,  first  commenced.  It  is  ob- 
tained by  distillation  in  the  usual  method, 
by  a  still,  which  contains  five  or  six  quin- 
tals of  wine,  and  has  a  capital  and  worm 
tube  applied.  Its  peculiar  flavour  depends, 
no  doubt,  on  the  nature  of  the  volatile  prin- 
ciples, or  essential  oil,  which  come  over 
along  with  it,  and  likewise,  in  some  mea- 
sure, upon  the  management  of  the  fire,  the 
wood  of  the  cask  in  which  it  is  kept,  &c. 
It  is  said,  that  our  rectifiers  imitate  the 
flavour  of  brandy,  by  adding  a  small  pro- 
portion of  nitrous  ether  to  the  spirit  of  malt 
or  molasses.  See  ALCOHOL. 

BRASS.  An  elegant  yellow-coloured  com- 
pound metal,  consisting  of  copper  com- 
bined with  about  one-third  of  its  weight  of 
zinc.  The  best  brass  is  made  by  cementa- 
tion of  calamine,  or  the  ore  of  zinc,  with 
granulated  copper.  See  COPPER. 

BRASSTCA  RUBRA.  The  red  cabbage  af- 
fords a  very  excellent  test  both  for  acids 
and  alkalis;  in  which  it  is  superior  to  lit- 
mus, being  naturally  blue,  turning  green 
with  alkalis,  and  red  with  acids.  *  The 
minced  leaves  may  be  dried  before  the  fire 
till  they  become  quite  crisp,  when  they 
ought  to  be  put  into  a  bottle,  and  corked 
up.  Hot  water  poured  on  a  little  of  the  dried 
leaves,  affords  an  extemporaneous  test 
liquor  for  acids  and  alkalis.  The  purple 
VOL.  I. 


petals  of  violets  may  be  preserved  in  the 
same  way;  as  well  as  those  of  the  pink: 
coloured  lychnis,  and  scarlet  rose.* 

BRAZIL  WOOD.  The  tree  that  affords 
this  wood,  the  caesalpina  crista,  is  of  the 
growth  of  the  Brazils  in  South  America, 
and  also  of  the  Isle  of  France,  Japan,  and 
elsewhere.  It  is  chiefly  used  in  the  process 
of  dyeing.  The  wood  is  considerably  hard, 
is  capable  of  a  good  polish,  and  is  so  heavy 
that  it  sinks  in  water.  Its  colour  is  pale 
when  newly  cut,  but  it  becomes  deeper  by 
exposure  to  the  air  The  various  specimens 
diiier  in  the  intensity  of  their  colour;  but 
the  heaviest  is  reckoned  the  most  valuable. 
It  has  a  sweetish  taste  when  chewed,  and 
is  distinguished  from  red  sanders,  or  san- 
dal, by  its  property  of  giving  out  its  colour 
with  water,  which  this  last  does  not. 

If  the  brazil  wood  be  boiled  in  water  for 
a  sufficient  time,  it  communicates  a  fine  red 
colour  to  that  fluid.  The  residue  is  very 
dark  coloured,  and  gives  out  a  considerable 
portion  of  colouring  matter  to  a  solution  of 
alkali.  Alcohol  extracts  the  colour  from 
brazil  wood,  as  does  likewise  the  volatile 
alkali;  and  both  these  are  deeper  than  the 
aqueous  solution.  The  spirituous  tincture, 
according  to  Dufay,  stains  warm  marble  of 
a  purplish  red,  which  on  increasing'  the 
heat  becomes  violet;  and  if  the  stained  mar- 
ble be  covered  with  wax,  and  considerably 
heated,  it  changes  through  all  the  shades 
of  brown,  and  at  last  becomes  fixed  of  a 
chocolate  colour. 

*  The  colours  imparted  to  cloth  by  brazil 
wood  are  of  little  permanence.  A  very  mi- 
nute portion  of  alkali,  or  even  soap  darkens 
it  into  purple.  Hence  paper  stained  with  it 
may  be  used  as  a  test  of  saturation  with  the 
salts.  Alum  added  to  the  decoction  of  this 
wood,  occasions  a  fine  crimson-red  precipi- 
tate, or  lake,  which  is  increased  in  quantity 
by  the  addition  of  alkali  to  the  liquor.  The 
crimsonrred  colour  is  also  precipitated  by 
muriate  of  tin;  but  it  is  darkened  by  the 
salts  of  iron.  Acids  change  it  to  yellow, 
from  which,  however,  solution  of  tin  re- 
stores it  to  its  natural  hue.  The  extract  of 
brazil  wood  reddens  litmus  paper,  by  de- 
priving it  of  the  alkali  which  darkens  it.* 
BREAD.  I  am  not  acquainted  with  any 
set  of  experiments  regularly  instituted  and 
carried  into  effect,  for  ascertaining  what 
happens  in  the  preparation  of  bread.  Fari- 
naceous vegetables  are  converted  into  meal 
by  trituration,  or  grinding  in  a  mill,  and 
when  the  husk  or  bran  has  been  separated 
by  sifting  or  bolting,  the  powder  is  called 
flour.  This  is  composed  of  a  small  quantity 
of  mucilaginous  saccharine  matter,  solu- 
ble in  cold  water,  much  starch,  which  is 
scarcely  soluble  in  cold  water,  but  com- 
bines with  that  fluid  by  heat,  and  an  adhe- 
sive gray  substance  insoluble  in  water,  al- 


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BUE 


cohol,  oil,  or  ether,  and  resembling  an  ani- 
mal substance  in  many  of  its  properties. 
See  WHEAT,  STARCH,  GLUTEN  (VEGE- 
TABLE), MUCILAGE. 

When  flour  is  kneaded  tog-ether  \vith 
water,  it  forms  a  tough  paste,  containing 
these  principles  very  little  altered,  and  not 
easily  digested  by  the  stomach.  The  action 
of  heat  produces  a  considerable  change  in 
the  gluten,  and  probably  in  the  starch,  ren- 
dering the  compound  more  easy  to  Aasti- 
cate,  as  well  as  to  digest.  Hence  the  first 
approaches  towards  the  making  of  bread 
consisted  in  parching  the  corn,  either  for 
immediate  use  as  food,  or  previous  to  its 
trituration  into  meal;  or  else  in  baking  the 
flour  into  unleavened  bread,  or  boiling  it 
into  masses  more  or  less  consistent;  of  all 
which  we  have  sufficient  indications  in  the 
histories  of  the  earlier  nations,  as  well  as  in 
the  various  practices  of  the  moderns.  It  ap- 
pears likewise  from  the  Scriptures,  that  the 
practice  of  making  leavened  bread  is  of 
very  considerable  antiquity;  but  the  addi- 
tion of  yeast,  or  the  vinous  ferment,  now 
so  generally  used,  seems  to  be  of  modern 
date. 

Unleavened  bread  in  the  form  of  small 
cakes,  or  biscuit,  is  made  for  the  use  of 
shipping  in  large  quantities;  but  most  of 
the  bread  used  on  shore  is  made  to  under- 
go, previous  to  baking,  a  kind  of  ferment- 
ation, which  appears  to  be  of  the  same  na- 
ture as  the  fermentation  of  saccharine  sub- 
stances; but  is  checked  and  modified  by  so 
many  circumstances,  as  to  render  it  not  a 
little  difficult  to  speak  with  certainty  and 
precision  respecting  it.  See  FERMENTA- 
TION. 

When  dough  or  paste  is  left  to  undergo 
a  spontaneous  decomposition  in  an  open 
vessel,  the  various  parts  of  the  mass  are 
differently  affected,  according  to  the  hu- 
midity, the  thickness  or  thinness  of  the 
part,  the  vicinity  or  remoteness  of  fire,  and 
other  circumstances  less  easily  investigated. 
The  saccharine  partis  disposed  to  become 
converted  into  alcohol,  the  mucilage  has  a 
tendency  to  become  sour  and  mouldy,  \vlule 
the  gluten  in  all  probability  verges  toward 
the  putrid  state.  An  entire  change  in  the 
chemical  attractions  of  the  several  compo- 
nent parts  must  then  take  place  in  a  pro- 
gressive manner,  not  altogether  the  same 
in  the  internal  and  more  humid  parts  as  in 
the  external  parts,  which  not  only  become 
dry  by  simple  evaporation,  but  are  acted 
upon  by  the  surrounding  air.  The  outside 
may  therefore  become  mouldy  or  putrid, 
while  the  inner  part  may  be  only  advanced 
to  an  acid  state.  Occasional  admixture  of 
the  mass  would  of  course  not  only  produce 
some  change  in  the  rapidity  of  this  altera- 
tion, but  likewise  render  it  more  uniform 
throughout  the  whole.  The  effect  of  this 


commencing  fermentation  is  found  to  be, 
that  the  mass  is  rendered  more  digestible 
and  light;  by  which  last  expression  it  is 
understood,  that  it  is  rendered  much  more 
porous  by  the  disengagement  of  elastic 
fluid,  that  separates  its  parts  from  each 
other,  and  greatly  increases  its  bulk.  The 
operation  of  baking  puts  a  stop  to  this  pro- 
cess, by  evaporating  great  part  of  the  mois- 
ture which  is  requisite  to  favour  the  che- 
mical attraction,  and  probably  also  by  still 
farther  changing  the  nature  of  the  compo- 
nent parts.  It  is  then  bread. 

Bread  made  according  to  the  preceding 
method  will  not  possess  the  uniformity 
which  is  requisite,  because  some  parts  may 
be  mouldy,  while  others  are  not  yet  suffi- 
ciently changed  from  the  state  of  dough. 
The  same  means  are  used  in  this  case  as 
have  been  found  effectual  in  promoting  the 
uniform  fermentation  of  large  masses.  This 
consists  in  the  use  of  a  leaven  or  ferment, 
which  is  a  small  portion  of  some  matter  of 
the  same  kind,  but  in  a  more  advanced 
stage  of  the  fermentation.  After  the  leaven 
has  been  well  incorporated  by  kneading 
into  fresh  dough,  it  not  only  brings  on  the 
fermentation  with  greater  speed,  but  causes 
it  to  take  place  in  the  whole  of  the  mass  at 
the  same  time;  and  as  soon  as  the  dough 
has  by  this  means  acquired  a  due  increase 
of  bulk  from  the  carbonic  acid,  which  en- 
deavours to  escape,  it  is  judged  to  be  suffi- 
ciently fermented,  and  ready  for  the  oven. 

The  fermentation  by  means  of  leaven  or 
sour  dough  is  thought  to  be  of  the  acetous 
kind,  because  it  is  generally  so  managed 
that  the  bread  has  a  sour  flavour  and  taste. 
But  it  has  not  been  ascertained  that  this 
acidity  proceeds  from  true  vinegar.  Bread 
raised  by  leaven  is  usually  made  of  a  mix- 
ture of  wheat  and  rye,  not  very  accurately 
cleared  of  the  bran.  It  is  distinguished  by 
the  name  of  rye  bread;  and  the  mixture  of 
these  two  kinds  of  grain  is  called  bread- 
corn,  or  meslin,  in  many  parts  of  the  king- 
dom, where  it  is  raised  on  one  and  the 
same  piece  of  ground,  and  passes  through 
all  the  processes  of  reaping,  threshing-, 
grinding,  &c.  in  this  mixed  state. 

Yeast  or  barm  is  used  as  the  ferment  for 
the  finer  kinds  of  bread.  This  is  the  muci- 
laginous froth  which  rises  to  the  surface 
of  beer  in  its  first  stage  of  fermentation. 
When  it  is  mixed  with  dough,  it  produces 
a  much  more  speedy  and  effectual  ferment- 
ation than  that  obtained  by  leaven,  and  the 
bread  is  accordingly  much  lighter,  and 
scarcely  ever  sour.  The  fermentation  by 
yeast  seems  to  be  almost  certainly  of  the 
vinous  or  spirituous  kind. 

Bread  is  much  more  uniformly  miscible 
with  water  than  dough;  and  on  this  circum- 
stance its  good  qualities  most  probably  do 
in  a  great  measure  depend. 


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A  very  great  number  of  processes  are 
used  by  cooks,  confectioners,  and  others, 
to  make  cakes,  puddings,  and  other  kinds 
of  bread,  in  which  different  qualities  are 
required.  Some  cakes  are  rendered  brittle, 
or  as  it  is  called  short,  by  an  admixture  of 
sugar  or  of  starch.  Another  kind  of  brittle- 
ness  is  given  by  the  addition  of  butter  or 
fat.  White  of  egg-,  gum-water,  isinglass, 
and  other  adhesive  substances,  are  used, 
when  it  is  intended  that  the  effect  of  fer- 
mentation shall  expand  the  dough  into  an 
exceedingly  porous  mass.  Dr.  Percival  has 
recommended  the  addition  of  salep,  or  the 
nuti'itious  powder  of  the  orchis  root.  He 
says,  that  an  ounce  of  salep,  dissolved  in 
a  quart  of  water,  and  mixed  with  two 
pounds  of  flour,  two  ounces  of  yeast,  and 
eighty  grains  of  salt,  produced  a  remark- 
ably good  loaf,  weighing  three  pounds  two 
ounces;  while  a  loaf  made  of  an  equal 
quantity  of  the  other  ingredients,  without 
the  salep,  weighed  but  two  pounds  twelve 
ounces.  If  the  salep  be  in  too  large  quan- 
tity, however,  its  peculiar  taste  will  be  dis- 
tinguishable in  the  bread.  The  farina  of 
potatoes  likewise,  mixed  with  wheaten 
flour,  makes  very  good  bread.  The  reflect- 
ing chemist  will  receive  considerable  in- 
formation on  this  subject  from  an  attentive 
inspection  of  the  receipts  to  be  met  with 
in  treatises  of  cooking  and  confectionary. 

*  Mr.  Accum,  in  his  late  Treatise  on  Cu- 
linary Poisons,  states,  that  the  inferior 
kind'of  flour  which  the  London  bakers  ge- 
nerally use  for  making  loaves,  requires  the 
addition  of  alum  to  give  them  the  white 
appearance  of  bread  made  from  fine  flour. 
"  The  baker's  flour  is  very  often  made  of 
the  worst  kinds  of  damaged  foreign  wheat, 
and  other  cereal  grains  mixed  with  them  in 
grinding  the  wheat  into  flour.  In  this  capital, 
no  fewer  than  six  distinct  kinds  of  wheaten 
flour  are  brought  into  the  market.  They 
are  called  fine  flour,  secondsj  middlings, 
fine  middlings,  coarse  middlings,  and  twen- 
ty-penny flour.  Common  garden  beans  and 
peas  are  also  frequently  ground  up  among 
the  London  bread  flour. 

"  The  smallest  quantity  of  alum  that  can 
be  employed  with  effect  to  produce  a  white, 
light,  and  porous  bread  from  an  inferior 
kind  of  flour,  1  have  my  own  baker's  au- 
thority to  state,  is  from  three  to  four  ounces 
to  a  suck  of  flour  weighing  240  pounds." 

"  The  following  account  of  making  a  sack 
or  five  bushels  of  flour  into  bread,  is  taken 
from  Dr.  P.  Markham's  considerations  on 
the  ingredients  used  in  the  adulteration  of 
flour  and  bread,  p.  21. 

Fiv  bushels  of  flour, 

Eight  ounces  of  alum, 

Four  Ibs.  salt, 

Haifa  gallon  of  yeast  mixed  with  about 

Three  gallons  of  water. 


"Another  substance  employed  by  frau- 
dulent bakers  is  subcarbonate  of  ammonia. 
With  this  salt  they  realize  the  important 
consideration  of  producing  light  and  por- 
ous bread  from  spoiled,  or  what  is  techni- 
cally called  sour  four.  This  salt,  which  be- 
comes wholly  converted  into  a  g'aseous 
substance  during  the  operation  of  baking, 
causes  the  dough  to  swell  up  into  air  bub- 
bles, which  carry  before  them  the  stiff, 
dough,  and  thus  it  renders  the  dough  por- 
ous; the  salt  itself  is  at  the  same  time  to- 
tally volatilized  during  the  operation  of 
baking." — "  Potatoes  are  likewise  largely, 
and  perhaps  constantly  used  by  fraudulent 
bakers,  as  a  cheap  ingredient  to  enhance 

their  profit." "  There   are  instances  of 

convictions  on  record,  of  bakers  having 
used  gypsum,  chalk,  and  pipe-clay,  in  the 
manufacture  of  bread." 

Mr.  E.  Davy,  Prof,  of  Chemistry  at  the 
Cork  Institution,  has  made  experiments, 
showing  that  from  twenty  to  forty  grains 
of  common  carbonate  of  magnesia,  well 
mixed  with  a  pound  of  the  worst  neiv  se- 
conds flour,  materially  improved  the  qua- 
lity of  the  bread  baked  with  it. 

The  habitual  and  daily  introduction  of 
a  portion  of  alum  into  the  human  stomach, 
however  small,  must  be  prejudicial  to  the 
exercise  of  its  functions,  and  particularly 
in  persons  of  a  bilious  and  costive  habit. 
And  besides,  as  the  best  sweet  flour  never 
stands  in  need  of  alum,  the  presence  of 
this  salt  indicates  an  infei'ior  and  highly 
acescent  food;  which  cannot  fail  to  aggra- 
vate dyspepsia,  and  which  may  generate  a 
calculous  diathesis  in  the  urinary  organs. 
Every  precaution  of  science  and  law  ought 
therefore  to  be  employed  to  detect  and 
stop  such  deleterious  adulterations.  Bread 
may  be  analyzed  for  alum  by  crumbling  it 
down  when  somewhat  stale  in  distilled  wa- 
ter, squeezing  the  pasty  mass  through  a 
piece  of  cloth;  and  then  passing  the  liquid 
through  a  paper  filter.  A  limpid  infusion 
will  thus  be  obtained.  It  is  difficult  to  pro- 
cure it  clear  if  we  use  new  bread  or  hot 
water.  A  dilute  solution  of  muriate  of  ba- 
rytes  dropped  into  the  filtered  infusion, 
will  indicate  by  a  white  cloud,  more  or  less 
heavy,  the  presence  and  quantity  of  alum. 
I  find  that  genuine  bread  gives  no  precipi- 
tate by  this  treatment.  The  earthy  adulte- 
rations are  easily  discovered  by  incinerat- 
ing the  bread  at  a  red  heat  in  a  shallow 
earth  vessel,  and  heating  the  residuary 
ashes  with  a  little  nitrate  of  ammonia.  The 
eai-ths  themselves  will  then  remain,  charac- 
terized by  their  whiteness  and  insolubility. 

The  latest  chemical  treatise  en  the  art  of 
making  bread,  except  the  account  given  by 
Mr.  Accum  in  his  work  on  the  adulterations 
of  food,  is  the  article  Baking  in  the  Supple- 
ment to  the  Encyclopaedia  Britannicu,— • -a 


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work  adorned  by  the  dissertations  of  Biot,    within  a  few  periods  to  reduce  the  adulte= 
Brande,  Jeffrey,  Lesley,  Playfair,  and  Stew-    ration  to  one  ounce? 

That  this  voluntary  abstraction  of  -||-  of 
the  alum,  and  substitution  of  superior  and 
more  expensive  flour,  is  not  expected  by 
him  from  the  London  bakers,  is  sufficiently 
evident  from  the  following  story:  It  would 
appear  that  some  of  his  friends  had  invent- 
ed a  new  yeast  for  fermenting  dough  by 
mixing-  a  quart  of  beer  barm  with  a  paste 
made  often  pounds  of  flour  and  two  gal- 
lons of  boiling  water,  and  keeping  this 
mixture  warm  for  six  or  eight  hours. 

"  Yeast  made  in  this  way,'1  says  he,  "  an- 
swers the  purposes  of  the  baker  much  bet- 
ter than  brewer's  yeast,  because  it  is  clear- 
er, and  free  from  the  hop  mixture,  which 
sometimes  injures  the  yeast  of  the  brewer. 
Some  years  ago  the  bakers  of  London,  sen- 
sible of  the  superiority  of  this  artificial 
yeast,  invited  a  company  of  manufacturers 
from  Glasgow  to  establish  a  manufactory 


art 

Under  Process  of  Baking  we  have  the 
following  statement:  "  An  ounce  of  alum  is 
then  dissolved  over  the  fire  in  a  tin  pot,  and 
the  solution  poured  into  a  large  tub,  call- 
ed by  the  bakers  the  seasoning-tub.  Four 
pounds  and  a  half  of  salt  are  likewise  put 
into  the  tub,  and  a  pailful  of  hot  water." 
Note  on  this  passage. — "  In  London,  where 
the  goodness  of  bread  is  estimated  emirely 
by  its  whiteness,  it  is  usual  with  those 
bakers  who  employ  flour  of  an  inferior 
quality  to  add  as  much  alum  as  common 
salt  to  the  dough.  Or  in  other  words,  the 
quantity  of  salt  added  is  diminished  one- 
half,  and  the  deficiency  supplied  by  an 
equal  weight  of  alum.  This  improves  the 
look  of  the  bread  very  much,  rendering  it 
much  whiter  and  firmer." 

In  a  passage  which   we   shall  presently 


quote,  our  author  represents  the  bakers  of    of  it  in  London,  and  promised  to  use   no 

A~    '•      other.  About  5000/.  accordingly  were  laid 

out  on  buildings  and  materials,  and  the 
manufactory  was  begun  on  a  considerable 
scale.  The  ale  brewers,  finding  their  yeast, 
for  which  they  had  drawn  a  good  price,  lie 
heavy  on  their  hands,  invited  all  the  jour- 
neymen bakers  to  their  cellars,  gave  them 
their  full  of  ale,  and  promised  to  regale 
them  in  that  manner  every  day,  provided 
they  would  force  their  masters  to  take  all 
their  yeast  from  the  ale  brewers.  The  jour- 
neymen accordingly  declared  in  a  body, 
that  they  would  work  no  more  for  their 
masters  unless  they  gave  up  taking  any 
more  veast  from  the  new  manufactory.  The 
masters  were  obliged  to  comply;  the  new 
manufactory  was  stopped;  and  the  inhabi- 
tants of  London  -were  obliged  to  continue  to 
eat  ivorse  bread,  because  it  -was  the  interest 
of  the  ale  brewers  to  sell  the  yeast.  Such 
is  the  influence  of  journeymen  bakers  in 
the  metropolis  of  England!" 

This  doleful  diatribe  seems  rather  ex- 
travagant; for  surely  beer-yeast  can  derive 
nothing  noxious  to  a  porter-drinking  peo- 
ple, from  a  slight  impregnation  of  hops] 


London  joined  in  a  conspiracy  to  supply 
the  citizens  with  bad  bread.  We  may  hence 
infer,  that  the  full  allowance  he  assigns  of 
2i  pounds  of  alum  for  every  2$  pounds  of 
salt,  will  be  adopted  in  converting  a  sack 
of  flour  into  loaves.  But  as  a  sack  of  flour 
weighs  280  pounds,  and  furnishes  on  an 
average  80  quartern  loaves,  we  have  2? 

pounds  divided  by  80,  or    = 

197  grains,  for  the  quantity  present  by  this 
writer  in  a  London  quartern  loaf.  Yet  in 
the  very  same  page  (39th  of  volume  2d) 
we  have  the  following  passage:  "Alum  is 
not  added  by  all  bakers.  The  writer  of  this 
article  has  been  assured  by  several  bakers 
of  respectability,  both  in  Edinburgh  and 
Glasgow,  on  whose  testimony  he  relies,  and 
who  made  excellent  bread,  that  they  never 
employed  any  alum.  The  reason  for  ad- 
ding it  given  by  the  London  bakers  is,  that 
it  renders  the  bread  whiter,  and  enables 
them  to  separate  readily  the  loaves  from 
each  other.  This  addition  has  been  alleged 
by  medical  men,  and  is  considered  by  the 
community  at  large  as  injurious  to  the 


health,  by  occasioning  constipation.  But  if  while  it  must  form  probably  a  more  ener 
we  consider  the  small  quantity  of  this  salt  getic  ferment  than  the  fermented  paste  ol 
added  by  the  baker,  not  quite  j$  grains  to  the  new  company,  which  at  any  rate  could 


a  quartern  loaf,  we  will  not  readily  admit 
these  allegations.  Suppose  an  individual  to 
cat  the  seventh  part  of  a  quartern  loaf  a- 
duy,  he  would  only  swallow  eight-tenths  of 
a  grain  of  alum,  or  in  reality  not  quite  so 
much  as  half  a  grain,  for  one-half  of  this 
salt  consists  of  water.  It  seems  absurd  to 


be  prepared  in  six  or  eight  hours  by  an\ 
baker  who  found  it  to  answer  his  purpose 
of  making  a  pleasant  eating  bread.  But  i1 
is  a  very  serious  thing  for  a  lady  or  gentle 
man  of  sedentary  habits,  or  infirm  consti 
tution,  to  have  their  digestive  process  dail] 
itiated  by  damaged  flour,  whitened  wit! 


suppose  that  half  a  grain  of  alum*  swal-  197  grains  of  alum  per  quartern  loaf.  Aci 

lowed  at  different  times  during  the  course  dity    of  stomach,    indigestion,  flatulence 

of  a   day,  should  occasion    constipation."  headaches,    palpitation,    costiveness,    am 

Is  it  not  more  absurd  to  state  2i  pounds,  urinary  calculus,  may  be  the  probable  con 

or  36  ounces,  as  the  alum  adulteration  of  sequences  of  the  habitual   introduction   o 

a  sack  of  flour  by  the  London  bakers,  and  so  much  acidulous  and  acescent  matter. 


BUI 


BRO 


1  have  made  many  experiments  on  bread, 
and  have  found  the  "proportion  of  alum  very 
variable.  Its  quantity  seems  to  be  propor- 
tional to  the  badness  of  the  flour;  and  hence 
when  the  best  flour  is  used,  no  alum  need 
be  introduced.  That  alum  is  not  necessary 
for  giving  bread  its  utmost  beauty,  spongi- 
ness,  and  agreeableness  of  taste,  is  un- 
doubted, since  the  bread  baked  at  the  esta- 
blishment of  Mr.  Harley  of  Willowbank, 
Glasgow,  in  which  about  20  tons  of  flour 
are  converted  into  loaves  in  the  course  of 
a  week,  unites  every  quality  of  appearance, 
with  an  absolute  freedom  from  that  acido- 
astringent  drug.  He  uses  six  pounds  of 
salt  for  every  sack  of  flour;  which  from  its 
good  quality  generally  affords  83  or  84 
quartern  loaves  of  the  legal  weight,  of  four 
pounds  five  ounces  and  a  half  each.  The 
loaves  lose  nine  ounces  in  the  oven.  For  an 
account  of  the  constituents  of  wheat  flour, 
see  WHEAT.* 

BRECCIA.  An  Italian  term,  frequently 
used  by  our  mineralogical  writers  to  de- 
note such  compound  stones  as  are  com- 
posed of  agglutinated  fragments  of  consi- 
derable size.  When  the  agglutinated  parts 
are  rounded,  the  stone  is  called  pudding, 
stone.  Breccias  are  denominated,  according 
to  the  nature  of  their  component  parts. 
Thus  we  have  calcareous  breccia,  or  mar- 
bles, and  siliceous  breccias,  which  are  still 
more  minutely  classed,  according  to  their 
varieties. 

BREWING.  See  BEER,  ALCOHOL,  and 
FERMENTATION. 

BRICK.  Among  the.  numerous  branches 
of  the  general  art  of  fashioning  argillaceous 
earths  into  useful  forms,  and  afterward  har- 
dening them  by  fire,  the  art  of  making 
bricks  and  tiles  is  by  no  means  one  of  the 
least  useful. 

Common  clay  is  scarcely  ever  found  in  n 
state  approaching  to  purity  on  the  surface 
of  the  earth.  It  usually  contains  a  large  pro- 
portion of  siliceous  earth.  Bergmann  exa- 
mined several  clays  in  the  neighbourhood 
of  Upsal,  and  made  bricks,  which  he  baked 
with  various  degrees  of  heat,  suffered  them 
to  cool,  immersed  them  in  water  for  a  con- 
siderable time,  andthen  exposed  them  to  the 
open  air  for  three  years.  They  were  formed 
of  clay  and  sand.  The  hardest  were  those 
into  the  composition  of  which  a  fourth  part 
of  sand  had  entered.  Those  which  had  been 
exposed  for  the  shortest  time  to  the  fire 
were  almost  totally  destroyed,  and  crum- 
bled down  by  the  action  of  the  air;  such 
as  had  been  more  thoroughly  burned  suf- 
fered less  damage;  and  in  those  which  had 
been  formed  of  clay  alone,  and  were  half 
vitrified  by  the  heat,  no  change  whatever 
was  produced. 

On  the  whole  he  observes,  that  the  pro- 
portion of  sand  to  be  used  to  any  clay,  in 


making  bricks,  must  be  greater  the  more 
such  clay  is  found  to  contract  in  burning; 
but  that  the  best  clays  are  those  which  need 
no  sand.  Bricks  should  be  well  burned; 
but  no  vitrification  is  necessary,  when  they 
can  be  rendered  hard  enough  by  the  mere 
action  of  the  heat.  Where  a  vitreous  crust 
might  be  deemed  necessary,  he  recom- 
mends the  projection  of  a  due  quantity  of 
salt  into  the  furnace,  which  would  produce 
the  effect  in  the  same  manner  as  is  seen  in 
the  fabrication  of  the  English  pottery  call- 
ed stone-ware. 

A  kind  of  bricks  called  fire-bricks  are 
made  from  slate-clay,  which  are  very  hard, 
heavy,  and  contain  a  large  proportion  of 
sand.  These  are  chiefly  used  in  the  con- 
struction of  furnaces  for  steam-engines,  or 
other  large  works,  and  in  lining  the  ovens 
of  glass-houses,  as  they  will  stand  any  de- 
gree of  heat.  Indeed  they  should  always  be 
employed  where  fires  of  any  intensity  are 
required. 

"  BRICKS  (FLOATING).  Bricks,  that 
swim  on  water,  were  manufactured  by  the 
ancients;  and  Fabbroni  discovered  some 
years  since  a  substance,  at  Castel  del  Pi- 
ano, near  Santa  Fiora,  between  Tuscany 
and  the  States  of  the  Church,  from  which 
similar  bricks  might  be  made.  It  consti- 
tutes a  brown  earthy  bed,  mixed  with  the 
remains  of  plants.  Haiiv  calls  it  talc  pulve- 
rulent silicifere,  and  Brochant  considers  it 
as  a  variety  of  meerschaum.  The  Germans 
name  it  bergmehl,  (mountain  meal),  and  the 
Italians  latte  di  tuna,  (moon  milk).  By  Klap- 
roth's  analysis,  it  consists  of  79  silica,  5 
alumina,  3  oxide  of  iron,  12  water,  and  1 
loss,  in  100  parts.  It  agrees  nearly  in  com- 
position with  Kieselguhr* 

BRIMSTONE.     See  SULPHUR. 

*  BRIONIA  ABBA.  A  root  used  in  medi- 
cine. By  the  analysis   of  Vauquelin,   it  is 
found  to   consist  in   a   great   measure   of 
starch,  with  a  bitter  principle,   soluble  in 
water  and  alcohol,  some  gum,  a  vegeto- 
animal  matter,   precipitable  by  infusion  of 
galls,  some  woody  fibre,  a  little  sugar,  and 
supermalate  and  phosphate  of  lime.  It  has 
cathartic  powers;  but  is  now  seldom  pre- 
scribed by  physicians.* 

BROCATELLO.  A  calcareous  stone  or 
marble,  composed  of  fragments  of  four  co 
lours,  white,  gray,  yellow,  and  red. 

BRONZE.  A  mixed  metal,  consisting- 
chiefly  of  copper,  with  a  small  proportion 
of  tin,  and  sometimes  other  metals.  It  is 
used  for  casting  statues,  cannon,  bells,  and 
other  articles,  in  all  which  the  proportions 
of  the  ingredients  vary. 

*  BRONZ.ITE.  This  massive  mineral  has 
a  pseudo-metallic  lustre,  frequently  resem- 
bling bronze.    Its  colour  is   intermediate 
between  yellowish-brown  and  pinchbeck- 
brown.  Lustre  shining;  structure  lamellar 


BRU 


BUT 


with  joints,  parallel  to  the  lateral  planes 
of  a  rhomboidal  prism;  the  fragments  are 
streaked  on  the  surface.  It  is  opaque  in 
mass,  but  transparent  in  thin  plates.  White 
streak;  somewhat  hard,  but  easily  broken 
Sp.  grav.  3.2  It  is  composed  of  60  silica, 
27.5  magnesia,  10  5  oxide  of  iron,  and  0.5 
water.  It  is  found  in  large  masses  in  beds 
of  serpentine,  near  Kranbat,  in  Upper  Sti- 
ria;  and  in  a  syenitic  rock  in  Glen  T^lt,  in 
Perthshire.* 

*  BROWN  SPAR.  Pearl  Spar,  or  Sidero- 
calcite.  It  occurs  massive,  and  in  obtuse 
rhomboids  with   curvilinear  faces.  Its  co- 
lours are  white,  red,  and  brown,  or  even 
pearl-gray  and  black.  It  is  found  crystal- 
lized in  flat  and  acute  double  three-sided 
pyramids,  in  oblique  six-sided  pyramids, 
in  lenses  and  rhombs.  It  is  harder  than 
calcareous  spar,  but  yields  to  the  knife. 
Its  external  lustre  is  shining,  and  internal 
pearly.  Sp.  gr.  2.88.  Translucent,  crystals 
semi-transparent;  it  is  easily  broken  into 
rhomboidal  fragments.  It  effervesces  slow- 
ly with  acids.  It  is  composed  of  49.19  car- 
bonate of  lime,  44.39  carbonate  of  magne- 
sia, 3.4  oxide  of  iron,  and  1.5  manganese, 
by  Hisinger's  analysis.  Klaproth  found  32 
carbonate  of   magnesia,  7.5  carbonate  of 
iron,  2  carbonate  of  manganese,  and  51.5 
carbonate  of  lime.  There  is  a  variety  of  this 
mineral  of  a  fibrous  texture,  flesh -red  co- 
lour, and  massive.* 

*  BRUCIA,  or  BRUCINE.  A  new  vegeta- 
ble alkali,  lately  extracted  from  the  bark 
of  the  false  angustura,  or  Jirucea  antidy- 
senterica,  by  M.M.  Pelletier  and  Caventou. 
After  being  treated  with  sulphuric  ether, 
to  get  rid  of  a  fatty  matter,  it  was  subjec- 
ted to  the  action  of  alcohol.  The  dry  resi- 
duum from  the  evaporated  alcoholic  solu- 
tion, was  treated  with  Goulard's  extract, 
or  solution  of  sub-acetate  of  lead,  to  throw 
down  the  colouring  matter,  and  the  excess 
of  lead  was  separated  by  a  current  of  sul- 
phuretted hydrogen.  The  nearly  colourless 
alkaline  liquid  was  saturated  witli  oxalic 
acid,  and  evaporated  to  dryness.  The  sa- 
line mass  being  freed  from  its  remaining 
colouring  particles,  by  absolute   alcohol, 
was  then  decomposed  by  lime  or  magne- 
sia, when   the   brucia  was   disengaged.  It 
was  dissolved  in  boiling  alcohol,  and  ob- 
tained in  crystals,  by  the  slow  evaporation 
of  the  liquid.    These  crystals,  when   ob- 
tained by  very  slow  evaporation,  are  ob- 
lique prisms,  the  bases  of  which  are  par- 
allelograms. When  deposited  from  a  satu- 
rated solution  in  boiling  watt- r,  by  cooling, 
it  is  in  bulky  plates,  somewhat  similar  to 
boracic  acid  in  appearance.    It  is  soluble 
in  500  times  its  weight  of  boiling  water, 
and  in  850  of  cold.  Its  solubility  is  much 
increased  by  the  colouring  matter  of  the 
bark. 


Its  taste  is  exceedingly  bitter,  acrid,  and 
durable  in  the  mouth.  When  administered 
in  doses  of  a  few  grains,  it  is  poisonous, 
acting  on  animals  like  strychnia,  but  much 
less  violently.  It  is  not  affected  by  the  air. 
The  dry  crystals  fuse  at  a  temperature  a 
little  above  that  of  boiling  water,  and  as- 
sume the  appearance  of  wax.  At  a  strong- 
heat,  it  is  resolved  into  carbon,  hydrogen, 
and  oxygen;  without  any  trace  of  azote.  It 
combines  with  the  acids,  and  forms  both 
neutral  and  super-salts.  Sulphate  of  bru- 
cia crystallizes  in  long  slender  needles, 
which  appear  to  be  four-sided  prisms,  ter- 
minated by  pyramids  of  extreme  fineness. 
It  is  very  soluble  in  water,  and  moderately 
in  alcohol.  Its  taste  is  very  bitter.  It  is  de- 
composed by  potash,  soda,  ammonia,  ba- 
rytes,  strontites,  lime,  magnesia,  morphia, 
and  strychnia.  The  bisulphate  crystallizes 
more  readily  than  the  neutral  sulphate. 
The  latter  is  said  to  be  composed  of 
Sulphuric  acid,  8.84  5 

Brucia,  91.16         51.582 

Muriate  of  brucia  forms  in  four-sided 
prisms,  terminated  at  each  end  by  an  ob- 
lique face.  It  is  permanent  in  the  air,  and 
very  soluble  in  water.  It  is  decomposed  by 
sulphuric  acid.  Concentrated  nitric  acid 
destroys  the  alkaline  basis  of  both  these 
salts.  The  muriate  consists  of 

Acid,          5.953          4.575 
Brucia,     94.046        72.5 

Phosphate  of  brucia,  is  a  crystallizable, 
soluble,  and  slightly  efflorescent  salt.  The 
nitrate  forms  a  gummy-looking  mass;  the 
binitrate  crystallizes  in  acicular  four-sided 
prisms.  An  excess  of  nitric  acid  decom- 
poses the  brucia.  into  a  matter  of  a  fine 
red  colour  Acetate  and  oxulate  of  brucia 
both  crystallize.  Brucia  is  insoluble  in  sul- 
phuric ether,  the  fixed  oils,  and  very 
slightly  in  the  volatile  oils.  When  admin- 
istered" internally,  it  produces  tetanus,  and 
acts  upon  the  nerves  without  affecting  the 
brain,  or  the  intellectual  faculties.  Its  in- 
tensity is  to  that  of  strychnia,  as  1  to  12. 
From  the  discrepancies  in  the  prime  num- 
ber for  brucia,  deduced  from  the  above 
analyses,  we  see  that  its  true  equivalent  re- 
mains to  be  determined.  See  Journal  de 
Pharmacie,  Dec.  1819.* 

BRUNSWICK  GREEN.  This  is  an  ammo- 
niaco-muriate  of  copper,  much  used  for 
paper-hangings,  and  on  the  continent  in  oil 
painting.  See  COPPER. 

*  BUNTKUPFERZ.  Purple  copper  ore.* 

BUTTER.  The  oily  inflammable  part  of 
milk,  which  is  prepared  in  many  countries 
as  an  article  of  food.  The  common  mode 
of  preserving  it  is  by  the  addition  of  salt, 
which  will  keep  it  good  a  considerable 
time,  if  iu  sufficient  quantity.  Mr.  Eaton 


CAC 


CAD 


informs"~us,  in  his  Survey  of  the  Turkish 
Empire,  that  most  of  the  butter  used  at 
Constantinople  is  brought  from  the  Crimea 
and  Kirban,  and  that  it  is  kept  sweet,  by 
melting  it  while  fresh  over  a  very  slow  fire, 
and  removing-  the  scum  as  it  rises.  He  adds 
that  by  melting  butter  in  the  Tartarian 
manner,  and  then  salting  it  in  ours,  he  kept 
it  good  and  fine-tasted  for  two  years;  and 
that  this  melting  if  carefully  done,  injures 
neither  the  taste  nor  colour.  Thenard,  too, 
recommends  the  Tartarian  method.  He  di- 
rects the  melting  to  be  done  on  a  water- 
bath,  or  at  a  heat  not  exceeding  180°  F.; 
and  to  be  continued  till  all  the  caseous 
matter  has  subsided  to  the  bottom,  and  the 
butter  is  transparent.  It  is  then  to  be  de- 
canted, or  strained  through  a  cloth,  and 
cooled  in  a  mixture  of  pounded  ice  and 
salt,  or  at  least  in  cold  spring  water,  other- 
wise it  will  become  lumpy  by  crystalliz- 
ing, and  likewise  not  resist  the  action  of 
the  air  so  well.  Kept  in  a  close  vessel,  and 
in  a  cool  place,  it  will  thus  remain  six 
months  or  more,  nearly  as  good  as  at  first, 
particularly  after  the  top  is  taken  off.  If 
beaten  up  with  one-sixth  of  its  weight  of 
\  the  cheesy  matter  when  used,  it  will  in 
some  degree  resemble  fresh  butter  in  ap- 
pearance. The  taste  of  rancid  butter,  he 
adds,  may  be  much  corrected  by  melting 
and  cooling  in  this  manner. 

Dr.  Anderson  has  recommended  another 
mode  of  curing  butter,  which  is  as  follows: 
Take  one  part  of  sugar,  one  of  nitre,  and 
two  of  the  best  Spanish  great  salt,  and  rub 
them  together  into  a  fine  powder.  This 
composition  is  to  be  mixed  thoroughly  with 
the  butter,  as  soon  as  it  is  completely 
freed  from  the  milk  in  the  proportion  of 
one  ounce  to  sixteen;  and  the  butter  thus 
prepared  is  to  be  pressed  tight  into  the 
vessel  prepared  for  it,  so  as  to  leave  no  va- 
cuities. This  butter  does  not  taste  well, 
till  it  has  stood  at  least  a  fortnight;  it  then 
has  a  rich  marrowy  flavour,  that  no  other 
butter  ever  acquires;  and  with  proper  care 
may  be  kept  for  years  in  this  climate,  or 


carried  to  the  East  Indies,  if  packed  so  as 
not  to  melt. 

In  the  interior  parts  of  Africa,  Mr.  Park 
informs  us,  there  is  a  tree  much  resem- 
bling the  American  oak,  producing  a  nut 
in  appearance  somewhat  like  an  olive.  The 
kernel  of  this  nut,  by  boiling  in  water,  af- 
fords a  kind  of  butter,  which  is  whiter, 
firmer,  and  of  a  richer  flavour,  than  any 
he  ever  tasted  made  from  cows'  milk,  and 
will  keep  without  salt  the  whole  year.  The 
natives  call  it  shea  toulout  or  tree  butter. 
Large  quantities  of  it  are  made  every  sea- 
son. 

BUTTER  OP  ANTIMONY.  See  ANTI- 
MONY. 

BUTTER  or  CACAO.  An  oily  concrete 
white  matter,  of  a  firmer  consistence  than 
suet,  obtained  from  the  cacao  nut,  of  which 
chocolate  is  made.  The  method  of  separat- 
ing it  consists  in  bruising  the  cacao  and 
boiling  it  in  water.  The  greater  part  of  the 
superabundant  and  uncombined  oil  contain- 
ed in  the  nut  is  by  this  means  liquefied,  and 
rises  to  the  surface,  where  it  swims  and  is 
left  to  congeal,  that  it  may  be  the  more 
easily  taken  off".  It  is  generally  mixed  with 
small  pieces  of  the  nut,  from  which  it  may 
be  purified,  by  keeping  it  in  fusion  without 
water  in  a  pretty  deep  vessel,  until  the  seve- 
ral matters  have  arranged  themselves  ac- 
cording to  their  specific  gravities.  By  this 
treatment  it  becomes  very  pure  and  white. 

Butter  of  cacao  is  without  smell,  and  has 
a  very  mild  taste,  when  fresh;  and  in  all  its 
general  properties  and  habitudes,  it  resem- 
bles fat  oils;  among  which  it  must  there- 
fore be  classed.  It  is  used  as  an  ingredient 
in  pomatums. 

BUTTER  OF  TIN.     See  TIN. 

*  BYSSOLITE.  A  massive  mineral,  in 
short  and  somewhate  stiff  filaments,  of  an 
olive-green  colour,  implanted  perpendi- 
cularly like  moss,  on  the  surface  of  cer- 
tain stones.  It  has  been  found  at  the  foot 
of  Mount  Blanc,  and  also  near  Oisans-on- 
gneiss.* 


C 


CABBAGE  (RED).  See  BRASSICA.  Ru- 
BRA. 

CACAO  (BUTTER  OF).    SEE  BUTTER. 

*  CACHOLONG.  A  variety  of  quartz.  It 
is  opaque,  dull  on  the  surface,  internally 
of  a  pearly  lustre,  brittle,  with  a  flat  con- 
choidal  fracture,  and  harder  than  opal.  Its 
colour  is  milk-white,  yellowish,  or  grayish- 
white.  It  is  not  fusible  before  the  blow- 
pipe. Its  sp.  grav.  is  about  2.2.  It  is  found 
in  detached  masses  on  the  river  Cach  in 


Bucharia,  in  the  trap-rocks  of  Iceland,  in 
Greenland  and  the  Ferroe  Islands.  Accord- 
ing to  Brongniart,  cacholongs  are  found  also 
at  Champigny  near  Paris,  in  the  cavities  of 
a  calcareous  breccia,  some  of  which  are 
hard  and  have  a  shining  fracture,  while 
others  are  tender,  light,  adhere  to  the 
tongue,  and  resemble  chalk.* 

*  CADMIUM  A  new  metal,  first  disco- 
vered by  M.  Stromeyer,  in  the  autumn  of 
1817,  in  some  carbonate  of  zinc  which  he 


CAD 


CAD 


was  examining  in  Hanover.  It  has  been 
since  found  in  the  Derbyshire  silicates  of 
zinc. 

The  following  is  Dr.  Wollaston's  pro- 
cess  for  procuring  Cadmium.  It  is  distin- 
guished by  the  usual  elegance  and  preci- 
sion of  the  analytical  methods  of  this  phi- 
losopher. From  the  solution  of  the  salt  of 
zinc  supposed  to  contain  cadmium,  pre- 
cipitate all  the  other  metallic  impurities 
by  iron;  filter  and  immerse  a  cylinder  of 
zinc  into  the  clear  solution.  If  cadmium 
be  present,  it  will  be  thrown  down  in 
the  metallic  state,  and  when  redissolved 
in  muriatic  acid,  will  exhibit  its  peculiar 
character  on  the  application  of  the  proper 
tests. 

Mr.  Stromeyer's  process  consists  in  dis- 
solving the  substance  which  contains  cad- 
mium in  sulphuric  acid,  and  passing 
through  the  acidulous  solution  a  current 
of  sulphuretted  hydrogen  gas.  He  washes 
this  precipitate,  dissolves  it  in  concentra- 
ted muriatic  acid,  and  expels  the  excess 
of  acid  by  evaporation.  The  residue  is 
then  dissolved  in  water,  and  precipitated 
by  carbonate  of  ammonia,  of  which  an  ex- 
cess is  added,  to  redissolve  the  zinc  and 
the  copper  that  may  have  been  precipita- 
ted by  the  sulphuretted  hydrogen  gas. 
The  carbonate  of  cadmium  being  well 
washed,  is  heated  to  drive  off  the  carbonic 
acid,  and  the  remaining  oxide  is  reduced 
by  mixing  it  with  lampblack,  and  expos- 
ing it  to  a  moderate  red  heat  in  a  glass  or 
earthen  retort. 

The  colour  of  cadmium  is  a  fine  white, 
with  a  slight  shade  of  bluish  gray,  ap- 
proaching much  to  that  of  tin,  which  me- 
tal it  resembles  in  lustre  and  susceptibility 
of  polish.  Its  texture  is  compact,  and  its 
fracture  hackly.  It  crystallizes  easily  in 
octohedrons,  and  presents  on  its  surface, 
when  cooling,  the  appearance  of  leaves  of 
fern.  It  is  flexible,  and  yields  readily  to 
the  knife.  It  is  harder  and  more  tenacious 
than  tin;  and,  like  it,  stains  paper,  or  the 
fingers.  It  is  ductile  and  malleable,  but 
when  long  hammered,  it  scales  off  in  dif- 
ferent places.  Its  sp.  grav.  before  hammer- 
ing, is  8  6040;  and  when  hammered,  it  is 
8  6944.  It  melts,  and  is  volatilized  under  a 
red  heat.  Its  vapour,  which  has  no  smell, 
may  be  condensed  in  drops  like  mercury, 
which,  on  congealing,  present  distinct 
traces  of  crystallization. 

Cadmium  is  as  little  altered  by  exposure 
to  the  air  as  tin.  When  heated  in  the  open 
air,  it  burns  like  that  metal,  passing  into  a 
smoke,  which  falls  and  forms  a  very  fixed 
oxide,  of  a  brownish-yellow  colour.  Nitric 
acid  readily  dissolves  it  cold;  dilute  sul- 
phuric, muriatic,  and  even  acetic  acids, 
act  feebly  on  it  with  the  disengagement  of 


hydrogen.  The  solutions  are  colourless, 
and  are  not  precipitated  by  water. 

Cadmium  forms  a  single  oxide,  in  which 
100  parts  of  the  metal  are  combined  with 
14.352  of  oxygen.  The  prime  equivalent  of 
cadmium  deduced  from  this  compound 
seems  to  be  very  nearly  7,  and  that  of  the 
oxide  8.  This  oxide  varies  in  its  appear- 
ance according  to  circumstances,  from  a 
brownish-yellow  to  a  dark  brown,  and  even 
a  blackish  colour.  With  charcoal  it  is  re- 
duced with  rapidity  below  a  red  heat.  It 
gives  a  transparent  colourless  glass  bead 
with  borax.  It  is  insoluble  in  water,  but  in 
some  circumstances  forms  a  white  hydrate, 
which  speedily  attracts  carbonic  acid  from 
the  air,  and  gives  out  its  water  when  ex- 
posed to  heat. 

The  fixed  alkalis  do  not  dissolve  the 
oxide  of  cadmium  in  a  sensible  degree;  but 
liquid  ammonia  readily  dissolves  it.  On 
evaporating  the  solution,  the  oxide  falls  in 
a  dense  gelatinous  hydrate.  With  the 
acides  it  forms  salts,  which  are  almost  all 
colourless,  have  a  sharp  metallic  taste,  are 
generally  soluble  in  water,  and  possess  the 
following  characters: 

1.  The  fixed  alkalis  precipitate  the  oxide 
in  the  state  of  a  white  hydrate.  When  add- 
ed in   excess,  they  do  not  redissolve  the 
precipitate,  as  is  the  case  with  the  oxide 
of  zinc. 

2.  Ammonia  likewise  precipitates  the  ox- 
ide white,  and  doubtless  in  the  state  of  hy- 
drate; but  an  excess  of  the  alkali  immedi- 
ately redissolves  the  precipitate. 

3.  The  alkaline  carbonates  produce   a 
white  precipitate,  which  is  an  anhydrous 
carbonate.  Zinc  in  the  same  circumstances 
gives  a  hydrous  carbonate.  The  precipitate 
formed  by  the  carbonate  of  ammonia  is  not 
soluble  in  an  excess  of  this  solution.  Zinc 
exhibits  quite  different  properties. 

4.  Phosphate  of  soda  exhibits  a  white 
pulverulent   precipitate.    The    precipitate 
formed  by  the   same   salt  in  solutions  of 
zinc,  is  in  fine  crystalline  plates. 

5.  Sulphuretted  hydrogen  gas,  and  the 
hydrosulphurets,  precipitate  cadmium  yel- 
low or  orange.  This  precipitate  resembles 
orpiment  a  little  in  colour,  with  which  it 
might  be  confounded  without  sufficient  at- 
tention. But  it  may  be  distinguished  by  be- 
ing  more    pulverulent,  and   precipitating 
more  rapidly.  It  differs  particularly  in  its 
easy  solubility  muriatic  acid,  and  in   its 
fixity. 

6.  Ferroprussiate  of  potash  precipitates 
solutions  of  cadmium  white. 

7.  Nutgalls  do  not  occasion  any  change. 

8.  Zinc  precipitates  cadmium  in  the  me- 
tallic state  in  the  form  of  dendritical  leaves, 
which  attach  themselves  to  the  zinc. 


CAD 


CAF 


The  carbonate  consists,  by  Stromeyer,  of 
Acid,     100.00  25.4  2.750 

Oxide,  292.88  74.6  8.054 

The  sulphate  crystallizes  in  large  rectan- 
gular transparent  prisms,  similar  to  sulphate 
of  zinc,  and  very  soluble  in  water.  It  efflo- 
resces in  the  air.  At  a  strong  red  heat  it 
gives  out  a  portion  of  its  acid,  and  becomes 
a  subsulphate,  which  crystallizes  i«  plates 
that  dissolve  with  difficulty  in  water.  The 
neutral  sulphate  consists  of, 

Acid,     1UO.OO  38.3          5.000 

Oxide,  161.12  61.7  8.056 
100  parts  of  the  salt  takes  34.26  of  water  of 
crystallization.  Nitrate  of  cadmium  crystal- 
lizes in  prisms  or  needles,  usually  grouped 
in  rays.  It  is  deliquescent  Its  constituents 
are, 

Acid,     100.00        46  6.75000 

Oxide,  117.58  54.  7.93665 
100  parts  of  the  dry  salt  take  23.31  water 
«f  crystallization.  The  muriate  of  cadmium 
crystallizes  in  small  rectangular  prisms,  per- 
fectly transparent,  which  effloresce  easily 
when  heated,  and  which  are  very  soluble. 
It  melts  under  a  red  heat,  loses  its  water  of 
•crystallization,  and  on  cooling  assumes  the 
form  of  a  foliated  mass,  which  is  transparent, 
and  has  a  lustre  slightly  metallic  and  pearly. 
In  the  air,  it  speedily  loses  its  transpa- 
rency, and  falls  down  in  a  white  powder.  100 
.parts  effused  chloride  are  composed  of, 
Cadmium,  61.39  7.076 

Chlorine,   38.61  4.450 

Phosphate  of  cadmium  is  pulverulent,  in- 
soluble in  water,  and  melts,  when  heated  to 
redness,  into  a  transparent  vitreous  body. 
It  is  composed  of, 

Acid,     100  3.54 

Oxide,  225.49  8.00 

Borate  of  cadmium  is  scarcely  soluble  in 
water.  It  consists  of, 

Acid,   27.88  3.079 

Oxide,  72. 12  8.000 

Acetate  of  cadmium  crystallizes  in  small 
prisms,  usually  disposed  in  stars,  which  are 
not  altered  by  exposure  to  air,  and  are  very 
soluble  in  water.  The  tartrate  crystallizes 
in  small  scarcely  soluble  needles.  The  oxa- 
late  is  insoluble.  The  citrate  f9rms  a  crys- 
talline powder,  very  little  soluble. 

100  parts  of  cadmium  unite  with  28.172  of 
sulphur,  to  form  a  sulphuret  of  a  yellow  co- 
lour, with  a  shade  of  orange.  It  is  very  fixed 
in  the  h're.  It  melts  at  a  white-red  heat,  and 
on  cooling,  crystallizes  in  micaceous  plates 
of  the  finest  lemon-yellow  colour.  The  sul- 
phuret dissolves  even  cold  in  cowcentrated 
muriatic  acid,  with  the  disengagement  of 
sulphuretted  hydrogen  gas;  but  the  dilute 
acid  has  little  effect  on  it,  even  with  the  as- 
sistance of  heat.  It  is  best  formed  by  heat- 
ing together  a  mixture  of  sulphur  with  the 
oxide,  or  by  precipitating  a  salt  of  cadmium 
with  sulphuretted  hydrogen.  It  promises  to 
be  useful  in  painting. 
VOL.  I. 


Phosphuret  of  cadmium,  made  by  fusing 
the  ingredients  together,  has  a  gray  colour, 
and  a  lustre  feebly  metallic.  Muriatic  acid 
decomposes  it,  evolving  phosphuretted  hy- 
drogen gas.  Iodine  unites  with  cadmium, 
both  in  the  moist  and  dry  way.  We  obtain 
an  iodide  in  large  and  beautiful  hexahedral 
tables.  These  crystals  are  colourless,  trans- 
parent, and  not  altered  by  exposure  to  air. 
Their  lustre  is  pearly,  approaching  to  me- 
tallic. It  melts  with  extreme  facility,  and  as- 
sumes, on  cooling,  the  original  form.  At  a 
high  temperature,  it  is  resolved  into  cadmi- 
um and  iodine.  Water  and  alcohol  dissolve 
it  with  facility.  It  is  composed  of, 

Cadmium,  100.00  8.000 

Iodine,      227.43  18.1984? 

Cadmium  unites  easily  with  most  of  the 
metals,  when  heated  along  with  them  out  of 
contact  of  air  Most  of  its  alloys  are  brittle 
and  colourless.  That  of  copper  and  cad- 
mium is  white,  with  a  slight  tinge  of  yellow. 
Its  texture  is  composed  of  very  fine  plates. 
-1-  of  cadmium  communicates  a  good  deal 

300 

of  brittleness  to  copper.  At  a  strong  heat 
the  cadmium  flies  off.  Tutty  usually  con- 
tains oxide  of  cadmium.  The  alloy  con- 
sists of, 

€opper,    100. 

Cadmium,   84.2 

The  alloy  of  cobalt  and  cadmium  lias  a 
good  deal  of  resemblance  to  arsenical  cobalt. 
Its  colour  is  almost  silver  white.  100  parts 
of  platinum  combine  with  117.3  of  cadmium. 
Cadmium  and  -mercury  readily  unite  cold, 
into  a  fine  silver  white  amalgam,  of  a  granu- 
lar texture,  which  may  be  crvstallized  in  oc- 
tohedrons.  Its  specific  gravity  is  greater 
than  that  of  mercury!  It  fuses  at  167°  F. 
It  consists  of, 

Mercury,    100. 

Cadmium,    27.78 

Dr.  Clarke  found  in  100  gr.  of  the  fibrous 
silicate  of  zinc,  of  Derbyshire,  about  —  of  a 

grain  of  sulphuret  of  cadmium,  a  result 
which  agrees  with  the  experiments  of  Dr. 
Wollaston  and  Mr.  Children.* 

*CAFFEIN.  By  adding  muriate  of  tin  to 
an  infusion  of  unroasted  coffee,  M.  Chenevix 
obtained  a  precipitate,  which  he  washed  and 
decomposed  by  sulphuretted  hydrogen.  The 
supernatant  liquid  contained  a  peculiar  bitter 
principle,  which  occasioned  a  green  precipi- 
tate in  concentrated  solutions  of  iron.  When 
the  liquid  was  evaporated  to  dryness,  it  was 
yellow  and  transparent,  like  horn.  It  did 
not  attract  moisture  from  the  air  but  was 
soluble  in  water  and  alcohol.  The  solution 
had  a  pleasant  bitter  taste,  and  assumed  with 
alkalis  a  garnet-red  colour.  It  is  almost  as 
delicate  a  test  of  iron  as  infusion  of  galls  is; 
yet  gelatin  occasions  no  precipitate  with  it,* 


CAL 


CAL 


CAJEPTTT  On.  The  volatile  oil  obtained 
from  the  leaves  of  the  cajeput  tree.  Caje- 
puta  officinarum,  the  Melaleuca  Leucaden- 
dron  of  Linnaeus.  The  tree  which  furnishes 
the  cajeput  oil  is  frequent  on  the  mountains 
of  Amboyna,  and  other  Molucca  islands.  It 
is  obtained  by  distillation  from  the  dried 
leaves  of  the  smaller  of  two  varieties  It  is 
prepared  in  great  quantities,  especially  in  the 
island  of  Banda.  and  sent  to  Holland  in  cop- 
per flasks.  As  it  comes  to  us,  it  is  of  a  £ reen 
colour,  very  limpid,  lighter  than  water,  of  a 
strong  smell,  resembling  camphor,  and  a 
strong  pungent  taste,  like  that  of  cardamons. 
It  burns  entirely  away,  without  leaving  any 
residuum.  It  is  often  adulterated  with  other 
essential  oils,  coloured  with  the  resin  of  mil- 
foil. In  the  genuine  oil,  the  green  colour 
depends  on  the  presence  of  copper;  for  when 
rectified  it  is  colourless. 

CALAMINE.     A  native  carbonate  of  zinc. 

CALCAUKOUS  EAHTH.     See  LIME. 

*  CALCAnix>uB  SPATI.    Crystallized  carbo- 
nate of  lime.     It  occurs  crystallized  in  more 
than  600  different  forms,  all  having  for  their 
primitive   form    an  obtuse  rhomboid,  with 
angles  of  74°  55'  and  105°  5'.  It  occurs  also 
massive,  and  in  imitative  shapes.     Werner 
has  given  a  comprehensive  idea  of  the  va- 
rieties of  the  crystals,  by  referring  all  the 
forms  to  the  six-sided  pyramid,  the  six-sided 
prism,  and  the  three-sided  prism,  with  their 
truncations.     The  colours  of  culc-spar  are 
gray,  yellow,  red,  green,  and  rarely  blue. 
Vitreous  lustre.     Foliated  fracture,  with  a 
threefold  cleavage.    Fragments  rhomboidal. 
Transparent,  or  translucent.     The  transpa- 
rent crystals  refract  double.     It  is  less  hard 
than  fluor  spar,  and  is  easily  broken    Sp.gr. 
2.  7.  It  consists  of  43.6  carbonic  acid,  and 
56.4  lime.    It  effervesces  powerfully  with 
acids.  Some  varieties  are  phosphorescent  on 
hot  coals     It  is  found  in  veins  in  all  rocks, 
from  granite  to  alluvial  strata,    and   some- 
times in  strata  between  the  beds  of  calcare- 
ous mountains.     The  rarest  and  most  beau- 
tiful crystals  are  found  in  Derbyshire,  but  it 
exists  in  every  part  of  the  world.* 

*  CALCEDONY.     A  mineral  so  called  from 
Calcedon  in  Asia  Minor  where  it  was  found 
in  ancient  times.     There  are  several  sub- 
species: common  calcedony,  heliotrope,  cliry- 
sopruse,  plasma,  onyx,  sard,  and  sardonyx. 

Common  calcedony  occurs  in  various 
shades  of  white,  gray,  yellow,  brown,  green, 
and  blue.  The  blackish-brown  appears,  on 
looking  through  the  mineral,  to  become  a 
blood-red.  It  is  found  in  nodules;  botryoidal, 
staiactitical,  bearing  organic  impressions,  in 
I'eins,  and  also  massive.  Its  fracture  is  even, 
sometimes  flat  conchoidal,  or  fine  splintery. 
Semi-transparent,  harder  and  tougher  than 
flint.  Sp.  grav.  2.6.  It  is  not  fusible.  It 
may  be  regarded  as  pure  silica,  with  a  mi- 
nute portion  of  water.  Very  fine  stulactiti- 
«al  specimens  have  been  found  in  Trevascus 


mine  in  Cornwall.  It  occurs  in  the  toad- 
stone  of  Derbyshire,  in  the  trap  rocks  of 
Fifeshire,  of  the  Pentland-hills,  Mull,  Rum, 
Sky,  and  others  of  the  Scotish  Hebrides; 
likewise  in  Iceland,  and  the  Ferro  Islands. 
See  the  sub-species,  under  their  respective 
titles  * 

*  CALC  SIXTEH.     Staiactitical  carbonate  of 
lime.     It  is  found  in  pendulous  conical  rods 
or  tubes,  mamellated,  mussive,  ana  in  many 
imitative  shapes.     Fracture  lamellar,  or  di- 
vergent  fibrous.     Lustre   silky  or   pearly. 
Colours  white,  of   various  shades,  yellow, 
brown,  rarely  green,  passing  into  blue  or 
red.     Translucent — semihard — Aery  brittle. 
Large  stalactites  are  found  in  the  grotto  of 
Antiparos,  the  woodman's  cave  in  the  Hartz, 
the  cave  of  Auxelle  in  France,  in  the  cave  of 
Castleton  in  Derbyshire,  and  Macalister  cave 
in  Sky.     They  are  continually  forming  by 
the    infiltration  of  carbonated   l-me-water, 
through  the  crevices  of  the  roofs  of  caverns. 
Solid  masses  of  stalactite  have  been  called 
oriental  alabaster.     The  irregular  masses  on 
the  bottoms  of  caves  have  been  called  stal- 
agmites.* 

*  CALCHANTUM.  Pliny's  term  for  copperas.* 
CALCINATION.     The  fixed  residues  of  such 

matters  as  have  undergone  combustion  are 
called  cinders  in  common  language,  and 
calces,  or  now  more  commonly  oxides,  by- 
chemists;  and  the  operation,  when  consider- 
ed with  regard  to  these  residues,  is  termed 
calcination.  In  this  general  way  it  has  like- 
wise been  applied  to  bodies  not  really  com- 
bustible, but  only  deprived  of  some  of  their 
principles  by  heat.  Thus  we  hear  of  the 
calcination  of  chalk,  to  convert  it  into  lime, 
by  driving  off  its  carbonic  acid  and  water; 
of  gypsum  or  plaster  stone,  of  alum,  of  bo- 
rax, and  other  saline  bodies,  by  which  they 
are  deprived  of  their  water  of  crystallization; 
of  bones,  which  lose  their  volatile  parts  by 
this  treatment;  and  of  various  other  bodies. 
See  COMBUSTION  and  OXIDATION. 

*  CALCIUM.    The  metallic  basis  of  lime. 
Sir  H  Davy,  the  discoverer  of  this  metal, 
procured  it  by  the  process  which  he  used  for 
obtaining   barium;  which  see.      It   was   in 
such  small  quantities,    that  little  could  be 
said  concerning   its   nature.      It    appeared 
brighter  and  whiter  than  either  barium  or 
strontium;  and  burned  when  gently  heated, 
producing  dry  lime. 

There  is  only  one  known  combination  of 
calcium  and  oxygen,  which  is  the  important 
substance  called  lime.  The  nature  of  this 
substance  is  proved  by  the  phenomena  of 
the  combustion  of  calcium;  the  metal  chang- 
ing into  the  earth  with  the  absorption  of 
oxygen  gas.  When  the  amalgam  of  cal- 
cium is  thrown  into  water,  hydrogen  gas  is 
disengaged,  and  the  water  becomes  a  solu- 
tion of  lime.  From  the  quantity  of  hydro- 
gen evolved,  compared  with  the  quantity  of 
hme  formed  in  experiments  of  this  kind, 


CAL 


CAL 


M.  Berzelius  endeavoured  to  ascertain  the 
proportion  of  oxygen  in  lime.  The  nature 
of  lime  may  also  be  proved  by  analysis. 
When  potassium  in  vapour  is  sent  through 
the  earth  ignited  to  whiteness,  the  potassium 
was  found  by  Sir  H.  Davy  to  become  pot- 
ash, while  a  dark  gray  substance  of  metallic 
splendour,  which  is  calcium,  either  wholly 
or  partially  deprived  of  oxygen,  is  found  im- 
bedded in  the  potash,  for  it  effervesces  vio- 
lently, and  forms  a  solution  of  lime  by  the 
action  of  water. 

Lime  is  usually  obtained  for  chemical 
purposes,  from  marble  of  the  whitest  kind, 
or  from  calcareous  spar,  by  long  exposure  to 
a  strong  red  heat.  It  is  a  soft  white  sub- 
stance, of  specific  gravity  2.3.  It  requires 
an  intense  degree  of  heat  for  its  fusion;  and 
has  not  hitherto  been  volatilized.  Its  taste 
is  caustic,  astringent  and  alkaline.  It  is  so- 
luble in  450  parts  of  water,  according  to  Sir 
H.  Davy;  and  in  760  parts,  according  to 
other  chemists.  The  solubility  is  not  in- 
creased by  heat.  If  a  little  water  only  be 
sprinkled  on  new  burnt  lime,  it  is  rapidly 
absorbed,  with  the  evolution  of  much  heat 
and  vapour.  This  constitutes  the  phenome- 
non called  slaking.  The  heat  proceeds,  ac- 
cording to  Dr.  Black's  explanation,  from  the 
consolidation  of  the  liquid  water  into  the 
lime,  forming  a  hydrate,  as  slaked  lime  is 
now  called.  It  is  a  compound  of  3.56  parts 
of  lime,  with  1.125  of  water;  or  very  nearly 
3  to  1.  This  water  may  be  expelled  by  a 
red  heat,  and  therefore  does  not  adhere  to 
lime  with  the  same  energy  as  it  does  to  ba- 
rytes  and  strontites.  Lime  water  is  astrin- 
gent and  somewhat  acrid  to  the  taste.  It 
renders  vegetable  blues  green;  the  yellows 
brown;  and  restores  to  reddened  litmus 
its  usual  purple.  When  lime  water  stands 
exposed  to  the  air,  it  gradually  attracts  car- 
bonic acid,  and  becomes  an  insoluble  carbo- 
nate, while  the  water  remains  pure.  If 
lime  water  be  placed  in  a  capsule  under  an 
exhausted  receiver,  which  also  encloses  a 
saucer  filled  with  concentrated  sulphuric 
acid,  the  water  will  be  gradually  withdrawn 
from  the  lime,  which  will  concrete  into 
small  six-sided  prismatic  crystals. 

Berzelius  attempted  to  determine  the 
prime  equivalent  of  calcium,  from  the  pro- 
portion in  which  it  combines  with  oxygen, 
to  form  lime;  but  his  results  can  be  regard- 
ed only  as  approximations,  in  consequence 
of  the  difficulties  of  the  experiment.  The 
prime  equivalent  of  lime,  or  oxide  of  cal- 
cium, can  be  determined  to  rigid  precision, 
by  my  instrument  for  analyzing  the  carbo- 
nates. Ry  this  means,  I  find,  that  100 
parts  of  carbonate  of  lime,  consist  of  43.60 
carbonic  acid  -f-  56.4  lime;  whence  the 
prime  equivalent  proportions  are,  2.75  acid 
4-  3.562  base. 

If  a  piece  of  phosphorus  be  put  into  the 
sealed  end  of  a  glass  tube,  the  middle  part 


of  which  is  filled  with  bits  of  lime  about  the 
size  of  peas;  and  after  the  latter  is  ignited, 
if  the  former  be  driven  through  it  in  vapour, 
heating  the  end  of  the  tube,  a  compound  of 
a  dark  brown  colour,  called  phosphuret  of 
lime,  will  be  formed.  This  probably  consists 
of  1.5  phosphorus  -f-  3.56  lime;  but  it  has 
not  been  exactly  anal}  zed.  When  thrown 
into  water,  phosphuretted  hydrogen  gas  is 
disengaged  in  small  bubbles,' which  explode 
in  succession  as  they  burst. 

Sulphuret  of  lime  is  formed  by  fusing-  the 
constituents  mixed  together  in.  a  covered  cru- 
cible. The  mass  is  reddish  coloured  and  very 
acrid.  It  deliquesces  on  exposure  to  air,  and 
becomes  of  a  greenish-yellow  hue.  When  it 
is  put  into  water,  a  hydrogurei  ted  sulphuret 
of  lime  is  immediately  tormed.  The  same 
liquid  compound  may  be  directly  made,  by 
boiling  a  mixture  of  sulphur  and  lime  in 
water.  It  acts  corrosively  on  animal  bodies, 
and  is  a  powerful  reagent  in  precipitating 
metals  from  their  solutions.  Solid  sulphu- 
ret of  lime  probably  consists  of  2.  sulphur 
+  3.56  lime. 

When  lime  is  heated  strongly  in  contact 
with  chlorine,  oxygen  is  expelled,  and  the 
chlorine  is  absorbed.  For  every  two  parts 
in  volume  of  chlorine  that  disappear,  one 
of  oxygen  is  obtained.  When  liquid  muriate 
of  lime  is  evaporated  to  dryness,  and  ignit- 
ed, it  forms  the  same  substance,  or  chloride 
of  calcium.  It  is  a  semitransparent  crystalline 
substance;  fusible  at  a  strong  red  heat;  a  non- 
conductor of  electricity;  has  a  very  bitter  taste; 
rapidly  absorbs  water  from  the  atmosphere ; 
and  is  extremely  soluble  in  water.  (See  MU- 
RIATIC ACID).  It  consists  of  2.56  calcium  -f- 
4.45  chlorine  =  7.01.  Chlorine  combines  also 
with  oxide  of  calcium  or  lime,  forming  the 
very  important  substance  used  in  bleaching, 
under  the  name  of  oxymuriate.  of  lime;  but 
which  is  more  correctly  called  chloride  of 
lime. 

Several  years  ago  I  performed  a  series  of 
laborious,  and  rather  insalubrious  experi- 
ments, synthetical  and  analytical,  on  chlo- 
ride of  lime;  the  results  of  some  of  which 
were  detailed  in  a  manuscript  essay  on  alka- 
limetry, and  other  subjects  connected  with 
bleaching,  submitted  to  Dr.  Henry  in  1816. 
Having  since  then  been  occupied  in  extend- 
ing my  new  methods  of  chemical  research, 
I  have  delayed  publishing  till  my  plans 
shall  be  completed.  Meanwhile  I  shall  ob- 
serve, that  slaked  lime  absorbs  chlorine  very 
greedily,  though  unslaked  lime,  at  ordinary 
temperatures,  condenses  scarcely  an  appre- 
ciable quantity  of  the  dry  gas.  Under  a 
very  trifling  pressure,  hydrate  of  lime  is  ca- 
pable of  condensing  almost  its  own  weight 
of  chlorine;  or  3.56  lime  -f  1.125  water 
«=  4.685,  combine  with  4.45  chlorine. 
Hence,  it  is  really  a  chloride  of  lime,  and 
not  a  sub-bichlsride,  as  Dr.  Thomson  and 
JMr.  Dalton  have  hastily  inferred  from  con** 


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mercial  samples,  altered  by  carriage  and 
keeping1.  And  indeed,  as  it  is  not  the  in- 
terest of  the  manufacturer  to  make  so  rich 
and  pure  a  compound,  when  he  can  get  the 
market  price  for  what  contains  only  one- 
third  or  one-fourth  the  quantity  of  chlorine, 
it  is  absurd  to  assume  a  commercial  article 
as  the  just  chemical  standard,  or  equivalent 
combination.  In  my  first  set  of  experi- 
ments, I  took  a  certain  weight  of  pure  lime, 
sluiced  it,  and  saturated  it  with  pure  chlofine. 
1  next  ascertained,  by  analysis,  the  propor- 
tion of  lime,  water,  and  chlorine,  that  exist- 
ed in  the  compound.  The  synthesis  and 
analysis  agreed  very  well.  But  the  chloride 
slowly  changes  its  nature  from  the  disen- 
gagement of  oxygen,  by  the  superior  affinity 
of  the  chlorine  for  the  calcium.  Hence,  as 
well  as  from  negligence  or  fraud  in  the  ma- 
nufacture, the  chloride  of  lime  is  always 
mixed  with  more  or  less  of  the  common 
muriate.  For  this  reason,  as  well  as  for 
that  assigned  by  M.  Gay-Lussac,  in  his  ju- 
dicious critique  on  Dr.  Thomson's  paper  on 
oxy muriate  of  lime,  it  is  impossible  to  infer 
the  bleaching  power,  or  to  analyze  it,  by 
using  nitrate  of  silver.  This  test  shows 
ttroflgvii  in  fact,  when  the  power  is  weakest, 
or  when  the  oxymuriate  has  passed  into 
common  muriate,  to  use  the  manufacturer's 
language.  Nor  is  it  possible  to  analyze  the 
chloride  with  any  precision,  by  exposing  it 
to  heat  and  measuring  the  oxygen  expelled; 
because  variable  portions  of  chlorine  are  se- 
parated at  the  same  time,  in  very  uncertain 
states  of  combination.  It  is  difficult  to  con- 
ceive how  a  chemist  of  Dr.  Thomson's  high 
reputation,  should  ever  have  pitched  upon 
nitrate  of  silver  to  analyze  the  mingled  chlo- 
rides of  lime  and  calcium. 

In  performing  the  synthetic  experiment, 
the  hydrate  of  lime  must  be  kept  cool, 
otherwise  the  heat  produced  by  the  chemical 
union,  is  very  apt  to  expel  oxygen  from  the 
lime,  and  generate  some  chloride  of  calcium. 
Mr.  Dalton  advises  the  use  of  solution  of 
copperas,  to  analyze  the  bleaching  powder. 
He  desires  us  to  add  it,  till  all  the  chlorine 
smell  disappears,  and  to  measure  the  quan- 
tity of  copperas  employed.  I  tried  this  me- 
thod, and  was  nearly  killed  by  it.  The  re- 
peated and  careful  application  of  the  nostrils 
to  the  mixture,  and  the  inevitable  inhalation 
of  chlorine,  evolved  by  the  sulphate  ofiron, 
brought  on  a  very  painful  and  dangerous 
affection  of  the  lungs. 

There  is  usually  a  considerable  quantity 
of  unsaturated  lime  in  the  above  powder; 
the  amount  of  which  is  readily  ascertained 
by  digesting  it  in  water,  and  filtering.  It 
may  be  expected,  that  1  should  HOW  give  my 
own  method  of  analysis;  but  the  desire  of  ve- 
rifying it  by  some  further  experiments  of  a 
new  kind  tor  which  I  have  hitherto  wanted 
leisure,  induces  me  to  suppress  it  for  the 
present.  Ujider  LJLME,  gome  observations 


will   be   found   on   the   uses    of  this  sub- 
stance. 

If  the  liquid  hydriodate  of  lime  be  eva- 
porated to  dry  ness,  and  gently  heated,  an 
iodide  of  calcium  remains.  It  has  not  been 
applied  to  any  use.* 

*  CALCTUFF.    An  alluvial  formation  of  car- 
bonate of  lime,  probably  deposited  from  ral- 
careous  springs.    It  has  a  yellowish -gray  co- 
lour; a  dull  lustre  internally;  a  fine  grained 
earthy  fracture;  is  opaque,  and  usually  mark- 
ed with  impressions  of  vegetable  matter.  Its 
specific  gravity  is  nearly  the  same  with  that 
of  water.    It  is  soft,  and  easily  cut  or  bro- 
ken.* 

*  CALCULUS,  or  STONE.     This  name  is  ge- 
nerally given   to  all  hard  concretions,  not 
bony,  formed  in  the  bodies  of  animals.     Of 
these  the  most  important,  as  giving  rise  to 
one  of  the  most  painful  diseases  incident  to 
human  nature,    is  the  urinary   calculus,  or 
stone  in  the  bladder.     Different  substances 
occasionally  enter  into  the   composition  of 
this  calculus,  but  the  most  usual  is  the  lithic 
acid. 

If  we  except  Scheele's  original  observa- 
tion concerning  the  uric  or  lithic  acid,  all 
the  discoveries  relating  to  urinary  concre- 
tions are  due  to  Dr.  \VoIlaston;  discoveries 
so  curious  and  important,  as  alone  are  suffi- 
cient to  entitle  him  to  the  admiration  and 
gratitude  of  mankind.  They  have  been  fully 
verified  by  the  subsequent  researches  of 
MM.  Fourcroy,  Vauquelin,  and  Urande,  Drs. 
Henry,  Marcet,  and  Prout.  Dr.  Marcet,  in 
his  late  valuable  essay  on  the  chemical  his- 
tory and  medical  treatment  of  calculous  dis- 
orders, arranges  the  concretions  into  nine 
species. 

1.  The  lithic  acid  calculus. 

2.  The  ammonia-magnesian  phosphate  cal- 
culus. 

3.  The  bone  earth  calculus,  or  phosphate 
of  lime. 

4.  The  fusible  calculus,  a  mixture  of  the 
2d  and  3d  species. 

5.  The  mulberry  calculus,  or  oxalate  of 
lime. 

6.  The  cystic  calculus;  cystic  oxide  of 
Dr.  Wollaston. 

7.  The  alternating  calculus,  composed  of 
alternate  layers  of  different  species. 

8.  The  compound  calculus,  whose  ingre- 
dients are  so  intimately  mixed,  as  to  be  se- 
parable only  by  chemical  analysis. 

9.  Calculus  from  the  prostate  gland,  which, 
by  Dr.  Wollaston's  researches,  is  proved  to 
be  phosphate  of  lime,  not  distinctly  strati- 
fied, and  tinged  by  the  secretion  of  the  pros- 
tate gland, 

To  the  above  Dr.  Mai-cet  has  added  two 
new  sub-species.  The  first  seems  to  have 
some  resemblance  to  the  cystic  oxide,  but  it 
possesses  also  some  marks  of  distinction.  It 
forms  a  bright  lemon-yellow  residuum  en 
evaporating  its  nitric  aud  solution,  and  is 


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composed  of  laminae.  But  the  cystic  oxide 
is  not  laminated,  and  it  leaves  a  white  resi- 
duum from  the  nitric  acid  solution.  Though 
they  are  both  soluble  in  acids  as  well  as  al- 
kalis, yet  the  oxide  is  more  so  in  acids  than 
the  new  calculus,  which  has  been  called  by 
Dr.  Marcet,  from  its  yellow  residuum,  xanthic 
oxide.  Dr.  Maroet's  other  new  calculus,  was 
found  to  possess  the  properties  of  the  fibrin 
of  the  blood,  of  which  it  seems  to  be  a  depo- 
site.  He  terms  itjibrinous  calculus. 

Species  I.  Uric  acid  calculi.  Dr  Henry 
says,  in  his  instructive  paper  on  urinary  and 
other  morbid  concretions,  read  before  the 
Medical  Society  of  London,  March  2,  1819, 
that  it  has  never  yet  occurred  to  him  to  exa- 
mine calculi  composed  of  this  acid  in  a 
state  of  absolute  purity.  They  contain  about 
9-10ths  of  the  pure  acid,  along  with  urea, 
and  an  animal  matter  which  is  not  gelatin, 
but  of  an  albuminous  nature.  This  must 
not,  however,  be  regarded  as  a  cement.  The 
calculus  is  aggregated  by  the  cohesive  attrac- 
tion of  the  lithic  acid  itself.  The  colour  of 
lithic  acid  calculi  is  yellowish,  or  reddish- 
brown,  resembling  the  appearance  of  wood. 
They  have  commonly  a  smooth  polished  sur- 
face, a  lamellar  or  radiated  structure,  and 
consist  of  fine  particles  well  compacted. 
Their  sp.  gravity  varies  from  1.3  to  1.8. 
They  dissolve  in  alkaline  lixivia,  without 
evolving  an  ammoniacal  odour,  arid  exhale 
the  smell  of  horn  before  the  blow-pipe.  The 
relative  frequency  of  lithic  acid  calculi  will 
be  seen  from  the  following  statement.  Of 
150  examined  by  Mr.  Brunde,  16  were  com- 
posed wholly  of  this  acid,  and  almost  all  con- 
tained more  or  less  of  it.  Fourcroy  and 
Vauquelin  found  it  in  the  greater  number  of 
500  which  they  analyzed.  All  those  exa- 
mined by  Scheele  consisted  of  it  alone;  and 
SOJ  analyzed  by  Dr.  Pearson,  contained  it  in 
greater  or  smaller  proportion.  According 
to  Dr.  Henry's  experience,  it  constitutes  10 
urinary  concretions  out  of  26,  exclusive  of 
the  alternating  calculi.  And  Mr  Brande 
lately  states,  that  out  of  58  cases  of  kidney 
calculi,  51  were  lithic  acid,  6  oxalic,  and  1 
cystic. 

Species  2.  Ammonia-magnesian  phos- 
phate. This  calculus  is  white  like  chalk,  is 
friable  between  the  fingers,  is  often  covered 
with  dog-tooth  crystals,  and  contains  semi- 
orystalline  layers.  It  is  insoluble  in  alkalis, 
but  soluble  in  nitric,  muriatic,  and  acetic 
acids  According  to  Dr.  Henry,  the  earthy 
phosphates,  comprehending  the  2d  and  3d 
species,  were  to  the  whole  number  of  con- 
cretions, in  the  ratio  of  10  to  85.  Mr. 
Brande  justly  observes,  in  the  16tli  number 
of  his  Journal,  that  the  urine  lias  at  all  times 
a  tendency  to  depositethe  triple  phosphate, 
upon  any  body  over  which  it  passer.  Hence 
drains  by  which  urine  is  carried  off',  are  often 
incrusted  with  its  regular  crystals;  and  in 
cases  where  extraneous  bodies  have  got  into 


the  bladder,  they  have  often  in  a  very  shod: 
time  become  considerably  enlarged  by  depo- 
sition of  the  same  substance.  When  this 
calculus,  or  those  incrusted  with  its  semi- 
crystalline  particles  are  strongly  heated  be- 
fore the  blow-pipe,  ammonia  is  evolved,  and 
an  imperfect  fusion  takes  place.  When  a 
little  of  the  calcareous  phosphate  is  present, 
however,  the  concretion  readily  fuses.  Cal- 
culi composed  entirely  of  the  ammonia-mag- 
nesian  phosphate  are  very  rare.  Mr.  Brande 
has  seen  only  two.  They  were  crystallized 
upon  the  surface,  and  their  fracture  was 
somewhat  foliated.  In  its  pure  state,  it  is 
even  rare  as  an  incrustation.  The  powder 
of  the  ammonia-phosphate  calculus  has  a 
brilliant  white  colour,  a  faint  sweetish  taste, 
and  is  somewhat  soluble  in  water.  Four- 
croy  and  Vauquelin  suppose  the  above  depo- 
sites  to  result  from  incipient  putrefaction  of 
urine  in  the  bladder.  It  is  certain  that  the 
triple  phosphate  is  copiously  precipitated 
from  urine  in  such  circumstances  out  of  the 
body. 

Species  3.  The  bone  earth  calculus.  Its 
surface  according  to  Dr.  Wollaston,  is  ge- 
nerally pale  brown,  smooth, and  when  sawed 
through,  it  appears  of  a  laminated  texture, 
easily  separable  into  concentric  crusts.  Some- 
times, also,  each  lamina  is  striated  in  a  di- 
rection perpendicular  to  the  surface,  as  from 
an  assemblage  of  crystalline  needles.  It  is 
difficult  to  tuse  this  calculus  by  the  blow- 
pipe, but  it  dissolves  readily  in  dilute  mu- 
riatic acid,  from  which  it  is  precipitable  by 
ammonia.  This  species,  as  described  by 
Fourcroy  and  Vauquelin,  was  white,  without 
lustre,  friable,  staining  the  hands,  paper,  and 
cloth.  It  had  much  of  a  chalky  appearance, 
and  broke  under  the  forceps,  and  was  inti- 
mately mixed  with  a  gelatinous  matter,  which 
is  left  in  a  membranous  form,  when  the 
earthy  salt  is  withdrawn  by  dilute  muriatic 
acid.  Dr.  Henry  says  that  he  has  never  been 
able  to  recognize  a  calculus  of  pure  phos- 
phate of  lime,  in  any  of  the  collections  which 
he  has  examined;  nor  did  he  ever  find  the 
preceding  species  in  a  pure  state,  though  a 
calculus  in  Mr.  White's  collection  contained 
more  than  90  per  cent  of  ammonia-magne- 
sian  phosphate. 

Species  4.  The  fusible  calculus.  This  is 
a  very  friable  concretion,  of  a  white  colour, 
resembling  chalk  in  appearance  and  texture; 
it  often  breaks  into  layers,  and  exhibits  a 
glittering  appearance  internally,  from  inter- 
mixture of  the  crystals  of  triple  phosphate. 
Sp.  grav.  from  1.14  to  1.47.  Soluble  in 
dilute  muriatic  and  nitric  acids,  but  not  in 
alkaline  lixivia.  The  nucleus  is  generally 
hthic  acid.  In  4  instances  only  out  of  187, 
did  Dr.  Henry  find  the  calculus  composed 
throughout  of  the  earthy  phosphates.  The 
analysis  of  fusible  calculus  is  easily  perform- 
ed by  distilled  vinegar,  wrhich  at  a  gentle 
heat  dissolves  the  ammonia-magnesian  phos- 


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phate,  but  not  the  phosphate  of  lime;  the 
latter  may  be  taken  up  by  dilute  muriatic 
acid.  The  lithic  acid  present  will  remain, 
and  may  be  recognized  by  its  solubility  in 
the  water  of  pure  potash  or  soda.  Or  the 
lithic  acid  may,  in  the  first  instance,  be  re- 
moved by  the  alkali,  which  expels  the  am- 
monia, and  leaves  the  phosphate  of  magne- 
sia and  lime. 

Species  5.  The  mulberry  calculus.  Its 
surface  is  rough  and  tuberculated;  Colour 
deep  reddish-brown.  Sometimes  it  is  pale 
brown,  of  a  crytalline  texture,  and  covered 
with  flat  octohedral  crystals.  This  calculus 
has  commonly  the  density  and  hardness  of 
ivory,  a  sp.  grav.  from  1.4  to  1.98,  and  ex- 
hales the  odour  of  semen  when  sawed.  A 
moderate  red  heat  converts  it  into  carbonate 
of  lime.  It  does  not  dissolve  in  alkaline 
lixivia,  but  slowly  and  with  difficulty  in 
acids.  When  the  oxalate  of  lime  is  voided 
directly  after  leaving  the  kidney,  it  is  of  a 
grayish-brown  colour,  composed  of  small  co- 
hering spherules,  sometimes  with  a  polished 
surface  resembling  hempseed.  They  are 
easily  recognized  by  their  insolubility  in 
muriatic  acid,  and  their  swelling  up  and 
passing  into  pure  lime  before  the  blow-pipe. 
Mulberry  calculi  contain  always  an  admix- 
ture of  other  substances  besides  oxalate  of 
lime.  These  are,  uric  acid,  phosphate  of 
lime,  and  animal  matter  in  dark  flocculi. 
The  colouring  matter  of  these  calculi  is  pro- 
bably effused  blood.  Dr.  Henry  rates  the 
frequency  of  this  species  at  1  in  17  of  the 
whole  which  he  has  compared;  and  out  of 
187  calculi,  he  found  that  17  were  formed 
round  nuclei  of  oxalate  of  lime. 

Species  6.  The  cystic-oxide  calculus.  It 
resembles  a  little  the  triple  phosphate,  or 
more  exactly  magnesian  limestone.  It  is 
somewhat  tough  when  cut,  and  has  a  pecu- 
liar greasy  lustre.  Its  usual  colour  is  pale 
brown,  bordering  on  straw-yellow;  and  its 
texture  is  irregularly  crystalline.  It  unites 
in  solution  with  acids  and  alkalis,  crystal- 
lizing with  both.  Alcohol  precipitates  it 
from  nitric  acid.  It  does  not  become  red 
with  nitric  acid,  and  it  has  no  effect  upon 
vegetable  blues.  Neither  water,  Alcohol,  nor 
ether  dissolves  it.  It  is  decomposed  by  heat 
into  carbonate  of  ammonia  and  oil,  leaving  a 
minute  residuum  of  phosphate  of  lime.  This 
concretion  is  of  very  rare  occurrence.  Dr. 
Henry  states  its  frequency  to  the  whole,  as 
10  to  985.  In  two  which  he  examined,  the 
nucleus  was  the  same  substance  with  the 
rest  of  the  concretion;  and  in  a  third,  the 
mucleus  of  an  uric  acid  calculus  was  a  small 
spherule  of  cystic  oxide.  Hence,  as  Dr. 
Marcet  has  remarked,  this  oxide  appears  to 
be  in  reality  the  production  of  the  kidneys, 
and  not,  as  its  name  would  import,  to  be  ge- 
nerated in  the  bladder.  It  might  be  called 
with  propriety  renal  oxide,  if  its  eminent 
discover  shouJd  think  fit. 


Species  7.  The  alternating  calculus.  The 
surface  of  this  calculus  is  usually  white  like 
chalk,  and  friable  or  semi-crystalline,  accord- 
ing as  the  exterior  coat  is  the  calcareous  or 
ammonia-magnesian  phosphate.  They  are 
frequently  of  a  large  size,  and  contain  a 
nucleus  of  lithic  acid.  Sometimes  the  two 
phosphates  form  alternate  layers  round  the 
nucleus.  The  above  are  the  most  commoa 
alternating  calculi;  next  are  those  of  oxa- 
late of  lime  with  phosphates;  then  oxalate 
of  lime  with  lithic  acid;  and  lastly,  those  in 
which  the  three  substances  alternate.  The 
alternating,  tak.n  all  together,  occur  in  10 
out  of  25,  in  Dr.  Henry's  list;  the  lithic 
acid  with  phosphates  as  10  to  48 ;  the  oxa- 
late of  lime  with  phosphates,  as  10  to  116; 
the  oxalate  of  lime  with  lithic  acid,  as  10  to 
170;  the  oxalate  of  lime,  with  lithic  acid  and 
phosphates,  as  10  to  265. 

Species  8.  The  compound  calculus.  This 
consists  of  a  mixture  of  lithic  acid  with  the 
phosphates  in  variable  proportions,  and  is 
consequently  variable  in  its  appearance. 
Sometimes  the  alternating  layers  are  so  thin 
as  to  be  undistinguishable  by  the  eye,  when 
their  nature  can  be  determined  only  by  che- 
mical analysis.  This  species,  in  Dr.  Henry's 
list,  forms  10  in  235.  About  l-40th  of  the 
calculi  examined  by  Fourcroy  and  Vauque- 
lin  were  compjound. 

Species  9.  has  been  already  described. 

In  almost  all  calculi,  a  central  nucleus 
may  be  discovered,  sufficiently  small  to 
have  descended  through  the  ureters  into 
the  bladder.  The  disease  of  stone  is  to  be 
considered,  therefore,  essentially  and  ori- 
ginally as  belonging  to  the  kidneys.  Its  in- 
crease in  the  bladder  may  be  occasioned, 
either  by  exposure  to  urine  that  contains  an 
excess  of  the  same  ingredient  as  that  com- 
posing the  nucleus,  in  which  case  it  will  be 
unifomrly  constituted  throughout;  or  if  the 
morbid  nucleus  deposite  should  cease,  the 
concretion  will  then  acquire  a  coating  of  the 
earthy  phosphates.  It  becomes,  therefore, 
highly  important  to  ascertain  the  nature  of 
the  most  predominant  nucleus.  Out  of  187 
calculi  examined  by  Dr.  Henry,  17  were 
formed  round  nuclei  of  oxalate  of  lime;  3 
round  nuclei  of  cystic  oxide;  4  round  nuclei 
of  the  earthy  phosphates;  2  round  extra- 
neous substances;  and  in  3  the  nucleus  was 
replaced  by  a  small  cavity,  occasioned  pro- 
bably  by  the  shrinking  of  some  animal  mat- 
ter, round  which  the  ingredients  of  the  cal- 
culi (fusible)  had  been  deposited.  Ran  has- 
shown  by  experiment,  that  pus  may  form  the 
nucleus  of  an  urinary  concretion.  The  re- 
maining 158  calculi  of  Dr.  Henry's  list,  had 
central  nuclei  composed  chiefly  oftithic  acid. 
It  appears  also,  that  in  a  very  great  majority 
of  the  cases  referred  to  by  him,  the  disposi- 
tion to  secrete  an  excess  of  lithie  acid  has 
been  the  essential  cause  of  the  origin  of 
stone.  Hence  it  becomes  a  matter  of  great 


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importance  to  inquire,  what  are  the  circum- 
stances which  contribute  to  its  (  xcessive  pro- 
duction, and  to  ascertain  by  what  plan  of 
diet  and  medicine  this  morbid  action  of  the 
kidneys  may  best  be  obviated  or  removed. 
A  calculus  in  Mr.  White's  collection  had  for 
its  nucleus  a  fragment  of  a  bougie,  that  had 
slipped  into  the  bladder.  It  belonged  to  the 
fusible  species,  consisting  of, 

20  phosphate  of  lime 

60  ammonia-magnesian  phosphate 

JO  lithic  acid 

10  animal  matter 

100 

In  some  instances,  though  these  are  com- 
paratively very  few,  a  morbid  secretion  of 
the  earthy  phosphates  in  excess,  is  the  cause 
of  the  formation  of  stone.  Dr.  Henry  re- 
lates the  case  of  a  gentleman,  who,  during 
parox\sms  of  gravel,  preceded  by  severe 
sickness  and  vomiting,  voided  urine  as 
opaque  as  milk,  which  deposited  a  great 
quantity  of  an  impalpable  powder,  consist- 
ing of  the  calcareous  and  triple  phosphate 
in  nearly  equal  proportions.  The  weight 
of  the  body  was  rapidly  reduced  from  188 
to  100  pounds,  apparently  by  the  abstrac- 
tion of  the  earth  of  his  bones;  for  there  was 
no  emaciation  of  the  muscles  corresponding 
to  the  above  diminution. 

The  first  rational  views  on  the  treatment 
of  calculous  disorders,  were  given  by  Dr. 
"Wollaston.  These  1m  e  been  followed  up 
lately  by  some  very  judicious  observations  of 
Mr.  Brande,  in  the  12th,  15th,  aud  16th 
numbers  of  his  Journal;  and  also  by  Dr. 
Marcet,  in  his  excellent  treatise  already  re- 
ferred to.  Of  the  many  substances  con- 
tained in  human  urine,  there  are  rarely 
more  than  three  which  constitute  gravel; 
viz.  calcareous  phosphate,  ammonia-magne- 
sian phosphate,  and  lithic  acid.  The  for- 
mer two  form  a  white  sediment;  the  latter 
a  red  or  brown.  The  urine  is  always  an 
acidulous  secretion.  Since  by  this  excess  of 
acid,  the  earthy  salts,  or  white  matter,  are 
heid  in  solution,  whatever  disorder  of  the 
system,  or  impropriety  of  food  and  medicine, 
diminishes  that  acid  excess,  favours  the  for- 
mation of  white  deposite.  The  internal  use 
of  acids  was  shown  by  Dr.  Wollaston,  to  be 
the  appropriate  remedy  in  this  case. 

White  gravel  is  frequently  symptomatic 
of  disordered  digestion,  arising  from  excess 
in  eating  or  drinking;  and  it  is  often  pro- 
duced by  too  farinaceous  a  diet.  It  is  also 
occasioned  by  the  indiscreet  use  of  magnesia, 
sociu  water,  or  alkaline  medicines  in  general. 
Medical  practitioners,  as  well  as  their  pa- 
tients, ignorant  of  chemistry,  have  often 
committed  fatal  mistakes,  by  considering 
the  white  gravel,  passed  on  the  administra- 
tion of  alkaline  medicines,  as  the  dissolution 
of  the  calculus  itself;  and  have  hence  push- 
-ed  a  practice,  which  has  rapidly  increased 


the  size  of  the  stone.  Magnesia,  in  many 
cases,  acts  more  injuriously  than  alkali,  in 
precipitating  insoluble  phosphate  from  the 
urine.  The  acids  of  urine,  which,  by  their 
excess,  hold  the  earths  in  solution,  are  the 
phosphoric,  lithic,  and  carbonic.  Mr.  Brande 
has  uniformly  obtained  the  latter  acid,  by 
placing  urine  under  an  exhausted  receiver; 
and  he  has  formed  carbonate  of  barytes, 
by  dropping  barytes  water  into  urine  re- 
cently voided. 

The  appearance  of  white  sand  does  not 
seem  deserving  of  much  attention,  where  it 
is  merely  occasional,  following  indigestion 
brought  on  by  an  accidental  excess.  But  if 
it  invariably  follows  meals,  and  if  it  be  ob- 
served in  the  urine,  not  as  a  mere  deposite, 
but  at  the  time  the  last  drops  are  voided,  it 
becomes  a  matter  ot  importance,  as  the  fore- 
runner of  other  and  serious  forms  of  the  dis 
order.  It  has  been  sometimes  viewed  as  the 
effect  of  irritable  bladder,  where  it  was  in 
reality  the  cause.  Acids  are  the  proper 
remed} ,  and  unless  some  peculiar  tonic  effect 
be  sought  for  in  sulphuric  acid,  the  vegeta- 
ble acids  ought  to  be  preferred.  Tartar,  or 
its  acid,  may  be  prescribed  with  advantage, 
but  the  best  medicine  is  citric  acid,  in  daily 
doses  of  from  5  to  30  grains.  Persons  re- 
turning from  warm  climates,  with  dyspeptic 
and  hepatic  disorders,  often  void  this  white 
gravel,  for  which  they  have  recourse  to  em- 
pyrical  solvents,  for  the  most  part  alkaline, 
and  are  deeply  injured.  They  ought  to  adopt 
an  acidulous  diet,  abstaining  from  soda  water, 
alkalis,  malt  liquor,  madeira  and  port;  to  eat 
salads  with  acid  fruits;  and  if  habit  requires 
it,  a  glass  of  cyder,  champagne  or  claret,  but 
the  less  of  these  fermented  liquors  the  better. 
An  effervescing  draught  is  often  very  bene- 
ficial, made  by  dissolving  30  grains  of  bi- 
carbonate of  potash,  and  20  of  citric  acid,  in 
separate  tea  cups  of  water,  mixing  the  solu- 
tion in  a  large  tumbler,  and  drinking  the 
whole  during  the  effervescence.  This  dose 
may  be  repeated  3  or  4  times  a-day.  The  car- 
bonic acid  of  the  above  medicine  enters  the 
circulation,  and  passing  off  by  the  bladder,  is 
useful  in  retaining,  particularly,  the  triple 
phosphate  in  solution,  as  was  first  pointed  out 
by  Dr.  Wollaston.  The  bowels  should  be  kept 
regular  by  medicine  and  moderate  exercise. 
The  febrile  affections  of  children  are  fre- 
quently attended  by  an  apparently  formida- 
ble deposite  of  white  sand  in  the  urine.  A 
dose  of  calomel  will  generally  carry  off  both 
the  fever  and  the  sand.  Air,  exercise,  bark, 
bitters,  mineral  tonics,  are  in  like  manner 
often  successful  in  removing  the  urinary 
complaints  of  grown  up  persons. 

In  considering  the  red  gravel,  it  is  neces- 
sary to  distinguish  between  those  cases  in 
which  the  sand  is  actually  voided,  and  those 
in  which  it  is  deposited,  after  some  hours, 
from  originally  limpid  urine.  In  the  first, 
the  sabulous  appearance  is  an  alarming  in- 


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dication  of  a  tendency  to  form  calculi;  in  the 
second,  it  is  often  merely  a  fleeting  symp- 
tom of  indigestion.  Should  it  frequently  re- 
cur, however,  it  is  not  to  be  disregarded. 

Bicarbonate  of  potash  or  soda  is  the  pro- 
per remedy  for  the  red  sancL  or  lithic  acid 
deposite.  The  alkali  may  often  be  benefi- 
cially combined  with  opium  Ammonia,  or 
its  crystallized  carbonate,  may  be  resorted  to 
with  advantage,  where  symptoms  of  indiges- 
tion are  brought  on  by  the  other  alkalis; 
and  particularly  in  red  gravel  connected 
with  gout;  in  which  the  joints  and  kidneys 
are  affected  by  turns.  Where  potash  and 
soda  have  been  so  long  employed  as  to  dis- 
agree with  the  stomach,  to  create  nausea, 
flatulency,  a  sense  of  weight,  pain  and  other 
symptoms  of  indigestion,  magnesia  may  be 
prescribed  with  the  best  effects.  The  ten- 
dency which  it  has  to  accumulate  in  danger- 
ous quantities  in  the  intestines,  and  to  form 
a  white  sediment  in  urine,  calls  on  the  prac- 
titioner to  look  minutely  after  its  adminis- 
tration. It  should  be  occasionally  alternatrd 
"With  other  laxative  medicines.  Magnesia 
dissolved  in  carbonic  acid,  as  Mr.  Scheweppe 
used  to  prepare  it  many  years  ago,  by  the 
direction  of  Mr.  Brande,  is  an  elegant  form 
of  exhibiting  this  remedy. 

Care  must  be  had  not  to  push  the  alkaline 
medicines  too  far,  lest  they  give  rise  to  the 
deposition  of  earthy  phosphates  in  the  urine. 
Cases  occur  in  which  the  sabulous  depo- 
site consists  of  a  mixture  of  lithic  acid  with 
the  phosphates.  The  sediment  of  urine  in 
inflammatory  disorders  is  sometimes  of  this 
nature;  and  of  those  persons  who  habitually 
indulge  in  excess  of  wine;  and  also  of  those 
who,  labouring  under  hepatic  affections,  se- 
crete much  albumen  in  their  urine.  Purges, 
tonics,  and  nitric  acid,  which  is  the  solvent 
«f  both  the  above  sabulous  matters,  are  the 
appropriate  remedies.  The  best  diet  for  pa- 
tients labouring  under  the  lithic  deposite,  is 
a  vegetable.  Dr.  Wollaston's  fine  observa- 
tion, that  the  excrement  of  birds  fed  solely 
upon  animal  matter,  is  in  a  great  measure 
lithic  acid,  and  the  curious  fact  since  ascer- 
tained, that  the  excrement  of  the  boa  con- 
strictor, fed  also  entirely  on  animals,  is  pure 
lithic  acid,  concur  in  giving  force  to  the 
above  dietetic  prescription.  A  week's  ab- 
stinence from  animal  food  has  been  known 
to  relieve  a  fit  of  lithic  acid  gravel,  where 
the  alkalis  were  of  little  avail.  But  we  must 
not  carry  the  vegetable  system  so  far  as  to 
produce  flatulency  and  indigestion. 

Such  are  the  principal  circumstances  con- 
nected with  the  disease  of  gravel  in  its  inci- 
pient or  sabulous  state.  The  calculi  formed 
in  the  kidneys  are,  as  we  have  said  above, 
either  lithic,  oxalic,  or  cystic;  and  very  rare- 
ly indeed  of  the  phosphate  species.  An 
aqueous  regimen,  moderate  exercise  on 
horseback  when  not  accompanied  with  much 
irritation,  cold  bathing,  and  mild  aperients, 


along  with  the  appropriate  chemical  medi- 
cines, must  be  prescribed  in  kidney  cases. 
These  are  particularly  requisite  immediately 
after  acute  pain  in  the  region  of  the  ureter, 
and  inflammatory  symptoms  have  led  to  the 
belief  that  a  nucleus  lias  descended  into  the 
bladder.  Purges,  diuretics,  and  diluents, 
ought  to  be  liberally  enjoined.  A  large 
quantity  of  mucus  streaked  with  blood,  or  of 
a  purulent  aspect,  and  iiaemorrhagy,  are 
frequent  symptoms  ot  the  passage  of  the 
stone  into  the  bladder 

When  a  stone  has  once  lodged  in  the 
bladder,  and  increased  there  to  such  a  size 
as  no  longer  to  be  capable  of  passing  thro;  ,;h 
the  urethra,  it  is  generally  allowed,  by  all 
who  have  candidly  considered  the  subject, 
and  who  are  qualified  by  experience  to  be 
judges,  that  the  stone  can  never  again  be 
dissolved;  and  although  ic  is  possible  that  it 
may  become  so  loosened  in  its  texture,  as  to 
be  voided  piecemeal,  or  gradually  to  crumble 
away,  the  event  is  so  rare  as  to  be  barely 
probable. 

By  examining  collections  of  calculi  we 
learn,  that  in  by  far  the  greater  number  of 
cases,  a  nucleus  of  lithic  acid  is  enveloped 
in  a  crust  of  the  phosphates.  Our  endea- 
vours must  therefore  be  directed  towards  re- 
ducing the  excess  of  lithic  acid  in  the  urine 
to  its  natural  standard;  or,  on  tiie  other 
hand,  to  lessen  the  tendency  to  the  deposition 
of  the  phosphates.  The  urine  must  be  sub- 
mitted to  chemical  examination,  and  a  suit- 
able course  of  diet  and  medicines  prescribed. 
But  the  chemical  remedies  must  be  regu- 
lated nicely,  so  as  to  hit  the  happy  equili- 
brium, in  which  no  deposite  will  be  formed. 
Here  is  a  powerful  call  on  the  physicians 
and  surgeons  to  make  themselves  thoroughly 
versant  m  chemical  science;  for  they  will 
otherwise  commit  the  most  dangerous  blun- 
ders in  calculous  complaints. 

"  The  idea  of  dissolving  a  calculus  of 
uric  acid  in  the  bladder  by  the  internal  use 
of  the  caustic  alkalis,"  says  Mr.  Brande, 
"  appears  too  absurd  to  merit  serious  refuta- 
tion." In  respect  to  the  phosphates,  it  seems 
possible,  by  keeping  up  an  unusual  acidity 
in  the  urine,  so  tar  to  soften  a  crust  of  the 
calculus,  as  to  make  it  crumble  down,  or  ad- 
mit of  being  abraded  by  the  sound;  but  this 
is  the  utmost  that  can  be  looked  for;  and 
the  lithic  nucleus  will  still  remain.  « 1'hese 
considerations,"  adds  Mr.  Brande,  "  inde- 
pendent of  more  urgent  reasons,  show  the 
futility  of  attempting  the  solution  of  a  stone 
of  the  bladder  by  the  injection  of  acid  and 
alkaline  solutions.  In  respect  to  the  alkalis, 
if  sufficiently  strong  to  act  upon  the  uric 
crust  of  the  calculus,  they  would  certainly 
injure  the  coats  of  the  bladder;  thev  would 
otherwise  become  inactive  by  combination 
with  the  acids  of  the  urine,  and  they  would 
form  a  dangerous  precipitate  from  the  same 
cause." — "  it  therefore  appears  to  me,  that 


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Foiircroy,  and  others  who  have  advised  the 
J>lan  of  injection,  have  thought  little  of  all 
these  obstacles  to  success,  and  have  regarded 
the  bladder  as  a  lifeless  receptacle  into  which, 
.as  into  an  India  rubber  bottle,  almost  any 
solvent  might  be  injected  with  impunity." — 
Jvurnal  of  Science,  vol.  vii,  p.  216. 

1  have  judged  it  an  imperative  duty  to  in- 
sert the  above  cautions,  from  an  eminent 
chemist  who  has  studied  this  subject  in  its 
medical  relations,  lest  the  medical  student, 
misled  by  Dr.  Thomson's  favourable  tran- 
script of  the  injection  scheme,  might  be  hur- 
ried into  very  dangerous  practice. 

ft  does  not  appear  that  the  peculiarities  of 
water  in  different  districts,  have  any  influence 
upon  the  production  of  calculous  disorders. 
Dr.  Wollaston's  discovery  of  the  analogy  be- 
tween urinary  and  gouty  concretions,  has 
led  to  the  trial  m  gravel  of  the  vinum  c'ilchi- 
<"/,  the  specific  for  gout.  Bv  a  note  to  Mr. 
Brando's  dissertution  we  learn,  that  benefit 
has  bten  derived  from  it  in  a  case  of  red 
gravel. 

Dr  Henry  confirms  the  above  precepts  in 
the  following  decided  language.  "  These 
cases,  and  others  of  the  same  kind,  which  I 
think  it  unnecessary  to  mention,  tend  to  dis- 
courage all  attempts  to  dissolve  a  stone  sup- 
posed to  consis*  of  uric  acid,  after  it  has  at- 
tained considerable  size  in  the  bladder;  all 
that  can  be  effected  under  such  circum- 
stances by  alkaline  medicines  appears,  as  Mr. 
Brande  has  remarked,  to  be  the  precipitating 
upon  it  a  coating  of  the  earthy  phosphates 
from  the  urine,  a  sort  of  concretion  which, 
as  has  been  observed  by  various  practical 
writers,  increases  much  more  rapidly  than 
that  consisting  of  uric  acid  only.  The  same 
unfavourable  inference  may  be  drawn  also 
from  the  dissections  of  those  persons  in  whom 
a  stone  was  supposed  to  be  dissolved  by  al- 
kaline medicines;  for  in  these  instances  it  has 
been  found  either  encysted,  or  placed  out  of 
the  reach  of  the  sound  by  an  enlargement  of 
the  prostate  gland.* 

The  urinary  calculus  of  a  dog,  examined 
by  Dr.  Pearson,  was  found  to  consist  princi- 
pally of  the  phosphates  of  lime  and  ammo- 
nia, with  animal  matter.  Several  taken 
from  horses,  were  of  a  similar  composition. 
One  of  a  rabbit  consisted  chiefly  of  carbo- 
nate of  lime  and  animal  matter,  with  perhaps 
a  little  phosphoric  acid.  A  quantity  of  sabu- 
lous matter,  neither  crystallized  nor  con- 
crete, is  sometimes  found  in  the  bladder  of 
the  horse:  in  one  instance  there  were  nearly 
45  pounds.  These  appear  to  consist  of  car- 
bonate of  lime  and  animal  matter.  A  cal- 
culus of  a  cat  gave  Fourcroy  three  parts  of 
carbonate,  and  one  of  phosphate  of  lime. 
That  of  a  pig,  according  to  Bertholdi,  was 
phosphate  of  lime. 

The  renal  calculus  in  man  appears  to  be 
of  the  same  nature  as  the  urinary.     In  that 
of  the  horse,  Fourcroy  fftflnd  3  parts  of  car- 
VOL.  I. 


bonate,  and  one  of  phosphate  of  lime.  Dir,. 
Pearson,  in  one  instance,  carbonate  of  lime, 
and  animal  matter;  in  two  others,  phos- 
phates of  lime  and  ammonia,  with  animal 
matter. 

Arthritic  calculi,  or  those  formed  in  the 
joints  of  gouty  persons,  were  once  supposed 
to  be  carbonate  of  lime,  whence  they  were 
called  chalkstones;  afterward  it  was  sup- 
posed that  they  were  phosphate  of  lime; 
but  Dr.  Wollaston  has  shown,  that  they  are 
lithate  of  soda.  The  calculi  found  some- 
times in  the  pineal,  prostate,  salivary,  and 
bronchial  glands,  in  the  pancreas,  in  the  cor- 
pora cavernosa  penis,  and  between  the  mus- 
cles, as  well  as  the  tartar,  as  it  is  called,  that 
encrusts  the  teeth,  appear  to  be  phosphate 
of  lime.  Dr.  Grompton,  however,  examined 
a  calculus  taken  from  the  lungs  of  a  de- 
ceased soldier,  which  consisted  of  lime  45, 
carbonic  acid  37,  albumen  and  water  18.  It 
was  very  hard,  irregularly  spheroidal,  and 
measured  about  6^  inches  in  circumfer- 
ence. 

For  the  biliary  calculi,  see  GALL.  Those 
called  bezoars  have  been  already  noticed  un- 
der that  article.  . 

It  has  been  observed,  that  the  lithic  acid, 
which  constitutes  the  chief  part  of  most  hu- 
man urinary  calculi,  and  abounds  in  the  arth- 
ritic, has  been  found  in  no  phytivorous  ani- 
mal; and  hence  has  been  deduced  a  practi- 
cal inference,  that  abstinence  from  animal 
food  would  prevent  their  formation.  But  we 
are  inclined  to  think  this  conclusion  too  has- 
ty. The  cat  is  carnivorous;  but  it  appeared 
above,  that  the  calculus  of  that  animal  is 
equally  destitute  of  lithic  acid.  If,  therefore, 
we  would  form  any  deduction  with  respect 
to  regimen,  we  must  look  for  something  used 
by  man,  exclusively  of  all  other  animals;  and 
this  is  obviously  found  in  fermented  liquors, 
but  apparently  in  nothing  else:  and  this  prac- 
tical inference  is  sanctioned  by  the  most  re- 
spectable medical  authorities. 

Ox  CALOUIC.    By  Dr.  Ure. 

*  CALORIC.  The  Agent  to  which  the  phe- 
nomena of  heat  and  combustion  are  ascribed. 
This  is  hypothetically  regarded  as  a  fluid, 
of  inappreciable  tenuity,  whose  particles  are 
endowed  with  indefinite  idio-repulsive  pow- 
ers, and  which  by  their  distribution  in  various 
proportions  among  the  particles  of  pondera- 
ble matter,  modify  cohesive  attraction,  giv- 
ing birth  to  the  three  general  forms  of  ga- 
seous, liquid,  and  solid. 

Many  eminent  philosophers,  however,  have 
doubted  the  separate  entity  of  a  calorific  mat- 
ter, and  have  adduced  evidence  to  show  that 
the^hejiomena  might  be  rather  referred  to 
a  vibratory  or  intestinal  motion  of  the  par- 
ticles of  common  matter.  The  most  distin- 
guished advocate  of  this  opinion  in  modern 
times  is  Sir  H.  Davy,  the  usual  justness  ami 
28 


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profundity  of  whose  views  entitle  them  to 
deference.  The  following  sketch  of  his  ideas 
on  this  intricate  subject,  though  it  graduates 
perhaps  info  the  poetry  of  science,  cannot 
jail  to  increase  our  admiration  of  his  genius, 
and  to  inculcate  moderation  on  the  partisans 
of  the  opposite  doctrine. 

*<  Calorific  repulsion  has  been  accounted 
for  by  supposing1  a  subtile  fluid  capable  of 
combining  with  bodies,  and  of  separating 
their  parts  from  each  other,  which  ha»  been 
named  the  matter  of  heat  or  caloric- 

"  Many  of  the  phenomena  admit  of  a  hap- 
py explanation  on  this  idea,  such  as  the  cold 
produced  during  the  conversion  of  solids 
into  fluids  or  gases,  and  the  increase  of  tem- 
perature connected  with  the  condensation  of 
gases  and  fluids."  In  the  former  case  we 
say  the  matter  of  heat  is  absorbed  or  com- 
bined;  ii\  the  latter  it  is  extruded  or  disen- 
gaged from  combination.  "  But  there  are 
ether  facts  which  are  not  so  easily  reconciled 
to  the  opinion.  Such  are  the  production  of 
heat  by  friction  and  percussion;  and  some 
of  the  chemical  changes  which  have  been 
just  referred  to."  These  are  the  violent  heat 
produced  in  the  explosion  of  gunpowder, 
where  a  large  quantity  of  aeriform  matter  is 
disengaged;  and  the  fire  which  appears  in 
the  decomposition  of  the  euchlorine  gas,  or 
protoxide  of  chlorine,  though  the  resulting 
gases  occupy  a  greater  volume. 

"  When  the  temperature  of  bodies  is  raised 
by  friction,  there  seems  to  be  no  diminution 
of  their  capacities,  using  the  word  in  its  com- 
mon sense;  and  in  many  chemical  changes, 
connected  with  an  increase  of  temperature, 
there  appears  to  be  likewise  an  increase  of 
capacity.  A  piece  of  iron  made  red-hot  by 
hammering,  cannot  be  strongly  heated  a  se- 
cond time  by  the  same  means,  unless  it  has 
been  previously  introduced  into  a  fire.  This 
fact  has  been  explained  by  supposing  that 
the  fluid  of  heat  has  been  pressed  out  of  it, 
by  the  percussion,  which  is  recovered  in  the 
fire;  but  this  is  a  very  rude  mechanical  idea: 
the  arrangements  of  its  parts  are  altered  by 
hammering  in  this  way,  and  it  is  rendered 
brittle.  By  a  moderate  degree  of  friction, 
as  would  appear  from  Rumford's  experi- 
ments, the  same  piece  of  metal  may  be  kept 
hot  for  any  length  of  time;  so  that,  if  heat  be 
•pressed  out,  the  quantity  must  be  inexhaust- 
ible. When  any  body  is  cooled,  it  occupies 
a  smaller  volume  than  before;  it  is  evident 
therefore  that  its  parts  must  have  approached 
to  each  other;  when  the  body  is  expanded 
by  heat,  it  is  equally  evident  that  its  parts 
inust  have  separated"  from  each  other.  The 
immediate  cause  of  the  phenomena  of  heat, 
then,  is  motion,  and  the  laws  of  its  commu- 
nication are  precisely  the  same  as  the  bjws 
of  the  communication  of  motion."  Since  all 
matter  may  be  made  to  fill  a  smaller  volume 
by  cooling,  it  is  evident  that  the  particles  of 
^flatter  must  have  space  between  themj  and 


since  every  body  can  communicate  the  pow- 
er of  expansion  to  a  body  of  a  lower  tempe- 
rature, that  is,  can  give"  an  expansive  mo- 
tion to  its  particles,  it  is  a  probable  infer- 
ence that  its  own  particles  are  possessed  of 
motion;  but  as  there  is  no  change  in  the  po- 
sition of  its  parts  as  long  as  its  temperature 
is  uniform,  the  motion,  if  it  exist,  must  be  a 
vibratory  or  undulatory  motion,  or  a  motion 
of  the  particles  round  their  axes,  or  a  mo- 
tion of  particles  round  each  other. 

"  It  seems  possible  to  account  for  all  the 
phenomena  of  heat,  if  it  be  supposed  that  in 
solids  the  particles  are  in  a  constant  state  of 
vibratory  motion,  the  particles  of  the  hottest 
bodies  moving  with  the  greatest  velocity, 
and  through  the  greatest  space;  that  in  li- 
quids and  elastic  fluids,  besides  the  vibratory 
motion,  which  must  be  conceived  greatest 
in  the  last,  the  particles  have  a  motion  round 
their  own  axes,  with  different  velocities,  the 
particles  of  elastic  fluids  moving  with  the 
greatest  quickness;  and  that  in  ethereal  sub- 
stances," the  particles  move  round  their  own 
axes,  and  separate  from  each  other,  penet ra- 
ting in  right  lines  through  space.  Tempe- 
rature maybe  conceived  to  depend  upon  the 
velocities  of  the  vibrations;  increase  of  capa- 
city on  the  motion  being  performed  in  great- 
er space  ;and  the  diminution  of  temperature, 
during  the  conversion  of  solids  into  flu  ids  or 
gases,  may  be  explained  on  the  idea  of  (he 
loss  of  vibratory  motion,  in  consequence  of 
the  revolution  of  particles  round  their  axes, 
at  the  moment  when  the  body  becomes  li- 
quid or  aeriform;  or  from  the  Joss  of  rapidi- 
ty of  vibration,  in  consequence  of  the  mo- 
tion of  the  particles  through  greater  space. 

"If  a  specific  fluid  of  heat  be  admitted, 
it  must  be  supposed  liable  to  most  of  the  af- 
fections which  the  particles  of  common  mat- 
ter are  assumed  to  possess,  to  account  for  the 
phenomena;  such  as  losing  its  motion  when 
combining  with  bodies,  producing  motion 
when  transmitted  from  one  body  to  another, 
and  gaining  projectile  motion  when  pass- 
ing into  free  space;  so  that  many  hypotheses 
must  be  adopted  to  account  for  its  agency, 
which  renders  this  view  of  the  subject  less 
simple  than  the  other.  Very  delicate  expe- 
riments have  been  made,  which  show  that 
bodies,  when  heated,  do  not  increase  in 
weight.  This,  as  far  as  it  goes,  is  an  evi- 
dence against  a  subtile  elastic  fluid,  produc- 
ing the  calorific  expansion;  but  it  cannot  be 
considered  as  decisive,  on  account  of  the  im- 
perfection of  our  instruments.  A  cubical 
inch  of  inflammable  air  requires  a  good  ba- 
lance to  ascertain  that  it  has  any  sensible 
weight,  and  a  substance  bearing  the  same  re- 
lation to  this,  that  this  bears  to  platinum, 
could  not  perhaps  be  weighed  by  any  method 
in  our  possession."! 

•fThis  view  of  the  subject  is  to  me  unsa- 
tisfactory. It  Is  true  that  the  idea  of  hc«* 


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1$.  has  been  supposed,  on  the  other  hand,    son  the  calorific  rays  which  accompany  those 
that  the  observations  of  Sir  Wm.  Herschel     of  light  in  the  solar  beam,  afford  decisive 


being-  motion,  is  sanctioned  by  Newton,  as 
well  as    by    the    illustrious   chemist  above 
named.  But  the  former  adopted  his  opinion 
at  a  time,  when  the  existence  of  heat  in  a 
latent  state   was    as  yet  unsuspected,  and 
when  many  phenomena  unfavourable  to  the 
notion  he  suggested  were  unknown.     It  is 
fully  established  in  mechanics,  that  when  a 
body   in  motion  is  blended  with  and  thus 
made  to   communicate  motion   to  another 
body,  previously  at  rest,  or  moving  slower, 
the  velocity  of  the  compound  mass  after  the 
impact  will  be  found,    by  multiplying1  the 
weight  of  each  body,  by  its  respective  ve- 
locity, and  dividing  the  sum  of  the  products, 
by  the   aggregate  weight  of  both  bodies. 
Of  course  it  will  be  more  than  a  mean  or 
less  than  a  mean, accordingly  as  the  quicker 
body  was  lighter  or  heavier  than  the  other. 
Now  according  to  Sir  Humphrey  Davy,  the 
particles  of  substances  which  are  unequally 
heated  are  moving  with  unequal  degrees  of 
velocity;   of  course  when  they  are  reduced 
by  contact  to  a  common  temperature,  the 
heat,  or  what  is  the  same  (in  his  view),  the 
velocity  of  the  movements  of  their  particles, 
ought  to  be  found  by  multiplying1  the  heat 
of  each  by  its  weight  and  dividing  the  sum 
of  the   product  by  the  aggregate  weight. 
Hence  if  equal  weights  of  matter  be  mixed, 
the  temperature  ought  to  be  a  mean;  and  if 
equal  bulks,  it  ought  to  be  as  much  nearer 
the  previous  temperature   of  the    heavier 
substance   as  the    weight  of  the  latter   is 
greater;  but  the   opposite    is   in   most  in- 
stances true.     When  equiponderant  quanti- 
ties  of  mercury  and  water  are   mixed   at 
different  temperatures,  the  result  is  such  as 
might  be  expected  from  the  mixture  of  the 
water,  were  it  three  times  heavier;,  so  much 
nearer  to  the  previous  heat  of  the  water,  is 
the    consequent  temperature.    It   may   be 
said  that  this  motion  is  not  measurable  upon 
mechanical  principles.  How  then,  I  ask  does 
it  produce  mechanical  effects?  These  must 
be  produced  by  the  force  of  the  vibrations, 
which  are  by  the  hypothesis  mechanical:  for 
whatever  laws  hold  good  in  relation  to  mov- 
ing matter  in  mass-,  must  operate  in  regard 
to  each  particle  of  that  matter;  the  effect 
of  the  former,  can  only  be   a  multiple  of 
that  of  the  latter.   Indeed,  one  of  Sir  Hum- 
phrey Davy's  reasons  for  thinking  heat  to 
consist  of  corpuscular  motions  is  that  me- 
chanical attrition  generates  it.    Surely  tlien 
a  motion,   produced  by  mechanical   means, 
and  which  produces  mechanical  effects,  may 
be  estimated  on-  mechanical  principles. 

In  the  case  cited  above,  the  power  of  re- 
ciprocal communication  of  heat  in  two  fluids, 
is  shown  to  be  inconsistent  with  the  views 
of  this  ingenious  theorist.  If  we  compare 
the  same  jjovrcr  in  solids,  the  result  will  be 


equally    objectionable.     Thus  the    heating 
power  of  glass  being  443,  that  of  an  equal 
bulk  of  lead  will  be  487,  though  so  many 
times  heavier;  and  if  equal  weights  be  com- 
pared, the  effect  of  the  glass,  will  be  four 
times  greater  than  that  of  the  lead.  If  it  be 
said,  that  the  movements  of  the.tlenser  mat- 
ter are  made  in  less  space  and  therefore  re- 
quire less  motion,  I  answer  that  if  they  be 
made  with   equal   velocity,   they  must   go 
through   equal    space   in   the    same    time, 
their    alternations*    being    more    frequent. 
And  if  they   be  not  made  with  the  same 
velocity,   they   could    not  communicate    to 
matter  of  a  lighter  kind,  a  heat  equally  greats 
since  agreeably  to  experience  no  superiority 
of  weight   will   enable   a   body,  acting  di- 
rectly on  another  to  produce  in  it  a  niotioQ 
quicker  than  its  own.   Consistently  with  this 
doctrine,  the  particles  of  an  aeriform  fluid, 
when  they  oppose  a  mechanical  resistance, 
do  it  by  aid  of  a  certain   movement,  which 
causes  them  effectively  to  occupy  a  greater 
space  than  when  at  rest.    It  is  true,  a  body, 
by  moving  backwards  and  forwards,   may 
keep  off  other  bodies  from  the  space  in 
which  it  moves.    Thus  let  a  weight  be  par- 
tially counterbalanced  by  means  of  a  scale 
beam,  so  that  if  left  to  itself  it  would  de- 
scend gently.    Place  exactly  under  it  another 
equally  solid   mass,    on    which   the  weight 
would  fall  if  unobstructed.    If  between  the 
two  bodies  thus  situated,  a  third  be  caused 
to  undergo  an  alternate  motion,  it  may  keep 
the   upper  weight  from   descending,   pro- 
vided the  force  with  which  the  latter  de- 
scends, be  no  greater  than  that  of  the  move- 
ment in  the  interposed  mass,  and  the  latter 
acts  with  such  celerity,  that  between  each 
stroke  the  time  be  too  small  for  the  weight 
to  move  any  sensible  distance.    Here  then 
we  have  a  case  analagous  to  that  supposed, 
in  which  the  alternate  movements  or  vibra- 
tions of  matter  enable  it  to  preserve  to  it- 
self a  greater  space  in  opposition  to  a  force 
impressed;  and  it  must  be  evident  that  length- 
ening or  shortening  the  extent  of  the  vibra- 
tions of  the  interposed  body,  provided  they 
are  made   in  the  same  time,   will  increase 
or  diminish  the  space  apparently  occupied 
by  it,  as  the  volume  of  substances  is  aliected 
by  an    increase    or  reduction   of  heat.    It 
ought  however  to  be  recollected  that  in  the 
case  we  have  imagined,  there  is  a  constant 
expenditure  of  momentum  to  compensate 
for  that  generated  in  the  weight  by  gravity^ 
during  each    vibration.     In    the    vibrations 
conceived  to  constitute  heat,  there   is  no 
generating  power  to  make  up  for  this  loss, 
A  body  preserves  the -expansion  communi- 
cated by  lu-at  in  -sacuo,    where,  insulated 
from  all  other  matter,  the  only  momentum, 
by  whifh  the  vi  brut  ions- of  its  particles  OA\ 


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evidence  of  the  materiality  of  caloric,  or  at 
least  place  the  proof  of  its  existence  and  that 
of  liffht,  on  the  same  foundation.  That  cele- 

be  supported,  must  liuve  been  received  be- 
fore its  being  thus  situated.     If  we  pour 
mercury  into  a  glass   tube  shaped   li'ke  a 
shepherd's  crook,  the  hook  being  down- 
wards,  the  fluid  will  be  prevented  from  oc- 
cupying that  part  of  the  tube  where  the  air 
is  in  such  position  as  not  to  escape.    In  this 
case,  according  to  the  hypothesis  in  question, 
the  mercury  is  prevented  from  entering  the 
space  the  air  occupies,  by  a  series  of  im- 
palpable gyratory  movements;  so  that  the 
collision  of*  tire  aerial  particles  against  each 
other,  causes  each  to  occupy  a  larger  share 
of  space  in  the  manner  above  illustrated  by 
the  descending  weight  and  interposed  body. 
The  analogy  will  be  greater,  if  we  suppose  a 
row  of  interposed  bo*dies  alternately  striking 
against   each   other,    and    the    descending 
Wright;  or  we  may  imagine  a  vibration  in 
all  the    particles   of   the    interposed  mass, 
equal  in  aggregate  extent  and  force  to  that 
of  the  whole,  \\hen  performing'  a  con  mon 
movement.    If  the  aggregate  extent  of  the 
vibration  of  the  particles  very  much  exceed 
that  which  when  performed  in  mass  would 
be  necessary  to  preserve  a  certain  space,  it 
may  be  supposed  productive  of  a  substance 
like  the  air  by   which  the  mercury  is  re- 
sisted.   But  whence  is  the  momentum  ade- 
quate in  such  rare  media  to  resist  a  pressure 
of  a  fluid  so  heavy  as  mercury,  which  in 
this  case  performs  a  part  similar  to  that  of 
the  weight,  cited  for  the  purpose  of  illus- 
tration?   If  it  be  said  that  the  mercury  and 
glass  being  at  the  same  temperature  as  the 
air,  the  particles  of  these  substances  vibrate 
in  a  manner  to  keep  up  the  aerial  pulsations; 
I  ask,  when  the  experiment  is  tried  in  an 
exhausted  receiver,   what  is  to  supply  mo- 
mentum to  the  mercury  and  glass?  There  is 
no  small  difficulty  in  conceiving  under  the 
most  favourable  circumstances,  that  a  spe- 
cies of  motion,  that  exists  according  to  the 
hypothesis  as  the  cruise  of  expansion  in  a 
heated  solid,  should  cause  a  motion  produc- 
tive of  fluidity  or  vaporization,  as  when  by 
means  of  a  hot  iron,   we   convert  ice  into 
water,  and  water  into  vapour. 

How  inconceivable  is  it  that  the  iron 
boikr  of  a  steam  engine  should  give  to  the 
particles  of  water,  a  motion  s<»  totally  differ- 
ent from  any  it  can  itself  possess,  and  at  the 
same  time  capable  of  such  wonderful  effects, 
as  are  produced  by  the  agency  of  steam. 
Is  it  to  be  imagined  that  in  particles  whose 
weight  does  not  exceed  a  few  ounces,  suffi- 
cient momentum  can  be  accumulated  to 
move  as  many  tons?  There  appears  to  me 
another  very  serious  obstacle  to.  this  expla- 
nation of  the  nature  of  heat.  How  are  we 
to  account  for  its  radiation  in  vacuo,  which 
the  distinguished  advocate  of  the  hypothesis 


brated  astronomer  discovered  that  when  si- 
milar thermometers  were  placed  in  the  dif- 
ferent parts  of  the  solar  beam,  decomposed 
by  the  prism  into  the  primitive  colours,  they 
indicated  different  temperatures.  He  esti- 
mates the  power  of  heating  iu  the  red  rays, 
to  be  to  that  of  the  green  rays,  as  55,  to  26, 
and  to  that  of  the  violet  rays  as  55  to  16. 
And  in  a  space  beyond  the  red  rays,  where 
there  is  no  visible  light,  the  increase  of 
temperature  is  greatest  of  all.  Thus,  a 
thermometer  in  the  full  red  ray  rose  7° 
Fahr.  in  ten  minutes;  beyond  the  confines 
of  the  coloured  beam  entirely,  it  rose  in  an 
equal  time  9°.  *. 

These  experiments  were  repeated  by  Sir 
II.  Englefield  with  similar  results.  Mr.  He- 
rard,  however,  came  to  a  somewhat  diffe- 
rent conclusion.  To  render  his  experiments 
more  certain,  and  their  effects  more  sensible, 
this  ingenious  philosopher  availed  himself  of 
the  heliostat,  an  instrument  by  which  the  sun- 
beam can  be  steadily  directed  to  one  spot 
during  the  whole  of  its  diurnal  period.  He 
decomposed  by  a  prism  the  sunbeam,  re- 
flected from  the  mirror  of  the  heliostat,  and 
placed  a  sensible  thermometer  in  each  of  the 
seven  coloured  rays.  The  calorific  faculty 
was  found  to  increase  progressively  from  the 
violet  to  the  red  portion  of  the  spectrum,  in 
which  the  maximum  heat  existed,  and  not 
beyond  it,  in  the  unilluminated  space.  The 
greatest  rise  in  the  thermometer  took  place, 
while  its  bulb  was  still  entirely  covered  by 
the  last  red  rays;  and  it  was  observed  pro- 
gressively to  sink  as  the  bulb  entered  into 
the  dark."  Finally,  on  placing  the  bulb  quite 

has  himself  shown  to  ensue?  There  can  be 
no  motion  without  matter.  To  surmount 
this  difficulty,  he  calls  up  a  suggestion  of 
Newton's,  that  the  calorific  vibrations  of 
matter  may  send  off  radiant  particles,  which 
lose  their  own  momentum  in  communicating 
vibrations  to  bodies  remote  from  those, 
whence  they  emanate.  Thus  according  to 
Sir  Humphrey,  there  is  radiant  matter  pro- 
ducing heat,  and  radiant  matter  producing 
light.  Now,  the  only  serious  objection  made 
by  him  to  the  doctrine  which  considers 
heat  as  material,  will  apply  equally  against 
the  existence  of  material  calorific  emana- 
tions. That  the  cannon,  heated  by  friction 
in  the  noted  experiment  of  Kumford,  would 
have  radiated  as  well  as  if  heated  in  any  other 
way,  there  can,  I  think,  be  no  doubt;  and  as 
well  in  vacuo,  as  the  heat  excited  by  Sir 
Humphrey  in  a  similar  situation.  That  its 
emission  in  this  way  would  have  been  as 
inexhaustible  as  by  the  conducting  pro- 
cess caimot  be  questioned.  Why  then  is  it 
not  as  easy  to  have  an  inexhaustible  supply 
of  heat  as  a  material  substance,  as  to  have 
an  inexhaustible  supply  of  radiant  matter, 
communicating  the  vibrations  in  which  he 
represents  heat  to  consist? 


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<mt  of  the  visible  spectrum,  where  Herschel 
fixed  the  maximum  of  heat,  the  elevation  of 
its  temperature  above  the  ambient  air  was 
found,  by  M.  Berard,  to  be  only  one-fifth  of 
what  it  was  in  the  extreme  red  ray.  He  af* 
terwards  made  similar  experiments  on  the 
double  spectrum  produced  by  Iceland  crys- 
tal, and  also  on  polarized  light,  and  he  found 
in  both  cases  that  the  calorific  principle  ac- 
companied the  luminous  molecules;  and  that 
in  the  positions  where  light  ceased  to  be  re- 
flected, heat  also  disappeared. 

Newton  has  shown  that  the  diffeBMU  re- 
frangibility  of  the  rays  of  light  mayT>e  ex- 
plained by  supposing  them  composed  of  par- 
ticles differing  in  size,  the  largest  being  at 
the  red,  and  the  smallest  at  the  violet  ex- 
tremity of  the  spectrum.  The  same  great 
man  has  put  the  query,  Whether  light  and 
Common  matter  are  not  convertible  into  each 
other?  and  adopting  the  idea  that  the  phe- 
nomena of  sensible  heat  depend  upon  vibra- 
tions of  the  particles  of  bodies,  supposes  that 
a  certain  intensity  of  vibrations  may  send  off 
particles  into  free  space;  and  that  particles 
in  rapid  motion  in  right  lines,  in  losing  their 
own  motion,  may  communicate  a  vibratory, 
motion  to  the  particles  of  terrestrial  bodies, 
In  this  way  we  can  readily  conceive  how 
the  red  rays  should  impinge  most  forcibly, 
and  therefore  excite  the  greatest  degree  of 
heat. 

Enough  has  now  been  said  to  show  how 
Kttle  room  there  is  to  pronounce  dogmatic 
decisions  on  the  abstract  nature  of  heat.  If 
the  essence  of  the  cause  be  still  involved  in 
mystery,  many  of  its  properties  and  effects 
ha've  been  ascertained,  and  skilfully  applied 
to  the  cultivation  of  science  and  the  uses  of 
life.f 

|  We  see  the  same  matter,  at  different 
times,  rendered  self-attractive,  or  self-repel- 
tent;  now  cohering  in  the  solid  form  with 
great  tenacity,  and  now  flying  apart  with 
explosive  violence  in  the  state  of  vapour. 
Hence  the  existence,  in  nature,  of  two  op- 
posite kinds  ef  reaction;  between  particles, 
is  self  evident.  There  can  be  no  property, 
without  matter,  in  which  it  may  be  inher- 
ent. Nothing  can  have  no  property.  The 
question  then  is,  whether  these  opposite 
properties  can  belong  to  the  same  particles. 
Js  it  not  evident,  that  the  same  particles  can- 
not, at  the  same  time,  be  self-repellent,  and 
sett-attractive?  Suppose  them  to  be  so,  one 
or  the  other  must  predominate,  and  in  that 
Qase  we  should  not  perceive  the  existence 
of  the  other.  It  would  be  useless,  and  the 
particles  would  in  effect,  possess  the  predo- 
minant property  alone,  whether  attraction 
or  repulsion.  If  the  properties  were  equal 
in  power,  they  would  annihilate  each  other, 
and  the  matter  would  be,  as  if  void  of  ei- 
ther properly.  There  must,  therefore,  be 
a  mutter,  in  which  the*  sett-rep  ellciit  power 


We  shall  consider  them  in  the  following 
order: 

1.  Of  the  measure  of  temperature. 

2.  Of  the  distribution  of  heat. 

3.  Of  the  general  habitudes  of  heat  with 
the  different  forms  of  matter. 

It  will  be  convenient  to  make  use  of  the 
popular  language,  and  to  speak  of  heat  as 
existing  in  bodies  in  greater  or  smaller  quan- 
tities, without  meaning  thereby  to  decide  o» 
the  question  of  its  nature. 

1.  Of  the  measure  of  temperature. 

If  a  rod  or  ring  of  metal  of  considerable 
size,  which  is  fitted  to  an  oblong  or  circular 
guage  in  its  ordinary  state,  be  moderately 
heated,  it  will  be  found,  on  applying  it  to 
the  cool  guage,  to  have  enlarged  its  dimen- 
sions. It  is  thus  that  coachmakers  enlarge 
their  strong  iron  rims,  so  as  to  make  them 
embrace  and  firmly  bind,  by  their  retraction 
when  cooled,  the  wooden  frame-work  of 
their  wheels. 

Ample  experience  has  proved,  that  bo- 
dies, by  being  progressively  heated,  pro- 
resides,  as  well  as  matter  in  which  attraction 
resides. 

There  must  also  be  as  many  kinds  of  mat- 
ter, as  there  are  kinds  of  repulsion,  of  which 
the  affinities,  means  of  production,  or  laws 
of  communication  are  different.  Hence  i 
do  firmly  believe  in  the  existence  of  mate- 
rial fluids,  severally  producing  the  pheno- 
mena of  heat,  light  and  electricity.  Sub- 
stances, endowed  with  attraction,  make 
themselves  known  to  us,  by  that  species  of 
this  power,  which  we  call  gravitation,  by 
which  they  are  drawn  towards  the  earth, 
and  are  therefore  heavy  and  called  ponde- 
rable; by  their  resistance  to  our  bodies,  pro- 
ducing the  sensation  of  feeling  or  touch; 
and  by  the  vibrations  or  movements  in  other 
matter,  affecting  the  ear  with  sounds,  and 
the  eye  by  a  modified  reflection  of  light. 
Where  we  perceive  none  of  these  usual 
concomitants  of  matter,  we  are  prone  to  in- 
fer its  absence.  Hence  ignorant  people  have 
no  idea  of  air,  except  in  the  state  of  wind, 
and  when  even  in  a  quiescent  state  desig- 
nate it  by  this  word.  But  that  the  princi- 
ples, the  existence  of  which  has  been  de~ 
monstrated,  should  not  be  thus  perceived* 
is  far  from  being  a  reason  for  doubting  their 
existence.  A  very  slight  attention  to  their 
qualities  will  make  it  evident,  that  they 
could  not  produce  any  of  the  efiects,  by 
which  the  existence  of  matter  in  its  ordina- 
ry form  is  recognized.  The  self-repellent 
property  renders  it  impossible  that  they 
should  resist  penetration;  their  deficiency  oY 
weight,  renders  their  momentum  nugato- 
ry When  in  combination,  they  are  not  per- 
ceived, but  the  bodies  with  which  they  com- 
bine; and  it  is  only  by  the  changesthey  pro- 
duce in  such  bodies,  or  their  efiects  upon 
our  nerves,  that  thev  can  be  clet??cted-. 


CAL 


CAL 


gyessively  increase  in  bulk.  On  this  princi- 
ple are  constructed  the  various  instruments 
for  measuring  temperature.  If  the  body  se- 
lected for  indicating1,  by  its  increase  of  bulk, 
the  increase  of  heat,  suffered  equal  expan- 
sions by  equal  increments  of  the  calorific 
power,  then  the  instrument  would  be  per- 
fect, and  we  should  have  a  just  thermometer, 
or  pyrometer.  But  it  is  very  doubtful  whe- 
ther any  substance,  solid,  liquid,  or  aeriform, 
preserves  this  equable  relation,  between  its 
increase  of  volume  and  increase  of  heat. 
The  following  quotation  from  a  paper  which 
the  Royal  Society  did  me  the  honour  to 
publish  in  their  1'ransactious  for  1818,  con- 
veys my  notions  on  this  subject: 

"  I  think  it  indeed  highly  probable,  that 
every  species  of  matter,  both  solid  and 
liquid,  follows  an  increasing  rate  in  its  en- 
largement by  caloric.  Each  portion  that 
enters  into  a  body  must  weaken  the  antago- 
nist force,  cohesion,  and  must  therefore  ren- 
der more  efficacious  the  operation  of  the 
next  portion  that  is  introduced.  Let  1000 
represent  the  cohesive  attraction  at  the  com- 
mencement, then,  after  receiving  one  incre- 
ment of  caloric,  it  will  become  1000 —  1 
=  999.  Since  the  next  unit  of  that  divel- 
Jent  agent  will  have  to  combat  only  this  di- 
minished cohesive  force,  it  will  produce  an 
effect  greater  than  the  first,  in  the  propor- 
tion of  1000  to  999,  and  so  on  in  continued 
progression.  That  the  increasing  ratio  is, 
however,  greatly  less  than  Mr.  Dulton  main- 
tains, may,  I  think,  be  clearly  demonstrated." 
P.  34. 

The  chief  object  of  the  second  chapter  of 
that  memoir,  is  the  measure  of  temperature. 
The  experiments  on  which  the  reasoning  of 
that  part  is  founded,  were  made  in  the  years 
1812  and  1813,  in  the  presence  of  many  phi- 
losophical friends  and  pupils.  By  means  of 
two  admirable  micrometer  microscopes  of 
Mr.  Troughton's  contraction,  attached  to  a 
peculiar  pyrometer,  I  found,  that  between 
the  temperatures  of  melting  ice,  and  the 
540th  degree  Fahr.,the  apparent  elongations 
of  rods  of  pure  copper  and  iron  correspond- 


ed pco'iprtssu  with  the  indications  of  two  mer« 
cunal  thermometers  of  singular  nicety,  made 
by  Mr.  Crighton  ot  Glasgow,  one  of  which 
cost  three  guineas,  and  the  other  two,  and 
they  were  compared  with  a  very  fine  one 
of  Mr  Troughton's.  I  consider  the  above 
results,  and  others  contained  in  that  same* 
paper,  as  decisive  against  Mr.  Dalton's  hy- 
pothetical graduation  of  thermometers.  They 
were  obtained  and  detailed  in  public  lec- 
tures many  years  before  the  elaborate  re- 
searches of  Messrs.  Petit  and  Dulong  on  the 
same  Abject  appeared;  and  indeed  the  pa- 
per itself  passed  through  Dr.  Thomson's 
hands,  to  London,  many  months  before  the 
excellent  dissertation  of  the  French  philo- 
sophers was  published.  Their  memoir  gain- 
ed a  well-merited  prize,  voted  by  the  Aca- 
demy of  Sciences,  on  the  16th  of  March 
1818.  My  paper  was  submitted  the  preced- 
ing summer,  in  its  finished  state,  to  three 
professors  of  the  University  of  Glasgow,  as 
well  as  to  Dr.  Brewster  and  Dr.  Murray. 

The  researches  of  MM.  Dulong  and  Petit 
are  contained  in  the  7th  volume  of  the 
Annales  de  Chimie  et  Physique.  They 
commence  with  some  historical  details,  in 
which  they  observe,  "  that  Mr.  Dalton,  con- 
sidering this  question  from  a  point  of  view 
much  more  elevated,  has  endeavoured  to 
establish  general  laws  applicable  to  the  mea- 
surement of  all  temperatures.  These  laws, 
it  must  be  acknowledged,  form  an  imposing 
whole  by  their  regularity  and  simplicity. 
Unfortunately,  this  skilful  philosopher  pro- 
ceeded with  too  much  rapidity  to  generalize 
his  very  ingenious  notions,  but  which  de- 
pended on  uncertain  data.  The  consequence 
is,  that  there  is  scarcely  one  of  his  assertions 
but  what  is  contradicted  by  the  result  of  the 
researches,  which  we  are  now  going  to  make 
known."  M.  Gay-Lussac  had  previously 
shown,  that  between  the  limits  of  freezing1 
and  boiling  water,  a  mercurial  and  air  ther- 
mometer did  not  present  any  sensible  dis- 
cordance. The  following  table  of  MM.  Du- 
long and  Petit  gives  the  results  from  nearly 
the  freezing-  to  the  boiling  point  of  mercury* 


TdBLE  of  Comparison  of  the  Mercurial  and  Jtir  Thermometer. 


Temperature  indicated  by  the 
mercurial. 

Corresponding 
volt,  of  the  same 

Temperature  indicated  by  an  air 
thermometer,  corrected  for 
the  dilatation  of  glass. 

Centigr. 

Fahr. 

mass  of  air. 

Centigr. 

Fahr. 

—36° 

—32.8° 

0.8650 

—36.00° 

—328° 

0 

4-32. 

1.0000 

0.00 

+  32.0 

100 

212 

1.3750 

100.00 

212.0 

150 

302 

1.5576 

148.70 

299.66 

200 

392 

1.7389 

197.05 

386.69 

250 

482 

1.9189 

245.05 

47509 

300 

572 

2.    76 

292.70 

558.86 

Boiling,360 

680 

2.3125 

350  00 

662.00 

CAL 


CAL 


The  well  known  uniformity  in  the  princi- 
pal physical  properties  of  all  the  gases,  and 
particularly  the  perfect  identity  in  the  laws 
of  their  dilatation,  render  it  very  probable, 
that  in  this  class  of  bodies  the  disturbing1 
causes,  to  which  I  have  adverted  in  my  pa- 
per, have  not  the  same  influence  as  in  solids 
and  liquids;  and  that  consequently  the 
changes  in  volume  produced  by  the  action  of 
heat  upon  air  and  gast-s,  are  more  immedi- 
ately dependent  upon  the  force  which  pro- 
<luccs  them.  It  is  therefore  very  probable, 
•that  the  greatest  number  of  the  phenomena 
relating'  to  heat  will  present  themselves  un- 
der a  more  simple  form,  if  we  measure  the 
temperatures  by  an  air  thermometer. 

I  coincide  with  these  remarks  of  the  French 
chemists,  and  think  they  were  justified  by 
such  considerations  to  employ  the  scale  of 
an  air  thermometer  in  their  subsequent  re- 
searches, which  form  the  second  part  of 
their  memoir  on  the  laws  of  the  communi- 
cation of  heat. 

The  boiling  point  of  mercury,  according 
to  M  M.  Duiong  and  Petit,  measured  by  a 
true  thermometer,  is  662°  of  Fahr.  degrees. 
Now  by  Mr.  (Brighton's  thermometer  the 
boiling1  point  is  656°,  a  difference  of  only 
6°  in  that  prodigious  range.  Hence  we  see, 
as  I  pointed  out^in  my  paper,  that  there  is  a 
compensation  produced  between  the  une- 
quable expansions  of  mercury  and  glass,  and 
tiie  lessening  mass  of  mercury  remaining  in 
the  bulb  as  the  temperature  rises  whereby 
his  thermometer  becomes  a  true  measurer  of 
the  increments  of  sensible  caloric.  From 
all  the  experiments  which  have  been  made 
with  care,  we  are  safe  in  assuming  the  appa- 
rent expansion  of  mercury  in  glass  to  be 
l-63d  part  of  its  volume  on  an  average  for 
every  180°  Fahr.  between  32°  and  662°,  or 
through  an  interval  of  7  times  90  degrees. 
Hence  the  apparent  expansion  in  glass  for 

the  whole  is,  JL  =  *  =  S?  =  35°  Fahr. 

126          18  l» 

Were  the  whole  body  of  the  thermome- 
ter, stem  and  bulb,  immersed  in  boiling  mer- 
cury, it  would  therefore  indicate  35°  more 
than  it  does  when  the  bulb  alone  is  immersed, 
or  it  woidd  mark  nearly  691°  by  Crighton. 
But  the  abstraction  made  of  these  35°,  in 
consequence  of  the  bulb  alone  being  im- 
mersed in  the  heated  liquids,  brings  back 
the  common  mercurial  scale,  when  well  exe- 
cuted, near  to  the  absolute  and  just  scale  of 
an  air  thermometer,  corrected  for  the  ex- 
pansions of  the  containing  glass. 

Dr.  Thomson  in  his  Annals  for  March, 
1819,  has,  in  his  account  of  my  paper,  ha- 
zarded some  remarks  on  this  subject,  which 
it  will  be  necessary  merely  to  quote  in  order 
to  see  their  futility:  "From  Mr.  Crighton's 
mode  of  graduating  thermometers,"  says  he, 
"it  is  obvious  that  in  the  higher  parts  of  the 
scale  the  degrees  are  below  the  truth.  Thus 
mercury  boils,  as  determined  by  his  thermo- 
meters, at  556°,  the  real  boiling1  point,  as 


determined  by  Ditlong  and  Petit,  is  580*. 
It  is  probable  that  Dr.  Ure  also  employed  a 
thermometer,  made  bv  Crighton.  But  it  is 
unlikely  that  it  should  be  better  than  mine, 
as  Mr.  Crighton  was  at  great  pains  to  make 
mine  as  correct  as  possible,  and  1  paid  him  a 
high  price  for  it."  Making  due  allowance 
for  the  oblique  censure  of  this  insinuation, 
as  well  as  for  the  typographical  error  of 
580°  instead  of  680°,  it  is  obvious  that 
Dr.  Thomson  has  misunderstood  the  merits 
of  the  discussion.  The  real  temperature 
of  boiling  mercury  by  Duiong  and  Petit  is 
662°  F.;  the  apparent  temperature,  measur- 
ed by  mercury  in  glass,  both  heated  to  the 
boiling  point  of  the  former,  is  680°.  But 
the  latter  is  a  false  indication,  and  Mr. 
(Brighton's  compensated  number  656°  is 
rery  near  the  truth.  We  may  therefore  con- 
sider a  well  made  mercurial  thermometer  as 
a  sufficiently  just  measurer  of  temperature. 
For  its  construction  and  graduation,  see 
THERMOMETEK. 

2.  Of  the  distribution  of  heat. 

This  head  naturally  divides  into  two  parts; 
first,  the  modes  of  distribution,  or  the  laws  of 
cooling,  and  the  communication  of  heat 
among  aeriform,  liquid,  and  solid  substances, 
and,  secondly,  the  specific  heats  of  different 
bodies  at  the  same  and  at  different  tempe- 
ratures. 

The  first  views  relative  to  the  laws  of  the 
communication  of  heat  are  to  be  found  in 
the  opuscula  of  Newton.  This  great  philo- 
sopher assumes  a  priori,  that  a  heated  body 
exposed  to  a  constant  cooling  cause,  such  as 
the  uniform  action  of  a  current  of  air,  ought 
to  lose  at  each  instant  a  quantity  of  heat 
proportional  to  the  excess  of  its  temperature 
above  that  of  the  ambient  air;  and  that  con- 
sequently its  losses  of  heat  in  equal  and  suc- 
cessive portions  of  time  ought  to  form  a  de- 
creasing geometrical  progression.  Though 
Martin,  in  his  Essays  on  Heat,  pointed  out 
long  ago  the  inaccuracy  of  the  preceding 
law,  which  indeed  could  not  fail  to  strike 
any  person,  as  it  struck  me  forcibly  the  mo- 
ment that  1  watched  the  progressive  cooling 
of  a  sphere  of  oil  which  had  been  heated  to 
the  500th  degree,  yet  the  proposition  has 
been  passed  from  one  systematist  to  ano- 
ther without  contradiction. 

Erxleben  proved,  by  very  accurate  obser- 
vations, that  the  deviation  of  the  supposed 
law  increases  more  and  more  as  we  consider 
greater  differences  of  temperatures;  and  con- 
cludes that  we  should  fall  into  very  great 
errors  if  we  extended  the  law  much  beyond 
the  temperature  at  which  it  has  been  veri- 
fied. Yet  Mr.  Leslie  since,  in  his  ingenious 
researches  on  heat,  has  made  this  law  the 
basis  of  several  determinations,  which  from 
that  very  cause  are  inaccurate,  as  has  been 
proved  by  Duiong  and  Petit.  At  length 
these  gentlemen  have  investigated  the  true 
la  >v  in  a  masterly  manner. 


CAL 


CAL 


"When  a  body  cools  in  vacuo,  its  lieat  is 
entirely  dissipated  by  radiation.  When  it  is 
placed  in  air,  or  in  any  other  fluid,  its  cool- 
ing becomes  more  rapid,  the  heat  carried 
-off'  by  the  fluid  being  in  that  case  added  to 
that  which  is  dissipated  by  radiation.  It  is 
natural  therefore  to  distinguish  these  two 
effects;  and  as  they  are  subject  in  all  proba- 
bility to  different  laws,  they  ought  to  be 
separately  studied. 

MM.  Dulong  and  Petit  employed  fn  this 
research  mercurial  thermometers,  whose 
bulbs  were  from  0.8  of  an  inch  to  2.6;  the 
latter  containing  about  three  Ibs.  of  mercury. 
They  found  by  preliminary  trials,  that  the 
ratio  of  cooling  was  not  affected  by  the  size 
of  the  bulb,  and  that  it  held  also  in  compari- 
sons of  mercury,  with  water,  with  absolute 
alcohol,  and  with  sulphuric  acid,  through  a 
range  of  temperature,  from  60  to  30  of  the 
centigrade  scale;  so  that  the  ratio  of  the 
velocity  of  cooling  between  60  and  50,  and 
40  and  30,  was  sensibly  the  same.  On 
cooling  water  in  tin  plate,  and  in  a  glass 
sphere,  they  found  the  law  of  cooling  to  be 
more  rapid  in  the  former,  at  temperatures 
under  the  boiling  point;  but  by  a  very  re- 
markable casualty,  the  contrary  effect  takes 
place  in  bodies  heated  to  high  temperatures, 
when  the  law  of  cooling  in  tin  plate  becomes 
least  rapid.  Hence,  generally,  that  which 
cools  by  a  most  rapid  law  at  the  lower  part 
of  the  scale,  becomes  the  least  rapid  at  high 
temperatures. 

"  Mr.  Leslie  obtained  such  inaccurate  re- 
sults respecting  this  question,  because  he  did 
not  make  experiments  on  the  cooling  of  bo- 
dies raised  to  high  temperatures,"  say  MM. 
Dulong  and  Petit,  who  terminate  their  preli- 
minary researches  by  experiments  on  the 
cooling  of  water  in  three  tin-plate  vessels  of 
the  same  capacity,  the  first  of  which  was  a 
sphere*  the  second  and  third  cylinders;  from 
which  we  learn  that  the  law  'of  cooling  is 
not  affected  by  the  difference  of  shape. 

The  researches  on  cooling  in  a  vacuum 
were  made  with  an  exhausted  balloon;  and 
a  compensation  was  calculated  for  the  mi- 
nute quantity  of  residuary  gas.  The  follow- 
ing series  was  obtained  when  the  balloon 
was  surrounded  with  ice.  The  degrees  are 
centigrade. 

Excess  of  the  therm.        Corresponding  ve- 

abov  e  the  balloon.  locities  of  cooling. 

2400  1Q69 

220  8.81 

200  7.40 

180  6.10 

160  4.89 

140  3  88 

120  3  o» 

100  2.30 

80  1.74 

The  first  column  contains  the  excesses  of 

temperature  above  the  walls  of  the  balloon; 

that  is  to  say,  the  temperatures  themselves, 

since  the  balloon  was  at  0°.  The  second  co- 


lumn contains  ihc  corresponding1  velocities  of 
cooling,  calculated  and  corrected.  These  ve- 
locities are  the  numbers  of  degrees  that  the 
thermometer  would  sink  in  a  minute.  The 
first  series  shows  clearly  the  inaccuracy  of  the 
geometrical  law  of  Kichmann;  for  according 
to  that  law,  the  velocity  of  cooling  at  2<jO° 
should  be  double  of  that  at  100°;  whereas 
we'  find  it  as  7.4  to  2.3,  or  more  than  triple; 
and  in  like  manner,  when  we  compare  the 
loss  of  heat  at  240°  and  at  80°,  we  find  the 
first  about  6  times  greater  than  the  last; 
while,  according  to  the  law  of  IJiclimann,  it 
ought  to  be  merely  triple.  From  the  above 
and  some  analogous  experiments,  the  fol- 
lowing law  has  been  deduced;  U'km  a  body 
cwls  in  vacuo  surrounded  by  a  medium  whose 
temperature  is  constant,  ths  velocity  of  cooling 
for  excess  of  temperature  in  arithmetical  pro- 
gression, increases  as  the  terms  of  a  geomntri- 
cat  progression,  diminished  by  a  certain  quan- 
tity Or,  expressed  in  algebraic  language, 
the  following  equation  contains  the  law  of 

6     t 
cooling  in  vacuo:  V  =  m.a  (a  —  1). 

6  is  the  temperature  of  the  substance  sur- 
rounding the  vacuum;  and  t  that  of  the  heated 
body  above  the  former.  The  ratio  a  of  this 
progression  is  easily  found  for  the  thermome- 
ter, whose  cooling  is  recorded  above;  for 
when  8  augments  by  20°,  t  remaining  the 
same,  the  velocity  of  cooling  is  then  multi- 
plied by  1.165;  which  number  is  the  mean 
of  all  the  ratios  experimentally  determined. 

20  _  '__ 

We  have  then  a  =  \/  Lib.)  —  1.0077. 

It  only  remains,  in  order  to  verify  the  ac- 
curacy of  this  law,  to  compare  it  with  the 
different  series  contained  in  the  table  insert- 
ed above.  In  that  case,  .n  which  the  sur- 
rounding medium  was  0°,  it  is  necessary  te 

?i 
make  m  —  2.037,  form   =  -  ,  and  n  is 

log.  « 

an  intermediate  number;  we  have  tlien  V 
t 


Excesses  of  temp.     Values  of    Values  of  V 
or  values  oft.         V  observed,     calculated: 
240°  10.69  10.68 

220  8.81  8.89 

200  7.40  7  34 

ISO  6.10  6.03 

160  4.89  4.87 

140  S.88  3.89 

120  3.02  3.05 

100  2.30  2.33 

80  1.74  1.72 

The  laws  of  cooling  invacuo  being  known, 
nothing  is  more  simple  than  to  separate 
from  the  total  cooling  of  a  body  surrounded 
with  air,  or  with  any  other  gas,  the  portion 
of  the  effect  due  to  the  contact  of  the  fluid. 
For  this,  it  is  obviously  sufficient  to  sub- 
tract from  the  real  velocities  of  cooling, 
those  velocities  which  would  take  place  if 
the  body  c<cteris  paribits  were  placed  in  va> 


1 


CAL 


CAL 


cuo.  This  subtraction  may  be  easily  accom- 
plished now  that  we  have  a  formula*  which 
represents  this  velocity  with  great  preci- 
sion, and  for  all  possible  cases. 

From  numerous  experimental  compari- 
sons the  following  law  was  deduced:  The 
'velocity  of  cooling  of  a  body,  owing  to  the  sole 
contact  of  a  gas,  depends  for  the  same  excess 
of  temperature,  on  the  density  and  tempera- 
ture of  the  fluid;  but  this  dependence  is  such, 
that  the  velocity  of  cooling  remains  the  same, 
if  the  density  and  the  temperature  of  the  gas 
change  in  such  a  "way  that  the  elasticity  re- 
mains constant. 

If  we  call  P  the  cooling  power  of  air  un- 
der the  pressure  p,  this  power  will  become 
P  (1.366)  under  a  pressure  2/v  P  (1.366)2 
under  a  pressure  4  p;  and  under  a  pressure 

n  n  P' 

p  2  ,  it  will  be  P  (1.366)  .    Hence  —  = 

P 


//A0.45 

v  ~p  i    ' 


^e  same 


for  hydrogen,  -p  =  \J  j°>o8. 

For  carbonic  acid,  the  exponent  will  be 
0.517,  and  for  olefiant  gas  0.501,  while  for 
air  as  we  see  it  is  0.45.  These  last  three 
numbers  differing  little  from  0.5  or  ^,  we 
may  say  that  in  the  aeriform  bodies  to  which 
they  belong,  the  cooling  power  is  nearly 
as  the  square  root  of  the  elasticity.  "  If 
we  compare  the  law  which  we  have  thus 
announced,"  say  MM.  Dulong  and  Petit, 
*'  with  the  approximations  of  Leslie  and 
Dalton,  we  shall  be  able  to  judge  of  the 
errors  into  which  they  have  been  led  by  the 
inaccurate  suppositions  which  serve  as  the 
basis  of  all  their  calculations,  and  by  the 
little  precision  attainable  by  the  methods 
which  they  have  followed."  But  for  these 
discussions,  we  must  refer  to  the  memoir 
itself. 

The  influence  of  the  nature  of  the  sur- 
face of  bodies  in  the  distribution  of  heat, 
was  first  accurately  examined  by  Mr.  Les- 
lie. This  branch  of  the  subject  is  usually 
called  the  radiation  of  caloric.  To  measure 
the  amount  of  this  influence  with  precision, 
he  contrived  a  peculiar  instrument,  called 
a  differential  thermometer.  It  consists  of  a 
glass  tube,  bent  into  the  form  of  the  letter 
U,  terminated  at  each  end  with  a  bulb.  The 
bore  is  about  the  size  of  that  of  large  ther- 
mometers, and  the  bulbs  have  a  diameter 
of  l-3d  of  an  inch  and  upwards.  Before 
hermetically  closing  the  instrument,  a  small 
portion  of  sulphuric  acid,  tinged  with  car- 
mine is  introduced.  The  adjustment  of  this 
liquid  so  as  to  make  it  stand  at  the  top  of 
one  of  the  stems,  immediately  below  the 
bulb,  requires  dexterity  in  the  operator. 
To  this  stem  a  scale  divided  into  100  parts 
VOL.  I. 


is  attached,  and  the  instrument  is  then  fixed 
upright  by  a  little  cement  on  a  wooden  sole. 
If  the  finger,  or  any  body  warmer  than  the 
ambient  air,  be  ;>pp:ie<t  to  one  of  these  bulbs, 
the  air  within  will  be  heated,  and  will  of 
course  expand,  und  issuing  in  part  from  the 
bulb,  depress  before  it  the  tinged  liquor. 
The  amount  of  this  depression  observed 
upon  the  scale,  will  denote  the  difference 
of  temperature  oftiie  two  balls.  But  if  the 
instrument  be  merely  carried  without  touch- 
ing either  ball,  from  a  warmer  to  a  cooler, 
or  from  a  cooler  to  a  warmer  air,  or  me- 
dium of  any  kind,  it  will  not  be  affected; 
because  the  equality  of  contraction  or  ex- 
pansion in  the  enclosed  air  of  both  bulbs, 
will  maintain  the  equilibrium  of  the  liquid 
in  the  stem.  Being  thus  independent  of  the 
fluctuations  of  the  surrounding  medium,  it 
is  well  adapted  to  measure  the  calorific 
emanations  of  different  surfaces,  success- 
ively converged  by  a  concave  reflector, 
upon  one  of  its  bulbs.  Dr.  Howard  has  de- 
scribed, in  the  16th  number  of  the  Journal 
of  Science,  a  differential  thermometer  of 
his  contrivance,  which  he  conceives  to  pos- 
sess some  advantages.  Its  form  is  an  imi- 
tation of  Mr  Leslie's;  but  it  contains  mere, 
iy  tinged  alcohol,  or  ether,  the  air  being 
expelled  by  ebullition  previous  to  the  her- 
metical  closure  of  the  instrument.  The  va- 
pour of  ether,  or  of  spirit  in  vacua,  affords, 
he  finds,  a  test  of  superior  delicacy  to  air. 
He  makes  the  two  legs  of  different  lengths; 
since  it  is  in  some  cases  very  convenient  to 
have  the  one  bulb  standing  quite  aloof  from 
the  other.  In  Mr.  Leslie's,  when  they  are 
on  the  same  level,  their  distance  asunder 
varies  from  l-3d  of  an  inch  to  1  or  up- 
wards, according  to  the  size  of  the  instru- 
ment. The  general  length  of  the  legs  of 
the  syphon  is  about  5  or  6  inches. 

His  reflecting  mirrors,  of  about  14  inches 
diameter,  consisted  of  planished  tin-plate, 
hammered  into  a  parabolical  form  by  the 
guidance  of  a  curvilinear  gauge.  A  hollow 
tin  vessel,  6  inches  cube,  was  the  usual 
source  of  calorific  emanation  in  his  experi- 
ments. He  coated  one  of  its  sides  with 
lampblack,  another  with  paper,  a  third  with 
glass,  and  a  fourth  was  left  bare.  Having 
then  filled  it  with  hot  water,  and  set  it  in  the 
line  of  the  axis,  and  4  or  6  feet  in  front  of 
one  of  the  mirrors,  in  whose  focus  the  bulb 
of  a  differential  thermometer  stood,  he 
noted  the  depiv  ssion  of  the  coloured  liquid 
produced  on  presenting  the  different  sides 
of  the  cube  towards  the  mirror  in  succes- 
sion. The  following  table  gives  a  general 
view  of  the  results,  with  these,  and  other 
coatings: 

Lampblack,  -          -         100 

Water  by  estimate,          -         100 -f- 
Writing  paper,  98 

Rosin,  -..          96 

29 


CAL 


CAL 


Sealing-  wax,  95 

Crown  glass,  90 

China  ink,  88 

Ice,          ....  85 

lied  lead,         ...  80 

Plumbago,  75 

Isinglass,         -  75 

Tarnished  lead,       -         -  45 

Mercury,         -         -         -  20  -{- 

Clean  lead,  19 

Iron  polished,  -  15 

Tin  plate,  -        -  12 

Gold,  Silver,  Copper,       -  12 

Similar  results  were  obtained  by  Leslie 
and  Rum  ford  in  a  simpler  form.  Vessels 
of  similar  shapes  and  capacities,  but  of  dif- 
ferent materials,  were  filled  with  hot  li- 
quids, and  their  rates  of  refrigeration  no- 
ted. A  blackened  tin  globe  cooled  a  certain 
number  of  degrees  in  81  minutes;  while  a 
bright  one  took  nearly  double  the  time,  or 
156  minutes;  a  naked  brass  cylinder  in  55 
minutes  cooled  ten  degrees,  while  its  fellow 
cased  in  linen,  was  36^  minutes  in  cooling 
the  same  quantity.  If  rapid  motions  be  ex- 
cited in  the  air,  the  difference  of  cooling 
between  bright  and  dark  metallic  surfaces 
becomes  less  manifest.  Mr.  Leslie  esti- 
mates the  diminution  of  effect  from  a  ra- 
diating surface  to  be  directly  as  its  dis- 
tance, so  that  double  the  distance  gives 
one-half,  and  treble  one-third  of  the  primi- 
tive heating  impression  on  thermometers 
and  other  bodies.  Some  of  his  experi- 
ments do  not  seem  in  accordance  with  this 
simple  law.  One  would  have  expected  cer- 
tainly, that,  like  light,  electricity,  and  other 
qualities  emanating  from  a  centre,  its  di- 
minution of  intensity  would  have  been  as 
the  square  of  the  distance;  and  particular- 
ly as  Mr.  Leslie  found  the  usual  analogy  of 
the  sine  of  inclination  to  hold,  in  present- 
ing the  faces  of  the  cube  to  the  plane  of 
the  mirror  under  different  angles  of  obli- 
quity. 

Some  practical  lessons  nW  from  the  pre- 
ceding results.  Since  bright  metals  project 
heat  most  feebly,  vessels  which  are  intend- 
ed to  retain  their  heat,  as  tea  and  coffee- 
pots, should  be  made  of  bright  find  polish- 
ed metals.  Steum-pipes  intended  to  convey 
heat  to  a  distant  apartment,  should  be  like- 
wise bright  in  their  course,  but  darkened 
when  they  reach  their  destination. 

By  coating  the  buib  of  his  thermometer 
with  different  substances,  Mr.  Leslie  inge- 
niously discovered  the  power  of  different 
surfaces  to  absorb  heat;  and  he  found  this 
to  follow  the  same  order  as  the  radiating 
or  projecting  quality.  The  same  film  of 
silver  leaf  which  obstructs  the  egress  of 
heat  from  a  body  to  those  surrounding  it, 
prevents  it  from  receiving  their  calorific 
emanations  in  return.  On  this  principle  we 
can  understand  how  a  metallic  mirror 


placed  before  a  fire,  should  scorch  sub- 
stances in  its  focus,  while  itself  remains 
cold;  and,  on  the  other  hand,  how  a  mirror 
of  darkened  or  even  of  silvered  glass, 
should  become  intolerably  hot  to  the  touch, 
while  it  throws  little  heat  before  it.  From 
this  absorbent  faculty  it  comes,  that  a  thitt 
pane  of  glass  intercepts  almost  the  whole 
heat  of  a  blazing  fire,  while  the  light  is 
scarcely  diminished  across  it.  By  degrees 
indeed,  itself  becoming  heated,  constitutes 
a  new  focus  of  emanation,  but  still  the  ener- 
gy of  the  fire  is  greatly  interrupted.  Hence 
also  we  see  why  the  thinnest  sheet  of  bright 
tin-foil  is  a  perfect  fire-screen;  so  impervi- 
ous indeed  to  heat,  that  with  a  masque 
coated  with  it,  our  face  may  encounter 
without  inconvenience,  the  blaze  of  a  glass- 
house furnace. 

Since  absorption  of  heat  goes  hand  in 
hand  with  radiation  in  the  above  table,  we 
perceive  that  the  inverse  of  absorption, 
that  is  reflection,  must  be  possessed  in  in- 
verse powers  by  the  different  substances 
composing  the  list.  Thus  bright  metals  re- 
flect most  heat,  and  so  on  upwards  in  suc- 
cession. 

Mr.  Leslie  is  anxious  to  prove  that  elas- 
tic fluids,  by  their  pulsatory  undulations, 
are  the  media  of  the  projection  or  radiation 
of  heat:  and  that  therefore  liquids,  as  well 
as  a  perfect  vacuum,  should  obstruct  the 
operation  of  this  faculty.  The  laws  of  the 
cooling  of  bodies  in  vacua,  experimentally 
established  by  MM.  Dulong  and  Petit,  are 
fatal  to  Mr.  Leslie's  hypothesis,  which  in- 
deed was  not  tenable  against  the  numerous 
objections  which  had  previously  assailed 
it.  The  following  beautiful  experiment  of 
Sir  H.  Davy  seems  alone  to  settle  the  ques- 
tion. He  had  an  apparatus  made,  by  which 
platina  wire  could  be  heated  in  any  elas- 
tic medium  or  in  -vacuo,-  and  by  which  the 
effects  of  radiation  could  be  distinctly  ex- 
hibited by  two  mirrors,  the  heat  being  ex- 
cited by  a  voltaic  battery.  In  several  expe- 
riments in  which  the  same  powers  were 
employed  to  produce  the  ignition,  it  was 
found  that  the  temperature  of  a  thermo- 
meter rose  nearly  three  times  as  much  in 
the  focus  of  radiation,  when  the  air  in  the 
receiver  was  exhausted  to  -r|'?T  as  wnen  it 
was  in  its  natural  state  of  condensation. 
The  cooling  power,  by  contact  of  the  rare- 
fied air,  was  much  less  than  that  of  the  air 
in  its  common  state,  for  the  glow  of  the 
platina  was  more  intense  in  the  first  case 
than  in  the  last;  and  this  circumstance  per- 
haps renders  the  experiment  not  altoge- 
ther decisive,  but  the  results  sf  em  favour- 
able to  the  idea,  that  the  terrestrial  radia- 
tion of  heat  is  not  dependent  upon  any 
motions  or  affections  of  the  atmosphere. 
The  plane  of  the  two  mirrors  was  placed 
parallel  to  the  horizon,  the  ignited  body 


CAL 


CAL 


being  in  the  focus  of  the  upper,  and  the 
thermometer  in  that  of  the  under  mirror. 
It  is  evident  that  a  diminished  density  of 
the  elastic  medium,  amounting1  to  -j-|-<j-» 
should,  on  Mr.  Leslie's  views,  have  occa- 
sioned a  greatly  diminished  temperature 
in  the  inferior  focus,  and  not  a  threefold 
increase,  as  happened;  making1  every  al- 
lowance for  the  diminished  intensity  of 
glow  resulting-  from  the  cooling1  power  of 
atmospheric  air.  The  experiments  with 
screens  of  glass,  paper,  &c.  which  Mr. 
Leslie  adduced  in  support  of  his  undula- 
tory  hypothesis,  have  been  since  confront- 
ed with  the  experiments  on  screens  of  Dr. 
Delaroche,  who,  by  varying-  them,  obtain- 
ed results  incompatible  with  Mr.  Leslie's 
views,  and  favourable  to  those  on  the  inti- 
mate connexion  between  light  and  heat, 
with  which  our  account  of  heat  was  pre- 
faced. He  shows  that  invisible  radiant  heat, 
in  some  circumstances,  passes  directly 
through  glass,  in  a  quantity  so  much  great- 
er relative  to  the  whole  radiation,  as  the 
temperature  of  the  source  of  heat  is  more 
elevated.  The  following  table  shows  the 
ratio  between  the  rays  passing  through 
clear  glass,  and  the  rays  acting  on  the 
thermometer,  when  no  screen  was  inter- 
posed, at  successive  temperatures. 

Temperature  JRays  transmit-         Total 

of  the  hot  body         ted  through  the         Rays, 
in  the  focus.  glass  screen. 

357°  10°  263° 

655  10  139 

800  10  75 

1760  10  34 

Argand's  lamp  with- 
out its  chimney,  10  29 
Do.  with  glass  chimney,  10  18 
He  next  shows  that  the  calorific  rays  which 
have  already  passed  through  a  screen  of 
glass,  experience,  in  passing  through  a  se- 
cond glass  screen  of  a  similar  nature,  a 
much  smaller  diminution  of  their  intensity 
than  they  did  in  passing  through  the  first 
screen;  and  that  the  rays  emitted  by  a  hot 
body  differ  from  each  other  in  their  faculty 
to  pass  through  glass;  that  a  thick  glass, 
though  as  much  as,  or  more  permeable  to 
light  than  a  thin  glass  of  worse  quality, 
allows  a  much  smaller  quantity  of  radiant 
heat  to  pass,  the  difference  being  so  much 
the  less,  the  higher  the  temperature  of  the 
radiating  source.  This  curious  fact,  that 
radiating  heat  becomes  more  and  more 
capable  of  penetrating  glass,  as  the  tem- 
perature increases,  till  at  a  certain  tempe- 
rature the  rays  become  luminous,  leads  to 
the  notion  that  heat  is  nothing  else  than  a 
modification  of  light,  or  that  the  two  sub- 
stances are  capable  of  passing  into  each 
other.  Dr.  Delaroche's  last  proposition  is, 
that  the  quantity  of  heat  which  a  hot  body 


yields  in  a  given  time  by  radiation  to  a 
cold  body  situated  at  a  distance,  increases 
cttteris  paribns,  in  a  greater  ratio  than  the 
excess  of  temperature  of  the  first  body 
above  the  second.  This  proposition,  which 
Dr.  Thomson  declared  in  his  Annals,  vol. 
ii.  p.  102.  to  be  "somewhat  puzzling,"  is 
in  philosophical  accordance  with  the  laws 
of  Dulong  and  Petit. 

For  some  additional  facts  on  radiation, 
see  LIGHT,  to  which  subject  indeed,  the 
whole  discussion  probably  belongs. 

Even  ice,  which  appears  so  cold  to  the 
organs  of  touch,  would  become  a  focus  of 
heat  if  transported  into  a  chamber  where 
the  temperature  of  the  air  was  at  0°  P.; 
and  a  mass  of  melting  ice  placed  before 
the  mirror,  would  affect  the  bulb  of  the 
thermometer,  just  as  the  cube  of  heated 
water  did.  A  mixture  of  snow  and  salt  at 
0°.  would  in  like  manner  become  a  warm 
body  when  carried  into  an  atmosphere  at 
— 40°.  In  all  this,  as  well  as  in  our  sensa- 
tions, we  see  nothing  absolute,  nothing  but 
mere  differences.  We  are  thus  led  to  con- 
sider all  bodies  as  projecting  heat  at  every 
temperature,  but  with  unequal  intensities, 
according  to  their  nature,  their  surfaces, 
and  their  temperature.  The  constancy  or 
steadiness  of  the  temperature  of  a  body, 
will  consist  in  the  equality  of  the  quan- 
tities of  radiating  caloric  which  it  emits 
and  receives  in  an  equal  time,  and  the 
equality  of  temperature  between  several 
bodies  which  influence  one  another  by  their 
mutual  radiation,  will  consist  in  the  per- 
fect compensation  of  the  momentary  inter- 
changes effected  among  one  and  all.  Such 
is  the  ingenious  principle  of  a  move.-. Me 
equilibrium,  proposed  by  Professor  Pre- 
vost,  a  principle  whose  application,  direct- 
ed with  discretion,  and  combined  with  th« 
properties  peculiar  to  different  surfaces, 
explains  all  the  phenomena  which  we  ob- 
serve in  the  distribution  of  radiating  calo- 
ric. Thus,  when  we  put  a  ball  of  snow  in 
the  focus  of  one  concave  mirror,  and  a 
thermometer  in  that  of  an  opposite  mirror 
placed  at  some  distance,  we  perceive  the 
temperature  instantly  to  fall,  as  if  there 
were  a  real  radiation  of  frigorific  particles, 
according  to  the  ancient  notion.  The  true 
explanation  is  derived  from  the  abstrac- 
tion of  that  return  of  heat  which  the  ther- 
moscope  mirror  had  previously  derived 
from  the  one  now  influenced  by  the  snow, 
and  now  participating  in  its  inferior  radi- 
ating tension.  Thus,  also  a  black  body 
placed  in  the  focus  of  one  mirror,  would 
diminish  the  light  in  the  focus  of  the  other; 
and,  as  Sir  H.  Davy  happily  remarks,  the 
eye  is,  to  the  rays  producing  light,  a  mea- 
sure, Similar  to  that  which  the  thermome- 
ter is  to  rays  producing  heat. 

This  interchange  of  heat  is  finely  exem- 


CAL 


CAL 


plified  in  the  relation  which  subsists  be-  in  the  stem  falls  and  rises  with  every  pas- 
tween  any  portion  of  the  sky  and  the  tern-  sing  cloud.  Dr.  Howard's  modification  of 
perature  of  the  subjacent  surface  of  the  the  thermoscope  would  answer  well  here, 
earth.  In  the  year  1788  Mr.  Six  of  Canter-  The  diffusion  of  heat  among  the  particles 
bury  mentioned,  in  a  paper  transmitted  to  of  fluids  Memse/r>es,a"depends  upon  their 
the  "Royal  Society,  that  on  clear  and  dewy  specific  gravity  and  specific  heat  conjunct- 
nights  "he  always  found  the  mercury  lower  ly,  and  therefore  must  vary  for  each  par- 
in  a  thermometer  laid  upon  the  ground,  ticular  substance.  The  mobility  of  the  par- 
ticles in  a  fluid,  and  their  reciprocal  inde- 
pendence on  one  another,  permit  them  to 
change  their  places  whenever  they  are  ex- 
panded or  contracted  by  alternations  of 
temperature;  and  hence  the  immediate  and 
inevitable  effect  of  communicating  heat  to 


in  a  meadow  in  his  neighbourhood,  than  it 
was  in  a  similar  thermometer  suspended 
in  the  air  6  feet  above  the  former;  and  that 
upon  one  night  the  difference  amounted 
to  5°  of  Fahrenheit's  scale.  And  Dr.  Wells, 
in  autumn  1811,  on  laying  a  thermometer 
upon  grass  wet  with  dew,  and  suspending 
a  second  in  the  air  2  feet  above  the  sur- 
face, found  in  an  hour  afterwards,  that  the 
former  stood  8°  lower  than  the  latter.  He 
at  first  regarded  this  coldness  of  the  sur 


the  under  stratum  of  a  fluid  mass,  or  of  ab- 
stracting it  from  the  upper  stratum,  is  to 
determine  a  series  of  intestine  movements. 
The  colder  particles,  by  their  superior  den- 
sity, descend  in  a  perpetual  current,  and 


face  to  be  the  effect  of  the  evaporation  of    force  upwards  those  rarefied  by  the  heat. 


the  moisture,  but  subsequent  observations 
and  experiments  convinced  him,  that  the 
cold  was  not  the  effect,  but  the  cause  of 
deposition  of  dew.  Undef  a  cloudless  sky, 
the  earth  projects  its  heat  without  return, 


When  however  the  upper  stratum  primari- 
ly acquires  an  elevated  temperature,*  it 
seems  to  have  little  power  of  imparting 
heat  to  the  subjacent  strata  of  fluid  parti- 
cles. Water  may  be  kept  long  in  ebullition 


into  empty  space;  but  a  canopy  of  cloud  is     at  the  surface  of  a  vessel,  while  the  bottom 


a  concave  mirror,  which  restores  the  equi- 
librium by  counter-radiation.  See  DEW. 


remains  ice  cold,  provided  we  take  mea- 
sures to  prevent  the  heat  passing  down- 
On  this"  principle  Professor  Leslie  has  wards  through  the  sides  of  the  vessel  itself 
constructed  a  pretty  instrument,  which  he  Count  Rumford  became  so  strongly  per- 
calls  JEthrioscope,  whose  function  it  is  to  suaded  of  the  impossibility  of  communica- 
denote  the  clearness  and  coolness  of  the  ting  heat  downwards  through  fluid  parti 
sky.  It  consists  of  a  polished  metallic  cup,  cles,  that  he  regarded  them  as  utterly  des 
of  an  oblong  spheroidal  shape;  very  like  a  titute  of  the  faculty  of  transmitting  that 
silver  porter-cup,  standing  upright,  with  the  power  from  one  to  another,  and  capable  o1 

1_  11  /»         _          J'J3?        A.'    _   1        Al. «.,   In  ^s-isl  „.-'          '  1 .,  1--      *  «  1   •          •      1  1 


bulb  of  a  differential  thermometer  placed 
in  its  axis,  and  the  stem  lying  parallel  to 
the  stalk  of  the  cup.  The  other  ball  is  gilt, 
and  turned  outwards  and  upwards,  so  as 
to  rest  against  the  side  of  the  vessel.  The 


acquiring  heat,  only  in  individual  rotatior 
and  directly,  from  a  foreign  source.  The 
proposition  thus  absolutely  announced  if 
absurd,  for  we  know  that  by  intermixture 
and  many  other  modes,  fluid  particles 


best  form  of  the  cup  is  an  ellipsoid,  whose     part  heat  to  each  other;  and  experiment! 
eccentricity  is  equal  to  half  the  transverse     ' 
axis,  and  the  focus  consequently   placed  at 
the  third  part  of  the  whole   height  of  the 


have  been  instituted,  which  prove  the  ac 
tual  descent  of  heat  through  fluids  by  com 
munication  from  one  stratum  to  another 


cavity;  while  the  diameter  of  the  thermos-    But  unquestionably  this  communication  i 


cope  ball  should  be  nearly  the  third  part 
of  the  orifice  of  the  cup.  A  lid  of  the  same 
thin  metal  unpolished,  is  fitted  to  the 
mouth  of  the  cup,  and  removed  only  when 
an  observation  is  to  be  made.  The  scale  at- 


amazingly  difficult  and  slow.  We  are  henc< 
led  to  conceive,  that  it  is  an  actual  contac 
of  particles,  which  in  the  solid  conditioi 
facilitates  the  transmission  of  heat  s< 
speedily  from  point  to  point  through  thei 


tached  to  the  stem  of  the   thermoscope,     mass.  This  contact  of  certain  poles  in  th 


may  extend  to  60  or  70  millesimal  degrees 
above  the  zero,  and  about  15  degrees  be- 
low it. 

This  instrument  exposed  to  the  open  air 
in  clear  weather,  will  at  all  times,  both  dur- 
ing the  day  and  the  night,  "  indicate  an  im- 
pression of  cold  shot  downward  from  the 
higher  regions,"  in  the  figurative  language 
of  the  inventor.  Yet  the  effect  varies  ex- 
ceedingly. It  is  greatest  while  the  sky  has 
the  pure  azure  hue;  it  diminishes  fast  as  the 
atmosphere  becomes  loaded  with  spreading 
clouds;  and  it  is  almost  extinguished  when 
low  fogs  settle  on  the  surface.  The  liquid 


molecules,  is  perfectly  consistent  with  voi< 
spaces,  in  which  these  molecules  may  slid< 
over  each  other  in  every  direction;  b; 
which  movements  or  condensations,  hea 
may  be  excited  The  fluid  condition  revert 
or  averts  the  touching  and  cohering  poles 
whence  mobility  results.  This  statemen 
may  be  viewed  either  as  a  representatio 
of  facts,  or  an  hypothesis  to  aid  concep 
tion. 

Since  the   diffusion  of  heat  through 
fluid  mass  is  accomplished  almost  solel 
by  the   intestine   currents,   whatever  ob 
structs  these  must  obstruct  the  change  c 


CAL 


CAL 


temperature.  Hence  fluids  intermingled 
with  porous  matter,  such  as  silk,  wool,  cot- 
ton, downs,  fur,  hair,  starch,  mucilage,  &c. 
are  more  slowly  cooled  than  in  their  pure 
and  limpid  state.  Hence  apple-tarts  and 
pottages  retain  their  heat  very  long,  in 
comparison  of  the  same  bulk  of  water  heat- 
ed to  the  same  degree,  and  exposed  in 
similar  covered  vessels  to  the  cool  air.  Of 
the  conducting  power  of  gaseous  bodies, 
we  have  already  taken  a  view.  1  know  of  no 
experiments  which  have  satisfactorily  de- 
termined in  numbers,  the  relative  conduct- 
ing power  of  liquids.  Mercury  for  a  liquid, 
possesses  a  high  conducting  faculty,  due 
to  its  density  and  metallic  nature,  and 
small  specific  heat. 

The  transmission  of  heat  through  solids 
was  made  the  subject  of  some  pleasing  po- 
pular experiments  by  Dr.  Ingenhausz.  He 
took  a  number  of  metallic  rods  of  the  same 
length  and  thickness,  and  having  coated 
one  of  the  ends  of  them  for  a  few  inches 
with  beeswax,  he  plunged  their  other  ends 
into  a  heated  liquid.  The  heat  travelled  on- 
wards among  the  matter  of  each  rod,  and 
soon  became  manifest  by  the  softening  of 
the  wax.  The  following  is  the  order  in 
which  the  wax  melted;  and  according  to 
that  experiment,  therefore,  the  order  of 
conducting  power  relative  to  heat. 

1.  Silver. 

2.  Gold. 


Platinum,     i 

Iron,  \  much  inferior  to 

Steel,  1    the  others. 

Lead,  ) 

In  my  repetition  of  the  experiment,  I 
found  silver  by  much  the  best  conductor, 
next  copper,  then  brass,  iron,  tin,  much 
the  same,  then  cast  iron,  next  zinc,  and 
last  of  all,  lead.  Dense  stones  follow  metals 
in  conducting  power,  then  bricks,  pottery, 
and  at  a  long  interval,  glass.  A  rod  of  this 
singular  body  may  be  held  in  the  fingers 
for  a  long  time,  at  a  distance  of  an  inch 
from  where  it  is  ignited  and  fused  by  the 
blow-pipe.  It  is  owing  to  the  inferior  con- 
ducting power  of  stone,  pottery,  glass, 
and  cast  iron,  that  the  sudden  application 
of  heat  so  readily  cracks  them.  The  part 
acted  on  by  the  caloric  expands,  while  the 
adjacent  parts  retaining  their  pristine  form 
and  volume,  do  not  accommodate  them- 
selves to  the  change;  whence  a  fissure  must 
necessarily  ensue.  Woods  and  bones  are 
better  conductors  than  glass;  but  the  pro- 
gress of  heat  in  them  at  elevated  tempera- 
tures, may  be  aided  by  the  vaporization  of 
their  juices.  Charcoal  and  saw -dust  rank 
very  low  in  conducting  power.  Hence  the 
former  is  admirably  fitted  for  arresting  the 
dispersion  of  heat  in  metal  furnaces.  If  the 


sides  of  these  be  formed  of  double  plates, 
with  an  interval  between  them  of  an  inch 
filled  with  pounded  charcoal,  an  intense 
heat  may  exist  within,  while  the  outside  is 
scarcely  affected.  Morveati  has  rated  the 
conducting  power  of  charcoal  to  that  of 
fine  sand,  as  -<>  to  3,  a  difference  much  too 
small.  Spongy  organic  substances,  silk, 
wool,  cotton,  &c.  are  still  worse  conduct- 
ors than  any  of  the  above  substances;  and 
the  finer  the  fibres,  the  less  conducting 
power  they  possess.  The  theory  of  clothing 
depends  on  this  principle.  The  heat  gene- 
rated by  the  animal  powers,  is  accumula- 
ted round  the  body  by  the  imperfect  con- 
ductors of  which  clothing  is  composed. 

To  discover  the  exact  law  of  the  distri- 
bution of  heat  in  solids,  let  us  take  a  pris- 
matic bar  of  iron,  three  feet  long,  and  with 
a  drill  form  three  cavities  in  one  of  its 
sides,  at  10,  20,  and  30  inches  from  its  end, 
each  cavity  capable  of  receiving  a  little 
mercury,  and  the  small  bulb  of  a  delicate 
thermometer.  Cut  a  hole  fitting  exactly  the 
prismic  bar,  in  the  middle  of  a  sheet  of 
tin-plate,  which  is  then  to  be  fixed  to  the 
bar,  to  screen  it  and  the  thermometer, 
from  the  focus  of  heat.  Immerse  the  ex- 
tremity of  the  bar  obliquely  into  oil  or 
mercury  heated  to  any  known  degree,  and 
place  the  thermometers  in  their  cavities 
surrounded  with  a  little  mercury.  Or  the 
bar  may  be  kept  horizontal,  if  an  inch  or 
two  at  its  end  be  incurvated,  at  right  an- 
gles to  its  length.  Call  the  thermometers 
A,  B,  C.  Were  there  no  dissipation  of  the 
heat,  each  thermometer  would  continue  to 
mount  till  it  attained  the  temperature  of 
the  source  of  heat.  But  in  actual  experi- 
ments, projection  and  aerial  currents  mo- 
dify that  result,  making  the  thermometers 
rise  more  slowly,  and  preventing  them 
from  ever  reaching  the  temperature  of  the 
end  of  the  bar.  Their  state  becomes  in- 
deed stationary  whenever  the  excess  of 
temperature,  each  instant  communicated 
by  the  preceding  section  of  the  bar,  merely 
compensates  what  they  lose  by  the  contact 
of  the  succeeding  section  of  the  bar,  and 
the  other  outlets  of  heat.  The  three  ther- 
mometers now  indicate  three  steady  tem- 
peratures, but  in  diminishing  progression. 
In  forming  an  equation  from  the  experi- 
mental results,  M.  Laplace  has  shown,  that 
the  difficulties  of  the  calculation  can  be  re- 
moved only  by  admitting,  that  a  deter- 
minate point  is  influenced  not  only  by  those 
points  which  touch  it,  but  by  others  at  a 
small  distance  before  and  behind  it.  Then 
the  laws  of  homogeneity,  to  which  differ- 
entials are  subject,  are  re-established,  and 
all  the  rules  of  the  differential  calculus  are 
observed.  Now,  in  order  that  the  calorific 
influence  may  thus  extend  to  a  distance  in 
the  interior  of  the  bar,  there  must  operate 


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through  the  very  substance  of  the  solid  ele- 
ments a  true  radiation,  analogous  to  that 
observed  in  air,  but  whose  sensible  influ- 
ence is  bounded  to  distances  incomparably 
smaller.  This  result  is  in  no  respect  impro- 
bable. In  fact,  Newton  has  taught  us,  that 
all  bodies,  even  the  most  opaque,  become 
transparent  when  rendered  sufficiently 
thin;  and  the  most  exact  researches  on  ra- 
diating caloric,  prove  that  it  does  not«man- 
ate  solely  from  the  external  surface  of  bo- 
dies, but  also  from  material  particles  situa- 
ted within  this  surface,  becoming1  no  doubt 
insensible  at  a  very  slight  depth,  which 
probably  varies  in  the  same  body,  with  its 
temperature. 

M.  Biot,  M.  Fourier,  and  M.  Poisson, 
three  of  the  most  eminent  mathematicians 
and  philosophers  of  the  age,  have  distin- 
guished themselves  in  this  abstruse  inves- 
tigation. The  following  is  the  formula  of 
M.  Biot,  when  one  end  of  the  bar  is  main- 
tained at  a  constant  temperature,  and  the 
other  is  so  remote  as  to  make  the  influ- 
ence of  the  source  insensible.  Let  y  repre- 
sent, in  degrees  of  the  thermometer,  the 
temperature  of  the  air  by  which  the  bar  is 
surrounded;  let  the  temperature  of  the  fo- 
cus be  y  -f-  Y;  then  the  integral  becomes, 

log.t/^log.Y-^-^/^ 

a 

x  is  the  distance  from  the  hot  end  of  the 
bar;  a  and  b  are  two  coefficients,  supposed 
constant  for  the  whole  length  of  the  bar, 
which  serve  to  accommodate  the  formula 
to  every  possible  case,  and  which  must  be 
assigned  in  such  case,  agreeably  to  two  ob- 
servations. M  is  the  modulus  of  the  or- 
dinary logarithmic  tables,  or  the  number 
2.302585.  M.  Biot  presents  several  tables 
of  observations,  in  which  sometimes  8,  and 
sometimes  14  thermometers  were  applied 
all  at  once  to  successive  points  of  the  bar; 
and  then  he  computes  by  the  above  formu- 
la, what  ought  to  be  the  temperature  of 
these  successive  points,  having  given  the 
temperature  of  the  source;  and  vice  versa, 
what  should  be  the  temperature  of  the 
source  from  the  indications  of  the  ther- 
mometers. A  perfect  accordance  is  shown 
to  exist  between  fact  and  theory.  Whence 
we  may  regard  the  view  opened  up  by  the 
latter,  as  a  true  representation  of  the  con- 
dition of  the  bar.  With  regard  to  the  ap- 
plication of  this  theorem,  to  discover  for 
example,  the  temperature  of  a  furnace,  by 
thrusting  the  end  of  a  thermoscopic  iron 
bar  into  it,  we  must  regret  its  insufficiency. 
M.  Biot  himself  after  showing  its  exact  co- 
incidence at  all  temperatures,  up  to  that 
of  melting  lead,  declares  that  it  ought  not 
to  apply  at  high  heats.  But  I  see  no  diffi- 
culty in  making  a  very  useful  instrument 
of  this  kind,  by  experiment,  tb  give  very 
valuable  pyrometrical  indications.  The  end 


of  the  bar  which  is  to  be  exposed  to  the 
heat,  being  coated  with  fire-clay,  or  sheath- 
ed with  platinum,  should  be  inserted  a  few 
inches  into  the  flame,  and  drops  of  oil  be- 
ing put  into  three  successive  cavities  of 
the  bar,  we  should  measure  the  tempera- 
tures of  the  oil,  when  they  have  become 
stationary  and  note  the  time  elapsed,  to  pro- 
duce this  effect.  A  pyroscope  of  this  kind 
could  not  fail  to  give  useful  information  to 
the  practical  chemist,  as  well  as  to  the 
manufacturers  of  glass,  pottery,  steel,  &c. 

2.  Of  specific  heat.— If  we  take  equal 
weights,  or  equal  bulks,  of  a  series  of  sub- 
stances; for  example,  a  pound  or  a  pint  of 
water,  oil,  alcohol,  mercury,  and  having 
heated  each  separately,  in  a  thin  vessel,  to 
the  same  temperature,  say  to  80°  or  1UO* 
Fahr.  from  an  atmospherical  temperature 
of  60°,  then  in  the  subsequent  cooling  of 
these  four  bodies  to  their  former  state, 
they  will  communicate  to  surrounding  me- 
dia very  different  quantities  of  heat.  And 
conversely,  the  quantity  of  heat  requisite 
to  raise  the  temperature  of  equal  masses 
of  different  bodies,  an  equal  number  of 
thermometric  degrees,  is  different,  but 
specific  for  each  body.  There  is  another 
point  of  view  in  which  specific  heats  of  bo- 
dies may  be  considered  relative  to  their 
change  of  form,  from  gaseous  to  liquid, 
and  from  liquid  to  solid.  Thus  the  steam 
of  water,  at  21<;0,  in  becoming  a  liquid, 
does  not  change  its  thermometric  tempe- 
rature 212°,  yet  it  communicates,  by  this 
change,  a  vast  quantity  of  heat  to  sur- 
rounding bodies;  and,  in  like  manner,  li- 
quid water  at  32°,  in  becoming  the  solid 
called  ice,  does  not  change  its  temperature 
as  measured  by  a  thermometer,  yet  it  im- 
parts much  heat  to  surrounding  matter. 
We  therefore  divide  the  study  of  specific 
heats  into  two  branches:  1.  The  specific 
heats  of  bodies  while  they  retain  the  same 
state;  and  2.  The  specific  heats,  connected 
with,  or  developed  by,  change  of  state. 
The  first  has  been  commonly  called  the 
capacities  of  bodies  for  caloric;  the  second, 
the  latent  heat  of  bodies.  The  latter  we 
shall  consider  after  change  of  state. 

1.  Of  the  specific  heats  of  bodies,  while 
they  experience  no  change  of  state. 

Three  distinct  experimental  modes  have 
been  employed  to  determine  the  specific 
heats  of  bodies;  in  the  whole  of  which 
modes,  that  of  water  has  been  adopted  for 
the  standard  of  comparison  or  unity.  1.  In 
the  first  mode,  a  given  weight  or  bulk  of 
the  body  to  be  examined,  being  heated  to 
a  certain  point,  is  suddenly  mixed  with  a 
given  weight  or  bulk  of  another  body,  at 
a  different  temperature;  and  the  resulting 
temperature  of  the  mixture  shows  the  re- 
lation between  their  specific  heats.  Hence, 
if  the  second  body  be  water,  or  any  other 
substance  whose  relation  to  water  is  ascer- 


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tainecl,  the  relative  heat  of  die  first  to  that 
of  water  will  be  known.  It  is  an  essential 
precaution  in  using  this  mode,  to  avoid  all 
such  chemical  action  as  happens  in  mixing- 
water  with  alcohol  or  acids.  Let  us  take 
oil  for  an  example.  If  a  pound  of  it,  at  90° 
Fahr.  be  mixed  with  a  pound  of  water  at 
60°,  the  resulting  temperature  will  not  be 
the  mean  75°,  but  only  70°.  And  converse- 
ly, if  we  mix  a  pound  of  water  heated  to 
90°,  with  a  pound  of  oil  at  60°,  the  tempe- 
rature of  the  mixture  will  be  80°.  We  see 
here,  that  the  water  in  the  first  case  ac- 
quired 10°,  while  the  oil  lost  20°;  and  in 
the  second  case,  that  the  water  lost  10° 
while  the  oil  gained  20°.  Hence  we  say, 
that  the  specific  heat  of  water  is  double  to 
that  of  oil;  or  that  the  same  quantity  or  in- 
tensity of  heat  which  will  change  the  tem- 
perature of  oil  20°,  will  change  that  of  wa- 
ter only  10°;  and  therefore  if  the  specific 
beat,  or  capacity  for  heat,  of  water  be  call- 
ed 1.000,  that  of  oil  will  be  0.500.  When 
the  experiment  has  been,  from  particular 
circumstances,  made  with  unequal  weights, 
the  obvious  arithmetical  reduction,  for  the 
difference,  must  be  made.  This  is  the  ori- 
ginal method  of  Black,  Irvine,  and  Craw- 
ford. 

The  second  mode  is  in  some  respects  a 
modification  of  the  first.  The  heated  mass 
of  the  matter  to  be  investigated,  is  so  sur- 
rounded by  a  large  quantity  of  the  stand- 
ard substance  at  an  inferior  temperature, 
that  the  whole  heat  evolved  by  the  first, 
in  cooling,  is  received  by  the  second.  We 
may  refer  to  this  mode,  1st,  Wilcke's  prac- 
tice of  suspending  a  lump  of  heated  inetal 
in  the  centre  of  a  mass  of  cold  water  con- 
tained in  a  tin  vessel:  2</,  The  plan  of  La- 
voisier and  Laplace,  in  which  a  heated  mass 
of  matter  was  placed  by  means  of  their  ele- 
gant CALORIMETER,  in  the  centre  of  a 
shell  of  ice;  and  the  specific  heat  was  in- 
ferred from  the  quantity  of  ice  that  was  li- 
quefied: And  3d,  The  method  of  Berard 
and  Delaroche,  in  which  gaseous  matter, 
heated  to  a  known  temperature,  was  made 
to  traverse,  slowly  and  uniformly,  the  con- 
volutions of  a  spiral  pipe,  fixed  in  a  cylin- 
der of  cool  water,  till  this  water  rose  to 
a  stationary  temperature;  when  "reckon- 
ing from  this  point,  the  excess  of  the  tem- 
perature of  the  cylinder,  above  that  of  the 
ambient  air,  becomes  proportional  to  the 
quantity  of  heat  given  out  by  the  current 
of  gas  that  passed  through  the  cylinder." 
Kach  gas  was  definitely  heated,  'by  being 
passed  through  a  straight  narrow  tube, 
placed  in  the  axis  of  a  large  tube,  filled 
with  the  steam  of  boiling  water.  The  spe- 
cific heats  were  then  compared  to  water 
by  two  methods.  The  firbt  consists  in  sub- 
jecting the  cylinder,  which  they  call  the 
calorimeter,  to  the  action  of  a  current  of 
water  perfectly  regulur,  and  so  slow,  that 


it  will  hardly  produce  a  greater  effect  than 
the  current  of  the  different  gases.  The  se- 
cond method  consists  in  determining,  by 
calculation,  the  real  quantity  of  iieat  which 
the  calorimeter,  come  to  its  stationary  tem- 
perature, can  lose  in  a  given  time;  for  since, 
after  it  reaches  this  point,  it  does  not  be- 
come hotter,  though  the  source  of  heat 
continues  to  be  applied  to  it,  it  is  evident 
that  it  loses  as  much  heat  as  it  receives. 
MM.  Berard  and  Delaroche  employed  these 
two  methods  in  succession.  From  the  sin- 
gular ingenuity  of  their  apparatus,  and  pre- 
cision of  their  observations,  we  may  regard 
their  determinations  as  deserving  a  degree 
of  confidence  to  which  the  previous  results, 
on  the  specific  heat  of  the  gases,  are  not  at 
all  entitled.  They  have  completely  over- 
turned the  hypothetical  structures  of  Black, 
Lavoisier,  and  Crawford,  on  the  heat  de- 
veloped in  combustion  and  respiration, 
while  they  give  great  countenance  to  the 
profound  views  of  Sir  H.  Davy.  See  Coi-f. 

BUSTION. 

The  third  method  of  determining  the 
specific  heats  of  bodies,  is  by  raising  a 
given  mass  to  a  certain  temperature,  sus- 
pending it  in  a  uniform  cool  medium,  till 
it  descends  through  a  certain  number  of 
thermometric  degrees,  and  carefully  noting 
by  a  watch  the  time  elapsed.  It  is  evident, 
that  if  the  bodies  be  invested  with  the 
same  coating,  for  instance,  glass  or  bur- 
nished metals;  if  they  be  suspended  in  the 
same  medium,  with  the  same  excess  of 
temperature,  and  if  their  interior  constitu- 
tion relative  to  the  conduction  of  heat  be 
also  the  same,  then  their  specific  heats  will 
be  directly  as  the  times  of  cooling.  I  have 
tried  this  method,  and  find  that  it  readily 
gives,  in  common  cases,  good  approxima- 
tions. Some  of  my  results  were  published 
in  the  Annals  of  Phil,  for  October  1817,  on 
water,  sulphuric  acid,  spermaceti  oil,  and 
oil  of  turpentine.  "  A  thin  glass  globe,  ca- 
pable of  holding  18JO  grains  of  water,  was 
successively  filled  with  this  liquid,  and  with 
the  others;  and  being  in  each  case  heated 
to  the  same  degree,  was  suspended,  with 
a  delicate  thermometer  immersed  in  it,  in 
a  large  room  of  uniform  temperature.  The 
comparative  times  of  cooling1,  through  au 
equal  range  of  the  thermometric  scale, 
were  carefully  noted  by  a  watch  in  each 
case."  The  difference  of  mobility  in  the  li- 
quid particles  may  be  regarded  as  very 
trifling,  at  temperatures  from  lUo°  to  200°. 
At  inferior  temperatures,  under  80°  for  ex- 
ample, oil  of  vitriol,  as  well  as  spermaceti 
oil,  becoming  viscid,  would  introduce  er- 
roneous results. 

This  mode  has  been  lately  practised  with 
the  utmost  scientific  refinement  by  MM. 
Dulong  and  Petit.  Their  experiments  were 
made  on  ruetaia  reduced  to  fine  filings, 
strongly  pressed  into  a  cylindrical  vessel 


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of  silver,  very  thin,  very  small,  and  the 
axis  of  which  was  occupied  by  the  reser- 
voir of  the  thermometer.  This  cylinder, 
containing1  about  460  grains  of  the  sub- 
stance, heated  about  12°  F.  above  the  am- 
bient medium,  was  suspended  in  the  cen- 
tre of  a  vessel  blackened  interiorly,  sur- 
rounded with  melting1  ice,  and  exhausted 
of  air,  to  prolong1  the  period  of  refrigera- 
tion, which  lasted  generally  15  migutes. 
Their  results  have  disclosed  a  beautiful 
and  unforeseen  relation,  between  the  spe- 
cific heats  and  primitive  combining-  ratios 
or  atoms  of  the  metals;  namely,  that  the 
atoms  of  all  simple  bodies  have  exactly  the 
same  capacity  for  heat.  Hence  the  specific 
heat  of  a  simple  substance,  multiplied  into 
the  weight  of  its  atom  or  prime  equivalent, 
ought  to  give  always  the  same  product. 

The  law  of  specific  heats  being  thus  esta- 
blished for  elementary  bodies,  it  became 
very  important  to  examine,  under  the  same 
point  of  view,  the  specific  heats  of  com- 
pound bodies.  The  process  applying  indif- 
ferently to  all  substances,  whatever  be  their 
conductibility  or  state  of  aggregation,  they 
had  it  in  their  power  to  subject  to  experi- 
ment, a  great  many  bodies  whose  propor- 
tions may  be  considered  as  fixed;  but  when 
they  endeavoured  to  mount  from  these  de- 
terminations to  that  of  the  specific  heat  of 
each  compound  atom,  by  a  method  analo- 
gous to  that  employed  for  the  simple  bo- 
dies, they  found  themselves  stopped  by  the 
number  of  equally  probable  suppositions 
among  which  they  had  to  choose.  "  If 
the  method,"  say  they,  "  of  fixing  the 
weights  of  the  atoms  of  simple  bodies  has 
not  yet  been  subjected  to  any  certain  rule, 
that  of  the  atoms  of  compound  bodies  has 
been,  a  fortiori,  deduced  from  supposi- 
tions purely  arbitrary.'  They  satisfy  them- 
selves by  saying,  in  the  mean  time,  that, 
abstracting  every  particular  supposition, 
the  observations  which  they  have  hitherto 
made  tend  to  establish  this  remarkable 
law,  that  there  always  exists  a  very  simple 
ratio  between  the  capacity  for  heat  of  the 
compound  atoms,  and  that  of  the  element- 
ary atoms. 

We  shall  insert  here  tabular  views  of  the 
specific  heats  determined  by  the  recent  re- 
searches of  these  French  chemists,  reserv- 
ing, for  the  end  of  the  volume,  the  usual 
more  extended,  but  less  accurate  tables  of 
specific  heat.  MM.  Petit  and  Dulong  justly 
remark,  that  "  the  attempts  hitherto  made 
to  discover  some  laws  in  the  specific  heats 
of  bodies  have  been  entirely  unsuccessful. 
We  shall  not  be  surprised  at  this,  if  we  at- 
tend to  the  great  inaccuracy  of  some  of  the 
measurements;  for  if  we  except  those  of 
Lavoisier  and  Laplace  (unfortunately  very 
few),  and  those  by  Delaroche  and  Berard 
for  elastic  fluids,  we  are  forced  to  admit,  that 
the  greatest  part  of  the  others  are  extreme- 


ly inaccurate,  as  our  own  experiments  have 
informed  us,  and  as  might  indeed  be  con- 
cluded from  the  great  discordance  in  the 
results  obtained  for  the  same  bodies  by 
different  experimenters."  From  this  cen- 
sure, we  must  except  the  recent  results  of 
MM.  Clement  and  Desormes  on  gases, 
which  I  believe  may  be  regarded  as  enti- 
tled to  equal  confidence  with  those  of  Be- 
rard and  Delaroche. 

TABLE  I.—  Of  the  Specific  Heats  of  Gase6t 
by  MM.  HERAKD  and  DELAROCHE. 
Equal        Equal        Sp. 
volumes,  -weights.  Gravity. 
Air,  1.0000       1.0000    1.0000 

Hydrogen,  0.9033     12.3401     0.0732 

CarbonicAcid,  1.2583  0.8280  1.5196 
Oxygen,  0.9765  0.8848  1.1036 

Azote,  1.0000       1.0318     0.9691 

Oxide  of  Azote,  1.3503  0.8878  1.5209 
Olefiant  gas,  1.5530  1.5763  0.9885 

Carbonic  Oxide,  1.0340  1.0805  0.9569 
To  reduce  the  above  numbers  to  the 
standard  of  water,  three  different  methods 
were  employed;  from  which  the  three  num- 
bers, 0.2-198,  0.2697,  and  0.2813  were  ob- 
tained for  atmospheric  air.  The  experi- 
menters have  taken  0.2669  as  the  mean,  to 
which  all  the  above  results  are  referred,  as 
follows: 

TABLE  II. 

Water  1.0000 

Air  0.2669 

Hydrogen  gas       3.2936 

Carbonic  acid        0.2210 

Oxygen  0.2361 

Azote  0.2754 

Oxide  of  azote      0.2369 

Olefiant  gas  0.4207 

Carbonic  Oxide     0.2884 

Aqueous  vapour    0.8470 

The  following  are  the  results  given  by 

MM.    Clement   and  Desormes,   for   equal 

volumes  at  temperatures  from  0°  to  60° 

centigrade,  or  32°  to  140°  Fahr. 

TABLE  III. 

Inches  Clement  &   Delaroche 
Barom.  Desormes.  &  Berard. 
Atmospheric 

air  at  39.6        1.215        1.2396 

Ditto.          29.84        llOOO        1.0000 
Ditto.          14.92        0.693 
Ditto.  7.44        0.540 

Ditto.  3.74        0.368 

Do.  charged !    29.84        1.000 

with  ether,  5 

Azote,  29.84        1.000        1.0000 

Oxygen,  29.84        1.000        0.974 

Hydrogen,          29.84        0.664        0.9033 
Carbonic  acid,  29.84        1.500        1.2583 

The  relative  specific  heat  of  air  to  wa- 
ter, is  by  MM.  Clement  and  Desormes 
0.250  to  1.000,  or  exactly  onetfourth.  The 
last  table  which  is  extracted  from" the  Jour- 


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nal  de  Physique,  gives  the  specific  heat  of 
oxygen  by  Delai-oche  and  Berard,  a  little 
different  from  their  own  number,  Table  I. 
from  the  Annales  de  Chimie,  vol.  85.  The 
most  remarkable  result  given  by  M  M. 
Clement  and  Desormes  regards  carbonic 
acid,  which  being  reduced  to  the  standard 
of  weights,  gives  a  specific  heat  compared 
to  air  of  about  0.987  to  1.000,  while  oxy- 
gen is  only  0.9000.  The  former  tables  of 
Crawford  and  Dalton  give  the  sp.  heat  of 
oxygen  2.65,  and  of  carbonic  acid  0.586, 
compared  to  air  1.000.  And  upon  these 
Very  erroneous  numbers,  they  reared  their 
hypothetical  fabric  of  latent  heat,  combus- 
tion and  animal  temperature. 

We  shall  refer  to  the  above  table  in 
treating  of  combustion. 

We  see  from  the  experiments  on  air,  at 
different  densities,  that  its  specific  heat  di- 
minishes in  a  much  slower  rate  than  its 
specific  gravity.  When  air  is  expanded  to 
a  quadruple  volume,  its  specific  heat  be- 
comes 0.540,  and  when  expanded  to  eight 
times  the  volume,  its  specific  heat  is  0.368. 
The  densities  in  the  geometrical  progres- 
sion 1.  Y  •£  •§•  correspond  nearly  to  the  spe- 
cific heats  in  the  arithmetical  series  5,  4, 
3,  2.  Hence  also  the  specific  heat  of  atmos- 
pherical air,  and  of  probably  all  gases,  con- 
sidered in  the  ratio  of  its  weight  or  mass, 
diminishes  as  the  density  increases.  On 
the  principle  of  the  increase  of  specific 
heat,  relative  to  its  mass,  has  been  explain- 
ed the  long  observed  phenomenon  of  the 
intense  cold  which  prevails  on  the  tops  of 
mountains,  and  generally  in  the  upper  re- 
gions of  the  atmosphere;  and  also  that  of 
the  prodigious  evolution  of  heat,  when  air 
is  forcibly  condensed.  According  to  M. 
Gay-Lussac,  a  condensation  of  volume 
amounting  to  four-fifths,  is  sufficient  to 
ignite  tinder.  If  a  syringe  of  glass  be  used, 
a  vivid  flash  of  light  is  seen  to  accompany 
the  condensation. 

TABLE  IV.— Of  Specific  Heats  of  some  So- 
lids  determined  by  D  u  L  o  N  c  and  PETIT. 

Specific      Weight  of  Product 

heats,  that  the  atoms,  of  these 

of  water     oxygen  be-  two  num- 

being  100.  ing  1.  bers. 
Bismuth,  0.0288  13.300  0-3830 
Lead,  0.0293  12.950  0-3794 
Gold,  0.0298  12.430  0.3704 
Platinum,  0.0314  11.160  0.3740 
Tin,  0.0514  7.350  0.3779 
Silver,  0.0557  6.750  0.3759 
Zinc,  0.0927  4,030  0.3736 
Tellurium,  0.0912  4.030  0.3675 
Copper,  0.0949  3.957  0.3755 
Nickel,  0.1035  3.690  0.3819 

Iron,  0.1100          3.392  0.3731 

Cobalt,  0.1498          2.460        0.3685 

Sulphur,         0.1880          2.011        0.3780 
VOL.  I. 


The  above  products,  which  express  the 
capacities  of  the  different  atoms,  approach 
so  near  equality,  that  the  slight  differ- 
ences must  be  owing  to  slight  errors, 
either  in  the  measurement  of  the  capaci- 
ties, or  in  the  chemical  analyses,  especial- 
ly if  we  consider,  that  in  certain  cases, 
these  errors  derived  from  these  two 
sources,  may  be  on  the  same  side,  and  con- 
sequently be  found  multiplied  in  the  re- 
sult. Each  atom  of  these  simple  bodies 
seems,  therefore,  as  was  formerly  stated, 
to  have  the  same  capacity  for  heat 

An  important  question  now  occurs,  whe- 
ther the  relative  capacities  for  heat  of  dif- 
ferent solid  and  liquid  bodies  be  uniform 
at  different  temperatures,  or  whether  it 
vary  with  the  temperature?  This  question 
may  be  perhaps  more  clearly  expressed 
thus:  Whether  a  body,  in  cooling  a  certain 
thermometric  range  at  a  high  temperature, 
gives  out  the  same  quantity  of  heat  that 
it  does  in  cooling  through  the  same  range 
at  a  lower  temperature?  No  means  seem 
better  adapted  for  solving  this  problem, 
than  to  measure  the  refrigeration  produ- 
ced, by  the  same  weights  of  ice,  on  uni- 
form weights  of  water,  at  different  tempera- 
tures. Mr.  Dalton  found  in  this  way,  that 
"  176.5°  expresses  the  number  of  degrees 
of  temperature,  such  as  are  found  be- 
tween 200°  and  212°  of  the  old  or  com- 
mon scale,  entering  into  ice  of  32°  to  con- 
vert it  into  water  of  32°;  150°  of  the  same 
scale,  between  122°  and  130°,  suffice  for 
the  same  effect;  and  between  45°  and  50°, 
128°  are  adequate  to  the  conversion  of  the 
same  ice  to  water.  These  three  resulting 
numbers,  (128,  150,  176.5),  are  nearly  as 
5,  6,  7-  Hence  it  follows,  that  as  much  heat 
is  necessary  to  raise  water  5°  in  the  lower 
part  of  the  old  scale,  as  is  required  to  raise 
it  7C  in  the  higher,  and  6°  in  the  middle." 
See  his  New  System  of  Chemical  Philos.  vol.  i. 
p.  53. 

Mr.  Dalton,  instead  of  adopting  the  ob- 
vious conclusion,  that  the  capacity  of  wa- 
ter for  heat  is  greater  at  lower  than  it  is 
at  higher  temperatures,  and  that  there- 
fore a  smaller  number  of  degrees  at  the 
former,  should  melt  as  much  ice  as  a  great- 
er number  at  the  latter,  ascribes  the  devia- 
tion denoted  by  these  numbers,  5,  6,  and  7, 
to  the  gross  errors  of  the  ordinary  ther- 
mometric graduation,  which  he  considers 
so  excessive,  as  not  only  to  equal,  but  great- 
ly to  overbalance  the  really  increased  spe- 
cific heat  or  capacity  of  water;  which, 
viewed  in  itself,  he  conceives  would  have 
exhibited  opposite  experimental  results. 
That  our  old,  and,  according  to  his  notions, 
obsolete  thermometric  scale,  has  no  such 
prodigious  deviation  from  truth,  is,  I  be- 
lieve, now  fully  admitted  by  chemical  philo- 
sophers; and  therefore  the  only  legitimate 
30 


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inference  from  these  very  experiments  of 
Mr.  Dalton,  is  the  decreasing  capacity  of 
water,  with  the  increase  of  its  temperature. 
It  deserves  to  be  remarked,  that  my  ex- 
periments on  the  relative  times  of  cooling 
a  globe  of  glass,  successively  filled  with 
water,  oil  of  vitriol,  common  oil,  and  oil  of 
turpentine,  give  exactly  the  same  results  as 
Mr.  Dalton  had  derived  from  mixtures  of 
two  ounces  of  ice  with  60  of  water,  aj.  dif- 
ferent temperatures.  This  concurrence  is 
the  more  satisfactory,  since  when  my  pa- 
per on  the  specific  heats  of  the  above  bo- 
dies, published  in  the  Annals  of  Philosophy 
for  October  1817,  was  written,  I  had  no  re- 
collection of  Mr.  Dalton's  expei'iments. 

In  the  Annals  of  Philosophy  for  March 
1819,  Dr.  Thomson  has  made  the  following 
remarks  in  reviewing  my  paper  on  heat: 
"The  second  topic  which  Dr.  Ure  discusses 
in  this  paper,  is  Mr.  Dalton's  opinion  that 
the  common  thermometer  is  an  inaccurate 
measurer  of  heat,  and  that  mercury  and  all 
liquids  expand  as  the  square  of  the  tem- 
perature, reckoning  from  the  freezing 
point.  It  is  not  necessary  to  give  a  particu- 
lar detail  of  the  facts  contained  in  this  part, 
as  Mr.  Dalton's  opinions  on  this  subject  had 
been  already  overturned  by  the  experi- 
ments of  Dulong  and  Petit.  Dr.  Ure's  no- 
tion, that  the  capacity  of  bodies  for  heat 
diminishes  as  the  temperature  increases, 
is  directly  contrary  to  the  results  of  the 
experiments  of  Dulong  and  Petit  on  the 
subject.  It  seems  also  contrary  to  analogy 
in  other  cases.  We  know  that  the  capacity 
of  elastic  fluids  increases  as  they  become 
rarer,  and  that  the  rarest  of  all  the  elastic 
fluids  has  the  greatest  capacity.  It  is  rea- 
sonable, I  think,  that  this  should  be  the 
case;  for  the  further  the  particles  of  a  body 
are  removed  from  each  other,  the  greater 
must  the  quantity  of  heat  be,  which  shall 
be  capable  of  producing  a  given  effect  on 
it."  From  the  early  part  of  this  passage, 
readers  of  the  Annals  would  naturally  in- 
fer, that  I  had  undertaken  a  refutation 
which  had  been  already  accomplished.  But 
it  is  consistent  with  Dr.  Thomson's  person- 
al knowledge,  that  my  paper  on  heat  was 
finished  and  sent  off  to  London  many 
months  before  the  paper  of  MM.  Dulong 
and  Petit  was  published.  Besides,  in  a  ques- 
tion of  such  vital  importance  to  the  whole 
of  physical  science,  as  whether  the  ther- 
mometer be  a  crude  or  correct  indicator  of 
the  increments  of  temperature,  it  is  surely 
desirable  to  have  the  investigation  con- 
ducted in  two  original  and  independent 
methods.  Dr.  Thomson  has  misconceived 
my  views  with  regard  to  capacity.  I  ad- 
duce some  experimental  evidence  to  show 
that  the  capacity  of  water  for  heat  dimi- 
nishes as  we  raise  it  from  the  freezing 
to  the  boiling  point;  but  I  did  not  so  far 
violate  the  rules  of  philosophy,  as  to  make 


a  general  inference  from  a  particular  case, 
a  practice,  it  must  be  confessed,  too  com- 
mon with  some  chemical  writers.  So  far 
from  asserting  the  proposition  for  all  bo- 
dies, the  idea  is  thrown  out,  of  its  being 
perhaps  a  property  peculiar  to  water,  like 
that  of  its  expanding  by  dimiuntion  of  its 
heat,  after  being  cooled  down  to  39°. 

The  total  absence  in  the  gases  of  cohe- 
sive attraction,  that  power  which  governs 
the  phenomena  of  solids  as  to  heat,  and 
modifies  those  of  liquids,  renders  the  ana- 
logy of  elastic  fluids  adduced  by  Dr.  Thom- 
son quite  irrelevant.  "  The  above  circum- 
stance in  water,  renders  it  peculiarly  quali- 
fied for  serving  as  the  magazine  and  equal- 
izer of  the  temperature  of  the  globe.  Since 
at  our  ordinary  atmospherical  heats,  it 
possesses  the  greatest  capacity  for  caloric, 
small  variations  in  its  temperature  gave  it 
a  great  modifying  power  over  the  circum- 
ambient air."  See  New  Experimental  Re- 
searches on  some  of  the  leading  doctrines 
of  Caloric,  in  the  Philosophical  Transac- 
tions for  1818,  or  in  Tilloch's  Magazine, 
vol.  53.  I  have  looked  with  attention  over 
MM.  Dulong  and  Petit's  paper,  for  the  re- 
sults of  their  experiments  on  the  subject, 
which  Dr.  Thomson  pronounces  to  be  di- 
rectly contrary  to  mine,  but  I  could  find 
nothing  which  affects  my  proposition  with 
regard  to  water.  Their  experiments  lead 
them  to  conclude,  that  the  capacities  of  the 
following  metallic  bodies  increase  with  the 
elevation  of  their  temperature,  in  the  fol- 
lowing proportions. 

TABLE  V.—  Of  Capacities  for  Heat. 


Mean  capacity  bet-ween 

0°  and  100°. 
Mercury,        0.0330 
Zinc,     '  0.0927 

Antimony,       0.0507 
Silver,  0.0557 

Copper,  0.0949 

Platinum,        0.0355 
Glass,  0.1770 


Mean  capacity  be- 


0.0350 
0.1015 
0.0549 
0.06  LI 
0.1013 
0.0355 
0.1900 


The  capacity  of  iron  was  determined  at 
the  four  following  intervals: 

From  0°  to  100°,  the  capacity  is  0.1098 
0°  to  200  0.1150 

0°  to  300  0.1218 

0°  to  350  0.1255 

If  we  estimate  the  temperatures,  as  some 
philosophers  have  proposed,  by  the  ratios 
of  the  quantities  of  heat  which  the  same 
body  gives  out  in  cooling  to  a  determinate 
temperature,  in  order  that  this  calculation 
be  exact,  it  would  be  necessary  that  the 
body  in  cooling,  for  example,  from  300°  to 
0°,  should  give  out  three  times  as  much 
heat  as  in  cooling  from  100°  to  0°.  But  it 
will  give  out  more  than  three  times  as 
much,  because  the  capacities  are  increas- 
ing. "We  should  therefore  find  too  high  a 


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temperature.  We  exhibit  in  the  following 
table  the  temperatures  that  would  be  de- 
duced by  employing  the  different  metals 
contained  in  the  preceding  table  We  must 
suppose  that  they  have  been  all  placed  in 
the  same  liquid  bath  at  300°,  measured  by 
an  air  thermometer. 

Iron,       -         -         -        332/2° 
Mercury,   -         -  318.2 

Zinc,      -         -         -         328.5 
Antimony,  324.8 

Silver,    "        -         -         329.3 
Copper,  320.0 

Platinum,       -        -        317.9 
Glass,      -  322.1 

Experiments  have  been  instituted,  and 
theorems  constructed,  for  determining  the 
absolute  quantity  of  heat  in  bodies,  and  the 
point  of  the  total  privation  of  that  power, 
or  of  absolute  cold,  on  the  thermometric 
scale.  The  general  principle  on  which 
most  of  the  inquirers  have  proceeded  is 
due  to  the  ingenuity  of  Dr.  Irvine.  Suppos- 
ing, for  example,  the  capacity  of  ice  to  be 
to  that  of  water  as  8  to  10,  at  the  tem- 
perature of  32°,  we  know  that  in  order  to 
liquefy  a  certain  weight  of  ice,  as  much 
heat  is  required  as  would  heat  the  same 
weight  of  water  to  140°  Kahr.  Hence  140° 
represent  two-tenths  or  one-fifth  of  the 
whole  heat  of  fluid  water;  and  therefore 
the  whole  heat  would  be  5  X  140°  =  700° 
below  32°.  It  is  needless  to  present  any 
algebraic  equations  on  a  principle  which  is 
probably  erroneous,  and  which  has  certain- 
ly produced  in  experiment  most  discordant 
results.  Mr.  Dalton  has  given  a  general 
view  of  them  in  his  section  on  the  zero  of 
temperature. 

If  we  estimate  the  capacity  of  ice  to  that 
of  water  as  9  to  10,  then  the  zero  will  come 
out  -  H00° 

Gadolin,  from  the  heat  evolved^  2936° 
in  mixing  sulphuric  acid  and  water  j  1710 
in  different  proportions, and  compa-  I  1510 
ring  the  capacity  of  the  compound  ,'2637 
with  those  of  its  components,  declu-  |  3230 
ced  the  opposite  numbers,  J  1740 

Mr.  Dalton,  from    sulphuric  acid  and 

water, 640t>° 

Do.  do.  do.  4150 

Do.  do.  do.  6000 

He  thinks  these  to  be  no  nearer  approxi- 
mations to  the  truth  than  Gadolin's. 
From  the  heat  evolved  in  slaking"^ 
lime,  compared  to  the  specific  heats  j 
of  the  compound,  and  its  constitu-  )-4260 
ents,  lime  and  water,   Mr.  Dalton  | 
gives  as  the  zero,  J 

From  nitric  acid  and  lime,  Mr.  Dalton 
finds  -  -  -  11 000 

From  the  combustion  of  hydrogen,  5400 
From    Lavoisier    and  Laplace's  experi- 
ments on  slaked  lime,  3428 
From   their  expei'iments    on    sulphuric 
asid  and  water,                                     7262 


Do.  do.  do.  259S 

Do.  from  nitric  acid  and  lime,  -{-  23837 
Dr.  Irvine  placed  it  below  30°,  —  900 
Dr.  Crawford  do.  do.  =  1500 

The  above  result  of  Lavoisier  and  La- 
place on  nitric  acid  and  lime,  shows  the 
theorem  in  a  very  absurd  point  of  view,  for 
it  places  the  zero  of  cold,  above  melting 
platina.  MM.  Clement  and  Desormes  have 
been  lately  searching  after  the  absolute 
zero,  and  are  convinced  that  it  is  at  266.66° 
below  the  zero  of  the  centigrade  scale,  or 
—  448°  F.  This  is  a  more  conceivable  re- 
sult. But  MM.  Dulong  and  Petit  have  been 
led  by  their  investigation  to  fix  the  abso- 
lute zero  at  infinity.  "  This  opinion,"  say 
they,  "  rejected  by  a  great  many  philoso- 
phers because  it  leads  to  the  notion,  that 
the  quantity  of  heat  in  bodies  is  infinite, 
supposing  their  capacity  constant,  becomes 
probable,  now  that  we  know  that  the  spe- 
cific heats  diminish  as  the  temperatures 
sink.  In  fact  the  law  of  this  diminution 
may  be  such,  that  the  integral  of  heat,  ta- 
ken to  a  temperature  infinitely  low,  may 
notwithstanding  have  a  finite  value."  They 
farther  infer,  that  the  quantity  of  heat  de- 
veloped at  the  instant  of  the  combination 
of  bodies  has  no  relation  to  the  capacity  of 
the  elements;  and  that  in  the  greatest  num- 
ber of  cases  this  loss  of  heat  is  not  follow- 
ed by  any  diminution  in  the  capacity  of  the 
compounds  formed.  This  consequence  of 
their  researches,  if  correct,  is  fatal  to  the 
theorem  of  Irvine,  and  to  all  the  inferences 
that  have  been  drawn  from  it. 

3.  Of  the  general  habittnles  of  heat t  with 
the  different  forms  of  matter. 

The  effects  of  heat  are  either  transient 
and  physical;  or  permanent  and  chemical, 
inducing  a  durable  change  in  the  constitu- 
tion of  bodies.  The  second  mode  of  opera- 
tion we  shall  treat  of  under  COMBUSTION. 
The  first  falls  to  be  discussed  here;  and 
divides  itself  naturally  into  the  two  heads, 
of  changes  in  the  volume  of  bodies  while 
they  retain  their  form,  and  changes  in  the 
state  of  bodies. 

1st,  The  successive  increments  of  vol- 
ume which  bodies  receive  with  successive 
increments  of  temperature,  have  been  the 
subjects  of  innumerable  researches.  The 
expansion  of  fluids  is  so  much  greater  than 
that  of  solids  by  the  same  elevation  of  their 
temperature,  that  it  becomes  an  easy  task 
to  ascertain  within  certain  limits  the  aug- 
mentation of  volume  which  liquids  :.nd 
gases  suffer  through  a  moderate  thermo- 
metric range.  \Ve  have  only  to  enclose 
them  in  a  glass  vessel  of  a  proper  form, 
and  expose  it  to  heat.  But  to  determine 
their  expansions  with  final  accuracy,  and 
free  the  results  from  the  errors  arising 
from  the  unequable  expansion  of  the  reci- 
pient, is  a  problem  of  no  small  difficulty. 
It  seems,  however,  afler  many  vain  at- 


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tempts  by  precedi ng  experimenters,  to  h ave 
been  finally  solved  by  MM.  Dulong  and 
Petit.  The  expansion  of  solids  had  been 
previously  measured  with  considerable  ac- 
curacy by  several  philosophers,  particular- 
ly by  Smeaton,  Roy,  Ramsden,  and  Trough- 
ton,  in  this  country,  and  Lavoisier  and  La- 
place in  France.  The  method  devised  by 
Genl.  Roy,  and  executed  by  him  in  conjunc- 
tion with  Ramsden,  deserves  the  pjefer- 
ence.  The  metallic  or  other  rod,  the  sub- 
ject of  experiment,  was  pluced  horizontally 
in  a  rectangular  trough  of  water,  which 
could  be  conveniently  heated.  At  any  ali- 
quot distance  on  the  rod,  two  micrometer 
microscopes  were  attached  at  right  angles, 
so  that  each  being  adjusted  at  first  to  two 
immoveable  points,  exterior  to  the  heating 
apparatus,  when  the  rod  was  elongated  by 
heat,  the  displacement  of  the  microscopes 
could  be  determined  to  a  very  minute  quan- 
tity, to  the  twenty  or  thirty  thousandth  of 
an  inch,  by  the  micrometrical  mechanism. 
The  apparatus  of  Lavoisier  and  Laplace 
was  on  Smeaton's  plan,  a  series  of  levers; 
but  differed  in  this  respect,  that  the  last 
lever  gave  a  vertical  motion  to  a  telescope 
of  six  feet  focal  length,  whose  quantity  of 
displacement  was  determined  by  a  scale  in 
its  field  of  view  from  100  to  200  yards  dis- 
tant. This  addition  of  a  micrometrical  tel- 
escope was  ingenious;  but  the  whole  me- 
chanism is  liable  to  many  objections,  from 
which  that  of  Ramsden  was  free.  Still,  when 
managed  by  such  hands  and  heads  as  those 
of  Lavoisier  and  Laplace,  we  must  regard 
its  results  with  veneration.  MM.  Dulong 
and  Petit  have  measured  the  dilatations  of 
some  solids,  as  well  as  mercury,  on  plans 
which  merit  equal  praise  for  their  origi- 
nality and  philosophical  precision.  They 
commenced  with  mercury.  Their  method 
with  it  is  founded  on  this  incontestable  law 
of  hydrostatics,  that  when  two  columns  of 
a  liqurd  communicate  by  means  of  a  lateral 
tube,  the  vertical  heights  of  these  two  co- 
lumns are  precisely  the  inverse  of  their 
densities.  In  the  axis  of  two  upright  cop- 
per cylinders,  vertical  tubes  of  glass  were 
fixed,  joined  together  at  bottom  by  an  hori- 
zontal glass  tube  resting  on  a  levelled  iron 
bar.  One  of  the  cylinders  was  charged  with 
ice,  the  other  with  oil  to  be  warmed  at 
pleasure  by  a  subjacent  stove.  The  rect- 
angular inverted  glass  syphon  was  filled 
nearly  to  the  top  with  mercury,  and  the 
height  at  which  the  liquid  sto'od  in  each 
leg  was  determined  with  nicety  by  a  teles- 
copic micrometer,  revolving  in  a  horizon- 
tal plane  on  a  vertical  rod.  The  telescope 
had  a  spirit  level  attached  to  it,  and  could 
be  moved  up  or  down  a  very  minute  quan- 
tity by  a  fine  screw.  The  temperature  of 
the  oil,  the  medium  of  heat,  was  measured 
by  both  an  air  and  a  mercurial  thermome- 
ter, whose  bulbs  occupied  nearly  the  whole 


vertical  extent  of  the  cylinder.  The  elon- 
gation of  the  heated  column  of  mercury 
could  be  rigorously  known  by  directing  the 
eye  through  the  micrometer,  first  to  its 
surface,  and  next  to  that  in  the  ice-cold  leg. 
Having  by  a  series  of  careful  trials  ascer- 
tained the  expansions  of  mercury  throug'h 
different  thermometric  ranges,  they  then 
determined  the  expansion  of  glass  from  the 
apparent  expansions  of  mercury  within  it. 
They  filled  a  thermometer  with  well  boiled 
mercury,  and  plunging  it  into  ice,  waited 
till  the  liquid  became  stationary,  and  then 
cut  across  the  stem  at  the  point  where  the 
mercury  stood.  After  weighing  it  exactly, 
they  immersed  it  for  some  time  in  boil- 
ing water.  On  withdrawing,  wiping,  and 
weighing  it,  they  learned  the  quantity  of 
mercury  expelled,  which  being  compared 
with  the  whole  weight  of  the  mercury  in  it 
at  the  temperature  of  melting  ice,  gave  the 
dilatation  of  volume.  This  is  precisely  the 
plan  employed  long  ago  by  Mr.  Crightou, 
as  well  as  myself,  and  which  gave  the  quan- 
tity 1-63(1,  employed  in  my  paper  for  the 
apparent  dilatation  of  mercury  in  glass. 

Their  next  project  was  to  measure  the 
dilatation  of  other  solids;  and  this  they  ac- 
complished with  much  ingenuity  by  en- 
closing a  cylinder  of  the  solid,  iron  for  ex- 
ample, in  a  glass  tube,  which  was  filled  up 
with  mercury,  after  its  point  had  been 
drawn  out  to  a  capillary  point.  The  mercu- 
ry having  been  previously  boiled  in  it,  to 
expel  all  air  and  moisture,  the  tube  was 
exposed  to  different  temperatures.  By  de- 
termining the  weight  of  the  mercury  which 
was  driven  out,  it  was  easy  to  deduce  the 
dilatation  of  the  iron;  for  the  volume  driven 
out  obviously  represents  the  sum  of  the  di- 
latations of  the  mercury  and  the  metal,  di- 
minished by  the  dilatation  of  the  glass.  To 
make  the  calculation,  it  is  necessary  to 
know  the  volumes  of  these  three  bodies  at 
the  temperature  of  freezing  water;  but  that 
of  the  iron  is  obtained  by  dividing  its  weight 
by  its  density  at  3i°.  We  deduce  in  the 
same  manner  the  volume  of  the  glass  from 
the  quantity  of  mercury  which  fills  it  at 
that  temperature.  That  of  the  mercury  is 
obviously  the  difference  of  the  first  two. 
The  process  just  pointed  out  may  be  ap- 
plied likewise  to  other  metals,  taking  the 
precaution  merely  to  oxidize  their  surface 
to  hinder  amalgamation. 

In  the  years  1812  and  1813  I  made  many 
experiments  with  a  micrometrical  appara- 
tus of  a  peculiar  construction,  for  measur- 
ing the  dilatation  of  solids.  I  was  particu- 
larly perplexed  with  the  rods  of  zinc,  which 
after  innumerable  trials  I  finally  found  to 
elongate  permanently  by  being  alternately 
heated  and  cooled.  It  would  seem  that  the 
plates  composing  this  metal,  in  sliding  over 
each  other  by  the  expansive  force  of  heat, 
present  such  an  adhesive  friction  as  to  pre- 


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vent  their  entire  retraction.  It  would  be  de- 
sirable to  know  the  limit  of  this  effect,  and 
to  see  what  other  metals  are  subject  to  the 
same  change.  1  hope  to  be  able  ere  long 
to  finish  these  pyrometrical  researches. 


I  shall  now  present  a  copious  table  of  di- 
latations, newly  compiled  from  the  best  ex- 
periments. 


TABLE  I.— Linear  Dilatation  of  Solids  by  Heat. 


Dimensions  which  a  bar  takes  at 

212°,  whose  length  at  32°  i 

5  1.000000. 

Dilatation 

in  Vulgar 

Fractions. 

Glass  tube, 

Smeaton, 

1.00083333 

do. 

Roy, 

1.00077615 

do. 

Deluc's  mean, 

1.00082800 

do. 

Dulong  and  Petit, 

1.00086130 

TTT3" 

do. 

Lavoisier  and  Laplace, 

1.00081166 

TlW 

Plate  glass, 

do.                     do. 

1.000890890 

TTW 

do.  crown  glass, 

do.                     do. 

1.00087572 

TTT¥ 

do.               do. 

do.                     do. 

1.00089760 

TTTT 

do.               do. 

do.                     do. 

1.00091751 

ToTO 

do.  rod, 

Roy, 

1.00080787 

Deal, 

Roy,  as  glass, 

Platina, 

Borda, 

1.00085655 

do. 

Dulong  and  Petit, 

1.00088420 

TT^T 

do. 

Troughton, 

1.00099180 

do.     and  glass, 

Berthoud, 

1.00110000 

Palladium, 

\Vollaston, 

1.00100000 

Antimony, 

Smeaton, 

1.00108300 

Cast  iron  prism, 

Roy, 

1.00110940 

Cast  iron, 

Lavoisier,  by  Dr.  Young, 

1.00111111 

Steel, 

Troughton, 

1.00118990 

Steel  rod, 

Roy, 

1.00114470 

Blistered  steel, 

Phil.  Trans.  1795.  428, 

1.00112500 

do. 

Smeaton, 

1.00115000 

Steel  not  tempered, 

Lavoisier  and  Laplace, 

1.00107875 

•sir 

do.  do.         do. 

do.                 do. 

1.00107956 

i 

do.  tempered  yellow, 

do.                 do. 

1.00136900 

do.         do.         do. 

do.                 do. 

1.00138600 

do.         do.        do.  at  a  higher  heat 

,              do.                 do. 

1.00123956 

¥o'7 

Steel, 

Troughton, 

1.00118980 

Hard  steel, 

Smeaton, 

1.00122500 

Annealed  steel, 

Muschenbroek, 

1.00122000 

Tempered  steel, 

do. 

1.00137000 

Iron, 

Borda, 

1.00115600 

do. 

Smeaton, 

1.00125800 

Soft  iron  forged, 

Lavoisier  and  Laplace, 

1.0012204: 

Round  iron,  wire-drawn, 

do.                 do. 

100123504 

Iron  wire, 

Troughton, 

1.00144010 

Iron, 

Dulong  and  Petit, 

1.00118203 

•ffis" 

Bismuth, 

Smeaton, 

1.00139200 

Annealed  gold, 

Muschenbroek, 

1.00146000 

Gold, 

Ellicot,  by  comparison, 

1.00150000 

f 

do.  procured  by  parting, 

Lavoisier  and  Laplace, 

1.00146606 

¥*1 

do.  Paris  standard,  unannealed. 

do.                  do. 

1.00155155 

<T*T 

do.           do.               annealed, 

do.                  do. 

1.00151361 

rft 

Copper, 

Muschenbroek, 

1.0019100 

do. 

Lavoisier  and  Luplace, 

1.00172244 

tfl 

do. 

do.                 do. 

1.00171222 

T8~T 

do. 

Troughton, 

1.00191880 

1 

do. 

Dulong  and  Petit, 

1.00171821 

TV* 

Brass, 

Borda, 

1.00178300 

do. 

Lavoisier  and  Laplace, 

1.00186671 

do. 

do.                    do. 

1.00188971 

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Brass  scale,  supposed  from  Hamburgh, 

Cast  brass, 

English  plate-brass,  in  rod, 

do.  do.          in  a  trough  form, 

Brass, 
Brass  wire, 
Brass, 

Copper  8,  tin  1, 
Silver, 

do. 

do. 

do.  of  cupel, 

do.  Paris  standard, 
Silver, 

Brass  16,  tin  1, 
Speculum  metal, 
Spelter  solder;  brass  2,  zinc  1, 
Malacca  tin, 
Tin  from  Falmouth, 
Fine  pewter, 
Grain  tin, 
Tin, 

Soft  solder;  lead  2,  tin  1, 
Zinc  8,  tin  1,  a  little  hammered, 
Lead, 

do. 
Zinc, 

Zinc,  hammered  out  £  inch  per  foot, 
Glass,  from  32°,  to  212°, 

do.     from  212°,  to  392°, 

do.     from  392°,  to  572°, 
The  last  two  measurements  by  an  air  thermometer. 


Roy, 

1.00185540 

Smeaton,    - 

1.00187500 

Roy, 

1.00189280 

do. 

1.00189490 

Troughton, 

1.00191880 

Smeaton, 

1.00193000 

Muschenbroek, 

1.00216000 

Smeaton, 

1.00181700 

Herbert, 

1.00189000 

Ellicot,  by  comparison, 

1.0021000 

Muschenbroek, 

1.00212000 

Lavoisier  and  Laplace, 

1.00190974 

TzT 

do.                     do. 

1.00190868 

•?2~4 

Troughton, 

1.0020826 

Smeaton, 

1.00190800 

do. 

1.00193300 

do. 

1.00-05800 

Lavoisier  and  Laplace, 

1.00193765 

TTf 

do.                     do. 

1.00217298 

4*2 

Smeaton, 

1.00228300 

do. 

1.00248300 

Muschenbroek, 

1.00284000 

Smeaton, 

1.00250800 

do. 

1.00269200 

Lavoisier  and  Laplace, 

1.00284836 

?T1 

Smeaton, 

1.00286700 

do. 

1.00294200 

Smeaton, 

1.00301100 

Dulong  and  Petit, 

1.00086130 

TiVr 

do.                do. 

1.00091827 

TF5T 

do.                do. 

1.00101114 

TST 

To  obtain  the  expansion  in  volume,  mul- 
tiply the  above  decimal  quantities  by  three, 
or  divide  the  denominators  of  the  vulgar 
fractions  by  three;  the  quotient  in  either 
case  is  the  dilatation  sought. 

We  see  that  a  condensed  metal,  one  whose 
particles  have  been  forcibly  approximated 
by  the  wire-drawing  process,  expands  more, 
as  might  be  expected,  than  metals  in  a 
looser  state  of  aggregation.  The  result  for 
pewter,  1  conceive,  must  be  inaccurate. 
Lead  ought  to  communicate  to  tin,  surely, 
a  greater  expansive  property.  Borda's  mea- 
sure of  platina  is  important.  It  was  observ- 
ed with  the  rules  which  served  for  mea- 
suring the  base  of  the  trigonometrical  sur- 
vey in  France.  The  observations  in  the  ta- 
ble on  tempered  steel,  are,  I  believe,  by 
that  eminent  artist,  Fortin,  though  they  are 
included  in  the  table  which  M.  Biot  publish- 
ed, under  the  title  of  Lavoisier  and  Laplace. 

The  amount  of  the  dilatation  of  metals 
becomes  very  useful  to  determine,  in  cer- 
tain cases,  the  change  of  dimension  to 
which  astronomical  instruments  are  liable. 
Thus  in  measuring  a  base  for  the  grand 
operation  of  the  meridian  of  France,  Bor- 
da  sought  to  elude  the  uncertainties  arising 
from  expansion  of  the  measuring  rods,  by 
combining  metallic  bars,  so  that  they  indi- 
cated, of  themselves,  their  variations  of 
temperature,  and  of  length.  A  rule  of  pla- 


tina, twelve  feet  long,  was  attached  by  one 
of  its  extremities  to  a  rule  of  copper  some- 
what shorter,  which  rested  freely  on  its 
surface,  when  placed  in  a  horizontal  posi- 
tion. Towards  the  loose  end  of  the  copper 
rule,  there  was  traced  on  the  platina  rule 
very  exact  linear  divisions,  the  parts  of 
which  were  millionths  of  the  total  length 
of  this  rule.  The  end  of  the  copper  rule 
carried  a  vernier,  whose  coincidences  with 
the  platina  graduations  were  observed  with 
a  microscope.  Now,  the  dilatations  of  the 
platina  and  copper  being  unequal  for  equal 
changes  of  temperature,  we  may  conceive 
that  the  vernier  of  the  copper  rule  would 
incessantly  correspond  to  variable  divi- 
sions, according  as  the  temperatures  varied. 
Borda  made  use  of  these  changes,  to  know 
at  every  instant  the  common  temperature 
of  these  two  bars,  and  the  ratio  of  the  ab- 
solute dilatations  of  their  two  metals.  The 
value  of  the  vernier  divisions  had  been  pre- 
viously ascertained,  by  plunging  the  com- 
pound bar  into  water  of  different  tempe- 
ratures, contained  in  an  oblong  wooden 
trough.  It  was  therefore  sufficient  to  read 
the  indications  of  this  metallic  thermome- 
ter, in  order  to  learn  the  true  temperature 
of  the  bars  in  the  atmosphere;  and  of  course 
the  compensation  to  be  made  on  the  meter 
rods  or  chains,  to  bring  them  to  the  true 
leng-th  of  the  standard  temperature1. 


CAL 


CAL 


An  exact  acquaintance  with  the  dilata- 
tion of  metals,  is  also  necessary  for  regu- 
lating the  length  of  the  pendulum  in  astro- 
nomical clocks.  When  the  ball  or  bob  of  a 
seconds  pendulum  is  let  down  y^  of  an 
inch,  the  clock  will  go  ten  seconds  slower 
in  24  hours;  and  therefore  TF6T)  of  an 
inch,  will  make  it  lose  one  second  per  day. 
Now,  as  the  effective  length  of  the  seconds 
pendulum  is  39. 1 3929  inches,  we  know  from 
the  previous  table  of  expansion,  that  a 
change  of  30°  of  temperature  by  Fahren- 
heit's scale,  will  alter  its  length  about 
TftVft  part,  which  is  equivalent  to  nearly 
0.0078,  or  y|  g"  °f  an  inch,  corresponding 
to  about  eight  seconds  of  error  in  the  day. 
The  first,  the  most  simple,  and  most  per- 
fect invention  for  obviating  these  varia- 
tions, is  due  to  Graham.  The  bob  of  his 
compensation  pendulum  consisted  of  a 
glass  cylinder,  about  six  inches  long,  hold- 
ing ten  or  twelve  pounds  of  mercury.  In 
proportion  as  the  iron  or  steel  rod  to  wh.ch 
this  was  suspended,  dilated  by  heat,  the 
mercury  also  expanded,  and  raised  thereby 
the  centre  of  oscillation,  just  as  much  as 
the  lengthening  of  the  rod  had  depressed 
it.  M.  Biot,  with  his  usual  accuracy,  has 
shown,  that  if  the  suspending  rod  were  of 
glass,  the  length  of  the  cylinder  of  mer- 
cury would  require  to  be  -j^  the  total 
length  of  the  pendulum,  namely,  about  four 
inches;  but  the  expansion  of  iron  being 
greater  in  the  ratio,  pretty  nearly  of  three 
to  two,  we  have  hence  the  length  of  the 


cylinder  in  the  latter  case,  equal  to  about 
six  inches.  The  late  very  ingenious  Mr. 
Gavin  Lowe,  prescribed  along  with  a  steel 
rod,  a  glass  cylinder  two  inches  diameter 
inside,  containing  6-j-j-  vertical  inches  of 
mercury,  weighing  ten  pounds.  From  ac- 
curate calculation  he  found,  that  if  such  a 
pendulum  should  go  perfectly  true,  when 
the  thermometer  is  at  30°,  but  that  at  90° 
it  should  go  one  second  slower  in  24  hours, 
it  would  be  remedied  by  pouring  in  ten 
ounces  more  quicksilver;  or,  by  taking  out 
that  quantity,  if  it  went  one  second  faster 
in  24  hours,  when  at  90°  than  at  30°  Fahr.; 
and  for  yg-  of  a  second  of  deviation  in 
24  hours,  the  compensation  is  the  addition 
or  abstraction  of  one  ounce  of  mercury. 
See  a  useful  paper  on  this  subject,  by  Mr. 
Firminger,  in  the  Philosophical  Magazine 
for  August  1819. 

The  balance  wheel  of  a  watch,  varies  in 
the  time  of  its  oscillations,  by  iis  expan- 
sions and  contractions  with  variations  of 
temperature.  The  invention  of  Arnold  fur- 
nished a  wheel  or  interrupted  ring,  com- 
posed of  concentric  laminae  of  two  rnetals, 
which,  obviating  the  above  defect  by  their 
difference  of  dilatation,  has,  under  the 
name  of  compensation  balance,  incalculably 
improved  the  accuracy  of  marine  chrono- 
meters. We  shall  describe  under  THER- 
MOMETER, an  elegant  instrument  con- 
structed on  similar  principles,  by  the  cele- 
brated M.  Breguet.  See  other  applications, 
infra. 


TABLE  II.— Dilatation  of  the  volume  of  LIQUIDS  by  being  heated 
from  32°  to  212°. 


Mercury,  Dalton, 

do.       Lord  Charles  Cavendish, 


Deluc, 

General  Roy, 

Slmckburgh, 

Lavoisier  and  Laplace, 

Haellstroem, 

Uulong  and  Petit,      - 

do.     from  212°,  to  392°, 
from  392°,  to  572°, 
in  glass,  from  32°,  to  212°, 
do.     from  212°,  to  392°, 
do.     from  392°,  to  572°, 


do. 

do. 

do. 

do. 

do. 

do. 

do. 

do. 

do. 

do. 

do. 

Water, 

Muriatic  acid,  (sp  gr.  1.137), 
Nitric  acid.  (sp.  gr.  1.40), 
Sulphuric  acid,  (sp.  gr.  1.85), 
Alcohol, 
Water, 


do. 
do. 
do. 
do. 


Kirwan,  from  39°,  its  maximum  density, 
Ualton, 
do. 
do. 
do. 
do. 


Water  saturated  with  common  salt,  do. 
Sulphuric  ether,  do. 

Fixed  oils,  do. 


0-020000 

W 

0.018370 
0.018000 
0.017000 
0.01851 

T3" 

¥ 

1 

TT 

0.01810 
0.0181800 

"v2 

0.0180180 

TV-TV 

0.0184331 
0.0188700 

TT-2'5- 

A 
i 

0.015432 

6T-8 

0.015680 

6T  ~TS 
l  

0  0158280 
0.043  >2 
0.0600 

2TV? 

Ty 

0.1100 
0.0600 

iV 

0.1100 

i 

0.0460 
0.0500 

A 

2^ 

0.0700 
0.0800 

rlT 

CAL 


CAL 


Oil  of  turpentine,  do.  0.0700 

The  quantities  given  by  Mr.  Dalton,  are  probably 

too  great,  as  is  certainly  the  case  with  mercury; 

his  experiments  being  perhaps  modified  by  his 

hypothetical  notions, 
Water  saturated  with  common  salt,  Robinson,         0.05198 


Dr.  Young,  in  his  invaluable  Catalogue 
raisonnte.  Natural  Philosophy,  vol.  ii.  p. 
39 i.  gives  the  following  table  of  the  ^cpan- 
sions  of  water,  constructed  from  a  colla- 
tion of  experiments  by  Gilpin,  Kirwan, 
and  A  chard.  He  says,  that  the  degrees 
of  Fahrenheit's  thermometer,  reckoning 
either  way  from  39°  being  called  /,  the 
expansion  of  water  is  nearly  expressed 
by  22/2  (1  — .002/)  in  10  million ths;  and 
the  diminution  of  the  specific  gravity  by 
.0000022/2— 00000000472/3.  This  equa- 
tion, as  well  as  the  table,  are  very  import- 
ant for  the  reduction  of  specific  gravities 
of  bodies,  taken  by  weighing  them  in  water. 


Sp. 

grav. 

30°  0.99980 
32  0.99988 
34  0.99994 
39  1.00000 
44  0.99994 

48  0.99982 

49  0.99978 
54   0.99951 
59   0.99914 


Dimin.  Expan- 
ofsp.gr.  sion< 
0.00020 
0.00012 
0.00006 
0.00000 
0.00006 
0.00018 
0.00022 
0.00049 
0.00086 


Sp. 

grav. 

60°  0.99£>06 

64   0.99867 

69   0.99812 

74   0.99749 

(77°)  0.99701  Achard       0.00299 

79   0.99680  Gilpin  0.00320  0.00321 

(82)  0.99612  Kirwan  0.00388  0.00389 

90   0.99511  Gilpin 

100   0.99313 

102   0.99246  Kirwan 

122   0.98757 

0.98872  Deluc 
142   0.98199  K. 
162   0.97583 
167   0.97480  Deluc 
182   0.96900  K. 
202   096145 

212   0.95848        . 

Deluc  introduced  into  a  series  of  ther- 
mometer glasses,  the  following  liquids,  and 
noted  their  comparative  indications  by  ex- 
pansion at  different  degrees  of  heat,  mea- 
suring on  Reaumur's  thermometer,  of 
which  80°  is  the  boiling  point  of  water, 
and  0°  the  melting  point  of  ice. 


Dimin.     Expan- 
of  sp.  gr.     sion. 
0.00094 
0.00133 
0.00188 
0.00251 


0.00489  0.00491 
0.00687  0.00692 
0.00754  0.00760 
0.01243  0.01258 
0.01128 

0.01801  0.01833 
0.02417  0.02481 
0.02520 

003100  0.03198 
0.03855  0.04005 
0.04152  0.04333 


TABLE  of  Thermometric  Indications  by  DELUC. 


J\fercnrv. 

Olive 
Oi. 

Es.  Oil  of 

Chamnmile. 

Oil  of 

Thyme. 

Alcohol. 

Brine. 

Water. 

R. 

Cent. 

Fahr. 

80° 

100° 

sis0 

80° 

80° 

80° 

80° 

80° 

80° 

75 

93$ 

200$ 

74.6 

74.7 

74.3 

73.8 

74.1 

71 

70 

87.5 

189$ 

69.4 

69.5 

68.8 

67.8 

68.4 

62 

65 

81. 

178J 

64.4 

64.3 

63.5 

61.9 

62.6 

53.5 

60 

75. 

167 

593 

59.1 

58.3 

56.2 

57.1 

45.8 

55 

68$ 

155$ 

54.2 

53.9 

53.3 

50.7 

51.7 

38.5 

50 

62$ 

144$ 

49.2 

48.8 

48.3 

45.3 

46.6 

32. 

45 

56* 

133-i 

44.0 

43.6 

43.4 

40.2 

41-2 

26.1 

40 

50 

122 

39.2 

38.6 

38.4 

35.1 

36.3 

20.5 

35 

43$ 

1  10$ 

34.2 

33.6 

33.5 

3Q.3 

31.3 

15.9 

30 

37$ 

99$ 

29.3 

28.7 

28.6 

25-6 

265 

11.2 

25 

3U 

88-j 

24.3 

23.8 

23.8 

21.0 

21.9 

7.3 

20 

25 

77 

19.3 

18.9 

19.0 

16.5 

17.3 

4.1 

15 

18$ 

65$ 

14.4 

14.1 

14.2 

12.2 

12.8 

1.6 

10 

12$ 

54$ 

9.5 

9.3 

9.4 

7.9 

8.4 

0.2 

5 

43* 

4.7 

4.6 

4.7 

3.9 

4.2 

0.4 

0 

0 

32 

0.0 

0.0 

0.0 

0.0 

0.0 

0.0 

—  5 

6i 

20$ 

—3.9 

—4.1 

—10 

12$ 

9$ 

—7.7    —8.1 

As  I  consider  these  results  of  Deluc  va-  added  the  two  columns  marked  Cent,  and 

luable,  in  so  far  as  they  enable  us  to  com-  Fahr.  to  give  at  once  the  reductions  to 

pare  directly  the  expansions  in  glass  of  the  centigrade  and  Fahrenheit  graduation, 

these  different  thermometric  liquids,  I  have  The  alcohol  was  of  such  strength  that  its 


CAL 


CAL 


flame  kindled  gunpowder,  and  it  was  found 
that  the  results  were  not  much  changed  by 
a  small  difference  in  the  strength  of  the 
spirit.  The  brine  was  water  saturated  with 
common  salt. 

M.  Biot,  in  the  first  volume  of  his  elabo- 
rate Trait  £  de  Physique,  has  investigated 
several  empyrical  formulae,  to  represent 
the  laws  of  dilatation  of  the  different  fluids. 
They  are  too  complex  for  a  work  of  this 
nature.  He  shows  that  for  all  liquids  whose 
dilatations  have  been  hitherto  observed, 
the  general  march  of  this  dilatation  may 
be  represented  at  every  temperature  by  an 

expression  of  this  form,  t  =  at  -f.  bt2  -f- 
cts,  in  which  t  denotes  the  temperature  in 
degrees  of  the  mercurial  thermometer;  a  b  c 
constant  coefficients,  which  depend  on  the 

nature  of  the  liquid,  and  t  the  true  dilata- 
tion for  the  volume  1.0  from  the  tempera- 
ture of  melting  ice.  We  shall  content  our- 
selves with  giving  one  example,  from  which 
we  may  judge  of  the  great  geometrical  re- 
sources of  this  philosopher.  For  olive  oil 

the  formula  becomes  T  =  0.95067  T  + 
0.00075  T»— 0.000001667  T*. 

The  following  table  gives  its  results  com- 
pared with  experiment. 
Of  the  mercurial.       Calculated.       Observed. 
80°  80°  80° 

70  69.64  69.41 


Of  the  mercurial. 
60° 
50 
40 
30 
20 
10 


Observed. 
59.3° 
49.2 
39.2 
29.3 
19.3 

9.5 

0. 


Calculated. 

59.37° 

49.2 

39.12 

29.15 

19.30 
9.53 
0.0 

M.  Gay-Lussac  has  lately  endeavoured 
to  discover  some  law  which  should  corres- 
pond with  the  rate  of  dilatation  of  different 
liquids  by  heat.  For  this  purpose,  instead 
of  comparing  the  dilatations  of  different 
liquids,  above  or  below  a  temperature  uni- 
form for  all,  he  set  out  from  a  point  variable 
with  regard  to  temperature,  but  uniform  as 
to  the  cohesion  of  the  particles  of  the  bo- 
dies; namely,  from  the  point  at  which  each 
liquid  boils  under  a  given  pressure.  Among 
those  which  he  examined,  he  found  two 
which  dilate  equally  from  that  point,  viz. 
alcohol  and  sulphuret  of  carbon,  of  which 
the  former  boils  at  173.14°,  the  latter  at 
115.9°  Fahr.  The  other  liquids  did  not 
present,  in  this  respect,  the  same  resem- 
blance. Another  analogy  of  the  above  two 
liquids  is,  that  the  same  volume  of  each 
gives,  at  its  boiling  point,  under  the  same 
atmospheric  pressure,  the  same  volume  of 
vapour;  or  in  other  words,  that  the  densities 
of  their  vapours  are  to  each  other  as  those 
of  the  liquids  at  their  respective  boiling 
temperatures.  The  following  table  shows 
the  results  of  this  distinguished  chemist. 


TABLE  of  the  Contractions  of  1000  parts  in  volume*  by  cooling. 


Water. 

Jllcohol.             Sulphuret  of  Curb. 

Ether. 

Contract       Ditto       Contract 
by  ex  [ft.  calculated,  by  exp  t 

Ditto 
(  alculated. 

C'jntruci 
by  exp't 

Ititto 

calculated. 

Contract      Ditto 
by  exp't.  calculated. 

Boiling. 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

0.00 

—  5° 

3.34 

3.35 

5.55 

556 

6.14 

6.07 

8.15 

>  .16 

—10 

6.61 

6.6.) 

li  4:: 

11.24 

•12.01 

12.08 

16  17 

16.01 

—15 

10.50 

989 

17.51 

17.00 

1   .98 

17.99 

^24.16 

23.60 

—20 

13.15 

13.03 

24.34 

23.41 

2380 

23.80 

31  83 

30.92 

—25 

16.06 

16.06 

29  15 

28.60 

29.65 

2950 

,-9.14 

3.-J.08 

—  30 

18.85 

18.95 

3474 

34.37 

35.06 

35.05 

46.42 

45.04 

—35 

21.52 

21.67 

40.28 

40.05 

40.48 

40.43 

£2*06 

51.86 

—40 

24.10 

24.20 

45.68 

4566 

45.77 

45.67 

5877 

58-77 

—45 

26.50 

26.52 

5085 

51  11 

51.08 

50.70 

65  .8 

6520 

—50 

28.56 

.861 

56.0 

5637 

50.28 

55.52 

72^1 

/  1  79 

—55 

30.60 

30.43 

61.01 

61.43 

61.14 

60  12 

78..5fc 

78.56 

—60 

32.42 

31.96 

6596 

06.23 

6621 

64.48 

—65 

34.02 

33.19 

1074 

70.75 

—70 

35.47 

34.09 

75.48 

74.93 

—75 

36.70 

34.63 

80.11 

78.75 

Their  respective  boiling  points  are: 
Water,  -         100°     Cent.  =  212°  F. 

Alcohol,   -        -    78.41  173 

Sulphuret  of  carb.  46.60  126 

Sulphuric  ether,    35.66  96 

VOL.  I. 


The  experiments  were  made  in  thermo- 
meter vessels,  hermetically  sealed. 

Alcohol,  at  78.41°  cent,  produces  483.3 
its  vol.  of  vapour. 

31 


CAL 


CAL 


Sulphuret  of  carbon,  at  46.60°  cent,  pro- 
duces 491.1  its  vol.  of  vapour. 

Ether,  at  35.66°  cent,  produces  285.9  its 
vol.  of  vapour. 

Water,  at  100.00°  cent,  produces  1633.1 
its  vol.  of  vapour. 

Dr.  Thomson,  treating  of  expansion, 
states,  that  "  different  kinds  of  glass  differ 
so  much  from  each  other,  that  no  general 
rule  can  be  laid  down." — System,  ^-ol.  i. 
page  73.  This  statement  is  at  variance 
with  the  results  of  MM.  Dulong  and  Petit, 
as  well  as  of  my  own  pyrometrical  mea- 
surements. "  Nor  have  we  found,"  say 
these  accurate  observers,  "  any  apprecia- 
ble difference  between  the  effects  observed 
in  tubes  of  ordinary  glass  obtained  from 
different  manufactories,  whatever  was  their 
calibre  or  their  thickness."  T  believe  the 
differences  to  have  arisen  from  the  errors 
of  the  previous  pyrometrical  measure- 
ments, applied  to  a  body  whose  dilatation 
is  so  small.  Thus  General  Roy,  perhaps 
the  most  accurate  of  all  experimenters, 
found  at  one  time,  that  a  glass  tube  ex- 
panded four  times  as  much  as  a  rod;  and 
he  afterwards  found;  on  the  contrary,  that 
the  rod  expanded  more  than  the  tube  by 
about  -%j,  the  glass  being  from  the  same 
pot.  I  found,  that  a  rod  and  tube  made 
out  of  the  same  glass  pot  expanded  the 
same  quantity,  through  a  range  of  400° 
Fahr.;  and  believe,  that  such  crystal  or 
flint-glass  as  is  used  in  Great  Britain  for 
chemical  purposes,  is  wonderfully  uniform 
in  its  rate  of  dilatation  by  heat,  through 
the  same  portions  of  the  thermometric 
scale.  Nor  are  the  differences  considera- 
ble between  the  expansions  of  crown  and 
plate  glass. 

The  different  rate  of  expansion  which 
liquids  undergo,  by  the  same  degree  of 
temperature,  has  been  theorized  upon  by 
Dr.  Thomson;  and  as  this  is  the  only  ex- 
ample in  his  writings  in  which  he  has  ven- 
tured to  propound  an  original  philosophi- 
cal law,  it  is  entitled  to  examination. 


'Alcohol,  0.1100=    i 

Nitric  acid,  (sp.  gr.  1.40)       -  0.1100  =    £ 

Fixed  oils,  -  0.080    =  ^ 

Sulphuric  ether,  0.070    =  tV 

Oil  of  turpentine,  -          -  0.070    —  •£% 

Muriatic  acid,  (sp.  gr.  1.137.)  0.060    =  -^ 

Sulphuric  acid,  (sp.  gr.  1.85.)  0  060    =  -£? 
Water  saturated  with  common  salt,  0.05      =  ^V 

Water,  .  0.0466  =  ^ 

Mercury,  .  .  0.02     =  «V 


"  The  expansion  of  liquid  bodies  differs 
from  that  of  the  elastic  fluids,  not  only  in 
quantity,  but  in  the  want  of  uniformity 
with  which  they  expand,  when  equal  ad- 
ditions are  made  to  the  temperature  of 
each.  This  difference  seems  to  depend 
upon  the  fixity  or  volatility  of  the  compo- 
nent parts  of  the  liquid  bodies;  for  in  gene- 
ral those  liquids  expand  most  by  a  given 
addition  of  heat  whose  boiling  tempera- 
tures are  lowest,  or  which  contain  in  them 
an  ingredient  which  readily  assumes  the 
gaseous  form.  Thus  mercury  expands 
much  less  when  heated  to  a  given  tempera- 
ture than  water,  which  boils  at  a  heat  much 
inferior  to  mercury;  and  alcohol  is  much 
more  expanded  than  water,  because  its 
boiling  temperature  is  lower.  In  like  man- 
ner, nitric  acid  is  much  more  expanded 
than  sulphuric  acid,  not  only  because  its 
boiling  point  is  lower,  but  because  a  por- 
tion of  it.  has  a  tendency  to  assume  the 
form  of  an  elastic  fluid.  This  rule  holds  at 
least  in  all  the  liquids  Avhos»e  expansions  I 
have  hitherto  tried.  We  may  consider  it 
therefore  as  a  pretty  general  fact,  that  the 
higher  the  temperature  necessary  to  cause 
a  liquid  to  boil,  the  smaller  the  expansion 
is  which  is  produced  by  the  addition  of  a 
degree  of  heat;  or,  in  other  words,  the  ex- 
pansibility of  liquids  is  nearly  inversely 
as  their  boiling  temperatures." — Thomson's 
Chemistry,  5th  edition,  vol.  i.  pp.  66  and  67. 

After  enforcing,  in  such  varied  expres- 
sions, his  new  law,  that  the  lower  the  boil- 
ing point  of  a  liquid  is,  the  greater  is  its 
expansibility  by  heat,  one  would  not  ex- 
pect to  find  it  completely  abrogated  and 
set  at  nought,  by  a  table  of  experimental 
results  in  the  very  same  page,  let  such  is 
the  fact,  as  its  quotation  will  prove. 

"  The  following  table  exhibits  the  dila- 
tation of  various  liquids,  from  the  tempera- 


boiling  point,    174° 


ditto 
ditto 
ditto 
ditto 
ditto 
ditto 
ditto 
ditto 
ditto 


247 
600 
98 
314 
217 
620 
225 
212 
636" 


I  have  added  the  boiling  points  as  set 
down  in  his  System.  We  here  remark  that 
alcohol  and  nitric  acid  have  the  same  rate 
of  expansion  affixed,  though  the  distances 
of  their  respective  boiling  points  from  32° 


are  as  2  to  3.  But  the  most  amusing  illus- 
tration of  the  converse  of  Dr.  Thomson's 
law,  is  presented  by  himself  with  regard 
to  fixed  oil  and  ether,  the  former  having 
the  greater  expansion,  though  its  boiling 


CAL 


GAL 


point   is  about -ten  times  more   distant  in 
thermometric  "degrees,  than  that  of  ether, 
from  32°.  Ether  and  oil  of  turpentine  ex- 
pand the  same  proportion,  and  yet  their 
boiling  points  differ  by  216°.  But'muriatic 
acid  and  sulphuric  acid  also   expand  the 
same  quantity,  though  their  boiling  points, 
and  "  their  tendencies  to  assume  the  form 
of  an  elastic  fluid"  are  exceedingly  differ- 
ent. Finally,  water  expands  less  than  sul- 
phuric acid,  while  its  boiling  temperature 
is   greatly  loiver.  Had   Dr.  Thomson  pro- 
pounded the  very  reverse  proposition,  viz. 
that  the  rate  of  expansion   in  iiquids  is 
higher  the  higher  their  boiling  temperatures, 
he  would  have  encountered  fewer  contra- 
dictory facts,  though  still  enow  to  explode 
the  generality  of  the  principle.  In  a  philo- 
sophical system  of  chemistry,  examples  of 
such  false  reasoning  are  injurious  to  the 
student,  and  lower  the  rank  of  the  science. 
Mercury  in  its  expansions,  follows  the 
rate  of  fluid  metals,  and  therefore  is  riot 
properly    comparable  to   oily,   watery,   or 
spirituous  liquids.  It  is  cui-ious  that  one  of 
the  examples  which  Dr.  Thomson  adduces 
to   illustrate   his   pretended    rule,   which 
"  holds,  he  says,  at  least  in  all  the  liquids 
whose  expansion  I  have   hitherto  tried," 
actually  breaks  it;  for  alcohol  expands  fully 
a  half  more  than  ether;  and  yet,  the  inter- 
val from  its  boiling  point  to  32°,  is  more 
than  double  that  interval  in  ether,  instead 
of  being  greatly  less  as  his  law  requires. 
Since  his  table  obviously  disqualifies  wa- 
ter, alcohol,  ether,   oils,  and  acids,  from 
constituting  such  a  series  in  expansion,  as 
his  rule  requires,  one  may  naturally  ask 
this  celebrated  chemist,  what  are  "  the  li- 
quids  whose   expansion   he  has   hitherto 
tried? 

In  solid  metals,  the  expansion  seems  to 
be  greater,  the  less  their  tenacity  and  den- 
sity, though  to  this  general  position,  we 
have  strikingexceptions  in  antimony  and  bis- 
muth, provided  they  were  accurately  mea- 
sured by  Smeaton's  apparatus,  of  which, 
however,  I  have  reason  to  doubt.  The  least 
flexure  in  the  expanding  rods,  will  evi- 
dently make  the  expansions  come  out  too 
small.  If  metallic  dilatability  vary  with 
some  unknown  function  of  density  and 
tenacity,  as  is  probable  a  priori,  we  would 
expect  their  rate  of  expansion  to  increase 
with  the  temperature.  This  view  coincides 
with  the  following  results  of  MM.  Duiong 
and  Petit. 

Temperatures  by  Expansions  in 

dilatation  of  air.  bulk  of 

Iron.  Cop.  Plat. 

0°  to  100°,  cent,  give  ^  TJT  -fa 

0°  to  300°,  mean  quantity,   ^-JT  T|y  ^.J^ 

Tripling  these  denominators,  we  have 
the  linear  expansions,  fractionally  express- 
ed, thus: 


Iron.  Cop.  Plat. 


0°  to  100°  cent. 
0°  to  300°,  mean, 

To  multiply  inductive  generalizations, 
that  is,  to  groupe  together  facts  which 
have  some  important  qualities  common  to 
them  all,  is  the  main  scope  and  business  of 
philosophy.  But  to  imagine  phenomena,  or 
to  twist  real  phenomena  into  a  shape  suit- 
ed  to  a  preconceived  constitution  of  things, 
was  the  vice  of  the  Peripatetic  schools, 
which  Bacon  so  admirably  exposed;  of 
which  in  our  times  and  studies,  according 
to  MM.  Duiong  and  Petit,  Mr.  Dalton's 
speculations  on  the  laws  of  heat,  afford  a 
striking  example. 

Mr.  Dalton  has  the  merit  of  having  first 
proved  that  the  expansions  of  all  aeriform 
bodies,  when  insulated  from  liquids,  are 
uniform  by  the  same  increase  of  tempera- 
ture; a  fact  of  great  importance  to  practi* 
cal  chemistry,  which  was  fully  verified  by 
the  independent  and  equally  original  re- 
searches of  M.  Gay-Lussac  on  the  sub- 
ject, with  a  more  refined  and  exact  appa- 
ratus. The  latter  philosopher  demonstra- 
ted, that  100  in  volume  at  :>2°  Fahr.  or  0° 
cent,  become  1.375  at  2lJ°  Fahr.  or  100 
cent.  Hence  the  increment  of  bulk  for  each 
degree  F.  is  °-~|-  =  0.002083  —  T^ff? 
and  for  the  centigrade  scale  it  is  °  '^  *•  = 

=0.00375  —  Beers'.  To  reduce  any  vo- 
lume of  gas,  therefore,  to  the  bulk  it  would 
occupy  at  any  standard  temperature,  we 
must  multiply  the  thermometric  difference 
in  degrees  of  Fahr.  by  0.002083,  or  -^ 
subtracting  the  product  from  the  given  vo- 
lume, if  the  gas  be  heated  above,  but  adding 
it,  if  the  gas  be  cooled  below,  the  standard 
temperature.  Thus  25  cubic  inches  at  120° 
Fahrenheit  will  at  60°  occupy  a  volume  of 
21 J;  for  -|^  X  60  =  _60_ __  £.  and  as 

==^g-,  which,  taken  from  25,  leaves  21-jjp 
A  table  of  reduction  will  be  found  under 
GAS.  When  the  table  is  expressed  deci- 
mally, indeed,  to  6  or  7  figures,  it  becomes 
more  troublesome  to  apply  than  the  above 
rule.  Vapours,  when  heated  out  of  con- 
tact of  their  respective  liquids,  obey  the 
same  law  us  gases,  a  discovery  due  to  M. 
Gay-Lussac. 

We  shall  now  treat  of  the  anomaly  pre- 
sented by  water  in  its  dilatations  by  change 
of  temperature,  and  then  conclude  this 
part  of  tiie  subject  with  some  practical  ap- 
plications of  the  preceding  facts. 

The  Florentine  academicians,  and  after 
them  Dr.  Croune,  observed,  that  on  cooling 
in  ice  and  salt,  the  bulb  of  a  thermometric 
glass  vessel  filled  with  water,  the  liquid 
progressively  sunk  in  the  stem,  till  a  cer- 
tain point,  after  which  the  further  pro- 
gress of  refrigeration  was  accompanied  by 


GAL 


CAL 


an  ascent  of  the  liquid,  indicating1  expan-  increase  or  decrease.   Having  omitted  to 

sion  of  the  water.  This  curious  phenome-  make  the  requisite  correction  for  the  ef- 

non  was  first  accurately  studied  by  M.  De  feet  of  the  expansion  of  the  glass  in  which 

Luc,    who    placed    the    apparent   term   of  the  water  was  contained,  it  was  found  af- 

greatest  density  at  40°  Fahr.,  and   consi-  tei  wards  by  Sir  Charles  Blitgden  and  Mr. 

dered  the   expansion  of  water  from  that  Gilpin,    who    introduced   this    correction, 

point,  to   vary  with  equal  amount,  by   an  that  the  real  term  of  greatest  density  was 

equal  change  of  temperature,  whether  of  39°  F. 

The  folio-wing'  Table  jpves  their  Experimental  results. 


Specific 
Gravity. 

Bulk  of 
Water. 

temperature.        Bvlk  * 
•water. 

Specific 
Gravity. 

I  00000 

39° 

1.00000 

1.UOOOO 

.00000 

38 

40 

1.00000 

1.00000 

0  999',9 

i.ooooi 

37 

41 

1.00001 

0.99999 

0.9(-998 

.OOOOJ 

36 

42 

1.00002 

0.99998 

0.99996 

.00004 

35 

43 

1.00004 

0.99996 

0.9999  h 

1.00006 

34 

44          1  00006 

0.99994 

0.99991 

.000-8 

33 

45     i     1.00009 

0.99991 

0.999H8 

1.00012 

3  J 

46          1  00012 

099988 

By  weighing1  a  cylinder  of  copper  and  of 
glass  in  water  at  diiferent  temperatures,  the 
maximum  density  comes  out  40°  F.  Final- 
ly Dr.  Hope,  in  1804,  published  a  set  of  ex- 
periments in  the  Edin.  I'hil.  Trans,  in  which 
the  complication  introduced  into  the  ques- 
tion by  the  expansion  of  solids,  is  very  phi- 
losophically removed.  He  shows  that  water 
exposed  in  tall  cylindrical  vessels,  to  a 
freezing  atmosphere,  precipitates  to  the 
bottom  its  colder  particles,  till  the  tempe- 
rature of  the  mass  sinks  to  39.5°  F.  after 
which  the  colder  particles  are  found  at  the 
surface.  He  varied  the  form  of  the  experi- 
ment by  applying-  a  zone  of  ice,  round  the 
top,  middle,  and  bottom  of  the  cylinders; 
and  in  each  case,  delicate  thermometers 
placed  at  the  surface  and  bottom  of  the 
water,  indicated  that  the  temperature  39.5°, 
coincided  with  the  maximum  density.  We 
may  therefore  regard  the  point  of  40°,  adop- 
ted by  the  French,  in  settling  their  stand- 
ard of  weights  and  measures,  as  sufficiently 
exact. 

The  force  with  which  solids  and  liquids 
expand  or  contract  by  heat  and  cold,  is  so 
prodigiously  great  as  to  overcome  the 
strongest  obstacles.  Some  years  ago  it  was 
observed  at  the  Conservatoire  des  arts  et 
metiers  at  Paris,  that  the  two  side  walls  of 
a  gallery  were  receding  from  each  other, 
being  pressed  outwards  by  the  weight  of 
the  roof  and  floors.  Several  holes  were 
made  in  each  of  the  walls,  opposite  to  one 
another,  and  at  equal  distances,  through 
which  strong  iron  bars  were  introduced  so 
as  to  traverse  the  chamber.  Their  ends 
outside  of  the  wall  were  furnished  with 
thick  iron  discs,  firmly  screwed  on  These 
were  sufficient  to  retain  the  walls  in  their 
actual  position.  But  to  bring  them  nearer 
together  would  have  surpassed  every  effort 
of  human  strength.  AH  the  alternate  bars 


of  the  series  were  now  heated  at  once  by 
lamps,  in  consequence  of  which  they  were 
elongated.  The  exterior  discs  being  thus 
freed  from  contact  of  the  walls,  permitted 
them  to  be  advanced  farther,  on  the  screw- 
ed ends  of  the  bars.  On  removing  the 
lamps,  the  bars  cooled,  contracted,  and 
drew  in  the  opposite  walls.  The  other  bars 
became  in  consequence  loose  at  their  ex- 
tremities, and  permitted  their  end  plates 
to  be  further  screwed  on.  The  first  series 
of  bars  being  again  heated,  the  above  pro- 
cess was  repeated  in  each  of  its  steps.  By 
a  succession  of  these  experiments  they  re- 
stored the  walls  to  the  perpendicular  posi- 
tion; and  could  easily  have  reversed  their 
curvature  inwards,  if  they  had  chosen. 
The  gallery  still  exists  with  its  bars,  to  at- 
test the  ingenuity  of  its  preserver  M.  Mo- 
lard. 

2d,  Of  the  change  of  state  produced  in 
bodies  by  caloric,  independent  of  change  of 
composition.  The  three  forms  of  matter,  the 
solid,  liquid,  and  gaseous,  seem  immediate- 
ly referable  to  the  power  of  heat,  modify- 
ing, balancing,  or  subduing  cohesive  attrac- 
tion. In  the  article  blow-pipe,  we  have  shown 
that  every  solid  maybe  liquefied,  and  many 
of  them,  as  well  as  all  liquids,  may  be  va- 
porized at  a  certain  elevation  of  tempera- 
ture. And  conversely  almost  every  known 
liquid  may  be  solidified  by  the  reduction  of 
its  temperature.  If  we  have  not  hitherto 
been  able  to  convert  the  air  and  other  elas- 
tic fluids  into  liquids  or  solids,  it  is  proba- 
bly owing  to  the  limited  power  we  possess 
over  thermometric  depression.  But  we 
know,  that  by  mechanical  approximation 
of  their  elastic  particles,  an  immense  evo- 
lution of  heat  is  occasioned,  which  must 
convince  us  that  their  gaseity  is  intimately 
dependent  on  the  operation  of  that  repul- 
sive power. 


CAL 


Sulphuric  ether,  always  a  liquid  in  our 
climate,  if  exposed  to  the  rigors  of  a  Sibe- 
rian winter,  would  become  a  solid,  and, 
transported  to  the  torrid  zone,  would  form 
a  permanent  gas.  The  same  transitions  are 
familiar  to  us  with  regard  to  water,  only 
its  vaporizing  point,  being  much  higher, 
leads  us  at  first  to  suppose  steam  an  unna- 
tural condition.  But  by  generalizing  our 
ideas,  we  learn  that  there  is  really  no  state 
of  bodies  which  can  be  called  more  natural 
than  another.  Solidity,  liquidity,  the  state 
of  vapours  and  gases,  are  only  accidents 
connected  with  a  particular  level  of  tempe- 
rature. If  we  pass  the  easily  condensed 
vapour  of  nitric  acid  through  a  red-hot  glass 
tube,  we  shall  convert  it  into  gases  which 
are  incondensable  by  any  degree  of  cold 
which  we  can  command.  The  particles 
which  formed  the  liquid  can  no  longer  join 
together  to  reproduce  it,  because  their  dis- 
tances are  changed,  and  with  these  have 
also  changed  the  reciprocal  attractions 
which  united  them. 

Were  our  planet  removed  much  further 
from  the  SUB,  liquids  and  gases  would  so- 
lidify; were  it  brought  nearer  that  lumi- 
nary, the  bodies  which  appear  to  us  the 
roost  solid,  would  be  reduced  into  thin  in- 
visible air.  We  see,  then,  that  the  princi- 
ple of  heat,  whatever  it  may  be,  whether 
matter  or  quality,  separates  the  particles 
of  bodies  when  its  energy  augments,  and 
suffers  them  to  approach  when  its  power 
is  enfeebled.  By  extending  this  view,  it 
has  been  drawn  into  a  general  conclusion, 
that  this  principle  was  itself  the  force  which 
maintains  the  particles  of  bodies  in  equi- 
libria against  the  effort  of  their  reciprocal 
attraction,  which  tends  continually  to  bring 
them  together.  But  although  this  conclu- 
sion be  extremely  probable,  we  must  re- 
member that  it  is  hypothetical,  and  goes 
further  than  the  facts.  We  see  that  the 
force  which  balances  attraction  in  bodies 
may  be  favoured  or  opposed  by  the  princi- 
ple of  heat,  but  this  does  not  necessarily 
prove  that  these  forces  are  of  the  same  na- 
ture. 

The  instant  of  equilibrium  which  sepa- 
rates the  solid  from  the  liquid  state,  de- 
serves consideration.  Whatever  may  be 
the  cause  and  law  of  the  attractions  which 
the  particles  exercise  on  one  another,  the 
effect  which  results  ought  to  be  modified 
by  their  forms.  When  all  the  other  quali- 
ties are  equal,  a  particle  which  mav  br  cy- 
lindrical, for  example,  will  not  exercise  the 
same  attraction  as  a  sphere,  on  a  point  pla- 
ced at  an  equal  distance  from  its  centre  of 
gravity.  Thus  in  the  law  of  celestial  gravi- 
tation, the  attraction  of  an  ellipsoid  on  an 
exterior  point,  will  be  stronger  in  the  di- 
rection of  its  smaller  than  in  that  of  its 
larger  axis,  at  the  same  distance  from  its 
surface.  Now  whatever  be  the  law  of  at- 


tractions which  holds  together  the  parti- 
cles of  bodies,  similar  differences  must  ex- 
ist. These  particles  must  be  attracted  more 
strongly  by  certain  sides  than  by  others. 
Thence  must  result  differences  in  the  man- 
ner of  their  arrangement,  when  they  are 
sufficiently  approximated  for  their  attrac- 
tions to  overcome  the  repulsive  power. 
This  explains  to  us  in  a  very  probable  man- 
ner, the  regular  crystallization  which  most 
solid  bodies  assume,when  they  concrete  un- 
disturbed. We  may  easily  conceive  how  the 
different  substance  of  the  particles,  as  well 
as  their  different  forms,  may  produce  in 
crystals  all  the  varieties  which  we  observe. 

The  system  of  the  world  presents  mag- 
nificent effects  of  this  attraction  dependent 
on  figure.  Such  are  the  phenomena  of  nu- 
tation and  the  precession  of  the  equinoxes, 
produced  by  the  attractions  of  the  sun  and 
moon  on  the  flattened  spheroid  of  the  earth. 
These  sublime  phenomena  would  not  have 
existed,  had  the  earth  been  a  sphere;  they 
are  connected  with  its  oblateness  and  rota- 
tion, in  a  manner  which  may  be  mathemati- 
cally deduced,  and  subjected  to  calculation. 

But  the  investigation  shows,  that  this  part 
of  the  attraction  dependent  on  figure,  de- 
creases more  rapidly  than  the  principal 
force.  The  latter  diminishes  as  the  square 
of  the  distance;  the  part  dependent  on 
figure  diminishes  as  the  cube  of  the  dis- 
tance. Thus  also,  in  the  attractions  which 
hold  the  parts  of  bodies  united,  we  ought 
to  expect  an  analogous  difference  to  occur. 
Hence  the  force  of  crystallization  may  be 
subdued,  before  the  principal  attractive 
force  is  overcome.  When  the  particles  are 
brought  to  this  distance,  they  will  be  indif- 
ferent to  all  the  positions  which  they  can 
assume  round  their  centre  of  gravity;  this 
will  constitute  the  liquid  condition.  Sup- 
pose now  that  the  temperature  falling,  the 
particles  approach  slowly  to  each  other,  and 
tend  to  solidify  anew;  then  the  forces  de- 
pendent on  their  figure  will  come  again  in- 
to play,  and  in  proportion  as  they  increase, 
the  particles  solicited  by  these  forces  will 
take  movements  round  their  centres  of 
gravity.  They  will  turn  towards  each  other 
their  faces  of  greatest  attraction,  to  arrive 
finally  at  the  positions  which  their  crystal- 
lization demands.  Now  according  to  the 
figure  of  the  particles,  we  may  conceive 
that  these  movements  may  react  on  their 
centre  of  gravity,  and  cause  them  to  ap- 
proach or  recede  gradually  from  each  other, 
till  they  finally  give  to  their  assemblage  the 
volume  due  to  the  solid  state;  a  volume 
which  in  certain  cases  may  be  greater,  and 
in  others  smaller,  than  that  which  they  oc- 
cupied as  liquids.  These  mechanical  con- 
siderations thus  explain,  in  the  most  prob- 
able and  satisfactory  manner,  the  dilatations 
and  contractions  of  an  irregular  kind,  which 
certain  liquids,  such  as  water  and  mercu- 


CAL 


CAL 


py,  experience,  on  approaching  the  term  of 
their  congelation.  Having-  given  these  gen- 
eral  views,  we  may  now  content  ourselves 
with  stating  the  facts  as  much  as  possible 
in  a  tabular  form. 

TABLE  of  the  Concreting  or  Congealing 
Temperatures  of  various  Liquids,  by  FAH- 
RENHEIT'S Scale. 


—  46° 

—  46 

1.424    —45.5 
1.6415  —  45 

—  39 


Sulphuric  ether, 

Liquid  ammonia,     - 

Nitric  acid,  sp.  §>r. 

Sulphuric  acid,  sp.  gr. 

Mercury, 

Nitric  acid,  sp.  gr.  1.407    —  30.1 

Sulphuric  acid,         -         1.8064  —  26 

Nitric  acid,      -  -     1.3880  —  18.1 

Do.  do.  1.2583  —  17.7 

Do.  do.  1.3290  —  2.4 

Brandy,  —  7.0 

Sulphuric  acid,          -         1.8376  -f  1. 

Pure  prussic  acid,         -  4  to  5 

Common  salt,  25  -f  water  75  4 

Do          22.2  -f     do.    77.8        7.2 
Sal  ammoniac,  20  -j-     do.   80  8 

C.  salt,  20  -f-     do.  80  9.5 

Do.  16.1  4-     do.   83.9        13.5 

Oil  of  turpentine,         -  -          14. 

Strong  wines,        -  -     20 

Rochelle  salt,  50  -f-  water  50  21. 

C.  salt,  10  -f     do.    90  21.5 

Oil  of  bergamot,  -        23 

Blood,         -  25 

C.  salt,  6.25  -f  water  93.75  25.5 
Eps  salts,  41.6  +  do.  58.4  25.5 
Nitre,  12.5  -f  do.  87.5  26. 

C.  salt,          4.16  +     do.    95.84       27.5 
Copperas,     41.6  +     do.    58  4 
Vinegar,  -        28 

Sul.  of  zinc,  53.3  -f-  water  46.7  28.6 
Milk,  -  -  30 

Water, 

Olive  oil,  -         36 

Sulphur  and  phosphorus,  eq.  parts,  40 
Sulphuric  acid,  sp.  gr.  1.741  42 

Do.  do.         -      1.780  46 

Oil  of  anise,         -  -  50 

Concentrated  acetic  acid,  50 

Tallow,  Dr.  Thomson,  92 

Phosphorus,  108 

Stearin  from  hog's  lard,  -  -  109 
Spermaceti,  -  -  -  -  112 
Tallow,  Nicholson,  -  127 

Margaric  acid,     -  -  134 

Potassium,  ....  136.4 
Yellow  wax,  -  142 

Do.     Do. 149 

White  wax,        -         -         -         -     155 

Sodium, 194 

Sulphur,  Dr.  Thomson,      -         -     218 

Do.      Dr.  Hope,    -         -         -     234 

Tin, 442 

Bismuth, 476 

Lead, 612 

Zinc,  by  Sir  H  .Davy,         -         -     680 


Zink,  Brongniart,     -         -        -        698° 
Antimony,          ....         809? 

See  PYROMETER  for  higher  heats. 

The  solidifying  temperature  of  the  bo- 
dies above  tallow,  in  the  table,  is  usually 
called  their  freezing  or  congealing  point; 
and  of  tallow  and  the  bodies  below  it,  the 
fusing  or  melting  point.  Now,  though  these 
temperatures  be  stated,  opposite  to  some 
of  the  articles,  to  fractions  of  a  thermo- 
metric  degree,  it  must  be  observed,  that 
various  circumstances  modify  the  concret- 
ing point  of  the  liquids,  through  several 
degrees;  but  the  liquefying  points  of  the 
same  bodies,  when  once  solidified,  are  uni- 
form and  fixed,  to  the  preceding  tempera- 
tures. 

The  preliminary  remarks  which  we  of- 
fered on  the  forces  concerned  in  the  tran- 
sition from  liquidity  to  solidity,  will  in  some 
measure  explain  these  variations;  and  we 
shall  now  illustrate  them  by  some  instruc- 
tive examples. 

If  we  fill  a  narrow-mouthed  matrass  with 
newly  distilled  water,  and  expose  it  very 
gradually  to  a  temperature  considerably 
below  32°,  the  liquid  water  will  be  observ- 
ed, by  the  thermometer  left  in  it,  to  have 
sunk  10  or  11  degrees  below  its  usual  point 
of  congelation.  M.  Gay-Lussac,  by  cover- 
ing the  surface  of  the  water  with  oil,  has 
caused  it  to  cool  '21^  degrees  Fahr.  below 
the  ordinary  freezing  temperature.  Its  vo- 
lume at  the  same  time  expanded  as  much 
as  if  it  had  been  heated  21^  degrees  above 
32°.  According  to  Sir  Charles  Blagden,  to 
whom  the  first  of  these  two  observations 
belongs,  its  dilatation  may  amount  to  l-7th 
of  the  total  enlargement,  which  it  receives 
by  solidifying.  Absolute  repose  of  the  li- 
quid particles  is  not  necessary  to  ensure 
the  above  phenomenon,  for  Sir  Charles  stir- 
red water  at  21°  without  causing  it  to 
freeze,  but  the  least  vibration  of  their  mass, 
or  the  application  of  icy  spiculx,  by  the 
atmosphere,  or  the  hand,  determines  an 
instantaneous  congelation. 

We  may  remark  here,  that  the  dilatation 
of  the  water  increasing  as  it  cools,  but  to  a 
less  extent  than  when  it  concretes,  is  a  proof 
that  its  constituent  particles,  in  obedience 
to  the  cooling  process,  turn  their  poles 
more  and  more  towards  the  position  of  the 
maximum  attraction,  which  constitutes 
their  solid  state.  But  this  position  may  be 
determined  instantaneously  by  the  ready 
formed  aqueous  solid,  the  particles  of 
which  presenting  themselves  to  those  of 
the  liquid,  by  their  sides  of  greatest  attrac- 
tion, will  compel  them  to  turn  into  similai' 
positions.  Then  the  particles  of  the  liquid 
first  reverted  will  act  on  their  neighbours 
like  the  exterior  crystal,  and  thus  from 
point  to  point  the  movement  will  be  pro- 
pagated through  the  whole  mass,  till  all  be 
congealed.  The  vibratory  movements  act  by 


CAL 


CAL 


throwing- the  pavticles,  into  positions  favor- 
able for  their  mutual  attraction. 

The  very  same  phenomena  occur  with 
saline  solutions.  If  a  hot  saturated  solution 
of  Glauber's  salt  be  cooled  to  5;j°  under  a 
film  of  oil,  it  will  remain  liquid,  and  will 
bear  to  be  moved  about  in  the  hand  with- 
out any  change;  but  if  the  phial  containing 
it  be  placed  on  a  vibrating-  table,  crystal- 
lization will  instantly  take  place.  In  a  paper 
on  saline  crystallization  which  I  published 
in  the  9th  number  of  the  Journal  of  Science, 
I  gave  the  following   illustration    of  the 
above  phenomena.  "  The  effect  of  mechani- 
cal disturbance  in  determining  crystalliza- 
tion, is  illustrated  bv  the  symmetrical  dis- 
position of  particles  of  dust  and  iron,  by 
electricity  and  magnetism.  Strew  these  up- 
on a  plane,  and  present  magnetic  and  elec- 
tric forces  at  a  certain  distance  from  it,  no 
effect  will  be  produced.  Communicate  to 
the  plane  a  vibrating  movement;  the  parti- 
cles, at  the  instant  of  being  liberated  from 
the  friction  of  the   surface,  will  arrange 
themselves  according  to  the  laws  of  their 
respective  magnetic  or  electric  attractions. 
The  water  of  solution  in  counteracting  so- 
lidity, not  only  removes  the  particles  to  dis- 
tances beyond  the  sphere  of  mutual  attrac- 
tion, but  probably  also  inverts  their  attract- 
ing poles."  Perhaps  the  term  avert  would 
be  more  appropriate  to  liquidity,  to  denote 
an  obliquity  of  direction  in  the  attracting 
poles;  and  revert  might  be  applied  to  gasei- 
ty,  when  a  repulsive  state  succeeds  to  the 
feebly  attractive  powers  of  liquid  particles. 
The  above  table  presents  some  interest- 
ing particulars  relative  to  the  acids.  I  have 
expressed  their  strengths,  by  specific  gra- 
vity, from  my  tables  of  the  acids,  instead  of 
by  the  quantity  of  marble  which  1000  grains 
of  them  could  dissolve,  in  the  original  state- 
ment of  Mr.  Cavendish.  Under  the  heads  of 
nitric  acid  and  equivalent,  some  observa- 
tions will  be  found  on  these  peculiarities 
with  regard  to  congelation.  We  see  that 
common  salt  possesses  the  greatest  effica- 
cy in  counteracting  the  congelation  of  wa- 
ter; and  next  to  it,  sal  ammoniac.  Mr.  Crigh- 
ton  of  Glasgow,  whose  accuracy  of  obser- 
vation is  well  known,  has  remarked,  that 
when  a  mass  of  melted  bismuth  cools  in  the 
air,  its  temperature  falls  regularly  to  463°, 
from    which    term    it    however    instantly 
springs  up  to  476°,  at  which  point  it  re- 
mains till  the  whole  be  consolidated.  Tin 
in  like  manner  sinks  and  then  rises  4  de- 
grees; while  melted  lead,  in   cooling,  be- 
comes stationary  whenever  it  descends  to 
612°.  We  shall  presently  find  the  probable 
cause  of  these  curious  phenomena. 

Water,  all  crystallizable  solutions,  and 
the  three  metals,  cast-iron,  bismuth,  and 
antimony,  expand  considerably  in  volume, 
at  the  instant  of  solidification.  The  greatest 
obstacles  cannot  resist  the  exertion  of  this 


expansive  force.  Thus  glass  bottles,  trunks 
of  trees  ,iron  and  lead  pipes,  even  mountain 
rocks,  are  burst  by  the  dilatation  of  the  wa- 
ter in  their  cavities,  when  it  is  converted 
into  ice.  In  the  same  way  our  pavements 
are  raised  in  winter.  The  beneficial  opera- 
tion of  this  cause  is  exemplified  in  the  com- 
minution or  loosening  the  texture  of  dense 
clay  soils,  by  the  winter's  frost,  whereby  the 
delicate  fibres  of  plants  can  easily  penetrate 
them.  Major  Williams  of  Quebec,  burst 
bombs,  which  were  filled  with  water  and 
plugged  up,  by  exposing  them  to  a  freezing 
cold. 

There  is  an  important  circumstance  oc- 
curs in  the  preceding  experiments  on  the 
sudden  congelation  of  a  body  kept  liquid 
below  its  usual  congealing  temperature,  to 
which  we  must  now  advert.  The  mass,  at 
the  moment  its  crystallization  commences, 
rises  in  temperature  to  the  term  marked  in 
the  preceding  table,  whatever  number  of 
degrees  it  may  have  previously  sunk  below: 
it.  Suppose  a  globe  of  water  suspended  in 
an  atmosphere  at  21°  F.;  the  liquid  will  cool 
and  remain  stationary  at  this  temperature, 
till  vibration  of  the  vessel,  or  contact  of  a 
spicula  of  ice,  determines  its  concretion, 
when  it  instantly  becomes  11  degrees  hot- 
ter than  the  surrounding  medium.  We  owe 
the  explanation  of  this  fact,  and  its  exten- 
sion to  many  analogous  chemical  phenome- 
na, to  the  sagacity  of  Dr.  Black.  His  truly 
philosophical  mind  was  particularly  struck 
by  the  slowness  with  which  a  mass  of  ice 
liquefies  when  placed  in  a  genial  atmos- 
phere. A  lump  of  ice  at  2^°  freely  suspend- 
ed in  a  room  heated  to  50°,  which  will  rise 
to  3.cfc°  in  5  minutes,  will  take  14  times  5, 
or  70  minutes,  to  melt  into  water,  whose 
temperature  will  be  only  32°.  Dr.  Black  sus- 
pended in  an  apartment  two  glass  globes  of 
the  same  size  alongside  of  each  other,  one 
of  which  was  filled  with  ice  at  32°,  the 
other  with  water  at  33°.  In  half  an  hour  the 
water  had  risen  to  40°;  but  it  took  10^ 
hours  to  liquefy  the  ice  and  heat  the  result- 
ing water  to  40°.  Both  these  experiments 
concur  therefore  in  showing  that  the  fusion 
of  ice  is  accompanied  with  the  expenditure 
of  140  degrees  of  calorific  energy,  which 
have  no  effect  on  the  thermometer.  For  the 
first  experiment  tells  us  that  10  degrees  of 
heat  entered  the  ice  in  the  space  of  5  mi- 
nutes, and  yet  14  times  that  period  passed 
in  its  liquefaction.  The  second  experiment 
shows  that  7  degrees  of  heat  entered  the 
globes  in  half  an  hour;  but  21  half  hours 
were  required  for  the  fusion  of  the  ice,  and 
for  heating  of  its  water  to  40°.  If  from  the 
product  of  7  into  21  =  147,  we  subtract  the 
7  degrees  which  the  water  was  above  33, 
we  have  140  as  before.  But  the  most  simple 
and  decisive  experiment  is  to  mingle  a 
pound  of  ice  in  small  fragments  with  a 
pound  of  water  at  172°.  Its  liquefaction  is 


CAL 


CAL 


instantly  accomplished,  but  the  tempera- 
ture of  the  mixture  is  only  .:.<2°.  Therefore 
140°  of  heat  seem  to  have  disappeared. 
Had  we  mixed  a  pound  of  ire-cold  water 
with  a  pound  of  water  at  17'^°,  the  result- 
ing" temperature  would  have  been  Iu2°, 
proving- that  the  70°  which  had  left  the  hot- 
ter portion,  were  manifestly  transferred  to 
that  which  was  cooler  The  converse  of  the 
preceding-  experiments  may  also  be  *le- 
monstrated;  for  in  suspending-  a  flask  of 
water,  at  55°  for  example,  in  an  atmosphere 
at  20°,  if  it  cool  to  3^°  in  S  minutes,  it  will 
take  l<iO  minutes  to  be  converted  into  ice 
of  32°;  because  the  heat  emanating-  at  the 
rate  of  1°  per  minute,  it  will  require  that 
time  for  140°  to  escape.  The,  latter  experi- 
ment, however,  from  the  inferior  conduct- 
ing1 power  of  ice,  and  the  uncertainty  when 
all  is  frozen  is  not  susceptible  of  the  pre- 
cision which  the  one  immediately  preceding 
admits.  The  tenth  of  140  is  obviously  14; 
and  hence  wre  may  infer  that  when  a  certain 
quantity  of  water,  cooled  to  22°,  or  10°,  be- 
low 32°,  is  suddenly  caused  to  congeal, 
1-Kth  of  the  weight  will  become  solid. 

We  can  now  understand  how  the  thaw 
which  supervenes  after  an  intense  frost; 
should  so  slowly  melt  the  wreaths  of  snow, 
and  beds  of  ice,  a  phenomenon  observable 
in  these  latitudes  from  the  origin  of  time, 
but  whose  explanation  was  reserved  for  Dr. 
Black.  Indeed,  had  the  transition  of  water 
from  its  solid  into  its  liquid  state  not  been 
accompanied  by  this  great  change  in  its  re- 
lation to  heat,  every  thaw  would  have  occa- 
sioned a  frightful  inundation,  and  a  single 
night's  frost  would  have  solidified  our  ri- 
vers and  lakes.  Neither  animal  nor  vegeta- 
ble life  could  have  subsisted  under  such 
sudden  and  violent  transitions.  Mr.  Caven- 
dish, who  had  discovered  the  above  fact, 
before  he  knew  of  its  being  inculcated  by 
Dr.  Black  in  his  lectures,  states  the  quan- 
tity of  heat  which  ice  seems  to  absorb  in 
its  fusion  to  be  150°;  Lavoisier  and  Laplace 
make  it  135°;  a  number  probably  correct, 
from  the  pains  they  took  in  constructing, 
on  this  basis,  their  calorimeter.  The  fixity 
of  the  melting  points  of  bodies  exposed  to 
a  strong  heat  need  no  longer  surprise  us; 
because  till  the  whole  mass  be  melted,  the 
heat  incessantly  introduced,  is  wholly  ex- 
pended in  constituting  liquidity,  without 
increasing  the  temperature.  \\?e  can  also 
comprehend  how  a  liquid  metal,  a  saline 
solution,  or  water,  should  in  the  career  of 
refrigeration,  sink  below  the  term  of  its 
congelation,  and  suddenly  remount  to  it. 
Those  substances,  in  which  the  attractive 
force  that  reverts  the  poles  into  the  solid 
arrangement  acts  most  slowly  or  feebly, 
will  most  readily  permit  this  depression  of 
temperature,  before  liquidity  begins  to 
cease.  Thus  bismuth,  a  brittle  metal,  takes 
8°  of  cooling  below  its  melting  point,  to  de- 


termine its  solidification;  tin  takes  4°,  but 
lead  passes  so  readily  into  the  solid  ar- 
rangement that  its  coo'ling  is  at  once  arrest- 
ed at  its  fusing  temperature.  In  illustration 
of  this  statement,  we  may  remark,  that  the 
particles  of  bismuth  and  tin  lose  their  co- 
hesive attraction  in  a  great  measure  long 
before  they  are  heated  to  the  melting  point; 
though  lead  continues  relatively  cohesive 
till  it  begins  to  melt.  Tin  may  be  easily  pul- 
verized at.  a  moderate  elevation  of  tempe- 
rature, and  bi.-muth  in  its  cold  state.  The 
instant,  however,  that  these  two  metals, 
when  melted,  begin  to  congeal,  they  rise 
to  the  proper  fusing  temperature,  because 
the  caloric  of  liquidity  is  then  disengaged. 
Drs.  Irvine,  father  and  son,  to  both  of 
whom  the  science  of  heat  is  deeply  in- 
debted, investigated  the  proportion  of  ca- 
loric disengaged  by  several  other  bodies 
in  their  passage  from  the  liquid  to  the  so- 
lid state,  and  obtained  the  following  re- 
sults: 


Caloric  of 

Do.  referred  to  the 

liquidity. 

sp.  heat  of  -water. 

Sulphur,          143.68 

27.14 

Spermaceti,    145. 

Lead,                162. 

5.6 

Bees  wax,       175. 

Zinc,                493. 

48.3 

Tin,                  500. 

33. 

Bismuth,          550 

23.25 

The  quantities  in  the  second  column  are 
the  degrees  by  which  the  temperatures  of 
each  of  the  bodies  in  its  solid  state,  would 
have  been  raised  by  the  heat  disengaged 
during  its  concretion.  An  exception  must 
be  made  for  wax  and  spermaceti;  which 
are  supposed  to  be  in  the  fluid  state,  when 
indicating  the  above  elevation.  Dr.  Black 
imagined  that  the  new  relation  to  heat 
which  solids  acquire  by  liquefaction,  was 
derived  from  the  absorption,  and  intimate 
combination  of  a  portion  of  that  fluid, 
which  thus  employing- all  its  repulsive  ener- 
gies in  subduing  the  stubborn  force  of  co- 
hesion, ceased  to  have  any  thermometric 
tension,  or  to  be  perceptible  to  our  senses. 
He  termed  this  supposed  quantity  of  calo- 
ric, their  latent  heat;  a  term  very  conveni- 
ent and  proper,  while  we  regard  it  simply 
as  expressing  the  relation  which  the  calo- 
rific agent  bears  to  the  same  body  in  its  fluid 
antl  solid  states.  To  the  presence  of  a  cer- 
tain portion  of  latent  or  combined  heat  in 
solids,  Dr.  Black  ascribed  their  peculiar  de- 
grees of  softness,  toughness,  malleability. 
Thus  we  know  that  the  condensation  of  a 
metal  by  the  hammer,  or  under  the  die, 
never  fails  to  render  it  brittle,  while,  at 
the  same  time,  heat  is  disengaged  Berthol- 
let  subjected  equal  pieces  of  copper  and 
silver  to  repeated  strokes  of  a  fly  press. 
The  elevation  of  their  temperature,  which 
was  considerable  by  the  first  blow,  dinun- 


CAL 


ished  greatly  at  each  succeeding  one,  and 
became  insensible  whenever  the  condensa- 
tion of  volume  ceased.  The  copper  suffered 
greatest  condensation,  and  evolved  most 
heat.  Here  the  analogy  of  a  sponge,  yield- 
ing its  water  to  pressure,  has  been  employ- 
ed to  illustrate  the  materiality  of  heat  sup- 
posed deducible  from  these  experiments. 
But  the  phenomenon  may  be  referred  to 
the  intestine  actions  between  the  ultimate 
particles  which  must  accompany  the  vio- 
lent dislocation  of  their  attracting  poles. 
The  cohesiveness  of  the  metal  is  greatly 
impaired. 

The  enlarged  capacity  for  heat,  to  use 
the  popular  expression,  which  solids  ac- 
quire in  liquefying,  enables  us  to  under- 
stand and  apply  the  process  of  artificial 
cooling,  by  what  are  called  freezing  mix- 
tures. When  two  solids,  such  as  ice  and 
salt,  by  their  reciprocal  affinity,  give  birth 
to  a  liquid,  then  a  very  great  demand  for 
heat  is  made  on  the  surrounding  bodies; 
or  they  are  powerfully  stripped  of  their 
heat,  and  their  temperature  sinks  of  course. 
Pulverulent  snow  and  salt  mixed  at  32°, 
will  produce  a  depression  of  the  thermo- 
meter plunged  into  them  of  about  3b°.  The 
more  rapid  the  liquefaction,  the  greater 
the  cold.  Hence  the  paradoxical  experi- 
ment of  setting  a  pan  on  the  fire  contain- 
ing the  above  freezing  mixture  with  a  small 
vessel  of  water  plunged  into  it.  In  a  few 
seconds  the  Water  will  be  found  to  be  fro- 
zen. The  solution  of  all  crystallized  salts 
is  attended  with  a  depression  of  tempera- 
ture, which  increases  generally  with  the 
solubility  of  the  salt. 

The  table  of  freezing  mixtures  in  the 
APPENDIX,  presents  a  copious  choice  of 
such  means  of  refrigeration.  Equal  parts 
of  sal  ammoniac  and  nitre,  in  powder,  form 
the  most  convenient  mixture  for  procuring 
moderate  refrigeration;  because  the  water 
of  solution  being  afterwards  removed  by 
evaporation,  the  pulverized  salts  are  equal- 
ly efficacious  as  at  first.  Under  the  articles 
CLIMATE,  CONGELATION,  TEMPERA- 
TURE, THERMO  METER,  and  WATER,  some 
additional  facts  will  be  found  on  the  pre- 
sent subject. 

But  the  diminution  of  temperature  by 
liquefaction  is  not  confined  to  saline  bodies. 
When  a  solid  amalgam  of  bismuth,  and  a 
solid  amalgam  of  lead,  are  mixed  together, 
they  become  fluid,  and  the  thermometer 
sinks  during  the  time  of  their  action. 

The  equilibrium  between  the  attractive 
and  repulsive  forces  which  constitutes  the 
liquid  condition  of  bodies,  is  totally  sub- 
verted by  a  definite  elevation  of  tempera- 
ture, when  the  external  compressing  forces 
do  not  vary.  The  transition  from  the  liquid 
state  into  that  of  elastic  fluidity  is  usually 
accompanied  with  certain  explosive  move- 

VOL.    I. 


ments,  termed  ebullition.  The  peculiar  tem- 
peratures at  which  different  liquids  under- 
go this  change  is  therefore  called  their 
boiling  point;  and  the  resulting  elastic  fluid 
is  termed  a  vapour,  to  distinguish  it  from 
a  gas,  a  substance  permanently  elastic,  und 
not  condensable  as  vapours  are,  by  mode- 
rate degrees  of  refrigeration.  It  is  evident 
that  when  the  attractive  forces,  however 
feeble  in  a  liquid,  are  supplanted  by  strong 
repulsive  powers,  the  distances  between 
the  particles  must  be  greatly  enlarged. 
Thus  a  cubic  inch  of  water  at  40°  becomes 
a  cubic  inch  and  l-25th  on  the  verge  of 
212°,  and  at  212*  it  is  converted  into  1600 
cubic  inches  of  steam.  The  existence  of 
this  steam  indicates  a  balance  between  its 
elastic  force  and  the  pressure  of  the  at- 
mosphere. If  the  latter  be  increased  beyond 
its  average  quantity  by  natural  or  artificial 
means,  then  the  elasticity  of  the  steam  will 
be  partially  overcome,  and  a  portion  of  it 
will  return  to  the  liquid  condition.  And 
conversely,  if  the  pressure  of  the  air  be  less 
than  its  mean  quantity,  liquids  will  assume 
elastic  fluidity  by  a  less  intensity  of  calo- 
rific repulsion,  or  at  a  lower  thermometric 
tension.  Professor  Hobison  performed  a  set 
of  ingenious  experiments,  which  appear 
to  prove,  that  when  the  atmospheric  pres- 
sure is  wholly  withdrawn,  that  is,  in  vacuot 
liquids  become  elastic  fluids  121°  below 
their  usual  boiling  points.  Hence  water  in 
vacuo  will  boil  and  distil  over  at  212°  — — 
124  =  88°  Fahr.  This  principle  was  long 
ago  employed  by  the  celebrated  Watt  in 
his  researches  on  the  steam  engine,  and  has 
been  recently  applied  in  a  very  ingenious 
way  by  Mr.  Tritton  in  his  patent  still,  (Phil. 
Mag.  vol.  51.),  and  Mr.  Barry,  in  his  eva- 
porator for  vegetable  extracts,  (Med.  Chir. 
Trans,  vol.  10)  See  ALCOHOL,  DISTILLA- 
TION, EXTRACTS. 

On  the  same  principle  of  the  boiling,  vary- 
ing with  the  atmospheric  pressure,  the  Rev. 
Mr.  Wollaston  has  constructed  his  beauti- 
ful thermometric  barometer  for  measuring 
heights.  He  finds  that  a  difference  of  1°  in 
the  boiling  point  of  water  is  occasioned  by 
a  difference  of  0.589  of  an  inch  on  the  ba- 
rometer. This  corresponds  to  nearly  520 
feet  of  difference  of  elevation.  By  using 
the  judicious  directions  which  he  has  given, 
the  elevation  of  a  place  may  thus  be  rigor- 
ously determined,  and  with  great  conveni- 
ence. The  whole  apparatus,  weighing  20 
ounces,  packs  in  a  cylindrical  tin  case,  2 
inches  diameter,  and  10  inches  long. 

When  a  vessel  containing  water  is  placed 
over  a  flume  a  hissing  sound  or  simmer- 
ing is  soon  perceived.  This  is  ascribed  to 
the  vibrations  occasioned  by  the  successive 
vaporization  and  condensation  of  the  parti- 
cles in  immediate  contact  with  the  bottom 
of  the  vessel.  The  sound  becomes  louder  as 
32 


CAL 


CAL 


the  liquid  is  heated,  and  terminates  in  ebul- 
lition The  temperature  becomes  now  of  a 
sudden  stationary  when  the  vessel  is  open, 
however  rapidly  it  rose  before,  and  whate- 
ver force  of  fire  be  applied.  Dr.  Black  set 
a  tin  cup  full  of  water  at  50°,  on  a  red  hot 
iron  plate.  In  four  minutes  it  reached  the 
boiling  point,  and  in  twenty  minutes  it  was 
all  boiled  off.  From  50°  to  212°,  the  eleva. 
tion  is  162°;  which  interval,  divided  4>y  4, 
gives  40|°  of  heat,  which  entered  the  tin 
cup  per  minute.  Hence  20  minutes,  or  5 
times  4  multiplied  into  40£  =  810,  will 
represent  the  quantity  of  heat  that  passed 
into  the  boiling  water  to  convert  it  into  a 
vapour.  But  the  temperature  of  this  is  still 
only  212°.  Hence,  according-  to  Black,  these 
810°  have  been  expended  solely  in  giving 
elastic  tension,  or,  according  to  Irvine,  in 
supplying  the  vastly  increased  capacity  of 
of  the  aeriform  state;  and  therefore  they 
may  be.  denominated  latent  heat,  being  in- 
sensible to  the  thermometer.  The  more  ex- 
act experiments  of  Mr.  Watt  have  shown, 
that  whatever  period  be  assigned  for  the 
heating  of  a  mass  of  water  from  50°  to 
212°,  6  times  this  period  is  requisite  with 
a  uniform  heat  for  its  total  vaporization. 
But  6  X  162°  —  972  =  the  latent  heat  of 
steam;  a  result  which  accords  with  my  ex- 
periments made  in  a  different  way,  as  will 
be  presently  shown.  Every  attentive  opera- 
tor must  have  observed  the  greater  explo- 
sive violence  and  apparent  difficulty  of  the 
ebullition  of  water  exposed  to  a  similar 
heat  in  glass,  than  in  metallic  vessels.  M. 
Gay-Lussac  has  studied  this  subject  with 
his  characteristic  sagacity.  He  discovered 
that  water  boiling  in  a  glass  vessel  has  a 
temperature  of  214.2°,  and  in  a  tin  vessel 
contiguous  to  it,  of  only  212°.  A  few  par- 
ticles of  pounded  glass  thrown  into  the 
former  vessel,  reduces  the  thermometer 
plunged  in  it  to  212.6,  and  iron  filings  to 
212.  When  the  flame  is  withdrawn  for  a 
few  seconds  from  under  a  glass  vessel  of 
boiling  water,  the  ebullition  will  recom- 
mence on  throwing  in  a  pinch  of  iron  filings. 
Professors  Munche  and  Gmelin  of  Hei- 
delberg have  extended  these  researches, 
and  given  the  curious  results  as  to  the  boil- 
ing points,  expressed  in  the  following  table: 


Substance  of  the 

Silver, 

Platina, 

Copper, 

Tinned  iron, 

Marble, 

Lead, 

Tin, 

Porcelain, 

White  glass, 

Green  glass, 


Th         Do.  £  inch 

beloiv  sitr- 


water. 

211-775°  211.  55° 

211.775  210.875 

212.900  212225 

213.24  211.66 

212.  10  211.  66 

212.  45  211.775 

212.    7  211.775 

212.     1  211.900 

212.  7  212.  00 

213.  8  213.  35 


Ditto,  212.    7°    212.  00° 

Delft  ware,  213.     8      212.    7 

Common  earthen  ware  213.  8  212.  45 
It  is  difficult  to  reconcile  these  varia- 
tions to  the  results  of  M.  Gay-Lussac. "  The 
vapour  formed  at  the  surface  of  a  liquid,'* 
he  remarks,  "  may  be  in  equilibria  with  the 
atmospheric  pressure;  while  the  interior 
portion  may  acquire  a  greater  degree  of 
heat  than  that  of  the  real  boiling  point,  pro- 
vided the  fluid  be  enclosed  in  a  vessel,  and 
heated  at  the  bottom.  In  this  case,  the  ad- 
hesion of  the  fluid  to  the  vessel  may  be 
considered  as  analogous  in  its  action  to  vis- 
cidity, in  raising  the  temperature  of  ebul- 
lition. On  this  principle  we  explain  the  sud- 
den starts  which  sometimes  take  place  in 
the  boiling  of  fluids.  This  frequently  oc- 
curs to  a  great  degree  in  distilling  sulphu- 
ric acid,  by  which  the  vessels  are  not  un- 
frequently  broken  when  they  are  of  glass. 
This  evil  may  be  effectually  obviated  by 
putting  into  the  retort  some  small  pieces 
of  platina  wire,  when  the  sudden  disen- 
gagement of  gas  will  be  prevented  and  con- 
sequently the  vessels  not  be  liable  to  be  bro- 
ken."— innalesde  Chimie,  March  1818.  See 
my  remarks  on  this  subject  under  the  DIS- 
TILLATION of  SULPHURIC  ACID,  extract- 
ed from  the  Journal  of  Science,  October 
1817.  If  we  throw  a  piece  of  paper,  a  crust 
of  bread,  or  a  powder,  into  a  liquid  slight- 
ly impregnated  with  carbonic  acid,  its  evo- 
lution will  be  determined.  See  some  cu- 
rious observations  by  M.  Thenard  under 
our  articles  OXYGENIZED  NITRIC  ACID, 
or  OXYGENIZED  WATER.  In  a  similar 
manner,  the  asperities  of  the  surface  of  a 
glass  or  other  vessel,  act  like  points  in  elec- 
tricity, in  throwing  ofl'  gas  or  vapour  pre- 
sent in  the  liquid  which  it  contains. 

In  all  the  examples  of  the  preceding  ta- 
ble, the  temperature  is  greater  at  the  bot- 
tom than  near  the  surface  of  the  liquid;  and 
the  specific  differences  must  be  ascribed 
to  the  attractive  force  of  the  vessel  to  wa- 
ter, and  its  conduction  of  heat.  We  must 
thus  try  to  explain  why  tinned  iron  gives 
a  temperature  to  boiling  water  in  contact 
with  it,  1.67  degrees  higher  than  silver  and 
platina.  Between  water,  and  iron,  tin,  or 
lead,  there  are  reciprocal  relations  at  ele- 
vated temperatures,  which  do  not  appa- 
rently exist  with  regard  to  silver  and  pla- 
tina. 

The  following  is  a  tabular  view  of  the 
boiling  points  by  Fahrenheit's  scale  of  the 
most  important  liquids,  under  a  mean  baro- 
metrical pressure  of  thirty  inches: — 

Soiling  point  a. 

Ether,  sp.  gr.  0. 7365  at  48°.  G.  Lussac,  100° 
Carburet  of  sulphur,       -          do. 
Alcohol,  sp.  gr.  0.813  Ure,     173.5 

Nitric  acid,         1.500  Dalton,    210 

Water,  212 

Saturated  sol.  of  Glaub.  salt.  Biot,       213? 


CAL 


GAL 


Boiling1  points. 

Saturated  sol.  of  sugar  of  lead,  Biot,  2l5f  ° 

Do.  do.        sea  salt,          do.  224-J- 

Muriate  of  lime  2  -f  water  1  Ure,  230 

Do.  35.5  -f-  do.  64.5  do.  235 

Do.  40.5  -f-  do.  59.5  do.  240 

Muriatic  acid,  1.094  Dalton,  232 

Do.  1.127  do.  222 

Do.  1.047  do.  222 

Nitric  acid,       1.45  do.  240 

Do.  1.42  do.  248 

Do.  1.40  do.  247 

Do.  1.35  do.  242 

Do.  1.30  do.  236 

Do.  1.16  do.  220 

Rectified  petroleum,        -          Ure,  306 

Oil  of  turpentine,  -          do.  316 

Sulp.  acid  sp.  gr.  1.30  +         Dalton,  240 

Do.  1.408  do.  260 

Do.  1.520  do.  290 

Do.  1.650  do.  350 

Do.  1.670  do.  360 

Do.  1.699  do.  374 

Do.  1.730  do.  391 

Do.  1.780  do.  435 

Do.  1.810  do.  473 

Do.  1.819  do.  487 

Do.  1.827  do.  501 

Do.  1.833  do.  515 

Do.  1.842  do.  545 

Do.  1.847  do.  575 

Do.  1.848  do.  590 

Do.  1.849  do.  605 

Do.  1.850  do.  620 

Do.  1.848  Ure,  600 

Phosphorus,        ....  554 

Sulphur,  -  570 

Linseed  oil,         ....  640? 

Mercury,  (Dulong,  662°),  656 

These  liquids  emit  vapours,  which,  at 
their  respective  boiling1  points,  balance  a 
pressure  of  the  atmosphere,  equivalent  to 
thirty  vertical  inches  of  mercury.  But  at 
inferior  temperatures  they  yield  vapours 
of  inferior  elastic  power.  It  is  thus  that  the 
vapour  of  quicksilver  rises  into  the  va- 
cuum of  the  barometer  tube;  as  is  seen  par- 
ticularly in  warm  climates,  by  the  mercu- 
rial dew  on  the  glass  at  its  summit.  Hence 
aqueous  moistures  adhering  to  the  mercu- 
ry, causes  it  to  fall  below  the  true  barome- 
ter level,  by  a  quantity  proportional  to  the 
temperature.  The  determination  of  the  elas- 
tic force  of  vapours,  in  contact  with  their 
respective  liquids,  at  different  tempera- 
tures, has  been  the  subject  of  many  ex- 
periments. The  method  of  measuring  their 
elasticities,  described  in  my  paper  on 
HEAT,  seems  convenient,  and  susceptible 
of  precision. 

A  glass  tube  about  one-third  of  an  inch 
internal  diameter,  and  6  feet  long,  is  seal- 
ed at  one  end,  and  bent  with  a  round  cur- 
vature in. the  middle,  into  the  form  of  a 
syphon,  with  its  two  legs  parallel,  and 


about  2£  inches  asunder.  A  rectangular 
piece  of  cork  is  adapted  to  the  interval  be- 
tween the  legs,  and  fixed  firmly  by  twine, 
about  6  inches  from  the  ends  of  the  sy- 
phon. Dry  mercury  is  now  introduced,  so 
as  to  fill  the  sealed  leg,  and  the  bottom  of 
the  curvature.  On  suspending-  this  syphon 
barometer  in  a  vertical  direction,  by  the 
cork,  the  level  of  the  mercury  will  take  a 
position  in  each  of  the  legs,  corresponding 
to  the  pressure  of  the  atmosphere.  The  dif- 
ference is  of  course  the  true  height  of  the 
barometer  at  the  time,  which  may  be  mea- 
sured by  the  application  of  a  separate  scale 
of  inches  and  tenths.  Fix  rings  of  fine  pla- 
tinum wire  round  the  tube  at  the  two  levels 
of  the  mercury.  Introduce  now  into  the 
tube  a  few  drops  of  distilled  water,  recent- 
ly boiled,  and  pass  them  up  through  the 
mercury.  The  vapour  rising  from  the  wa- 
ter will  depress  the  level  of  the  mercury 
in  the  sealed  leg,  and  raise  it  in  the  open 
leg,  by  a  quantity  equal  in  each  to  one-half  of 
the  real  depression.  To  measure  distinctly 
this  difference  of  level  with  minute  accu- 
racy, would  be  difficult;  but  the  total  de- 
pression, which  is  the  quantity  sought,  may 
be  readily  found,  by  pouring  mercury  in  a 
slender  stream  into  the  open  leg,  till  the 
surface  of  the  mercury  in  the  sealed  leg 
becomes  once  more  a  tangent  to  the  pla- 
tina  ring,  which  is  shewn  by  a  delicate 
film  of  light,  as  in  the  mountain  barome- 
ter. The  vertical  column  of  mercury  above 
the  lower  initial  level  being  measured,  it 
represents  precisely  the  elastic  force  of  the 
vapour,  since  that  altitude  of  mercury  was 
required  to  overcome  the  elasticity  of  the 
vapour.  The  whole  object  now  is  to  apply 
a  regulated  heat  to  the  upper  portion  of 
the  sealed  leg,  from  an  inch  below  the 
mercurial  level,  to  its  summit.  This  is  easi- 
ly accomplished,  by  passing  it  through  a 
perforated  cork  into  an  inverted  phial,  5 
inches  diameter  and  7  long,  whose  bottom 
has  been  previously  cracked  off  by  a  hot 
iron.  Or  a  phial  may  be  made  on  purpose. 
When  the  tapering  elastic  cork  is  now 
strongly  pressed  into  the  mouth  of  the  bot- 
tle, it  renders  it  perfectly  water-tight.  By 
inclining  the  syphon,  we  remove  a  little  of 
the  mercury,  so  that  when  reverted,  the 
level  in  the  lower  leg  may  nearly  coincide 
with  the  ring.  Having  then  suspended  it  in 
the  vertical  position  from  a  high  frame,  or 
the  roof  of  an  apartment,  we  introduce  wa- 
ter at  32°  into  the  cylindrical  glass  vessel. 
When  its  central  tube,  against  the  side  of 
which  the  bulb  of  a  delicate  thermometer 
rests,  acquires  the  temperature  of  the  sur- 
rounding medium,  mercury  is  slowly  add- 
ed to  the  open  leg,  till  the  primitive  level 
is  restored  at  the  upper  platina  ring.  The 
column  of  mercury  above  the  ring  in  the 
open  leg,  is  equivalent  to  the  force  of 
aqueous  vapour  at  32°.  The  effect  of  lower 


CAL 


CAL 


temperatures  may  be  examined,  by  putting 
saline  freezing  mixtures  in  the  cylinder. 
To  procure  measures  of  elastic  force  at 
higher  temperatures,  two  feeble  Argand 
flames  are  made  to  send  up  heated  air,  on 
the  opposite  shoulders  of  the  cylinder.  By 
adjusting  the  flames,  and  agitating  the  li- 
quid, very  uniform  temperatures  may  be 
given  to  the  tube  in  the  axis.  At  every  5° 
or  10°  of  elevation,  we  make  a  measurement 
by  pouring  mercury  into  the  open  leg,  till 
the  primitive  level  is  restored  in  the  other. 

For  temperatures  above  2lJ°,  I  employ 
the  same  plan  of  apparatus,  slightly  modi- 
fied. The  sealed  leg  of  the  syphon  has  a 
length  of  6  or  7  inches,  while  the  open  leg 
is  10  or  12  feet  long,  secured  in  the  groove 
of  a  graduated  wooden  prism  The  initial 
level  becomes  212°  when  the  mercury  in 
each  leg  is  in  a  horizontal  plane,  and  the 
heat  is  now  communicated  through  the  me- 
dium of  oil.  If  the  bending  of  the  tube,  be 
made  to  an  angle  of  about  35°  from  paral- 
lelism of  the  legs,  a  tubulated  globular  re- 
ceiver becomes  a  convenient  vessel  for 
holding  the  oil.  The  tapering  cork  through 
which  the  sealed  end  of  the  syphon  is  pas- 
sed, being  thrust  into  the  tapering  mouth 
of  the  receiver,  remains  perfectly  tight 
at  all  higher  temperatures,  being  progres- 
sively swelled  with  the  heat.  One  who  has 
not  made  such  trials,  may  be  disposed  to 
cavil  at  the  probable  tightness  of  such  a 
contrivance,  but  1  who  have  used  it  in  ex- 
periments for  many  months  together,  fcnow 
that  only  extreme  awkwardness  in  the 
operator,  can  occasion  the  dropping  out  of 
oil  heated  up  to  even  320°  of  Fahrenheit. 
The  tubulure  of  the  receiver  admits  the 
thermometer.  The  Tables  of  Vapour,  in  the 
Appendix,  exhibit  the  results  of  some  care- 
fully conducted  experiments. 

In  my  attempts  to  find  some  ratio  which 
would  connect  the  above  elasticities  of 
aqueous  vapour  with  the  temperatures,  the 
following  rule  occurred  to  me: 

"  The  elastic  force  at  212°  —  30  being 
divided  by  1.23,  will  give  the  force  for  10° 
below;  this  quotient  divided  by  1.24,  will 
give  that  10°  lower,  and  so  on  progressive- 
ly. To  obtain  the  forces  above  212°,  we 
have  merely  to  multiply  30  by  the  ratio 
1.23  for  the  force  at  222°;  this'product  by 
1.22  for  that  at  232°,  this  last  product  by 
1.21  for  the  force  at  242°,  and  thus  for 
each  successive  interval  of  10°  above  the 
boiling-  point."  The  following  modification 
of  the  same  rule  gives  more  accurate  re- 
sults. "  Let  r  r=  the  mean  ratio  between 
that  of  210°  and  the  given  temperature; 
n  —  the  number  of  terms  (each  of  10°) 
distant  from  210°;  F—  the  elastic  force  of 
steam  in  inches  of  mercury.  Then  Log.  of 
F  =  Log.  28.9  ^r  n  Log.  r,-  the  positive 
sign  being  used  above,  the  negative  below 


210°."  I  have  investigated  also  simple  ra- 
tios, which  express  the  connexion  between 
the  temperature  and  elasticity  of  the  va- 
pours of  alcohol,  ether,  petroleum,  and  oil 
of  turpentine,  for  which  I  must  refer  to 
the  paper  itself. 

Mr.  W.  Creighton  of  Soho  communicated 
in  March  1819,  to  the  Philosophical  Maga- 
zine, the  following  ingenious  formula  for 
aqueous  vapour.  "  Let  the  degrees  of  Fah- 
renheit -j-  85  =  D,  and  the  corresponding 
force  of  steam  in  inches  of  mercury  — 
0.09  ==  I.  Then  Log.  D  —  2.22679X6  = 
Log.  I. 

EXAMPLE. 

212°  -f  85=  297Log.  =  2.47276 

—  2.22679  constant 
number. 

0.24579 
X  6 


Log.  1.47582=  29.91  ~l 
-f  0.09  • 

Inches  30.00  D 

He  then  gives  a  satisfactory  tabular  view 
of  the  near  correspondences  between  the 
results  of  his  formula,  and  my  experi- 
ments. 

By  determining  experimentally  the  vo- 
lume  of  vapour  which  a  given  volume  of 
liquid  can  produce  at  212°,  M.  Gay-Lussac 
has  happily  solved  the  very  difficult  prob- 
lem of  the  specific  gravity  of  vapours.  He 
took  a  spherule  of  thin  glass,  with  a  short 
capillary  stem,  and  of  a  known  weight.  He 
filled  it  with  the  peculiar  liquid,  hermeti- 
cally sealed  the  orifice,  and  weighed  it. 
Deducting  from  its  whole  weight  the  known 
weight  of  the  spherule,he  knew  the  weight, 
and  from  its  sp.  gravity  the  bulk  of  the  li- 
quid. He  filled  a  tall  graduated  glass  re- 
ceiver, capable  of  holding  about  three  pints, 
with  mercury,  inverted  it  in  a  basin,  and  let 
up  the  spherule.  The  receiver  was  now 
surrounded  by  a  bottomless  cylinder,  which 
rested  at  its  lower  edge  in  the  mercury  of 
the  basin.  The  interval  between  the  two  cy- 
linders was  filled  with  water.  Heat  was 
applied  by  means  of  a  convenient  bath,  till 
the  water  and  the  included  mercury  as- 
sumed the  temperature  of  212°.  The  ex- 
pansible liquid  had  ere  this  burst  the  sphe- 
rule, expanded  into  vapour,  and  depressed 
the  mercury.  The  height  of  the  quicksilver 
column  in  the  graduated  cylinder  above  the 
level  of  the  basin,  being  observed,  it  was 
easy  to  calculate  the  volume  of  the  incum- 
bent vapour.  The  quantity  of  liquid  used 
was  always  so  small,  that  the  whole  of  it 
was  converted  into  vapour. 

The  following  exhibits  the  specific  gravi- 
ties as  determined  by  the  above  method: 


( 


CAL 


Spec. 
Vapour  of  water, 

Hydroprussic  acid, 
Absolute  alcohol, 
Sulphuric  ether, 
Hydriodic  ether, 
Oil  of  turpentine, 
Carburet  of  sulphur, 
Muriatic  ether, 


Grav.  Air  —  1. 

0.62349 

0.94760 

1.6050 

2.5860 

5.4749 

5.0130 

2.6447 

2.2190     Thenard, 


Boiling  point,  Fahr. 
212° 
79.7 
173 

96 
148 
316 
116 

52 


The  ahove  specific  gravities  are  estima- 
ted under  a  barometric  pressure  of  29.92 
inches. 

M.  Gay-Lussac  has  remarked,  that  when 
a  liquid  combination  of  alcohol  and  water, 
or  alcohol  and  ether,  is  converted  into  va- 
pour at  212°  Fahr.  or  100  cent.,  the  volvime 
is  exactly  the  sum  of  what  their  separate 
volumes  would  have  produced;  so  that  the 
condensation  by  chemical  action  in  the  li- 
quid state,  ceases  to  operate  in  the  gaseous. 
An  equal  volume  of  carburet  of  sulphur  and 
absolute  alcohol,  at  their  respective  boiling 
points  of  173°  and  126°,  is  said  to  yield 
each  an  equal  quantity  of  vapour  of  the 
same  density.  A  more  explicit  statement 
has  been  promised,  and  is  perhaps  required 
On  this  curious  subject. 

It  appears,  that  a  volume  of  water  at  40° 
forms  1694  volumes  of  steam  at  212°.  The 
subsequent  increase  of  the  volume  of  steam, 
and  of  other  vapours,  out  of  the  contact  of 
their  respective  liquids,  we  formerly  stated 
to  be  in  the  ratio  of  the  expansion  of  gases, 
forming  an  addition 'to  their  volume  of 
3-8ths  for  every  180°  Fahrenheit.  We  can 
now  infer,  both  from  this  expansion  of  one 
measure  into  1694,  and  from  the  table  of 
the  elastic  forces  of  steam,  the  explosive 
violence  of  this  agent  at  still  higher  tempe- 
ratures, and  the  danger  to  be  apprehended 
from  the  introduction  of  water  into  the  close 
moulds,  in  which  melted  metal  is  to  be 
poured.  Hence,  also,  the  formidable  acci- 
dents which  have  happened,  from  a  little 
water  falling  into  heated  oils.  The  little 
glass  spherules,  called  candle  bombs,  ex- 
hibit the  force  of  steam  in  a  very  striking 
manner;  but  the  risk  of  particles  of  glass 
being  driven  into  the  eye,  should  cause 
their  employment  to  be  confined  to  prudent 
experimenters.  Mr.  Watt  estimated  the 
volumes  of  steam  resulting  from  a  volume 
of  water  at  1800;  and  in  round  numbers  at 
1728;  a  number  differing  little  from  the 
above  determination  of  M.  Gay-Lussac. 
Desagulier's  estimate  of  14000  was  there- 
fore extravagant. 

It  has  been  already  mentioned,  that  the 
caloric  of  fluidity  in  steam  surpasses  that 
of  an  equal  weight  of  boiling  water  by 
about  972°.  This  quantity,  or  the  latent 
heat  of  steam,  as  it  is  called,  is  most  con- 
veniently determined,  by  transmitting  a 
certain  weight  of  it  into  a  given  weight  of 
water,  at  a  known  temperature,  and  from 


the  observed  elevation  of  temperature  in 
the  liquid,  deducing  the  heat  evolved  du- 
ring condensation.  Dr.  Black,  Mr.  Watt, 
Lavoisier,  Count  Rum  ford,  Clement,  and 
Desorrnes,  as  well  as  myself,  have  publish- 
ed observations  on  the  subject.  "  In  this 
research  I  employed  a  very  simple  appara- 
tus; and  with  proper  management,  1  be- 
lieve, it  is  capable  of  giving  the  absolute 
quantities  of  latent  heat  in  different  va- 
pours, as  exactly  as  more  refined  and  com- 
plicated mechanisms.  At  any  rate,  it  will 
afford  comparative  results  with  great  pre- 
cision. It  consisted  of  a  glass  retort  of  very 
small  dimensions  with  a  short  neck,  insert- 
ed into  a  globular  receiver  of  very  thin 
glass,  and  about  three  inches  in  diameter. 
The  globe  was  surrounded  with  a  certain 
quantity  of  water  at  a  known  temperature, 
contained  in  a  glass  basin.  200  grains  of 
the  liquid,  whose  vapour  was  to  be  exam- 
ined, were  introduced  into  the  retort,  and 
rapidly  distilled  into  the  globe  by  the  heat 
of  an  Argand  lamp.  The  temperance  of  the 
jiir  was  45°,  that  of  the  water  in  the  basin 
from  42°  to  43°,  and  the  rise  of  tempera- 
ture, occasioned  by  the  condensation  of  the 
vapour,  jsever  exceeded  that  of  the  atmos- 
phere by  four  degrees.  By  these  means,  as 
the  communication  of  heat  is  very  slow  be- 
tween bodies  which  differ  little  in  tempe- 
rature, I  found  that  the  air  could  exercise 
no  perceptible  influence  on  the  water  in  the 
basin  during  the  experiment,  which  was 
always  completed  in  five  or  six  minutes.  A 
thermometer  of  great  delicacy  was  continu- 
ally moved  through  the  water;  and  its  indi- 
cations were  read  off,  by  the  aid  of  a  lens, 
to  small  fractions  of  a  degree. 

"  In  all  the  early  experiments  of  Dr. 
Black  on  the  latent  heat  of  common  steam, 
the  neglect  of  the  above  precautions  intro- 
duced material  errors  into  the  estimate. 
Hence,that  distinguished  philosopher  found 
the  latent  heat  of  steam  to  be  no  more  than 
800°  01-  810°.  Mr.  Watt  afterwards  deter- 
mined  it  more  nearly  from  900  to  970°;  La- 
voisier and  Laplace  have  made  it  1000°, 
and  Count  Rumford  1040°. 

"  From  the  smallness  of  the  retort  in  my 
mode  of  proceeding,  the  shortness  of  the 
neck,  and  its  thorough  insertion  into  the 
globe,  we  prevent  condensation  by  the  air 
in  transitu;  while  the  surface  of  the  globe, 
and  the  mass  of  water  being  great,  relative 
to  the  quantity  of  vapour  employed,  the 


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heat  is  entirely  transferred  to  the  refrige- 
ratory, where  it  is  allowed  to  remain  with- 
out apparent  diminution  for  a  few  minutes. 
"  In  numerous  repetitions  of  the  same 
experiment  the  accordances  were  excellent 
The  following1  table  contains  the  mean  re- 
sults. The  water  in  the  basin  weighed  in 
each  case  32340  grs.,  and  200  grs.  of  each 
liquid  was  distilled  over.  The  globe  was 
held  steadily  in  the  centre  of  the  glob*  by 
a  slender  ring  fixed  round  the  neck."  For 
the  arithmetical  reductions  I  must  refer  to 
the  paper  itself.  Dr.  Thomson,  in  his  com- 
ments on  this  part  of  my  researches,  ob- 
serves, "  It  is  obvious,  that  the  latent  heats 
determined  in  this  way  must  be  considera- 
bly below  the  truth.  The  method  contrived 
by  Count  Rumford  seems  to  me  a  good  deal 
better.  He  cooled  the  water  surrounding 
the  globe  4°  below  the  temperature  of  the 
room,  and  continued  the  distillation  till  the 
temperature  of  the  water  was  exactly  4° 
above  that  of  the  room."  Surely  Dr.  Thom- 


son cannot  have  read  the  paper  with  atten- 
tion, or  he  would  have  perceived  the  fol- 
lowing sentence:  "I  found  that  the  air 
could  exercise  no  perceptible  influence  on 
the  water  in  the  basin  during  the  experi- 
ment, which  was  always  completed  in  five 
or  six  minutes."  In  fact,  I  left  the  glass 
basin  of  water  repeatedly  at  a  temperature 
of  4°  above  that  of  the  room  for  double 
the  duration  of  the  experiment,  and  found 
scarcely  a  perceptible  change  in  the  ther- 
mometer immersed  in  it.  This  source  of 
fallacy  was  sufficiently  guarded  against. 
But  [  have  found  since,  that  a  compensa- 
tion was  due  for  the  glass  basin  itself, 
which  I  omitted  by  accident  to  introduce 
into  the  arithmetical  reductions.  This  would 
have  raised  the  latent  heat  of  water  to  very 
nearly  1000,  and  that  of  the  other  vapours 
in  a  proportional  degree.  I  now  give  the 
original  table,  along  with  a  corrected  co- 
lumn: 


Table  of  Latent  Heat  of  Vapours. 

Vapour  of  water,  at  its  boiling  point, 
Alcohol,  pp.  gr.  825, 
Ether,  boiling  point  112°, 
Petroleum, 
Oil  of  turpentine, 

Nitric  acid,  sp.  gr.  1.494,  boiling  point  165°, 
Liquid  ammonia,  sp.  gr.  0.978, 
Vinegar,  sp.  gr.  1.007, 

"  Aqueous  vapour  of  an  elastic  force  ba- 
lancing the  atmospheric  pressure,  has  a 
specific  gravity  compared  to  air,  by  the  ac- 
curate experiments  of  M.  Gay-Lussac,  of  10 
to  16.  For  facility  of  comparison,  let  us  call 
the  steam  of  water  unity,  or  1.00;  then  the 
specific  gravity  of  the  vapour  of  pure  ether 
is  4.00,  while  the  specific  gravity  of  the  va- 
pour of  absolute  alcohol  is  2.60.  But  the 
vapour  of  ether,  whose  boiling  point  is  not 


967° 

442 

502.4 

177.8 

177.8 

532. 

837.3 

875.0 


Corrected  column. 
1000° 
457 
312.9 
183.8 
1838 
550. 
865.9 
903 


tains  some  alcohol;  hence  we  must  accord- 
ingly diminish  a  little  the  specific  gravity 
number  of  its  vapour.  It  will  then  become, 
instead  of  4.00,  3.55.  Alcohol  of  0.825  sp.  gr. 
contains  much  water;  sp.  gr.  of  its  vapour 
2.30.  That  of  water,  as  before  unity,  1.00. 
The  interstitial  spaces  in  these  vapours  will 
therefore  be  inversely  as  these  numbers,  or 
•g-jy  for  ether,  -j-g-^-  for  alcohol,  JJJ-Q  for  wa- 
ter. Hence,  -yly  of  latent  heat,  existing  in 
ethereal  vapour,  will  occupy  a  proportional 
space,  be  equally  condensed,  or  possess  the 
same  tension  with  -5^  in  alcoholic,  and 
-j-6"<j  in  aqueous  vapour.  A  small  modifi- 
cation will  no  doubt  be  introduced  by  the 
difference  of  the  thermometric  tensions,  or 
sensible  heats,  under  the  same  elastic  force. 
Common  steam,  for  example,  may  be  con- 
sidered as  deriving  its  total  elastic  energy 
<rom  the  latent  heat  multiplied  into  the 


specific  gravity  -f-  the  thermometric  ten- 
sion. 

"  Hence,  the  elastic  force  of  water,  ether, 
and  alcohol,  are  as  follows: — 

Ew  =  970  X  1-00  +  212°  =  1182 
EC  =  302  X  3.55  -f  112°  =  1184 
Ea[  =  440  X  23.0  +  175°  =  1185 

Three  equations,  which  yield,  according 
to  my  general  proposition,  equal  quanti- 
ties. When  the  elastic  forces  of  vapours 
are  doubled,  or  when  they  sustain  a  double 
pressure,  their  interstices  are  proportion- 
ably  diminished.  We  may  consider  them, 
now,  as  in  the  condition  of  vapours  pos- 
sessed of  greater  specific  gravities.  Hence, 
the  second  portion  of  heat  introduced  to 
give  double  the  elastic  force  need  not  be 
equal  to  the  first,  in  order  to  produce  the 
double  tension. 

"  This  view  accords  with  the  experi- 
ments of  Mr.  Watt,  alluded  to  in  the  be- 
ginning of  the  memoir.  He  found,  that  the 
latent  heat  of  steam  is  less  when  it  is  pro- 
duced under  a  greater  pressure,  or  in  a 
more  dense  state;  and  greater  when  it  is 
produced  under  a  less  pressure,  or  in  a  less 
dense  state.  Berthollet  thinks  this  fact  so 
unaccountable,  that  he  has  been  willing  to 
discard  it  altogether.  Whether  the  view  I 
have  just  opened,  of  the  relation  subsisting? 


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between  the  elastic  force,  density,  and  latent 
heat  of  different  vapours,  harmonize  with 
chemical  phenomena  in  general,  I  leave 
othei'S  to  determine.  It  certainly  agrees 
with  that  unaccountable  fact.  Whatever  be 
the  fate  of  the  general  law,  now  respect- 
fully offered,  the  statement  of  Mr.  Watt 
may  be  implicitly  received,  under  the  sanc- 
tion of  his  acknowledged  sagacity  and  can- 
dor." lire's  Researches  on  Heat,  pp.  54  and 
55. 

As  it  is  the  vastly  greater  relation  to  heat, 
which  steam  possesses  above  water,  that 
makes  the  boiling  point  of  that  liquid  so 
perfectly  stationary  in  open  vessels,  over 
the  strongest  fires,  we  may  imagine  that 
other  vapours  which  have  a  smaller  latent 
heat,  may  not  be  capable,  by  their  forma- 
tion, of  keeping  the  ebullition  of  their  re- 
spective liquids  at  a  uniform  temperature. 
I  observed  this  variation  of  the  boiling 
point  actually  to  happen  with  oil  of  turpen- 
tine, petroleum  and  sulphuric  acid.  When 
these  liquids  are  heated  briskly  in  apothe- 
caries' phials,  they  rise  20  or  30  degrees 
above  the  ordinary  point,  at  which  they 
boil  in  hemispherical  capsules.  Hence, 
also,  their  vapours  being  generated  with 
little  heat,  are  apt  to  rise  with  explosive 
violence.  Oil  of  turpentine  varies  more- 
over, in  its  boiling-  point,  according  to  its 
freshness  and  limpidity.  It  is  needless, 
therefore,  to  raise  an  argument  on  a  couple 
of  degrees  of  difference.  But,  in  Dr.  Mur- 
ray's, and  all  our  other  chemical  systems, 
published  prior  to  1817,  560°  was  assigned 
as  the  boiling  point  of  this  volatile  oil.  Mr. 
Dalton's  must  be  excepted,  for  he  says, 
"  several  authors  have  it,  that  oil  of  tur- 
pentine boils  at  560°.  I  do  not  know  how 
the  mistake  originated,  but  it  boils  below 
212°,  like  the  rest  of  the  essential  oils." 
Dr.  Thomson  makes  it  314°;  a  number 
which,  from  the  great  price  he  paid  for  his 
thermometer,  he  insinuates  to  be  more  ex- 
act than  mine  of  316°;  and  a  fortiori  than 
320°,  as  found  by  the  manufacturer  of  the 
oil,  to  whom  1  had  referred.  But  the  dif- 
ference of  our  two  numbers  is  in  reality 
frivolous,  and  to  be  ascribed  to  the  state  of 
the  oil  and  of  the  heat,  as  much  as  to  er- 
rors of  the  instruments  or  of  observation. 
It  is  probable  that  our  thermometers  were 
equally  correct,  and  used  with  equal  care. 
But  what  will  Dr.  Thomson  say  of  Mr.  Dal- 
ton's emendation? 

From  the  above  quotation  it  may  be  in- 
ferred, that  the  conversion  at  all  tempera- 
tures, however  low,  of  any  liquid  or  solid 
whatever,  into  a  vapour,  is  uniformly  ac- 
companied with  the  abstraction  of  heat 
from  surrounding  bodies,  or  in  popular  lan- 
guage, the  production  of  cold;  and  that  the 
degree  of  refrigeration  will  be  proportional 
to  the  capacity  of  the  vapour  for  heat,  and 
the  rapidity  of  its  formation.  The  applica- 


tion of  this  principle  to  the  uses  of  life,  first 
suggested  by  Drs.  Cullen  and  Black,  has 
been  improved  and  extended  by  Mr.  Leslie. 
We  shall  describe  his  methods  under  CON- 
GELATION. 

It  appears,  moreover,  probable,  that  the 
permanent  gases  have  the  same  superior 
relation  to  heat  with  the  vapours.  Hence, 
their  transition  to  the  liquid  or  solid  states 
ought  to  be  attended  with  the  evolution  of 
heat.  Accordingly,  in  the  combustion  of 
hydrogen,  phosphorus,  and  metals,  gaseous 
matter  is  copiously  fixed;  to  which  cause 
Black  and  Lavoisier  ascribed  the  whole  of 
the  heat  and  light  evolved.  We  shall  sec, 
however,  in  the  article  COMBUSTION,  many 
difficulties  to  the  adoption  of  this  plausible 
hypothesis.  The  best  illustration  of  the 
common  notion  as  to  the  latent  heat  of 
gases,  is  afforded  by  the  condensed  air  tin- 
der-tube; in  which  mechanical  compression 
appears  to  extrude  from  cold  air  its  latent 
stores  of  both  heat  and  light.  A  glass  tube, 
eight  inches  long,  and  half  inch  wide,  of 
uniform  calibre,  shut  at  one  end,  and  fitted 
with  a  short  piston,  is  best  adapted  for 
the  exhibition  of  this  pleasing  experiment. 
When  the  object,  however,  is  merely  to 
kindle  agaric-tinder,  a  brass  tube  3-8ths 
wide  and  4^  inches  long  will  suffice.  A 
dexterous  condensation  of  air  into  l-5th  of 
the  volume,  produces  the  heat  of  ignition. 

Under  the  head  of  specific  heat,  it  has 
been  shown  to  diminish  in  a  gas,  more  ra- 
pidly than  the  diminution  of  its  volume; 
and  therefore,  heat  will  be  disengaged  by 
its  condensation,  whether  we  regard  the 
phenomenon  as  the  expulsion  of  a  fluid,  or 
intense  actions  excited  among  the  particles 
by  their  violent  approximation.  The  con- 
verse of  the  above  phenomenon  is  exhibited 
on  a  great  scale,  in  the  Schemnitz  mines  of 
Hungary.  The  hydraulic  machine  for  drain- 
ing them,  consists  essentially  of  two  strong 
air-tight  copper  cylinders,  96  feet  verti- 
cally distant  from  each  other,  and  connec- 
ted by  a  pipe.  The  uppermost,  which  is 
at  the  mouth  of  the  pit,  can  be  charged  with 
water  by  the  pressure  of  a  reservoir,  ele- 
vated 136  feet  above  it.  The  air  suddenly 
dislodged  by  this  vast  hydrostatic  pressure, 
is  condensed  through  the  pipe,  on  the  sur- 
face of  the  water  standing  in  the  lower  cylin- 
der, which  it  forces  up  a  rising  water-pipe 
to  the  surface,  and  then  takes  its  place. 
When  the  stop-cocks  are  turned  to  re- 
charge the  lower  cylinder  with  water,  the 
imprisoned  air  expanding  to  its  natural 
volume,  absorbs  the  heat  so  powerfully,  as 
to  convert  the  drops  of  water  that  issue 
with  it,  into  hail  and  snow.  M.  Gay-Lus-^ 
sac  has  lately  proposed  a  miniature  imita- 
tion of  this  machine  for  artificial  refrigera- 
tion. He  exposes  the  small  body  to  be 
cooled,  to  a  stream  of  air  escaping  bv  a 
small  orifice,  from  a  box  in  which  it  had 


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been  strongly  condensed.  In  the  autumn  of 
1816, 1  performed  an  analogous  experiment 
in  the  house  of  M.  Breguet,  in  Paris.  This 
celebrated  artist  having  presented  me  with 
one  of  his  elegant  metallic  thermometers, 
I  immediately  proposed  to  determine  by 
means  of  it,  the  heat  first  abstracted,  and 
subsequently  disengaged,  in  the  exhaustion 
of  air,  and  its  readmission  into  the  receiver 
of  an  air-pump.  MM.  Breguet  politely  fa- 
voured me  with  their  assistance,  and  the 
use  of  their  excellent  air-pump.  Having 
enclosed  in  the  receiver  their  thermometer, 
and  a  delicate  one  by  Crighton,  which  I 
happened  to  have  with  me,  we  found,  on 
rapidly  exhausting  the  receiver,  that  M. 
Breguet's  thermometer  indicated  a  refrige- 
ration of  oO°  F.  while  (Brighton's  sunk  only 
7°.  After  the  two  hud  arrived  at  the  same 
temperature,  the  air  was  rapidly  admitted 
into  the  receiver.  M.  Breguet's  thermome- 
ter now  rose  50°,  while  (Brighton's  mounted 
7°  as  before.  See  THERMOMETER. 

Dr.  Darwin  has  ingeniously  explained  the 
production  of  snow  on  the  tops  of  the  high- 
est mountains,  by  the  precipitation  of  va- 
pour from  the  rarefied  air  which  ascends 
from  plains  and  valleys.  "  The  Andes," 
says  Sir  H.  Davy,  "  placed  almost  under 
the  line,  rise  in  the  midst  of  burning  sands; 
about  the  middle  height  is  a  pleasant  and 
mild  climate;  the  summits  are  covered  with 
unchanging  snows;  and  these  ranges  of 
temperature  are  always  distinct;  the  hot 
winds  from  below,  if  they  ascend,  become 
cooled  in  consequence  of  expansion  and  the 
cold  air;  if  by  any  force  of  the  blast  it  is 
driven  downwards,  it  is  condensed,  and 
rendered  warmer  as  it  descends." 

Evaporation  and  rarefaction,  the  grand 
means  employed  by  nature  to  temper  the 
excessive  heats  of  the  torrid  zone,  operate 
very  powerfully  among  mountains  and  seas. 
But  the  level  sands  are  devoured  by  un- 
mitigated heat.  In  milder  climates,  the  fer- 
vours of  the  solstitial  sun  are  assuaged  by 
the  vapours  copiously  raised  from  every 
river  and  field,  while  the  wintry  cold  is 
moderated  by  the  condensation  of  atmos- 
pheric vapours  in  the  form  of  snow. 

The  equilibrium  of  animal  temperature 
is  maintained,  by  the  copious  discharge  of 
vapour  from  the  lungs  and  the  skin.  The 
suppression  of  this  exhalation  is  a  common 
cause  of  many  formidable  diseases.  Among 
these,  fever  takes  the  lead.  The  ardour  of 
the  body  in  this  case  of  suppressed  pers- 
piration, sometimes  exceeds  the  standard 
of  health  by  six  or  seven  degrees.  The  di- 
rect and  natural  means  of  allaying  this 
morbid  temperature,  were  first  systemati- 
cally enjoined  by  Dr.  Currie  of  Liverpool. 
He  showed,  that  the  dashing  or  affusion  of 
cold  water  on  the  skin  of  a  fever  patient, 
has  most  sanatory  effects,  when  the  heat  is 
'eadily  above  98°,  and  when  there  is  no 


sensation  of  chilliness,  and  no  moisture  on 
the  surface.  Topical  refrigeration  is  ele- 
gantly procured,  by  applying  a  piece  of 
muslin  or  tissue  paper  to  any  part  of  the 
skin,  and  moistening  it  with  ether,  carbu- 
ret of  sulphur,  or  alcohol.  By  pouring  a 
succession  of  drops  of  ether,  on  the  sur- 
face of  a  thin  glass  tube  containing  water, 
a  cylinder  of  ice  may  be  formed  at  mid- 
summer The  most  convenient  plan  which 
the  chemist  can  employ,  to  free  a  gas  from 
vapour,  is  to  pass  it  slowly  through  a  long 
tortuous  tube  wrapt  in  porous  paper  wet- 
ted with  ether. 

On  the  other  hand,  when  he  wishes  to 
expose  his  vessels  to  a  regulated  heat,  he 
makes  hot  vapour  be  condensed  on  their 
cold  surface.  The  heat  thus  disengaged 
from  the  vapour,  passes  into  the  vessel,  and 
speedily  raises  it  to  a  temperature  which 
he  can  adjust  with  the  nicest  precision.  A 
vapour  bath  ought  therefore  to  be  provided 
for  every  laboratory.  That  which  I  got  con- 
structed a  few  years  ago  for  the  Institution, 
is  so  simple  and  efficacious  as  to  merit  a 
description. — A  square  tin  box,  about  18 
inches  long,  12  broad,  and  6  deep,  has  its 
bottom  hollowed  a  little  by  the  hammer  to- 
wards its  centre,  in  which  a  round  hole  is 
cut  of  five  or  six  inches  diameter.  Into  this, 
a  tin  tube  three  or  four  inches  long  is  sol- 
dered. This  tube  is  made  to  fit  tightly  into 
the  mouth  of  a  common  tea-kettle,  which 
has  a  folding  handle.  The  top  of  the  box 
has  a  number  of  circular  holes  cut  into  it, 
of  different  diameters,  into  which  evaporat- 
ing capsules  of  platina,  glass,  or  porcelain, 
are  placed.  When  the  kettle,  filled  with  wa- 
ter, and  with  its  nozzle  corked,  is  set  on  a 
stove,  the  vapour,  playing  on  the  bottoms 
of  the  capsules,  heats  them  to  any  required 
temperature;  and  being  itself  continually 
condensed,  it  runs  back  into  the  kettle,  to 
be  raised  again,  in  ceaseless  cohobation. 
With  a  shade  above,  to  screen  the  vapour 
chest  from  soot,  the  kettle  may  be  placed 
over  a  common  fire.  The  orifices  not  in  use, 
are  closed  with  tin  lids.  In  drying  precipi- 
tates, I  cork  up  the  tube  of  the  glass  funnel, 
and  place  it,  with  its  filter,  directly  into  the 
proper  sized  opening.  For  drying  red  cab- 
bage, violet  petals,  &c.  a  tin  tray  is  provid- 
ed, which  fits  close  on  the  top  of  the  box, 
within  the  rim  which  goes  about  it.  The 
round  orifices  are  left  open  when  this  tray 
is  applied.  Such  a  form  of  apparatus  is  well 
adapted  to  inspissate  the  pasty  mass,  from 
which  lozenges  and  troches  are  to  be  made. 

But  the  most  splendid  trophy  erected  to 
the  science  of  caloric,  is  the  steam-engine 
of  Watt.  This  illustrious  philosopher,  from 
a  mistake  of  his  friend  Dr.  Robison,  has 
been  hitherto  defrauded  of  a  part  of  his 
claims  to  the  admiration  and  gratitude  of 
mankind.  The  fundamental  researches  on 
the  constitution  of  steam,  which  formed  the 


CAL 


CAL 


solid  basis  of  his  g-ig-antic  superstructure, 
though  they  coincided  perfectly  with  Dr. 
Black's  results,  were  not  drawn  from  them. 
In  some  conversations  with  which  this  great 
ornament  and  benefactor  of  his  country  ho- 
noured me  a  short  period  before  his  death, 
he  described,  with  delightful  ndivett  the 
simple,  but  decisive  experiments,  by  which 
he  discovered  the  latent  heat  of  steam.  His 
means  and  his  leisure  not  then  permitting 
an  expensive  and  complex  apparatus,  he 
used  apothecaries'  phials.  With  these,  he 
ascertained  the  two  main  facts,  first,  that  a 
cubic  inch  of  water  would  form  about  a  cu- 
bic foot  of  ordinary  steam,  or  1728  inches; 
and  that  the  condensation  of  that  quantity 
of  steam  would  heat  six  cubic  inches  of 
water  from  the  atmospheric  temperature 
to  the  boiling  point.  Hence  he  saw  that  six 
times  the  difference  of  temperature,  or  ful- 
ly 900°  of  heat  had  been  employed  in  giv- 
ing elasticity  to  steam;  which  must  be  all 
abstracted  before  a  complete  vacuum  could 
be  procured  under  the  piston  of  the  steam- 
engine.  These  practical  determinations  he 
afterwards  found  to  agree  pretty  nearly 
with  the  observations  of  Dr.  Black.  Though 
Mr.  Watt  was  then  known  to  the  Doctor, 
he  was  not  on  those  terms  of  intimacy  with 
him,  which  he  afterwards  came  to  be,  nor 
was  he  a  member  of  his  class. 

Mr.  Watt's  three  capital  improvements, 
which  seem  to  have  nearly  exhausted  the 
resources  of  science  and  art,  were  the  fol- 
lowing 1.  The  separate  condensing  chest, 
immersed  in  a  body  of  cold  water,  and  con- 
nected merely  by  a  slender  pipe  with  the 
great  cylinder,  in  which  the  impelling  pis- 
ton moved.  On  opening  a  valve  or  stop-cock 
of  communication,  the  elastic  steam  which 
had  floated  the  ponderous  piston,  rushed 
into  the  distant  chest  with  magical  veloci- 
ty, leaving  an  almost  perfect  vacuum  in  the 
cylinder,  into  which  the  piston  was  forced 
by  atmospheric  pressure.  What  had  appear- 
ed impossible  to  all  previous  engineers 
was  thus  accomplished.  A  vacuum  was 
formed  without  cooling  the  cylinder  itself. 
Thus  it  remained  boiling  hot,  ready  the 
next  instant  to  receive  and  maintain  the 
elastic  steam.  2.  His  second  grand  improve- 
ment consisted  in  closing  the  cylinder  at 
top,  making  the  piston  rod  slide  through  a 
stuffing  box  in  the  lid,  and  causing-  the 
steam  to  give  the  impulsive  pressure  in- 
stead of  the  atmosphere.  Henceforth  the 
waste  of  heat  was  greatly  diminished.  3. 
The  final  improvement  was  the  double  im- 
pulse, whereby  the  power  of  his  engines, 
which  was  before  so  great,  was  in  a  mo- 
ment more  than  doubled.  The  counter- 
weight required  in  the  single  stroke  en- 
gine, to  depress  the  pump-end  of  the  work- 
ing beam,  was  now  laid  aside.  He  thus 
freed  the  machine  from  a  dead  weight  or 
VOL,  I. 


drag  of  many  hundred  pounds,  which  had 
hung  upon  it  from  its  birth,  about  seventy 
years  before. 

The  application  of  steam  to  heat  apart- 
ments, is  another  valuable  fruit  of  these 
studies.  Safety,  cleanliness,  and  comfort, 
thus  combine  in  giving  a  genial  warmth  for 
every  purpose  of  private  accommodation, 
or  public  manufacture.  It  has  been  ascer- 
tained, that  one  cubic  foot  of  boiler  will  heat 
about  tivo  thousand  feet  of  space,  in  a  cot- 
ton mill,  whose  average  heat  is  from  70°  to 
80°  Fahr.  And  if  we  allow  25  cubic  feet  of 
a  boiler  for  a  horse's  power  in  a.  steam-en- 
gine supplied  by  it,  such  a  boiler  would  be 
adequate  to  the  warming  of  fifty  thousand 
cubic  feet  of  space.  It.  has  been  also  ascer- 
tained, that  one  square  foot  of  surface  of 
steam  pipe,  is  adequate  to  the  warming  of 
two  hundred  cubic  feet  of  space.  This  quan- 
tity is  adapted  to  a  well  finished  ordinary 
brick  or  stone  building.  The  safety  valve  on 
the  boiler  should  be  loaded  with  2^  pounds 
for  an  area  of  a  square  inch,  as  is  the  rule 
for  Mr.  Watt's  engines.  Cast  iron  pipes  are 
preferable  to  all  others,  for  the  diffusion  of 
heat.  Freedom  of  expansion  must  be  al- 
lowed, which  in  cast  iron  may  be  taken  at 
about  a  tenth  of  an  inch  for  every  ten  feet 
in  length.  The  pipes  should  be  distribu- 
ted within  a  few  inches  of  the  floor. 

Steam  is  now  used  extensively  for  dry- 
ing muslin  and  calicoes.  Large  cylinders 
are  filled  with  it,  which,  diffusing  in  the 
apartment  a  temperature  of  100°  or  130°, 
rapidly  dry  the  suspended  cloth.  Occasion- 
ally the  cloth  is  made  to  glide  in  a  serpen- 
tine manner  closely  round  a  series  of  steam 
cylinders,  ammged  in  parallel  rows.  It  is 
thus  safely  and  thoroughly  dried  in  the 
course  of  a  minute.  Experience  has  shown, 
that  bright  dyed  yarns  like  scarlet,  dried 
in  a  common  stove  heat  of  128°,  have  their 
colour  darkened,  and  acquire  a  harsh  feel; 
while  similar  hanks,  laid  on  a  steam  pipe 
heated  up  to  165°,  retain  the  shade  and 
lustre  they  possessed  in  the  wetted  state. 
The  people  who  work  in  steam  drying- 
rooms  are  health} ;  those  who  were  former- 
ly employed  in  the  stove -heated  apart- 
ments, became  soon  sickly  and  emaciated. 
These  injurious  effects  must  be  ascribed  to 
the  action  of  cast  iron  at  a  high  tempera- 
ture on  the  atmosphere. 

The  heating  by  steam  of  large  quantities 
of  water  or  other  liquids,  either  for  baths 
or  manufactures,  may  be  effected  in  two 
ways;  that  is,  the  steam  pipe  may  be  plung- 
ed with  an  open  end  into  the  water  cistern; 
or  the  steam  may  be  diffused  around  the 
liquid  in  the  interval  between  the  wooden 
vessel  and  an  interior  metallic  case.  The 
second  mode  is  of  universal  applicability. 
Since  a  gallon  of  water  in  the  form  of 
steam  will  heat  6  gallons  at  50°,  up  to  the 
33 


GAL 


CAL 


boiling1  point,  or  162°;  1  gallon  of  the  for- 
mer will  be  adequate  to  heat  18  gallons  of 
the  latter  up  to  100°,  making  a  liberal  al- 
lowance for  waste  in  the  conducting  pipe. 

Cooking  of  food  for  man  and  cattle  is 
likewise  another  useful  application  of 
steam;  "for,"  says  Dr.  Black,  "it  is  the 
most  effectual  carrier  of  heat  that  can  be 
conceived,  and  will  deposite  it  only  on  such 
bodies  as  are  colder  than  boiling  wafer." 
Hence  in  a  range  of  pots,  whenever  the 
first  has  reached  the  boiling  point,  but  no 
sooner,  the  steam  will  go  onwards  to  the 
second,  then  to  the  third,  and  thus  in  suc- 
cession. Inspection  of  the  last  will  there- 
fore satisfy  us  of  the  condition  of  the  pre- 
ceding vessels.  Distillation  has  been  lately 
practised,  by  surrounding  the  still  with  a 
strong  metallic  case,  and  filling  the  inter- 
stice with  steam  heated  up  to  260°  or  280°. 
But  notwithstanding  of  safety  valves,  and 
every  ordinary  attention,  dangerous  explo- 
sions have  happened.  Distillation  in  vacua, 
by  the  heat  of  external  steam  of  ordinary 
strength,  would  be  a  safe  and  elegant  pro- 
cess. The  old,  and  probably  very  exact  ex- 
periments of  Mr.  Watt  on  this  subject,  do 
not  lead  us,  however,  to  expect  any  saving 
of  fuel,  merely  by  the  vacuum  distillation. 
'*  The  unexpected  result  of  these  experi- 
ments is,  that  there  is  no  advantage  to  be 
expected  in  the  manufacture  of  ardent 
spirits  by  distillation  in  vacua.  For  we  find, 
that  the'latent  heat  of  the  steam  is  at  least 
as  much  increased  as  the  sensible  heat  is 
diminished." — Dr.  Jilack's  Lectures,  vol.  i. 
p.  190. 

i  By  advantage  is  evidently  meant  saving 
of  fuel.  But  in  preparing  spirits,  ethers, 
vinegars,  and  essential  oils,  there  would 
undoubtedly  be  a  great  advantage  relative 
to  flavour.  Every  risk  of  empyreuma  is  re- 
moved. 

Chambers  filled  with  steam  heated  to 
about  123*  Fahr.  have  been  introduced 
with  advantage  into  medicine,  under  the 
name  of  vapour  baths.  Dry  air  has  also 
been  used.  It  can  be  tolerated  at  a  much 
greater  heat  than  moist  air;  see  TEMPE- 
RATURE. A  large  cradle,  containing  saw- 
dust heated  with  steam,  should  be  kept  in 
readiness  at  the  houses  erected  by  the  Hu- 
mane Society,  for  the  recovery  of  drowned 
persons;  or  a  steam  chamber  might  be  at- 
tached to  them  for  this  purpose,  as  well  as 
general  medicinal  uses. 

I  have  thus  completed  what  I  conceive  to 
belong  directly  to  caloric  in  a  chemical  dic- 
tionary. Under  alcohol,  attraction,  bloiv-pipe, 
climate,  combustion,  congelation,  digester,  dis- 
tillation, electricity,  gas,  light,  pyrometer, 
thermometer,  -water,  some  interesting  corre- 
lative facts  will  be  found. 

*  CALORIMETER.  An  instrument  con- 
trived by  Lavoisier  and  Laplace,  to  mea- 
sure the  heat  given  out  by  a  body  in  cooling, 


from  the  quantity  of  ice  it  melts.  It  consists 
of  3  vessels,  one  placed  within  the  other, 
so  as  to  leave  2  cavities  between  them;  and 
a  frame  of  iron  network,  to  be  suspended 
in  the  middle  of  the  inner  vessel.  This 
network  is  to  hold  the  heated  body.  The 
The  two  exterior  concentric  interstices  are 
filled  with  bruised  ice.  The  outermost 
serves  to  screen,  from  the  atmosphere,  the 
ice  in  the  middle  space,  by  the  fusion  of 
which  the  heat  given  out  by  the  central  hot 
body  is  measured.  The  water  runs  off 
through  the  bottom,  and  terminates  in  the 
shape  of  a  funnel,  with  a  stop-cock.* 

f  CALORIMO  TOR.  This  is  an  appellation 
given  by  me  to  galvanic  instruments,  in 
which  the  calorific  influence  or  effects  are 
attended  by  scarcely  any  electrical  power; 
and  especially  to  apparatus,  employed  by 
me,  consisting  of  one  or  two  galvanic  pairs 
of  enormous  size. 

Volta  considered  all  galvanic  apparatus 
as  consisting  of  one  or  more  electromo- 
tors, or  movers  of  the  electric  fluid.  To 
me,  it  appeared,  that  they  were  movers  of 
both  heat  and  electricity;  the  ratio  of  the 
quantity  of  the  latter  put  in  motion,  to  t 
quantity  of  the  former  put  in  motion, 
ing  as  the  number  of  the  series  to 
superficies.  Hence  the  word  electromotor 
can"on!y  be  applicable,  when  the  caloric  be- 
comes evanescent,  and  electricity  almost 
the  sole  product,  as  in  De  Luc's  and  Zam- 
boni's  Columns;  and  the  word  calonmotor 
ought  to  be  used,  when  electricity  becomes 
evanescent,  and  caloric  appears  the  sole 
product. 

The  heat  evolved  by  one  galvanic  pair 
has  been  found  by  the  experiments  which 
1  instituted,  to  increase  in  quantity,  but  to 
diminish  in  intensity,  as  the  size  of  the  sur- 
faces may  be  enlarged.  A  pair  containing 
about  fifty  square  feet  of  each  metal,  will 
not  fuse  platina,  nor  deflagrate  iron,  how- 
ever small  may  be  the  wire  employed;  for 
the  heat  produced  in  metallic  wires  is  not 
improved  by  a  reduction  in  their  size  be- 
yond a  certain  point.  Yet  the  metals  above- 
mentioned  are  easily  fused  or  deflagrated 
by  smaller  pairs,  which  would  have  no  per- 
ceptible influence  on  masses  that  might  be 
sensibly  ignited  by  larger  pairs.  These  cha- 
racteristics were  fully  demonstrated,  not 
only  by  my  own  apparatus,  but  by  those 
constructed  by  Messrs.  Wetherill  and 
Peale,  and  which  were  larger,  but  less  ca- 
pable of  exciting  intense  ignition.  Mr. 
Peale's  apparatus  contained  nearly  seventy 
square  feet,  Mr.  Wetherill's  nearly  one 
hundred,  in  the  form  of  concentric  coils; 
yet  neither  could  produce  a  heat  above  red- 
ness on  the  smallest  wires.  At  my  sugges- 
tion, Mr.  Peale  separated  the  two  surfaces 
in  his  coils  into  four  alternating,  constitut- 
ing two  galvanic  pairs  in  one  recipient. 
Iron  wire  was  then  easily  burned  and  pla- 


CAM 


CAM 


tina  fused  by  it.  These  facts,  tog-ether  with 
the  incapacity  of  the  calorific  fluid  extri- 
cated by  the  calorimotor  to  permeate  char- 
coal, next  to  metals  the  best  electrical  con- 
ductor, must  sanction  the  position  I  assign- 
ed to  it,  as  being1  in  the  opposite  extreme 
from  the  columns  of  De  Luc  and  Zamboni. 
For  as  in  these,  the  phenomena  are  such  as 
are  characteristic  of  pure  electricity,  so  in 
one  very  large  galvanic  pair,  they  almost 
exclusively  demonstrate  the  agency  of  pure 
caloric. 

A  plate  of  a  calorimotor  will  be  found 
at  the  end  of  this  work,  with  a  description. 
When  this  instrument  is  lowered  into  a 
solution,  containing  about  a  seventieth  of 
sulphuric  acid,  a  wire,  placed  between  the 
poles,  becomes  white  hot,  and  takes  fire, 
emitting  the  most  brilliant  sparks.  In  the 
interim,  an  explosion  usually  gives  notice 
of  the  extrication  of  hydrogen  in  a  quantity 
adequate  to  reach  the  burning  wire.  Imme- 
diately after  the  explosion,  the  hydrogen  is 
reproduced  with  less  intermixture  of  air, 
and  rekindles,  corrusrating  from  among 
the  forty  interstices,  and  passing  from  one 
side  of  the  machine  to  the  other,  in  oppo- 
site directions  and  at  various  times,  so  that 
the  combinations  are  innumerable.  The 
flame  assumes  various  hues,  from  the  so- 
lution of  more  or  less  of  the  metals,  and  a 
froth,  apparently  on  fire,  rolls  over  the  sides 
of  the  recipient.  When  the  calorimotor  is 
withdrawn  from  the  acid  solution,  the  sur- 
face of  this  fluid  for  many  seconds,  pre- 
sents a  sheet  of  fiery  foam. 

I  ascertained  that  the  galvanic  fluid,  as 
extricated  by  this  apparatus,  does  not  per- 
meate charcoal.  This  demonstrates  that  it 
cannot  be  electricity,  as  of  the  latter,  char- 
coal is  next  to  metals  the  best  conductor. 

See  Memoirs  on  a  JWw  Theory  of  Gal- 
vanism in  Sillimarfs  Journal,  Annals  of  Phi- 
losophy,  and  Philosophical  JW>gazine.'\ 

*  CAI.P.     An    argillo-ferruginous   lime- 
stone.* 

*  CAMELEON  MINERAL.     When   pure 
potash  and  black  oxide  of  manganese  are 
fused  together  in  a  crucible,  a  compound  is 
formed   whose  solution  in  water,   at  first 
green,   passes  spontaneously  through  the 
whole  series  of  coloured  rays  to  the  red. 
From  this  latter  tint,  the  solution  may  be 
made  to  retrograde  in  colour  to  the  origi- 
nal green,  by  the  addition  of  potash;  or  it 
may  be  rendered  altogether  colourless,  by 
adding  either  sulphurous  acid  or  chlorine 
to  the  solution,  in  which  case  there  may  or 
may  not  be  a  precipitate,  according  to  cir- 
cumstances.   MM.  Chevillot  and  Edouard 
have  lately  read  some  interesting  memoirs 
on  this  substance,  before  the  Academy  of 
Sciences.    They  found,  that  when  potash 
and  the  green  oxide  of  manganese   were 
heated  in  close  vessels,  containing  azote,  no 
cameleon  is  formed.    The  same  result  fol- 


lowed with  the  brown  oxide,  and  ultimate- 
ly with  the  black.  They  therefore  ascribe 
the  phenomena  to  the  absorption  of  oxygen, 
which  is  greatest  when  the  oxide  of  man- 
ganese equals  the  potash  in  weight.  They 
regard  it  as  a  manganesiate  of  potash, 
though  they  have  hitherto  failed  in  their 
attempts  to  separate  this  supposed  tetrox- 
ide,  or  manganesic  acid.  When  acids  are 
poured  upon  the  green  cameleon,  or  an  al- 
kali upon  the  red,  they  are  equally  changed 
from  one  colour  to  the  other;  even  boiling 
and  agitation  are  sufficient  to  disengage 
the  excess  of  potash  in  the  green  cameleon, 
and  to  change  it  into  red.  Many  acids  also, 
when  used  in  excess,  decompose  the  came- 
leon entirely,  by  taking  the  potash  from  it, 
disengaging  the  oxygen,  and  precipitating 
the  manganese  in  the  state  of  black  oxide. 
Sugar,  gums,  and  several  other  substances, 
capable  of  taking  away  the  oxygen,  also  de- 
compose the  cameleon,  and  an  exposure  to 
the  air  likewise  produces  the  same  effect. 
Soda,  barytes,  and  strontites,  also  afford 
peculiar  cameleons.  The  red  potash  ca- 
meleon is  perfectly  neutral.  Phosphorus 
brought  in  contact  with  it  produces  a  de- 
tonation; and  it  sets  some  other  combusti- 
bles on  fire.  Exposed  alone  to  heat,  it  is  re- 
solved into  oxygen,  black  oxide  of  manga- 
nese, and  green  cameleon,  or  submangane- 
siate  of  potash.* 

CAMPEACHY  WOOD.  See  LOGWOOD. 
CAMPHOR.   There  are  two  kinds  grow 
in  the  East,  the  one  produced  in  the  islands 
of  Sumatra  and  Borneo,  and  the  other  pro- 
duced in  Japan  and  China. 

Camphor  is  extracted  from  the  roots, 
wood,  and  leaves  of  two  species  of  laurus, 
the  roots  affording  by  far  the  greatest 
abundance.  The  method  consists  in  distil- 
ling  with  water  in  large  iron  pots,  serving- 
as  the  body  of  a  still,  with  earthen  heads 
adapted,  stuffed  with  straw,  and  provided 
with  receivers.  Most  of  the  camphor  be- 
comes condensed  in  the  solid  form  among- 
the  straw,  and  part  comes  over  with  the 
water. 

The  sublimation  of  camphor  is  perform- 
ed in  low  flat-bottomed  glass  vessels  placed 
in  sand;  and  the  camphor  becomes  con- 
crete in  a  pure  state  against  the  upper  part, 
whence  it  is  afterwards  separated  with  a 
knife,  after  breaking  the  glass.  Lewis  as. 
serts  that  no  addition  is  requisite  in  the 
purification  of  camphor;  but  that  the  chief 
point  consists  in  managing  the  fire,  so  that 
the  upper  part  of  the  vessel  may  be  hot 
enough  to  bake  the  sublimate  together  in- 
to a  kind  of  cake.  Chaptal  says,  the  Hollan- 
ders mix  an  ounce  of  quicklime  with  every 
pound  of  camphor  previous  to  the  distilla- 
tion. 

Purified  camphor  is  a  white  concrete 
crystalline  substance,  not  brittle,  but  easily 
crumbled,  having  a  peculiar  consistence  re- 


GAM 


sembling  that  of  spermaceti,  but  harder.  It 
has  a  strong  lively  smell,  and  an  acrid  taste; 
is  so  volatile  as  totally  to  exhale  when  left 
exposed  in  a  warm  air;  is  light  enough  to 
swim  on  water;  and  is  very  inflammable, 
burning  with  a  very  white  flame  and  smoke, 
without  any  residue. 

The  roots  of  zedoary,  thyme,  rosemary, 
sage,  the  inula  hellenium,  the  anemony, 
the  pasque  flower  or  pulsatilla,  and  (Tther 
vegetables,  afford  camphor  by  distillation. 
It  is  obsei-vable,  that  all  these  plants  afford 
a  much  larger  quantity  of  camphor,  when 
the  sap  has  been  suffered  to  pass  to  the 
concrete  state  by  several  months'  drying. 
Thyme  and  peppermint,  slowly  dried,  af- 
ford much  camphor;  and  Mr.  Achard  has 
observed,  that  a  smell  of  camphor  is  disen- 
gaged when  volatile  oil  of  fennel  is  treated 
with  acids. 

Mr.  Kind,  a  German  chemist,  endeavour- 
ing to  incorporate  muriatic  acid  gas  with 
oil  of  turpentine,  by  putting  this  oil  into  the 
vessels  in  which  the  gas  was  received  when 
extricated,  found  the  oil  change  first  yel- 
low, then  brown,  and  lastly,  to  be  almost 
wholly  coagulated  into  a  crystalline  mass, 
which  comported  itself  in  every  respect 
like  camphor.  Tromsdorff  and  Boullay  con- 
firm this.  A  small  quantity  of  camphor  may 
be  obtained  from  oil  of  turpentine  by  sim- 
ple distillation  at  a  very  gentle  heat  Other 
essential  oils,  however,  afford  more.  By 
evaporation  in  shallow  vessels,  at  a  heat 
not  exceeding  57°  F.  Mr.  Proust  obtained 
from  oil  of  lavender  .25,  of  sage  .21,  of 
marjoram  .1014,  of  rosemary  .0625.  He 
conducted  the  operation  on  a  pretty  large 
scale. 

Camphor  is  not  soluble  in  water  in  any 
perceptible  degree,  though  it  communi- 
cates its  smell  to  that  fluid,  and  may  be 
burned  as  it  floats  on  its  surface.  It  is  said, 
however,  that  a  surgeon  at  Madrid  has  ef- 
fected its  solution  in  water  by  means  of  the 
carbonic  acid. 

Camphor  may  be  powdered  by  moisten- 
ing it  with  alcohol,  and  triturating  it  till 
dry.  It  may  be  formed  into  an  emulsion  by 
previous  grinding  with  near  three  times  its 
weight  of  almonds,  and  afterwards  gradu- 
ally adding  the  water.  Yolk  of  egg  and 
mucilages  are  also  effectual  for  this  pur- 
pose; but  sugar  does  not  answer  well. 

It  has  been  observed  by  Komieu,  that 
small  pieces  of  camphor  floating  on  water 
have  a  rotatory  motion. 

Alcohol,  ethers,  and  oils,  dissolve  cam- 
phor. 

The  addition  of  water  to  the  spirituous 
or  acid  solutions  of  camphor,  instantly  se- 
parates it. 

Mr.  Hatchett  has  particularly  examined 
the  action  of  sulphuric  acid  on  camphor.  A 
hundred  grains  of  camphor  were  digested 
in  an  ounce  of  concentrated  sulphuric  acid 


CAN 

for  two  days.  A  gentle  heat  was  then  ap- 
plied, and  the  digestion  continued  for  two 
days  longer.  Six  ounces  of  water  were  then 
added,  and  the  whole  distilled  to  dryness. 
Three  grains  of  an  essential  oil,  having  a 
mixed  odour  of  lavender  and  peppermint, 
came  over  with  the  water.  The  residuum 
being  treated  twice  with  two  ounces  of  al- 
cohol each  time,  fifty -three  grains  of  com- 
pact coal  in  small  fragments  remained  un- 
dissolved.  The  alcohol,  being  evaporated  in 
a  water  bath,  yielded  forty-nine  grains  of  a 
blackish-brown  substance  which  was  bit- 
ter, astringent,  had  the  smell  of  caromel, 
and  formed  a  dark  brown  solution  with  wa- 
ter. This  solution  threw  down  very  dark 
brown  precipitates,  with  sulphate  of  iron, 
acetate  of  lead,  muriate  of  tin,  and  nitrate 
of  lime.  It  precipitated  gold  in  the  metal- 
lic state.  Isinglass  threw  down  the  whole 
of  what  was  dissolved  in  a  nearly  black 
precipitate. 

When  nitric  acid  is  distilled  repeatedly 
in  large  quantities  from  camphor,  it  con- 
verts it  into  a  peculiar  acid.  See  ACID 
(CAMPHORIC). 

*  Camphor  melts  at  288°,  and  boils  at 
the  temperature  of  400°.  By  passing  it  in 
vapour  through  peroxide  of  copper,  Dr. 
Thomson  converted  it  into  carbonic  acid 
and  water.  He  operated  upon  a  single 
grain.  He  infers  its  composition  to  be 

Carbon,  0.738  8£  at'ms.  =  6.375  73.91 
Hydrogen,  0.144  10  =  1.250  14.49 

Oxygen,      0.118     1  =  1.000     11.60 


1.000 


8.625  100.00 


As  an  internal  medicine,  camphor  has  been 
frequently  employed  in  doses  of  from  5  to 
20  grains,  with  much  advantage;  to  pro- 
cure sleep  in  mania,  and  to  counteract 
gangrene.  Though  a  manifest  stimulant, 
when  externally  applied,  it  appears  from 
the  reports  of  Cullen  and  others,  rather  to 
diminish  the  animal  temperature  and  the 
frequency  of  the  pulse.  In  large  doses  it 
acts  as  a  poison,  an  effect  best  counteract- 
ed by  opium.  It  is  administered  to  alleviate 
the  irritating  effects  of  cantharides,  meze- 
reon,  the  saline  preparations  of  mercury 
and  drastic  purgatives.  It  lessens  the  nau- 
seating tendency  of  squill,  and  prevents  it 
from  irritating  the  bladder.  It  is  employed 
externally  as  a  discutient.*  Dissolved  in 
acetic  acid,  with  some  essential  oils,  it 
forms  the  aromatic  vinegar,  for  which  we 
are  indebted  to  the  elder  Mr.  Henry.  It  re- 
markably promotes  the  solution  of  copal. 
Its  effluvia  are  very  noxious  to  insects,  on 
which  account  it  is  much  used  to  defend 
subjects  of  natural  history  from  their  ra- 
vages. 

*  CANCER,  MATTER  OF.  This  morbid 
secretion  was  found  by  Dr.  Crawford  to 
give  a  green  colour  to  sirup  of  violets,  and 


CAN 


TAG 


treated  with  sulphuric,  acid,  to  emit,  a  gas 
resembling-  sulphuretted  hydrogen,  which 
he  supposes  to  have  existed  in  combination 
with  amiiraMa.in  the  ulcer.  Hence  the  ac- 
tion of  vmrlent  pus  on  metallic  salts.  He 
likewise  observed,  that  its  odour  was  des- 
troyed by  aqueous  chlorine,  which  he  there- 
fore recommends  for  washing  cancerous 
sores.* 


\NDLES.  Cylinders  of  tallow  or  wax, 
containing  in  their  axis  a  spongy  cord  of 
cotton  or  hemp.  A  few  years  ago  I  made  a 
set  of  experiments  on  the  relative  intensi- 
ties of  light,  and  duration  of  different  can- 
dles, the  result  of  which  is  contained  in  the 
following  table: — 


Number  in 

a  Pound. 

.Duration  of 
a  Candle. 

Weight  in 
grains. 

Consumption 

per  hour, 
grains. 

Proportion 
of 
Light. 

Economy 
of 
Light. 

Candles 
equal 
one  argand. 

10  mould. 
10  dipped. 
8  mould. 
6     do. 
4     do. 
Argand  oil 
flame. 

5h.    9  in. 
4      36 
6      31 
7       2i 
9     36 

682 
672 
856 
1160 
1787 

132 
150 
132 
163 
186 

512 

isi 

13 
10$ 

Hf 
20i 

69-4 

68 
65| 

59£ 
66 
80 

100 

5.7 
5.25 
6.6 
5.0 
3.5 

A  Scotch  mutchkin,  or  l-8th  of  a  gallon 
of  good  seal  oil,  weighs  6010  gr.  or  13  and 
l-10th  oz.  avoirdupois,  and  lasts  in  a  bright 
argand  lamp,  11  hours  44  min.  The  weight 
of  oil  it  consumes  per  hour,  is  equal  to  four 
times  the  weight  of  tallow  in  candles,  8  to 
the  pound,  and  3  l-7th  times  the  weight  of 
tallow  in  candles,  6  to  the  pound.  But  its 
light,  being  equal  to  that  of  5  of  the  latter 
candles,  it  appears  from  the  above  table, 
that  2  pounds  weight  of  oil,  value  Is.  in  an 
argand,  are  equivalent  in  illuminating  pow- 
er to  3  pounds  of  tallow  candles,  which  cost 
about  three  shillings.  The  larger  the  flame 
in  the  above  candles,  the  greater  the  eco- 
nomy of  light.* 

*  CANNEL  COAL.  See  COAL.* 

*  CANNON  METAL.  See  COPPER.* 
"CANTHARIDES.  Insects  vulgarly  called 

Spanish  flies:  lytta  vesicatoria  is  the  name 
adopted  from  Gmelin,  by  the  London  col- 
lege. This  insect  is  two-thirds  of  an  inch 
in  length,  one-fourth  in  breadth,  oblong, 
and  of  a  gold  shining  colour,  with  soft  ely- 
tera  or  wing  sheathes,  marked  with  three 
longitudinal  raised  stripes,  and  covering 
brown  membranous  wings.  An  insect  of  a 
square  form,  with  black  feet,  but  possessed 
of  no  vesicating  property,  is  sometimes 
mixed  with  the  cantharides.  They  have  a 
heavy  disagreeable  odour,  and  acrid  taste. 
If  the  inspissated  watery  decoction  of 
these  insects  be  treated  with  pure  alcohol, 
a  solution  of  a  resinous  matter  is  obtained, 
which  being  separated  by  gentle  evapora- 
tion to  dryness,  and  submitted  for  some 
time  to  the  action  of  sulphuric  ether,  forms 
a  yellow  solution.  By  spontaneous  evapora- 
tion crystalline  plates  are  deposited,  which 
may  be  freed  from  some  adhering  colour- 
ing matter  by  alcohol.  Their  appearance  is 
like  spermaceti.  They  are  soluble  in  boil- 
ing alcohol,  but  precipitate  as  it  cools. 


They  do  not  dissolve  in  water.  According 
to  M.  Robiquet,  who  first  discovered  them, 
these  plates  form  the  true  blistering  prin- 
ciple. They  might  be  called  VESICATO- 
RIN.  Besides  the  above  peculiar  body,  can- 
tharides contain,  according  to  M.  Robiquet, 
a  green  bland  oil,  insoluble  in  water,  solu- 
ble in  alcohol;  a  black  matter,  soluble  in 
water,  insoluble  in  alcohol,  without  blister- 
ing properties;  a  yellow  viscid  matter,  mild, 
soluble  in  water  and  alcohol;  the  crystal- 
line plates;  a  fatty  bland  matter;  phosphates 
of  lime  and  magnesia;  a  little  acetic  acid, 
and  much  lithic  or  uric  acid.  The  blister- 
ing fly  taken  into  the  stomach  in  doses  of 
a  few  grains,  acts  as  a  poison,  occasioning 
horrible  satyriasis,  delirium,  convulsions, 
and  death.  Some  frightful  cases  are  related 
by  Orfila,  vol.  i.  part2d.  Oils,  milk,  sirups, 
frictions  on  the  spine,  with  volatile  lini- 
ment and  laudanum,  and  draughts  contain- 
ing musk,  opium,  and  camphorated  emul- 
sion, are  the  best  antidotes.* 

CAOUTCHOUC.  This  substance,  which 
has  been  improperly  termed  elastic  gum, 
and  vulgarly,  from  its  common  application 
to  rub  out  pencil  marks  on  paper,  India 
rubber^  is  obtained  from  the  milky  juice  of 
different  plants  in  hot  countries.  The  chief 
of  these  are  the  Jatropha  elastica,  and  Ur- 
ceola  elastica. 

The  juice  is  applied  in  successive  coat- 
ings on  a  mould  of  clay,  and  dried  by  the 
fire  or  in  the  sun;  and  when  of  a  sufficient 
thickness,  the  mould  is  crushed,  and  the 
pieces  shaken  out.  Acids  separate  the  ca- 
outchouc from  the  thinner  part  of  the  juice 
at  once  by  coagulating  it.  The  juice  of  old 
plants  yields  nearly  two-thirds  of  its  weight; 
that  of  younger  plants  less.  Its  colour* 
when  fresh,  is  yellowish  white,  but  it  grows 
darker  by  exposure  to  the  air. 

The  elasticity  of  this  substance  is  ita 


CAO 


CAR 


most  remarkable  property:  when  warmed, 
as  by  immersion  in  hot  water,  slips  of  it 
may  be  drawn  out  to  seven  or  eight  times 
their  original  length,  and  will  return  to 
their  former  dimensions  nearly  Cold  ren- 
ders it  stiff  and  rig-id,  but  warmth  restores 
its  original  elasticity.  Exposed  to  the  fire 
it  softens,  swells  up,  and  burns  with  a 
bright  flame.  In  Cayenne  it  is  used  to  give 
light  as  a  candle  Its  solvents  are  etheiyVo- 
Jatile  oils,  and  petroleum.  The  ether,  how- 
ever, requires  to  be  washed  with  water  re- 
peatedly, and  in  this  state  it  dissolves  it 
completely.  Pelletier  recommends  to  boil 
the  caoutchouc  in  water  for  an  hour;  then 
to  cut  it  into  slender  threads;  to  boil  it 
again  about  an  hour;  and  then  to  put  it  into 
rectified  sulphuric  ether  in  a  vessel  close 
stopped.  In  this  way  he  says  it  will  be  totally 
dissolved  in  a  few  days,  without  heat,  ex- 
cept the  impurities,  which  will  fall  to  the 
bottom,  if  ether  enough  be  employed.  Ber- 
niard  says,  the  nitrous  ether  dissolves  it 
better  than  the  sulphuric.  If  this  solution  be 
spread  on  any  substance,  the  ether  evapo- 
rates very  quickly,  and  leaves  a  coating  of 
caoutchouc,  unaltered  in  its  properties. 
Naphtha,  or  petroleum,  rectified  into  a  co- 
lourless liquid,  dissolves  it,  and  likewise 
leaves  it  unchanged  by  evaporation.  Oil  of 
turpentine  softens  it,  and  forms  a  pasty 
mass,  that  may  be  spread  as  a  varnish,  but 
is  very  long  in  drying.  A  solution  of  caout- 
chouc in  five  times  its  weight  of  oil  of  tur- 
pentine, and  this  solution  dissolved  in  eight 
times  its  weight  of  drying  linseed  oil  by 
boiling,  is  said  to  form  the  varnish  of  air- 
balloons.  Alkalis  act  upon  it  so  as  in  time 
to  destroy  its  elasticity.  Sulphuric  acid  is 
decomposed  by  it;  sulphurous  acid  being 
evolved,  and  the  caoutchouc  converted  into 
charcoal.  Nitric  acid  acts  upon  it  with  heat; 
nitrous  gas  being  given  out,  and  oxalic  acid 
crystallizing  from  the  residuum.  On  distil- 
lation it  gives  out  ammonia,  and  carburet- 
ted  hydrogen. 

Caoutchouc  may  be  formed  into  various 
articles  without  undergoing  the  process  of 
solution.  If  it  be  cut  into  a  uniform  slip  of 
a  proper  thickness,  and  wound  spirally 
round  a  glass  or  metal  rod,  so  that  the 
edges  shall  be  in  close  contact,  and  in  this 
state  be  boiled  for  some  time,  the  edges 
will  adhere  so  as  to  form  a  tube.  Pieces  of 
it  may  be  readily  joined  by  touching  the 
edges  with  the  solution  in  ether:  but  this 
is  not  absolutely  necessary,  for,  if  they  be 
merely  softened  by  heat,  and  then  pressed 
together,  they  will  unite  very  firmly. 

If  linseed  oil  be  rendered  very  drying 
by  digesting  it  upon  an  oxide  of  lead,  and 
afterwards  applied  with  a  small  brxish  on 
any  surface,  and  dried  by  the  sun  or  in  the 
smoke,  it  will  afford  a  pellicle  of  consider- 
able firmness,  transparent,  burning  like 
caoutchouc,  and  wonderfully  elastic.  A 


pound  of  this  oil,  spread  upon  a  stone,  and 
exposed  to  the  air  for  six  or  seven  months, 
acquired  almost  all  the  properties  of  ca- 
outchouc: it  was  used  to  make  catheters 
and  bougies,  to  varnish  balloons,  and  for 
other  purposes. 

Of  the  mineral  caoutchouc  there  are  se- 
rai varieties:  1  Of  a  blackish-brown  inclin- 
ing to  olive,  soft,  exceedingly  compressi- 
ble, unctuous,  with  a  slightly  aromatic 
smell.  It  burns  with  a  bright  flame,  leaving1 
a  black  oily  residuum,  which  does  not  be- 
come dry.  2.  Bls.ck,  dry,  and  cracked  on 
the  surface,  but,  when  cut  into,  of  a  yellow- 
ish-white. A  fluid  i-esembling  pyrolignic 
acid  exudes  from  it  when  recently  cut.  It 
is  pellucid  on  the  edges,  and  nearly  of  a 
hyacinthine  red  colour.  3.  Similar  to  the 
preceding,  but  of  a  somewhat  firmer  tex- 
ture, and  ligneous  appearance,  from  having 
acquired  consistency  in  repeated  layers. 

4.  Resembling  the  first  variety,   but  of  a 
darker  colour,  and  adhering  to  gray  calca- 
reous spar,  with    some   grains   of  galrcna. 

5.  Of  a  liver-brown  colour,  having  the   as- 
pect of  the  vegetable  caoutchouc,  but  pass- 
ing by  gradual  transition  into  a  brittle  bi- 
tumen, of  vitreous  lustre,  and  a  yellowish 
colour.  6.  Dull  reddish-brown,  of  a  spongy 
or  cork-like  texture,   containing  blackish- 
gray  nuclei  of  impure  caoutchouc.   Many 
more  varieties  are  enumerated. 

One  specimen  of  this  caoutchouc  has 
been  found  in  a  petrified  marine  shell  en- 
closed in  a  rock,  and  another  enclosed  in 
crystallized  fluor  spar. 

The  mineral  caoutchouc  resists  the  ac- 
tion of  solvents  still  more  than  the  vegeta- 
ble. The  rectified  oil  of  petroleum  affects 
it  most,  particularly  when  by  partial  burn- 
ing it  is  resolved  into  a  pitchy  viscous  sub- 
stance. A  hundred  grains  of  a  specimen 
analyzed  in  the  dry  way  by  Klaproth,  af- 
forded carburetted  hydrogen  gas  38  cubic 
inches,  carbonic  acid  gas  4,  bituminous  oil 
73  grains,  acidulous  phlegm  1.5,  charcoal 
6. '25,  lime  2,  silex  1.5,  oxide  of  iron  .75, 
sulphate  of  lime  .5,  alumina  .25. 

CARAT.     See  ASSAY. 

CARBON.  When  vegetable  matter,  parti- 
cularly the  more  solid,  as  wood,  is  exposed 
to  heat  in  close  vessels,  the  volatile  parts 
fly  off,  and  leave  behind  a  black  porous 
substance,  which  is  charcoal.  If  this  be 
suffered  to  undergo  combustion  in  contact 
with  oxygen,  or  with  atmospheric  air,  much 
the  greater  part  of  it  will  combine  with  the 
oxygen,  and  escape  in  the  form  of  gas; 
leaving  about  a  two-hundredth  part,  which 
consists  chiefly  of  different  saline  and  me- 
tallic substances.  This  pure  inflammable 
part  of  the  charcoal  is  what  is  commonly 
called  carbon;  and  if  the  gas  be  received 
into  proper  vessels,  the  carbon  will  be 
found  to  have  been  converted  by  the  oxy- 


CAR 


CAR 


g-en  into  an  acid,  called  the  carbonic.  See 
ACID  (CARBONIC). 

From  the  circumstance,  that  inflammable 
substances  refract  light,  in  a  ratio  greater 
than  that  of  their  densities,  Newton  infer- 
red, that  the  diamond  was  inflammable. 
The  quantity  of  the  inflammable  part  of 
charcoal  requisite  to  form  a  hundred  parts 
of  carbonic  acid,  was  calculated  by  Lavoi- 
sier to  be  twenty-eight  parts.  From  a  care- 
ful experiment  of  Mr.  Tennant,  27.t>  parts 
of  diamond,  and  72.4  of  oxygen,  formed 
100  of  carbonic  acid;  and  hence  lie  infer- 
red the  identity  of  the  diamond,  and  the 
inflammable  part  of  charcoal. 

*  Diamonds  had  been  frequently  con- 
sumed in  the  open  air  with  burning  glasses; 
but  Lavoisier  first  consumed  them  in  oxy- 
gen gas,  and  discovered  carbonic  acid  to 
be  the  only  result.  Sir  George  Mackenzie 
showed,  that  a  red  heat,  inferior  to  what 
melts  silver,  is  sufficient  to  burn  diamonds. 
They  first  enlarge  somewhat  in  volume, 
and  then  waste  with  a  feeble  flame.  M. 
Guyton  Morveau  was  the  first  who  dropped 
diamonds  into  melted  nitre,  and  observed 
the  formation  of  carbonic  acid. 

From  a  number  of  experiments  M.  Biot 
has  made  on  the  refraction  of  different  sub- 
stances, he  has  been  led  to  form  a  differ- 
ent opinion.  According  to  him,  if  the  ele- 
ments of  which  a  substance  is  composed  be 
known,  their  proportions  ma)'  be  calcula- 
ted with  the  greatest  accuracy  from  their 
refractive  powers.  Thus  he  finds,  tint  the 
diamond  cannot  be  pure  carbon,  but  re- 
quires at  least  one-fourth  of  hydrogen, 
which  has  the  greatest  refractive  power  of 
any  substance,  to  make  its  refraction  com- 
mensurate to  its  density. 

In  1809,  Messrs.  Allen  and  Pepys  made 
some  accurate  researches  on  the  combus- 
tion of  various  species  of  carbon  in  oxygen, 
by  means  of  an  elegant  apparatus  of  their 
own  contrivance.  Aplatinatube  traversing 
a  furnace,  and  containing  a  given  weight 
of  the  carbonaceous  substance,  was  con- 
nected at  the  ends  with  two  mercurial  gas- 
ometers, one  of  which  was  filled  with  oxy- 
gen gas,  and  the  other  was  empty.  The 
same  weight  of  diamond,  carbon,  and  plum- 
bago, yielded  very  nearly  the  same  volume 
of  carbonic  acid.  Sir  M.  Davy  was  the  first 
to  show  that  the  diamond  was  capable  of 
supporting  its  own  combustion  in  oxygen, 
without  the  continued  application  of  ex- 
traneous heat,  and  he  thus  obviated  one  of 
the  apparent  anomalies  of  this  body,  com- 
pared with  charcoal.  This  phenomenon, 
by  his  method,  can  now  be  easily  exhibit- 
ed. If  the  diamond,  supported  in  a  per- 
forated cup,  be  fixed  at  the  end  of  a  jet, 
so  that  a  stream  of  hydrogen  can  be  thrown 
on  it,  it  is  easy,  by  inflaming  the  jet,  to  ig- 
nite the  gem,  and  whilst  in  that  state  to 
introduce  it  into  a  globe  or  flask  containing- 


oxygen.  On  turning  off  the  hydrogen,  the 
diamond  enters  into  combustion,  and  will 
go  on  burning  till  nearly  consumed.  The 
loss  of  weight,  and  corresponding  produc- 
tion of  carbonic  acid,  were  thus  beautifully 
shown.  A  neat  form  of  apparatus  for  this 
purpose  is  delineated  by  Mr.  Faraday,  in 
the  9ih  volume  of  the  Journal  of  Science. 
Sir.  H.  Davy  found,  that  diamonds  gave  a 
volume  of  pure  carbonic  acid,  equal  to  the 
oxygen  consumed;  charcoal  and  plumbago 
afforded  a  minute  portion  of  hydrogen.* 
See  DIAMOND. 

Well-burned  charcoal  is  a  conductor  of 
electricity,  though  wood  simply  deprived  of 
its  moisture  by  baking  is  a  non-conductor; 
but  it  is  a  very  bad  conductor  of  caloric, 
a  property  of  considerable  use  on  many  oc- 
casions, as  in  lining  crucibles. 

It  is  insoluble  in  water,  and  hence  the 
utility  of  charring  the  surface  of  wood  ex- 
posed  to  that  liquid,  in  order  to  preserve 
it,  a  circumstance  not  unknown  to  the  an- 
cients. This  preparation  of  timber  has  been 
proposed  as  an  effectual  preventive  of  what 
is  commonly  called  the  dry  rot.  It  has  an 
attraction,  however,  for  a  certain  portion  of 
water,  which  it  retains  very  forcibly.  Heat- 
ed red-hot,  or  nearly  so,  it  decomposes 
water;  forming  with  its  oxygen,  carbonic 
acid,  or  carbonic  oxide,  according  to  the 
quantity  present;  and  with  the  hydrogen  a 
gaseous  carburet,  called  carburetted  hy- 
drogen, or  heavy  inflammable  air. 

Charcoal  is  infusible  by  any  heat.  If  ex- 
posed to  a  very  high  temperature  in  close 
vessels  it  loses  little  or  nothing  of  its  weight, 
but  shrinks,  becomes  more  compact,  and 
acquires  a  deeper  black  colour. 

Recently  prepared  charcoal  has  a  re- 
markable property  of  absorbing  different 
gases,  and  condensing  them  in  its  pores, 
without  any  alteration  of  their  properties 
or  its  own. 

*  The  following  are  the  latest  results  of 
M.  Theodore  de  Saussure,  with  boxwood 
charcoal,  the  most  powerful  species: 

Gaseous  ammonia,  -  90  vols. 

Ditto       muriatic  acid,  85 

Ditto       sulphurous  acid,  65 

Sulphuretted  hydrogen,  55 

Nitrous  oxide,  40 

Carbonic  oxide,  -  35 

Olefiant  gas,  35 
Carbonic  oxide,             -  9.42 

Oxygen,  -         -         -  9,25 

Azote,  -         -         -  7.5 

Light  gas  from  moist  charcoal,  5.0 
Hydrogen,  -         -         -          1.75 

Very  light  charcoal,  such  as  that  of  cork,, 
absorbs  scarcely  any  air;  while  the  pit-coal 
of  Rastiberg,  sp.  gr.  1.326,  absorbs  10£ 
times  its  volume.  The  absorption  was  al- 
ways completed  in  24  hours.  This  curious 
faculty,  which  is  common  to  all  porous  bo» 


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dies,  resembles  the  action  of  capillary  tubes 
on  liquids.  When  a  piece  of  charcoal, 
charged  with  one  gas,  is  transferred  into 
another,  it  absorbs  some  of  it,  and  parts 
with  a  portion  of  that  first  condensed.  In 
the  experiments  of  Messrs.  Allen  and  Pe- 
pys,  charcoal  was  found  to  imbibe  from 
the  atmosphere  in  a  day  about  l-8th  of  its 
weight  of  water.  For  a  general  view  of  ab- 
sorption, see  GAS. 

When  oxygen  is  condensed  by  charcoal, 
carbonic  acid  is  observed  to  form  at  the 
end  of  several  months.  But  the  most  re- 
markable property  displayed  by  charcoals 
impregnated  with  gas,  is  that  with  sulphu- 
retted hydrogen,  when  exposed  to  the  air 
or  oxygen  gas.  The  sulphuretted  hydro- 
gen is  speedily  destroyed,  and  water  and 
sulphur  result,  with  the  disengagement  of 
considerable  heat.  Hydrogen  alone  has  no 
such  effects.  When  charcoal  was  exposed 
by  Sir  II.  Davy  to  intense  ignition  in  vacua, 
and  in  condensed  azote,  by  means  of  Mr. 
Children's  magnificent  voltaic  battery,  it 
slowly  volatilised,  and  gave  out  a  little 
hydrogen.  The  remaining  part  was  always 
much  harder  than  before;  and  in  one  case 
so  hard  as  to'scratch  glass,  while  its  lustre 
was  increased  This  fine  experiment  may 
be  regarded  as  a  near  approach  to  the  pro- 
duction of  diamond.* 

Charcoal  has  a  powerful  affinity  for  oxy- 
gen, whence  its  use  in  disoxygenating  me- 
tallic oxides,  and  restoring  their  base  to  its 
original  metallic  state,  or  reviving  the  me- 
tal. Thus  too  it  decomposes  several  of  the 
acids,  as  the  phosphoric  and  sulphuric, 
from  which  it  abstracts  their  oxygen,  and 
leaves  the  phosphorus  and  sulphur  free. 

Carbon  is  capable  of  combining  with  sul- 
phur, and  with  hydrogen.  With  iron  it 
forms  steel;  and  it  unites  with  copper  into 
a  carburet,  as  observed  by  Dr.  Priestley. 

A  singular  and  important  property  of 
chat-coal  is  that  of  destroying  the  smell, 
colour,  and  taste  of  various  substances:  for 
the  first  accurate  experiments  on  which  we 
are  chiefly  indebted  to  Mr-  Lowitz  of  Pe- 
tersburg!), though  it  had  been  long  before 
recommended  to  correct  the  foetor  of  foul 
ulcers,  and  as  an  antiseptic.  On  this  ac- 
count it  is  certainly  the  best  dentifrice. 
Water  that  has  become  putrid  by  long 
keeping  in  wooden  casks,  is  rendered  sweet 
by  filtering  through  charcoal  powder,  or 
by  agitation  with  it;  particularly  if  a  few 
drops  of  sulphuric  acid  be  added.  Com- 
mon vinegar  boiled  with  charcoal  powder 
becomes  perfectly  limpid.  Saline  solutions, 
that  are  tinged  yellow  or  brown,  are  ren- 
dered colourless  in  the  same  way,  so  as  to 
afford  perfectly  white  crystals.  The  impure 
carbonate  of  ammonia  obtained  from  bones, 
is  deprived  both  of  its  colour  and  fetid 
smell  by  sublimation  with  an  equal  weight 
of  charcoal  powder.  Malt  spirit  is  freed 


greeable  flavour  by  distillation 
al;  but  if  too  much  be  used, 


from  its 
from  charcoal 

part  of  the  spirit  is  decomposed.  Simple 
maceration,  for  eight  or  ten  days,  in  the 
proportion  of  about  1-UOth  of  the  weight 
of  the  spirit,  improves  the  flavour  much. 
It  is  necessary,  that  the  charcoal  be  well 
burned,  brought  to  a  red  heat  before  it  is 
used,  and  used  as  soon  as  may  be,  or  at 
least  be  carefully  excluded  from  the  air. 
The  proper  proportion  too  should  be  as- 
certained by  experiment  on  a  small  scale. 
The  charcoal  may  be  used  repeatedly,  by 
exposing  it  for  some  time  to  a  red  heat 
before  it  is  again  employed. 

Charcoal  is  used  on  particular  occasions 
as  fuel,  on  account  of  its  giving  a  strong 
and  steady  heat  without  smoke.  It  is  em- 
ployed to  convert  iron  into  steel  by  ce- 
mentation. It  enters  into  the  composition 
of  gunpowder.  In  its  finer  states,  as  in  ivory 
black,  lampblack,  &c.  it  forms  the  basis  of 
black  paints,  Indian  ink,  and  printers'  ink. 

*  The  purest  carbon  for  chemical  pur- 
poses is  obtained  by  strongly  igniting  lamp- 
black in  a  covered  crucible.   This  yields, 
like  the  diamond,  unmixed  carbonic  acid 
by  combustion  in  oxygen. 

Carbon  unites  with  all  the  common  sim- 
ple combustibles,  and  with  azote,  forming 
a  series  of  most  important  compounds. 
With  sulphur  it  forms  a  curious  limpid 
liquid  called  carburet  of  sulphur,  or  sul- 
phuret  of  carbon.  With  phosphorus  it  forms 
a  species  of  compound,  whose  properties 
are  imperfectly  ascertained.  It  unites  with 
hydrogen  in  two  definite  proportions,  con- 
stituting-  sub-carburetted  and  carburetted 
hydrogen  gases.  With  azote  it  forms  prus- 
sic  gas,  the  cyanogen  of  M.  Gay-Lussac. 
Steel  and  plumbago  are  two  different  com- 
pounds of  carbon  with  iron.  In  black  chalk 
we  find  this  combustible  intimately  asso- 
ciated with  silica  and  alumina.  The  prim- 
itive combining  proportion,  or  prime  equi- 
valent of  carbon,  is  0.75  on  the  oxygen 
scale.* 

*  CARBON  (MINERAL),  is  of  a  grayish- 
black  colour.  It  is  charcoal,  with   various 
proportions  of  earth  and  iron,  without  bi- 
tumen. It  has  a  silky  lustre,  and  the  fibrous 
texture  of  wood.  It  is  found  in  small  quan- 
tities, stratified  with  brown  coal,  slate  coal, 
and  pitch  coal.* 

*  CARBONATES.     Compounds  of  carbo- 
nic acid  with  the  salifiable  bases.  They  are 
composed  either  of  one  prime  of  the  acid 
and  one  of  the  base,  or  of  two  of  the  acid 
and  one  of  the  base.     The  former  set  of 
compounds  is  called  carbonates,  the  latter 
bicarbonates.  See  CARBONIC  ACID. 

As  the  system  of  chemical  equivalents, 
or  atomic  theory  of  chemical  combination, 
derives  some  of  its  fundamental  or  prime 
proportions  from  the  constitution  of  the 
carbonates,  their  analysis  requires  peculiat- 


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precautions.  In  the  Annals  of  Philosophy 
for  October  181 7,  I  gave  a  description  of  a 
new  instrument  for  accomplishing1  this  pur- 
pose with  the  minutest  precision. 

The  usual  mode  of  analysis  is  to  put  a 
given  weight  of  the  carbonate  in  a  phial, 
and  add  to  it  a  certain  quantity  of  a  liquid 
acid  which  will  dissolve  the  base,  and  dis- 
engage the  carbonic  acid.  I  found,  with 
every  care  I  could  take  in  this  method, 
that  variable  and  uncertain  quantities  of 
the  liquid  acid  were  apt  to  be  carried  off 
in  vapour  with  the  carbonic  gas,  while  a 
portion  of  this  gaseous  acid  was  generally 
retained  in  the  saline  liquid.  Hence,  in  the 
analysis  of  crystallized  carbonate  of  lime, 
the  most  uniform  of  all  compounds,  we  have 
the  following  discordant  results,  which  are 
of  importance  in  the  doctrine  of  equiva- 
lents:— 

Mr.  Kirwan  makes  it  consist  of 

45       acid  -j-  55  lime. 
MM.  Aiken,  44  +  56 

Dr.  Marcet,  43.9  -f-  56.1 

Dr.  Wollaston,        43.7  +  56.3 

M.  Vauquelin,         43.5  +  56.5 

M.  Thenard,  43.28  -f  56-72 

Dr.  Thomson,  43.137  -f  56.863 
If  we  deduce  the  equivalent  of  lime  from 
the  analysis  of  Dr.  Marcet,  so  well  known 
for  his  philosophical  accuracy  we  shall  have 
Lime  =  35.1  to  carb.  acid  27.5 
Dr.  Thomson's  is  36.25  to  do.  27.5 
I  adduced  the  following  experiment,  se- 
lected from  among  many  others,  as  capable 
of  throwing  light  on  the  cause  of  these  varia- 
tions: "  Into  a  small  pear-shaped  vessel  of 
glass,  with  a  long  neck,  and  furnished  with 
a  hollow  spherical  stopper,  drawn  out, 
above  and  below,  into  a  tube  almost  capil- 
lary, some  dilute  muriatic  acid  was  put. 
The  whole  being  poised  in  a  delicate  ba- 
lance, 100  grains  of  calc  spar  in  rhomboi- 
dal  fragments  were  introduced,  and  the 
stopper  was  quickly  inserted.  A  little  while 
after  the  solution  was  completed,  the  di- 
minution of  weight,  indicating  the  loss  of 
carbonic  acid,  was  found  to  be  42.2  grains. 
Withdrawing  the  stopper,  inclining  the 
vessel  to  one  side  for  a  few  minutes,  to  al- 
low the  dense  gas  to  flow  out,  the  diminu- 
tion became  43.3.  Finally,  on  heating  the 
body  of  the  vessel  to  about  70®,  while  the 
hollow  stopper  was  kept  cool,  small  bub- 
bles of  gas  escaped  from  the  liquid,  and 
the  loss  of  weight  was  found  to  be  43  65, 
at  which  point  it  was  stationary.  This  is  a 
tedious  process."  The  instrument  which  I 
subsequently  employed  is  quick  in  its  ope- 
ration, and  still  more  accurate  in  its  results. 
It  consists  of  a  glass  tube  of  the  same 
strength  and  diameter  with  that  usually 
employed  for  barometers,  having  a  strong 
egg-shaped  bulb,  about  2  inches  long,  and 
If  wide,  bloAvn  at  one  of  its  ends,  while 
VOL.  I. 


the  other  is  open  and  recurved  like  a  sy- 
phon. The  straight  part  of  the  tube,  be- 
tween the  ball  and  bend,  is  about  7  inches 
long.  The  capacity,  exclusive  of  the  cur- 
ved part,  is  a  little  more  than  5  cubic 
inches.  It  is  accurately  graduated  into  cu- 
bic inches  and  hundredth  parts,  by  the 
successive  additions  of  equal  weights  of 
quicksilver,  from  a  measure  thermometric 
tube.  Seven  troy  ounces  and  66  grains  of 
quicksilver  occupy  the  bulk  of  one  cubic 
inch.  Four  and  a  half  such  portions  being 
introduced,  will  fill  the  ball,  and  the  be- 
ginning of  the  stem.  The  point  in  the  tube, 
which  is  a  tangent  to  the  surface  of  the 
mercury,  is  marked  with  a  file  or  a  dia- 
mond. Then  34^  grains,  equal  in  volume  to 
l-100th  of  a  cubic  inch,  being  drawn  up 
into  the  thermometric  tube,  rest  at  a  cer- 
tain height,  which  is  also  marked.  The 
same  measure  of  mercury  is  successively 
introduced  and  marked  off,  till  the  tube  is 
filled. 

"  In  the  instrument  thus  finished,  l-200th 
of  a  cubic  inch  occupies  on  the  stem  about 
l-14th  of  an  inch,  a  space  very  distinguisha- 
ble. The  weight  of  carbonic  acid,  equiva- 
lent to  that  number,  is  less  than  l-400th  of 
a  grain.  The  mode  of  using  it  is  perfectly 
simple  and  commodious,  and  the  analytical 
result  is  commonly  obtained  in  a  few  mi- 
nutes." 

For  example,  five  grains  of  calcareous 
spar  in  three  or  four  rhomboids  were 
weighed  with  great  care  in  a  balance 
by  Crighton,  which  turns  with  jp-eVoTT  °f 
the  weight  in  the  scales.  These  are"  intro- 
duced into  the  empty  tube,  and  made  to 
slide  gently  along  into  the  spheroid.  The 
instrument  is  then  held  in  nearly  a  hori- 
zontal position  with  the  left  hand,  the  top 
of  the  spheroid  resting  ag'ainst  the  breast, 
with  a  small  funnel  bent  at  its  point,  in- 
serted into  the  orifice  of  the  tube.  Quick- 
silver is  now  poured  in  till  it  be  filled, 
which  in  this  position  is  accomplished  in  a 
few  seconds.  Should  any  particles  of  air 
be  entangled  among  the  mercury,  they  are 
discharged  by  inverting  the  instrument, 
having  closed  the  orifice  with  the  finger. 
On  reverting  it,  and  tapping  the  ball  with 
the  finger,  the  fragments  of  spar  rise  to 
the  top.  Three  or  four  hundredth  parts  of 
a  cubic  inch  of  mercury  being  displaced 
from  the  mouth  of  the  tube,  that  bulk  of 
dilute  muriatic  acid  is  poured  in;  then 
pressing  the  forefinger  on  the  orifice,  and 
inclining  the  instrument  forwards,  the  acid 
is  made  to  rise  through  the  quicksilver. 
This,  as  it  is  displaced  by  the  cooled  car- 
bonic acid,  falls  into  a  stone-ware  or  glass 
basin,  within  which  the  instrument  stands 
in  a  wooden  frame.  When  the  solution  is 
completed,  the  apparent  volume  of  gas  is 
noted,  the  mercury  in  the  two  legs  of  the 
34 


CAB 


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syphon  is  brought  to  a  level,  or  the  differ- 
ence of  height  above  the  mercury  in  the  ba- 
sin is  observed,  as  also  the  temperature  of 
the  apartment,  and  the  height  of  the  baro- 
meter. Then  the  ordinary  corrections  being 
made,  we  have  the  exact  volume  of  carbo- 
nic acid  contained  in  five  grains  of  calc 
spar  In  very  numerous  experiments,  which 

1  have  made  in  very  different  circumstances 
of  atmospherical   pressure    and   tempera- 
ture, the  results  have  not  varied  one-hun- 
dredth of  a  cubic  inch,  on  five  grains,  care 
being  had  to  screen  the  instrument  from 
the  radiation  of  the  sun  or  a  fire. 

As  there  is  absolutely  no  action  exer- 
cised on  mercury  by  dilute  muriatic  acid  at 
ordinary  temperatures;  as  no  perceptible 
difference  is  made  in  the  bulk  of  air,  by 
introducing  to  it  over  the  mercury  a  little 
of  the  acid  by  itself;  and  as  we  can  expel 
every  atom  of  carbonic  acid  from  the  mu- 
riate of  lime,  or  other  saline  solution,  by 
gently  heating  that  point  of  the  tube  which 
contains  it,  it  is  evident  that  the  total  vo- 
lume of  gaseous  product  must  be  accu- 
rately determined.  When  a  series  of  ex- 
periments is  to  be  performed  in  a  short 
space  of  time,  I  wash  the  quicksilver  with 
water,  dry  it  with  a  sponge  first,  and  then 
with  warm  muslin.  The  tube  is  also  wash- 
ed out  and  drained.  According  to  my  ex- 
periments with  the  above  instrument,  5 
grains  of  calcareous  spar  yield,  4.7  cubic 
inches  of  carbonic  acid,  equivalent  to  43.616 
percent.  The  difference  between  this  num- 
ber and  Dr.  Wollaston's  is  inconsiderable. 

Among  other  results  which  I  obtained 
from  the  use  of  the  above  instrument,  it 
enabled  me  to  ascertain  the  true  composi- 
tion of  the  sublimed  carbonate;  of  ammo- 
nia, which  chemists  had  previously  mis- 
taken. I  showed  in  the  Annals  of  Philoso- 
phy for  September  1817,  that  this  salt  con- 
tained 54.5  of  carbonic  acid,  30.3  ammo- 
nia, and  15  water,  in  100  parts;  numbers 
which,  being  translated  into  the  language 
of  equivalents,  approach  to  the  following 
proportions: — 

Carbonic  acid,  3  primes,  8.25  55.89 
Ammonia,  2  4.26  28.86 

Water,  2  2.25       15.25 

14.76    100.00 

As  this  volatile  salt  possesses  the  cu- 
rious property  of  passing  readily  from  one 
system  of  definite  proportions  to  another, 
absolute  accordance  between  experiment 
and  theory  cannot  be  expected.  The  other 
salt  gave  for  its  constituents,  54.5  car- 
bonic acid-j-22.8  ammonia-j-  22.75  wa- 
ter =s  100.  Now,  if  these  numbers  be  re- 
ferred to  Dr.  Wollaston's  oxygen  scale,  we 
shall  have, —  Theory.  Expt. 

2  primes  carbonic  acid,  5.50     55.66      54.50 

1  ammonia  2.13    21.56      22.80 

2  water,  2-25    22.78      22-75 


These  near  approximations  to  the  equi- 
valent ratios  in  compounds  of  a  variable 
nature,  do  not  seem  to  have  attracted  no- 
tice at  the  time.  Dr.  Thomson  describes 
in  his  System  the  solid  subcarbonate  found 
in  the  shops  as  indefinite  in  the  proportion 
of  its  constituents.  In  the  14th  Number  of 
the  Journal  of  Science,  his  friend,  Mr.  Phil- 
lips, whose  attention  to  minute  accuracy  is 
well  known,  has  published  an  ingenious  pa- 
per on  the  subject,  which  begins  with  the 
following  handsome  acknowledgment  of 
my  labours:  "  During  some  late  researches, 
my  attention  being  directed  to  the  compo- 
sition of  the  carbonates  of  ammonia,  I  be- 
gan, and  had  nearly  completed  an  examina- 
tion of  them,  before  I  observed  that  they 
had  been  recently  analyzed  by  Dr.  Ure; 
and  I  consider  his  results  to  be  so  nearly 
accurate,  that  I  should  have  suppressed 
mine,  if  I  had  not  noticed  some  circum- 
stances respecting  the  compounds  in  ques- 
tion, which  have,  I  believe,  hitherto  escaped 
observation." 

Mr.  Phillips's  communication  is  valua- 
ble. It  presents  a  luminous  systematic  view 
of  the  carbonates  of  ammonia  and  soda.  Dr. 
Thomson,  in  his  Annals  for  July  1820, 
enumerates  that  account  of  the  carbonates 
of  ammonia  among  the  improvements  made 
in  1819,  without  any  allusion  to  my  expe- 
riments on  the  ammoniacal  salts,  publish- 
ed in  his  own  Magazine,  nearly  three  years 
before  he  printed  his  retrospect. 

The  indications  of  the  above  analytical 
instrument  are  so  minute,  as  to  enable  us, 
by  the  help  of  the  old  and  well  known 
theorem  for  computing  the  proportions  of 
two  metals  from  the  specific  gravity  of  an 
alloy,  to  deduce  the  proportions  of  the 
bases  from  the  volume  of  gas  disengaged 
by  a  given  weight  of  a  mixed  carbonate. 
A  chemical  problem  of  this  nature  was 
practically  solved[by  me,  in  presence  of  two 
distinguished  Professors  of  the  University 
of  Dublin,  in  May  1816.  But  such  an  appli- 
cation is  more  curious  than  useful,  since  a 
slight  variation  in  the  quantity  of  gas,  as 
well  as  accidental  admixtures  of  other  sub- 
stances, are  apt  to  occasion  considerable 
errors.  It  determines,  however,  the  nature 
and  value  of  a  limestone  with  sufficient 
practical  precision.  As  100  grains  of  mag- 
nesian  limestone  yield  99  cubic  inches  of 
gas,  a  convenient  rule  for  it  is  formed  when 
we  say,  that  10  grains  will  yield  10  cubic 
inches.  In  the  same  way  marls  and  com- 
mon limestones  may  be  examined,  by  sub- 
jecting a  certain  number  of  grains,  in  a 
graduated  syphon  tube,  to  the  action  of  a 
little  muriatic  acid  over  mercury.  From  the 
bulk  of  evolved  gas,  expressed  in  cubic  inches 
and  tenths,  deduct  l-20th,  the  remainder  -will 
express  the  proportion  of  real  limestone  pre- 
sent in  the  grains  employed* 


CAR 


CAR 


*  CARBONATE  of  BARYTES.  SeeWiTH- 
ERITE.* 

*  CARBONATE  of  LIME.  See  CALCARE- 
OUS SPAR.* 

*  CARBONATE   of   STRONTIAN.    See 
STRONTIAN  and  HEAVY  SPAR.* 

*  CARBONIC  ACID.   See  ACID  CARBO- 
NIC.* 

*  CARBONIC  OXIDE.   A    gaseous  com- 
pound of  one  prime  equivalent  of  carbon, 
and  one  of  oxygen,  consisting-  by  weight  of 
0.75  of  the  former,  and  1.00  of  the  latter. 
Hence  the  prime  of  the  compound  is  1.75, 
the  same  as  that  of  azote.  This  gas  can- 
not be  formed  by  the  chemist  by  the  direct 
combination  of  its  constituents;  for  at  the 
temperature  requisite  for  effecting  a  union, 
the  carbon  attracts  its  full  dose  of  oxygen, 
and  thus  generates  carbonic  acid.  It  may 
be  procured  by  exposing  charcoal  to  a  long 
continued  heat.  The  last  products  consist 
chiefly  of  carbonic  oxide. 

To  obtain  it  pure,  however,  our  only  plan 
is  to  abstract  one  proportion  of  oxygen 
from  carbonic  acid,  either  in  its  gaseous 
state,  or  as  condensed  in  the  carbonates. 
Thus  by  introducing  well  calcined  char- 
coal into  a  tube  traversing  a  furnace,  as 
is  represented  plate  I.  fig.  2.;  and  when  it 
is  heated  to  redness,  passing  over  it  back- 
wards and  forwards,  by  means  of  two  at- 
tached mercurial  gasometers  or  bladders, 
a  slow  current  of  carbonic  acid,  we  con- 
vert the  acid  into  an  oxide  more  bulky 
than  itself.  Each  prime  of  the  carbon  be- 
comes now  associated  with  only  one  of 
oxygen,  instead  of  two,  as  before.  The 
carbon  acting  here,  by  its  superior  mass, 
is  enabled  to  effect  the  thorough  satura- 
tion of  the  oxygen. 

If  we  subject  to  a  strong  heat,  in  a  gun 
barrel  or  retort,  a  mixture  of  any  dry  earthy 
carbonate,  such  as  chalk,  or  carbonate  of 
strontites,  with  metallic  filings  or  charcoal, 
the  combined  acid  is  resolved  as  before 
into  the  gaseous  oxide  of  carbon.  The  most 
convenient  mixture  is  equal  parts  of  dried 
chalk  and  iron,  or  zinc  filings.  By  passing 
a  numerous  succession  of  electric  explo- 
sions through  one  volume  of  carbonic  acid, 
confined  over  mercury,  two  volumes  of 
carbonic  oxide,  and  one  of  oxygen,  are 
formed,  according  to  Sir  H.  Davy. 

The  specific  gravity  of  this  gas  is  stated 
by  Gay-Lussac  and  Thenard,  from  theore- 
tical considerations,  to  be  0.96782,  though 
Mr.  Cruickshank's  experimental  estimate 
was  0.9569.  As  the  gas  is  formed  by  with- 
drawing from  a  volume  of  carbonic  acid 
half  a  volume  of  oxygen,  while  the  bulk 
of  the  gas  remains  unchanged,  we  obtain 
its  specific  gravity  by  subtracting  from  that 
of  carbonic  acid  half  the  specific  gravity 
of  oxygen.  Hence  1.5277  —  0.5555  = 
0.9722,  differing  slightly  from  the  above, 
in  consequence  of  the  French  chemists 


rating  the  specific  gravity  of  the  two  ori- 
ginal gases  at  1.51961  and  1.10359.  Hence 
100  cubic  inches  weigh  29-f  grains  at  mean 
pressure  and  temperature. 

This  gas  burns  with  a  dark -blue  flame. 
Sir  H.  Davy  has  shown,  that  though  carbo- 
nic oxide  in  its  combustion  produces  less 
heat  than  other  inflammable  gases,  it 
may  be  kindled  at  a  much  lower  tempera- 
ture. It  inflames  in  the  atmosphere,  when 
brought  into  contact  with  an  iron  wire 
heated  to  dull  redness,  whereas  carburet- 
ted  hydrogen  is  not  inflammable  by  a  si- 
milar wire,  unless  it  is  heated  to  whiteness, 
so  as  to  burn  with  sparks.  It  requires,  for 
its  combustion,  half  its  volume  of  oxygen 
gas,  producing  one  volume  of  carbonic 
acid.  It  is  not  decomposable  by  any  of 
the  simple  combustibles,  except  potassi- 
um and  sodium.  When  potassium  is  heat- 
ed in  a  portion  of  the  gas,  potash  is 
formed  with  the  precipitation  of  charcoal, 
and  the  disengagement  of  heat  and  light. 
Perhaps  iron,  at  a  high  temperature,  would 
condense  the  oxygen  and  carbon  by  its 
strong  affinity  for  these  substances.  Water 
condenses  -^  of  its  bulk  of  the  gas.  The 
above  processes  are  those  usually  pre- 
scribed in  our  systematic  works,  for  pro- 
curing the  oxide  of  carbon.  In  some  of 
them,  a  portion  of  carbonic  acid  is  evolved, 
which  may  be  withdrawn  by  washing  the 
gaseous  product  with  weak  solution  of 
potash,  or  milk  of  lime.  We  avoid  the 
chance  of  this  impurity  by  extricating  the 
gas  from  a  mixture  of  dry  carbonate  of  ba- 
rytes  and  iron  filings,  or  of  oxide  of  zinc, 
and  previously  calcined  charcoal.  The  ga- 
seous product,  from  the  first  mixture,  is 
pure  oxide  of  carbon.  Oxide  of  iron,  and 
pure  barytes,  remain  in  the  retort.  Carbonic 
oxide,  when  respired,  is  fatal  to  animal 
life.  Sir  H.  Davy  took  three  inspirations  of 
it,  mixed  with  about  one-fourth  of  common 
air;  the  effect  was  a  temporary  loss  of  sen- 
sation, which  was  succeeded  by  giddiness, 
sickness,  acute  pains  in  different  parts  of 
the  body,  and  exti-eme  debility.  Some  days 
elapsed  before  he  entirely  recovered.  Since 
then,  Mr.  Witter  of  Dublin  was  struck 
down  in  an  apoplectic  condition,  by  breath- 
ing this  gas;  but  he  was  speedily  restored, 
by  the  inhalation  of  oxygen.  See  an  inte- 
resting account  of  this  experiment,  by  Mr. 
Witter,  in  the  Phil.  Mag.  vol.  43. 

When  a  mixture  of  it  and  chlorine  is  ex- 
posed to  sunshine,  a  curious  compound, 
discovered  by  Dr.  John  Davy,  is  formed, 
to  which  he  gave  the  name  of  phosgene 
gas.  I  shall  describe  its  properties  in  treat- 
ing1 of  chlorine.  It  has  been  called  chloro- 
carbonic  acid,  though  chlorocarbonous  acid 
seems  a  more  appropriate  name.* 

*  CARBUNCLE,  a  gem  highly  prized  by 
the  ancients,  probably  the  alamandine.3  «*. 
variety  of  noble  Garnet* 


CAR 


CAR 


•CARBURET  OF  SULPHUR.  Called  also  er  tube.  The  liquid  carburet  occupies  the 
sulphuret  of  carbon,  and  alcohol  of  sul-  bottom  of  the  receiver  bottle,  and  may  be 
phur.  separated  from  the  supernatant  water,  by 

This  interesting  liquid  was  originally  ob-    putting  the  whole  into   a    funnel,   whose 
tained  by  Lampadius  in  distilling  a  mixture    tube  is  closed  with  the  finger,  and  letting 
of  pulverized  pyrites  and  charcoal  in  an    the  denser  brown  carburet  flow  out  below, 
earthen  retort,  and  was  considered  by  him    whenever  the  distinction  of  the  liquid  into 
as  a  peculiar  compound  of  sulphur  andhy-    two  strata  is  complete.  Thus  obtained,  the 
drogen.  But  MM.  Clement  and  Desormes,    carburet  is  always  yellowish,  containing  a 
with  the  precision  and  ingenuity  whidfdis-    small  excess  of  sulphur,  which  may  be  re- 
tinguish  all  their  researches,  first  ascer-    moved  by  distillation  from  a  glass  retort, 
tained  its  true  constitution  to  be  carburet-    plunged  in  water,  at  a  temperature  of  115°. 
ted  sulphur;  and  they  invented  a  process  of    It  is  now  transparent  and  colourless,  of  a 
great  simplicity,  for  at  once  preparing  it,    penetrating,  fetid  smell,  and  an  acrid  burn- 
and  proving  its  nature.  Thoroughly  cal-    ing  taste.  Its  specific  gravity  varies   from 
cined  charcoal  is  to  be  put  into  a  porcelain    1.263  to  1.272.  According*  to  Dr.  Marcet, 
tube,  that  traverses  a  furnace,  at  a  slight    it  boils  below  110°;  according  to  M.  The- 
angle  of  inclination.  To  the  higher  end  of    nard  at  113°  F.;  and  the  tension  of  its  va- 
the  tube,  a  retort  of  glass,  containing  sul-    pour  at  72  o°  is  equivalent  to  a  column   of 
phur,  is  luted;  and  to  the  lower  end  is  at-    12.53  inches  of  mercury.  At  53.5°,  accord- 
tached  an  adopter  tube,  which  enters  into    ing  to  Marcet  and  Berzelius,  the  tension  is 
a  bottle  with  two  tubulures,  half  full  of    equivalent  to  a  column  of -7-4  inches,  or 
water,  and  surrounded  Avith  very  cold  wa-    one-fourth  of  the  mean  atmospheric  pres- 
ter  or  ice.  From  the  other  aperture  of  the    sure;  hence  one-third  is  added  to  the  bulk 
bottle,  a  bent  tube  proceeds  into  the  pneu-    of  any  portion  of  air,  with  which  the  ii- 
matic  trough.  When  the  porcelain  tube  is    quid  may  be  mixed.  A  spirit  of  wine  ther- 
brought  into   a  state  of  ignition,  beat  is    mometer,  having  its  bulb  surrounded  with 
applied  to  the   sulphur,  which  subliming    colton  cloth  or  lint,  if  dipped  in  sulphuret 
into  the  tube,  combines  with  the  charcoal,    of  carbon,  and  suspended  in  the  air,  sinks 
forming  the  liquid  carburet.   The  conclu-    from  60°  to  0*.  If  it  be  put  into  the  receiver 


sive  demonstration  of  such  an  experiment 
\vas  however  questioned  by  M.  Berthollet 


of  an  air  pump,  and  a  moderate  exhaustion 
be  made,  it   sinks  rapidly  from  60°  to 


jun.  and  Cluzel.  But  MM.  Berthollet,  The-    81°.  If  a  tube  containing  mercury  be  treat- 


nard  and  Vauquelin,  the  reporters  on  M 
CluzePs  memoir,  having  made  some  expe- 
riments of  their  own  upon  the  subject, 
concluded  that  the  liquid  in  question  was 
a  compound  of  sulphur  and  carbon  only. 

Finally,  an  excellent  paper  was  written 
on  the  carburet  by  M  Berzelius  and  Dr. 
Marcet,  who  confirmed  the  results  of  MM. 
Clement  and  Desormes,  and  added  likewise 
several  important  facts. 


ed  in  the  same  way,  the  mercury  may  be 
readily  frozen  even  in  summer.  The  drier 
the  air  in  the  receiver,  the  more  easily  is 
the  cold  produced.  Hence  the  presence  of 
sulphuric  acid  may  be  of  some  service  in 
removing  the  vapour  from  the  air  in  the 
receiver. 

This  carburet  may  be  cooled  to  —  80° 
without  congealing;  a  conclusive  proof  that 
combination  changes  completely  the  con- 


If  about  ten  parts  of  well  calcined  char-  stitution  of  bodies,  since  two  substances 
coal  in  powder,  mixed  with  fifty  parts  of  usually  solid,  form  a  fluid  which  we  can- 
pulverixed  native  pyrites  (bisulphuret  of  not  solidify.  When  a  lighted  body  approach- 
iron),  be  distilled  from  an  earthen  retort,  es  the  surface  of  the  carburet,  it  immedi- 
into  a  tubulated  receiver  surrounded  with  ately  catches  fire,  and  burns  with  a  blue 
ice,  more  than  one  part  of  sulphuret  of  sulphurous  flame.  Carbonic  and  sulphurous 
carbon  may  be  obtained.  If  we  employ  the  acids  are  exhaled,  and  a  little  sulphur  is 
elegant  process  of  M.  Clement,  we  must  deposited.  A  heal  of  about  700°  inflames 
take  care  that  the  charcoal  be  perfectly  the  vapour  of  the  carburet.  Oxygen  dilated 
calcined,  otherwise  no  carburet  will  be  ob-  by  it  over  mercury  explodes  by  the  electric 
tained.  In  their  early  experiments,  they  at-  spark,  with  a  violent  detonation.  My  eudi- 
tached  to  the  higher  end  of  the  porcelain  ometer  is  peculiarly  adapted  to  the  exhi- 
tube  a  glass  one,  containing  the  sulphur  bition  of  this  experiment.  A  portion  of  oxy- 
iri  small  pieces,  and  pushed  these  succes-  gen  being  introduced  into  the  sealed  leg, 


sively  forwards  by  a  wire  passing  air-tight 
through  a  cork,  at  the  tipper  end  of  the 
tube. 

Besides  the  liquid  carburet,  there  is 
formed  some  carburetted  and  sulphuretted 
hydrogen,  and  a  reddish-brown  solid  and 
very  combustible  matter,  which  seems  to 
be  sulphur  slightly  carburetted.  This  sub- 
stance remains  almost  entirely  in  the  adopt- 


we  pour  a  few  drops  of  the  carburet  on  the 
surface  of  the  mercury  in  the  open  leg, 
and  closing  this  with  the  finger,  transfer 
the  liquid  to  the  other  by  a  momentary  in- 
clination  of  the  syphon.  The  expansion  of 
volume  can  be  now  most  accurately  mea- 
sured by  bringing  the  mercury  to  a  level 
in  each  leg. 
The  subsequent  explosion  occasions  no 


CAR 


CAR 


danger,  and  a  scarcely  audible  report.  The 
result  is  a  true  analysis,  if  we  have  mixed 
oxygen  saturated  with  the  vapour  at  ordi- 
nary pressure  and  temperature,  with  about 
its  volume  of  pure  oxygen.  Otherwise,  all 
the  sulphur  would  not  be  oxygenated.  We 
obtain,  then, sulphurous  and  carbonic  acids, 
with  the  excess  of  oxygen. 

The  carburet  of  sulphur  dissolves  cam- 
phor. It  does  not  unite  with  water;  but 
very  readily  with  alcohol  and  ether.  With 
chloride  of  azote  it  forms  a  non-detonating 
compound.  The  waters  of  potash,  barytes, 
and  lime,  slowly  decompose  it,  with  the 
evolution  of  carbonic  acid  gas.  It  combines 
with  ammonia  and  lime,  forming  carbo- 
sulphurets.  The  carburet,  saturated  with 
ammoniacal  gas,  forms  a  yellow  pulveru- 
lent substance,  which  sublimes  unaltered 
in  close  vessels,  but  is  so  deliquescent  that 
it  cannot  be  passed  from  one  vessel  to  ano- 
ther without  absorbing  moisture.  When 
heated  in  that  state,  crystals  of  hydrosul- 
phuret  of  ammonia  form.  The  compound 
with  lime  is  made  by  heating  some  quick- 
lime in  a  tube,  and  causing  the  vapour  of 
carburet  to  pass  through  it.  The  lime  be- 
comes incandescent  at  the  instant  of  com- 
bination. 

When  the  carburet  is  left  for  some  weeks 
in  contact  with  nitro-muriatic  acid,  it  is 
converted  into  a  substance  having  very 
much  the  appearance  and  physical  proper- 
ties of  camphor;  being  soluble  in  alcohol 
and  oils,  and  insoluble  in  water.  This  sub- 
stance is,  according  to  Berzelius,  a  triple 
acid,  composed  of  two  atoms  of  muriatic 
acid,  one  atom  of  sulphurous  acid,  and  one 
atom  of  carbonic  acid.  He  calls  it,  muria- 
tico-sulphurous-carbonic  acid. 

When  potassium  is  heated  in  the  vapour 
of  the  carburet,  it  burns  with  a  reddish 
flame,  and  a  black  film  appears  on  the  sur- 
face. On  admitting  water,  a  greenish  solu- 
tion of  sulphuret.  of  potash  is  obtained, 
containing  a  mixture  of  charcoal.  From  its 
vapour  passing  through  ignited  muriate  of 
silver,  without  occasioning  any  reduction 
of  the  metal,  it  is  demonstrated  that  this 
carburet  is  destitute  of  hydrogen. 

When  the  compound  of  potash,  water, 
and  carburet  of  sulphur,  is  added  to  me- 
tallic solutions,  precipitates  of  a  peculiar 
kind,  called  carbo-sulphurets,  are  obtain- 
ed. The  following  is  a  table  of  the  colours 
of  the  precipitates: 
Muriate  of  Cerium,  White  or  yellowish- 

white. 

Sulphate  of  Manga- 
nese, Greenish-gray. 
Sulphate  of  Zinc,        White. 
Perm uri ate  of  iron,     Dark  red. 
Submuriate  of  Anti- 
mony, Orange. 
Muriate  of  tin,            Pale    orange,    then 
brown. 


Nitrate  of  Cobalt, 

Nitrate  of  lead, 
Nitrate  of  copper, 
Pro  to  muriate  of  mer- 


Dark  olive-green,  at 

last  black. 
A  fine  scarlet. 
Dark  brown. 

Black. 


cury, 

Permuriate  of  mer- 
cury, Orange. 
Muriate  of  silver,        Reddish-brown. 

Carburet  of  sulphur  was  found  by  Dr. 
Brewster  to  exceed  all  fluid  bodies  in  re- 
fractive power,  and  even  the  solids,  flint- 
glass,  topaz,  and  tourmaline.  In  dispersive 
power  it  exceeds  every  fluid  substance  ex- 
cept oil  of  cassia,  holding  an  intermediate 
place  between  phosphorus  and  balsam  of 
tola. 

The  best  method  of  analyzing  the  car- 
buret of  sulphur,  is  to  pass  its  vapour  over 
ignited  peroxide  of  iron;  though  the  ana- 
lysis was  skilfully  effected  by  MM.  Ber- 
thollct,  Vauquelin,  and  Thenard,  by  trans- 
mitting the  vapour  through  a  red-hot  cop- 
per tube,  or  a  porcelain  one  containing 
copper  turnings.  Both  the  first  method,  as 
employed  by  Berzelius,  and  the  second, 
concur  in  showing  the  carburet  to  consist 
of  1  prime  of  carbon,  0.75  15.79 
2  primes  of  sulphur,  4.00  84.21 

4.75  100.00 

Vauquelin's  experimental  numbers  are, 
from  15  to  16  carbon,  and  from  86  to  85 
sulphur;  and  those  of  Berzelius  and  Mar- 
cet  are  15.17  carbon,  and  84.83  sulphur,  in 
100  parts. 

Of  the  cold  produced  by  the  evaporation 
of  the  carburet  of  sulphur,  the  following 
account  is  given  by  Dr.  Thomson  in  the 
;third  volume  of  his  Annals,  being  the  ex- 
tract of  a  letter  which  he  received  from 
Mr.  J.  Murray,  philosophical  lecturer: — " 
A  glass  of  water  has  remained  on  the  table 
since  the  preceding  evening,  and  though  it 
might  be  some  degrees  below  32°  Fahr.  it 
indicated  no  disposition  for  congelation.  A 
few  drops  of  sulphuret  of  carbon  were  ap- 
plied to  the  surface,  instantly  the  globules 
became  cased  with  a  shell  of  icy  spiculac 
of  retiform  texture.  Where  they  were  in 
contact  with  the  water,  plumose  branches 
darted  from  the  sulphuret  as  from  a  centre 
to  the  bottom  of  the  vessel,  and  the  whole 
became  solidified.  The  sulphuret  of  carbon 
in  the  interim  volatilized,  and  during  this 
period  the  spicules  exhibited  the  colours 
of  the  solar  spectrum  in  beautiful  array."* 
*  CARBURETTED  HYDROGEN  GAS.  Of 
this  compound  g'us,  formerly  called  heavy 
inflammable  uir,  we  have  two  species,  dif- 
fering in  the  proportions  of  the  constitu- 
ents. The  first,  consisting  of  1  prime  equi- 
valent of  each,  is  carburetted  hydrogen;  the 
second,  of  1  prime  of  carbon,  and  2  of  hy- 
drogen, is  subcarburetted  hydrogen.  l.Car- 
buretted  hydrogen,  the  percarburetted  by- 


CAR 


CAR 


drogen  of  the  French  chemists,  is,  accord- 
ing to  Mr.  Brande,  the  only  definite  com- 
pound of  these  two  elements.  To  prepare 
it,  we  mix  in  a  glass  retort,  1  part  of  alco- 
hol, and  4  of  sulphuric  acid,  and  expose 
the  retort  to  a  moderate  heat.  The  gas  is 
usually  received  over  water:  though  De 
Saussure  states  that  this  hquid  absorbs 
more  than  l-7th  of  its  volume  of  the^  gas. 
It  is  destructive  of  animal  life.  Its  specific 
gravity  is  U.978,  according  to  Saussure.  100 
cubic  "inches  weigh  28.80  gr.  It  possesses 
all  the  mechanical  properties  of  air  It  is 
invisible,  and  void  of  taste  and  smell,  when 
it  has  been  washed  from  a  little  ethereous 
vapour.  The  effect  of  heat  on  this  gas  is 
curious.  When  passed  through  a  porcelain 
tube,  heated  to  a  cherry  red,  it  lets  fall  a 
portion  of  charcoal,  and  nearly  doubles  its 
volume.  At  a  higher  temperature  it  depo- 
sites  more  charcoal,  and  augments  in  bulk; 
till  finally,  at  the  greatest  heat  to  which  we 
can  expose  it,  it  lets  fall  almost  the  whole 
of  its  carbon,  and  assumes  a  volume  3^ 
times  greater  than  it  had  at  first.  These  re- 
markable results,  observed  with  great  care, 
have  induced  the  illustrious  Berthollet  to 
conclude,  with  much  plausibility,  that  hy- 
drogen and  carbon  combine  in  many  suc- 
cessive proportions.  The  transmission  of  a 
series  of  electric  sparks  through  this  gas, 
produces  a  similar  effect  with  that  of  sim- 
ple heat. 

Carburetted  hydrogen  burns  with  a 
splendid  white  flame  When  mixed  with 
three  times  its  bulk  of  oxygen,  and  kind- 
led by  a  taper  or  the  electric  spark,  it  ex- 
plodes with  great  violence,  and  the  four 
volumes  are  converted  into  two  volumes  of 
carbonic  acid.  But  two  volumes  of  carbonic 
acid  contain  two  volumes  of  oxygen.  The 
remaining  volume  of  oxygen  therefore  has 
been  expended  in  forming  water  with  twc 
volumes  of  hydrogen.  Hence  the  original 
volume  of  carburetted  hydrogen  was  made 
up  of  these  two  volumes  of  hydrogen  = 
0.1398  (0.0694  X  2)  -f  2  volumes  of  gase- 
ous carbon  =  0  8333,  constituting  1  con- 
densed volume  =  0.9731.  By  gaseous  car- 
bon is  meant  the  vapour  of  this  solid,  as  it 
exists  in  carbonic  acid;  the  density  of  which 
vapour  is  found  bv  subtracting  the  specific 
gravity  of  oxygen,  from  that  of  carbonic 
acid.  Hence  1.5  277— 1.1111  =  0.4166,  re- 
presents the  density  of  gaseous  carbon.  M. 
Thenard  says,  that  if  we  mix  the  percarbu- 
retted  hydrogen  at  once  with  three  times 
its  volume  of  oxygen,  the  eudiometer  would 
be  broken;  so  sudden  and  powerful  is  the 
expansion.  The  eudiometer  referred  to  is 
that  of  Volta,  which  costs  three  guineas  in 
Paris.  My  eudiometer,  which  does  not  cost 
three  shillings,  bears  the  explosive  violence 
of  the  above  mixture,  without  any  danger. 
(See  EUDIOMETER).  When  it  is  detonated 
with  only  an  equal  volume  of  oxygen,  it  ex- 


pands greatly,  and  the  two  volumes  become 
more  than  three  and  a  half.  In  this  case  on- 
ly l-8th  or  1-1  Oth  of  a  volume  of  carbonic 
acid  is  formed;  but  more  than  a  volume  and 
a  half  of  carbonic  oxide;  a  little  hydrogen 
is  consumed,  but  the  greatest  part  remains 
untouched  and  mixed  with  the  carbonic 
oxide.  It  may  be  separated  by  combustion 
with  chlorine. 

If  we  refer  the  weights  above  found,  from 
the  combining  volumes,  to  the  equivalent 
oxygen  scale,  we  shall  have  the  gas  con- 
sisting of  1  prime  of  each  constituent. 

For  0.1398:  0.125:  :8333:  0.752;  now  0.125 
and  0.750  represent  the  prime  equivalents 
of  hydrogen  and  carbon. 

When  this  gas  is  mixed  with  its  own 
bulk  of  chlorine,  the  gaseous  mixture  is 
condensed  over  water  into  a  peculiar  oily- 
looking  compound.  Hence  this  carburetted 
hydrogen  was  called  by  its  discoverers,  the 
associated  Dutch  chemists,  olefiant  gas. 
MM.  Robiquetand  Colin  formed  this  liquid 
in  considerable  quantities,  by  making  two 
currents  of  its  constituent  gases  meet  in  a 
glass  globe.  The  olefiant  gas  should  be  in. 
rather  larger  quantity  than  the  chlorine, 
otherwise  the  liquid  becomes  of  a  green 
colour,  and  acquires  acid  properties.  When 
it  is  washed  with  water,  and  distilled  off 
dry  muriate  of  lime,  it  may  be  regarded  as 
pure.  It  is  then  a  limpid  colourless  essence 
of  a  pleasant  flavour,  and  a  sharp,  sweet, 
and  not  disagreeable  taste.  At  45°  its  spe- 
cific gravity  is  2.2201.  Its  boiling  point  is 
152°.  At  49°  is  vapour  is  said  to  be  capable 
of  sustaining  a  column  of  24-f  inches  of 
mercury.  The  specific  gravity  of  the  va- 
pour is  3.-I434,  compared  to  atmospheric 
air.  But  that  quantity  is  the  sum  of  the 
densities  of  chlorine  and  olefiant  gas.  It 
will  consist  therefore  by  weight  of 

Olefiant  gas,  0.9731  (2  X  0.875)  1.75 

Chlorine,        2.4733  4.45 

3.4464  6.20 

or  two  primes  of  the  first  and  one  of  the 
second.  Its  ultimate  constituents  are  there- 
fore 1  chlorine,  2  carbon,  and  2  hydrogen. 
This  substance  burns  with  a  green  flame, 
from  which  charcoal  is  deposited,  and  mu- 
riatic acid  gas  flies  off.  Decomposition, 
with  similar  results,  is  effected  by  passing 
the  liquid  through  a  red-hot  porcelain  tube. 
Its  constitution  probably  resembles  that  of 
muriatic  ether. 

Olefiant  gas  is  elegantly  analyzed  by 
heating  sulphur  in  it  over  mercury.  One 
cubic  inch  of  it,  with  2  grains  of  sulphur, 
yields  two  cubic  inches  of  sulphuretted  hy- 
drogen, and  charcoal  is  deposited.  Now  we 
know  that  the  latter  gas  contains  just  its 
own  volume  of  hydrogen. 

2.  Subcarburetted  hydrogen.  This  gas  is 
supposed  to  be  procured  in  a  state  of  defi- 
nite composition,  from  the  mud  of  stagnant 


CAR 


CAR 


pools  or  ditches.  We  have  only  to  fill  a 
wide  mouthed  goblet  with  water,  and  in- 
verting it  in  the  ditch-water,  stir  the  bot- 
tom with  a  stick.  Gas  rises  into  the  goblet. 
The  fire-damp  of  mines  is  a  similar  gas 
to  that  of  ditches.  There  is  in  both  cases 
an  admixture  of  carbonic  acid,  which  lime 
or  potash -water  will  remove.  A  proportion 
of  air  is  also  present,  tbe  quantity  of  which 
can  be  ascertained  by  analysis.  By  igniting 
acetate  of  potash  in  a  gun-barrel,  an  ana- 
logous species  of  gas  is  obtained.  Accord- 
ing to  M.  Berlhollet,  the  sp  gr.  of  the  car- 
buretted  hydrogen  from  ditch  mud,  exclu- 
sive of  the  azote,  is  0.5382. 


Subcarburetted  hydrogen  is  destitute  of 
colour,  taste,  and  smell.  It  burns  with  a 
yellow  flame,  like  that  of  a  candle.  When 
mixed  with  twice  its  volume  of  oxygen  and 
exploded,  we  obtain  exactly  its  own  bulk 
of  carbonic  acid,  while  water  is  precipi- 
tated. We  can  hence  infer  the  composition 
of  subcarburetted  hydrogen.  For  of  the  two 
volumes  of  oxygen,  one  remains  gaseous  in 
the  carbonic  acid,  and  another  is  condens- 
ed with  two  volumes  of  hydrogen  into  wa- 
ter 1  volume  of  vapour  of  carbon  -}-  2  vo- 
lumes of  hydrogen,  condensed  into  1  vo- 
lume, compose  subcarburetted  hydrogen 
gas.  Thus  in  numbers, 


1  volume  of  gaseous  carbon  =  0.4166  0.75  =  1  prime 

2  do.  hydrogen  =  0.1398   (0.125  X  2)  =    0.25  =  2  primes 

0.5J64 


Here  we  see  the  specific  gravity  0.5564, 
is  very  near  the  determination  of  Berthol- 
let.  We  also  perceive  the  compound  prime 
to  be  1.000,  the  same  as  oxygen.  Berthol- 
let  says  that  the  carburetted  hydrogen  ob- 
tained by  exposing  olefiant  gas  to  an  intense 
heat  contains  2  of  hydrogen  to  1  of  carbon 
by  weight.  This  proportion  corresponds  to 
12  primes  of  hydrogen  =  1.5 

And  1    do.       of  carbon       =  0.75 

As  the  gas  of  ditches  and  the  choke- 
damp  of  mines  are  evidently  derived  from 
the  action  of  water  on  decaying  vegetable 
or  carbonaceous  matter,  we  can  under- 
stand that  a  similar  product  will  be  obtain- 
ed by  passing  water  over  ignited  charcoal, 
or  by  heating  moistened  charcoal  or  vege- 
table matter  in  retorts.  Th<j  gases  are  here, 
however,  a  somewhat  complex  mixture,  as 
well  as  what  we  obtain  by  igniting  pit-coal 
and  wood  in  iron  retorts.  (See  COAL  GAS). 
The  combustion  of  subcarburetted  hydro- 
gen with  common  air  takes  place  only 
when  they  are  mixed  in  certain  propor- 
tions. If  from  6  to  12  parts  of  air  be  mixed 
with  1  of  carburetted  hydrogen,  we  have 
explosive  mixtures.  Proportions  beyond 
these  limits  will  not  explode.  In  like  man- 
ner, from  1  to  2$  of  oxygen,  must  be  mix- 
ed with  1  of  the  combustible  gas,  other- 
wise we  have  no  explosion.  Sir  H.  Davy 
says  that  this  gas  has  a  disagreeable  em- 
pyreumatic  smell,  and  that  water  absorbs 
l-30th  of  its  volume  of  it.* 

CARICA  PAPAYA.  Papaw  tree.  Every 
part  of  the  papaw  tree,  except  the  ripe 
fruit,  affords  a  milky  juice,  which  is  used 
in  the  Isle  of  France  as  an  effectual  remedy 
for  the  tape-worm.  In  Europe,  however, 
whither  it  has  been  sent  in  the  concrete 
state,  it  has  not  answered. 

The  most  remarkable  circumstance  re- 
garding  the  papaw  tree,  is  the  extraction 
from  its  juice  of  a  matter  exactly  resem- 


1.00 

bling  the  flesh  or   fibre  of  animals,    and 
hence  called  vegetable  fibrin;  which  see. 

CARMi]s7E.  A  red  pigment  prepared 
from  cochineal.  See  LAKE. 

*  CAR  N  ELI  AN  is  a  sub-species  of  calce- 
dony.  Its  colours  are  white,  yellow,  brown, 
and  red.  It  has  a  conchoidal  fracture  and  a 
specific  gravity  of  2.6.    It  is  semi-transpa- 
rent, and  has  a  glistening  lustre.  It  consists 
of  94  silica,  3.5  alumina,  and  0.75  oxide  of 
iron.  The  finest  specimens  come  from  Cam- 
bay  and  Surat  in  India.  It  is  found  in  the 
channels  of  torrents  in  Hindostan,  in  no- 
dules of  a  blackish  olive,  passing  into  gray. 
After    exposure    for    some    weeks  to  the 
sun,  these  are  subjected  to  heat  in  earthen 
pots,  whence  proceed  the    lively   colours 
for  which  they  are  valued  in  jewelry.   It 
is  softer  than  common  calcedony.* 

*  CAROMEL.  The  smell  exhaled  by  su- 
gar, at  a  calcining  heat.* 

CARTHAMUS,  SAFFLOWER,  or  BAS- 
TARD SAFFRON.  In  some  of  the  deep  red- 
dish, yellow,  or  orange-coloured  flowers, 
the  yellow  matter  seems  to  be  of  the  same 
kind  with  that  of  the  pure  yellow  flowers; 
but  the  red  to  be  of  a  different  kind  from  the 
pure  red  ones.  Watery  menstrua  take  up 
only  the  yellow,  and  leave  the  red,  which 
may  afterward  be  extracted  by  alcohol,  or 
by  a  weak  solution  of  alkali.  Such  particu- 
larly are  the  saffron-coloured  flowers  of  car- 
thamus.  These  after  the  yellow  matter  has 
been  extracted  by  water,  are  said  to  give 
a  tincture  to  ley;  from  which,  on  standing 
at  rest  for  some  time,  a  deep  red  fecula 
subsides,  called  saiflower,  and  from  the 
countries  whence  it  is  commonly  brought 
to  us,  Spanish  red  and  China  lake.  This 
pigment  impregnates  alcohol  with  a  beauti- 
ful red  tincture;  but  communicates  no  co- 
lour to  water. 

Rouge  is  prepared  from  carthamus. 
For  this  purpose  the  red  colour  is  extract- 
ed by  a  solution  of  the  subcarbonate  of 


CAS 


CAT 


soda,  and  precipitated  by  lemon  juice,  pre- 
viously depurated  by  standing.  This  pre- 
cipitate is  dried  on  earthen  plates,  mixed 
with  talc,  or  French  chalk,  reduced  to  a 
powder  by  means  of  the  leaves  of  shave- 
grass,  triturated  with  it  till  they  are  both 
very  fine,  and  then  sifted.  The  fineness  of 
the  powder  and  proportion  of  the  precipi- 
tate constitute  the  difference  between  the 
finer  and  cheaper  rouge.  It  is  likewise 
spread  very  thin  on  saucers,  and  sold  in 
this  state  for  dyeing. 

Carthamus  is  used  for  dyeing  silk  of  a 
poppy,  cherry,  rose,  or  bright  orange  red. 
After  the  yellow  matter  is  extracted  as 
above,  and  thec  akes  opened,  it  is  put  in- 
to a  deal  trough,  and  sprinkled  at  different 
times  with  pearl  ashes,  or  rather  soda  well 
powdered  and  sifted,  in  the  proportion  of 
six  pounds  to  a  hundred,  mixing  the  al- 
kali well  as  it  is  put  in  The  alkali  should 
be  saturated  with  carbonic  acid  The 
carthamus  is  then  put  on  a  cloth  in  a 
trough  with  a  grated  bottom,  placed  on  a 
larger  trough,  and  cold  water  poured  on, 
till  the  large  trough  is  filled.  And  this  is 
repeated,  with  the  addition  of  a  little  more 
alkali  toward  the  end,  till  the  carthamus  is 
exhausted  and  becomes  yellow.  Lemon 
juice  is  then  poured  into  the  bath,  till  it  is 
turned  of  a  fine  cherry  colour,  and  after  it 
is  well  stirred  the  silk  is  immersed  in  it. 
The  silk  is  wrung,  drained,  and  passed 
through  fresh  baths,  washing  and  drying 
after  every  operation,  till  it  is  of  a  proper 
colour;  when  it  is  brightened  in  hot  water 
and  lemon  juice.  For  a  poppy  or  fire  colour 
a  slight  annotta  ground  is  first  given;  but 
the  silk  should  not  be  alumed.  For  a  pale 
carnation  a  little  soap  should  be  put  into 
the  bath.  All  these  baths  must  be  used  as 
soon  as  they  are  made;  and  cold,  because 
heat  destroys  the  colour  of  the  red  feculae. 

*  CARTILAGE.  An  elastic,  semi-transpa- 
rent, animal  solid,  which  remains  of  the 
shape,  and  one-third  the  weight  of  the 
bones,  when  the  calcareous  salts  are  re- 
moved by  digestion  in  dilute  muriatic  acid. 
It  resembles  coagulated  albumen.  Nitric 
acid  converts  it  into  gelatin.  With  alkalis 
it  forms  an  animal  soap.  Cartilage  is  the 
primitive  paste,  into  which  the  calcareous 
salts  are  deposited  in  the  young  animal. 
In  the  disease  rickets,  the  earthy  matter  is 
withdrawn  by  morbid  absorption,  and  the 
bones  return  into  the  state  nearly  of  flexi- 
ble cartilage.  Hence  arise  the  distortions 
characteristic  of  this  disease.* 

CASE-HARDENING.  Steel  when  harden- 
ed is  brittle,  and  iron  alone  is  not  capable 
of  receiving  the  hardness  steel  may  be 
brought  to  possess.  There  is  nevertheless 
a  variety  of  articles  in  which  it  is  desirable 
to  possess  all  the  hardness  of  steel,  to- 
gether with  the  toughness  of  iron.  These 
requisites  arc  united  in  the  art  of  case- 


hardening,  which  does  not  differ  from  the 
making  of  steel,  except  in  the  shorter  du- 
ration of  the  process.  Tools,  utensils,  or 
ornaments  intended  to  be  polished,  are  first 
manufactured  in  iron  and  nearly  finished, 
after  which  they  are  put  into  an  iron  box, 
together  with  vegetable  or  animal  coals  in 
powder,  and  cemented  for  a  certain  time. 
This  treatment  converts  the  external  part 
into  a  coating  of  steel,  which  is  usually  very 
thin,  because  the  time  allowed  for  the  ce- 
mentation is  much  shorter  than  when  the 
whole  is  intended  to  be  made  into  steel. 
Immersion  of  the  heated  pieces  into  water 
hardens  the  surface,  which  is  afterward 
polished  by  the  usual  methods.  Moxon's 
Mechanic  "Exercises,  p.  56,  gives  the  fol- 
lowing receipt: — Cow's  horn  or  hoof  is  to 
be  baked  or  thoroughly  dried  and  pulver- 
ized. To  this  add  an  equal  quantity  of  bay 
salt:  mix  them  with  stale  chamber-ley,  or 
white  wine  vinegar:  cover  the  iron  with 
this  mixture,  and  bed  it  .in  the  same  iu 
loam,  or  enclose  it  in  an  iron  box:  lay  it 
then  on  the  hearth  of  the  forge  to  dry  and 
harden:  then  put  it  into  the  fire,  and  blow 
till  the  lump  have  a  blood-red  heat,  and  no 
higher,  lest  the  mixture  be  burned  too 
much.  Take  the  iron  out,  and  immerse  it 
in  water  to  harden. 

*  CASEIC  ACID.  The  name  which  Proust 
gave  to  a  substance  of  an  acid  nature,  which 
he  extracted  from  cheese;  and  to  which  he 
ascribes  many  of  the  properties  of  this  spe- 
cies of  food.* 

*  CASSAVA.  An  American  plant,  thej'a- 
tropha  manihaty  contains  the  nutritive  starch 
cassava,  curiously  associated  with  a  deadly 
poisonous  juice.    The  roots  ofjatropha  are 
squeezed  in  a  bag.  The  cassava  remains  in 
it;  and  the  juice,  which  is  used  by  the  In- 
dians to  poison  their  arrows,  gradually  lets 
fall  some  starch  of  an  innocent  and  very 
nutritious  quality.  The  whole  solid  matter 
is  dried  in  smoke,  ground,  and  made  into 
bread.* 

*CASSius'spurple precipitate.  See  GOLD.* 
CASTOR.  A  soft  grayish-yellow  or  light 
brown  substance,  found  in  four  bags  in 
the  inguinal  region  of  the  beaver.  In  a 
warm  air  it  grows  by  degrees  hard  and 
brittle,  and  of  a  darker  colour,  especially 
when  dried  in  chimneys,  as  is  usually  done. 
According  to  Bouillon  La  Grange,  it  con- 
sists of  a  mucilage,  a  bitter  extract,  a  resin, 
an  essential  oil,  in  which  its  peculiar  smell 
appears  to  reside,  and  a  flaky  crystalline 
matter,  much  resembling  the  adipocere  of 
biliary  calculi. 

Castor  is  regarded  as  a  powerful  anti- 
spasmodic. 

CATECHU.  A  brown  astringent  substance 
formerly  known  by  the  name  of  Japan 
earth.  It  is  a  dry  extract,  prepared  from 
the  wood  of  a  species  of  sensitive  plant,  the 
mimosa,  catechu.  It  is  imported  into  this 


CAW 


CEL 


country  from  Bombay  and  Bengal.  Accord- 
ing- to  Sir  H.  Davy,  who  analyzed  it,  that 
from  Bombay  is  of  uniform  texture,  red- 
brown  colour,  and  specific  gravity  1.39: 
that  from  Bengal  is  more  friable  and  less 
consistent,  of  a  chocolate  colour  externally, 
but  internally  chocolate,  streaked  with  red- 
brown,  and  specific  gravity  1.28.  The  cate- 
chu from  either  place  differs  little  in  its 
properties.  Its  taste  is  astringent,  leaving 
behind  a  sensation  of  sweetness.  It  is  al- 
most wholly  soluble  in  water. 

Two  hundred  grains  of  picked  catechu 
from  Bombay  afforded  109  grains  of  tan- 
nin, 68  extractive  matter,  13  mucilage,  10 
residuum,  chiefly  sand  and  calcareous 
earth.  The  same  quantity  from  Bengal: 
tannin  9?  grains,  extractive  matter  73,  mu- 
cilage 16,  residual  matter,  being  sand,  with 
a  small  quantity  of  calcareous  and  alumi- 
nous earths,  14.  Of  the  latter  the  darkest 
parts  appeared  to  afford  most  tannin,  the 
lightest  most  extractive  matter.  The  Hin- 
doos prefer  the  lightest  coloured,  which 
has  probably  most  sweetness,  to  chew  with 
the  betel-nut. 

Of  all  the  astringent  substances  we  know, 
catechu  appears  to  contain  the  largest  pro- 
portion of  tannin,  and  Mr.  Purkis  found, 
that  one  pound  was  equivalent  to  seven  or 
eight  of  oak  bark  for  the  purpose  of  tan- 
ning leather. 

As  a  medicine  it  has  been  recommended 
as  a  powerful  astringent,  and  a  tincture  of 
it  is  used  for  this  purpose,  but  its  aqueous 
solution  is  less  irritating.  Made  into  troches 
with  gum  arabic  and  sugar,  it  is  an  elegant 
preparation,  and  in  this  way  is  said  much  to 
assist  the  clearness  of  the  voice,  and  to  be 
remarkably  serviceable  in  disorders  of  the 
throat. 

*  CAT'S  Ers.    A  mineral  of  a  beautiful 
appearance,  brought  from  Ceylon. 

Its  colours  are  gray,  green,  brown,  red,  of 
various  shades.  Its  internal  lustre  is  shining, 
its  fracture  imperfectly  conchoidal,  and  it  is 
translucent.  From  a  peculiar  play  of  light, 
arising  from  white  fibres  interspersed,  it  has 
derived  its  name.  The  French  call  the  ap- 
pearance c/uttoyant.  It  scratches  quartz,  is 
easily  broken,  and  resists  the  blow-pipe. — 
Its  sp.  gr.  is  2.64.  Its  constituents  are,  ac- 
cording to  Klaproth,  95  silica,  1.75  alumina, 
1.5  lime,  and  0.25  oxide  of  iron.  It  is  va- 
lued for  setting  as  a  precious  stone.* 

CAUSTIC  (LUNAR.)  Fused  nitrate  of  sil- 
ver. See  SILVER. 

CAUSTICITT.  All  substances  which  have 
so  strong  a  tendency  to  combine  with  the 
principles  of  organized  substances,  as  to  de- 
stroy their  texture,  are  said  to  be  caustic. 
The  chief  of  these  are  the  concentrated 
acids,  pure  alkalis,  and  the  metalic  salts. 

*  CAUTERY  POTKN  IAL.     CAUSTIC.* 
GAWK.    A  term  by  which  the  miners  «Rs- 

VOL.  I. 


tinguish  the  opaque  specimens  of  sulphate 
of  barytes. 

*CELESTIXE.  Native  sulphate  of  stron- 
tites. This  mineral  is  so  named  from  its  oc- 
casional delicate  blue  colour;  though  it  is 
frequently  found  of  other  shades,  as  white, 
grayish  and  yellowish -white,  arid  red.  It 
occurs  both  massive  and  crystallized.  Some- 
times also  in  fibrous  and  stellated  forms. — 
According  to  Haiiy,  the  primitive  form  is  a 
right  rhomboidal  m-ism,  of  104°  48'  and  75* 
12'.  The  reflecting  goniometer  makes  these 
angles  104°  and  76°.  The  varieties  ot"  its 
crystals  may  be  referred  to  four  or  six-sided 
prisms,  terminated  by  two,  four,  or  eight- 
sided  summits.  It  has  a  shining  lustre,  and 
is  either  transparent,  translucent,  or  opaque. 
It  scratches  calcareous  spar,  but  is  scratched 
by  fluor.  It  is  very  brittle.  Jts  sp.  gr.  is  3.6. 
Before  the  blow-pipe  it  fuses  into  a  white, 
opaque,  and  friable  enamel. 

The  three  subspecies  are,  1st  The  com- 
pact found  in  Montmartre  near  Paris,  of  a 
yellowish -gray  colour,  in  rounded  pieces,  ot" 
a  dull  lustre,  opaque,  and  consisting,  by 
Vauqueliri's  analysis,  ,of  91.42  sulphate  o"f 
strontites,  8.33  carbonate  of  lime,  and  0.25 
oxide  of  iron.  2d,  The  fibrous,  whose  co- 
lours are  indigo-blue  and  bluish-gray;  some- 
times white.  It  occurs  both  massive  and 
crystallized.  Shining  and  some what  pearly 
lustre.  It  is  translucent.  Sp.  grav.  8.83. 
3d,  The  foliated,  of  a  milk-white  colour, 
falling  into  blue.  Massive  and  in  grouped 
crystals,  of  a  shining  lustre  and  straight  fo- 
liated kxiure.  Translucent.  Celestine  oc- 
curs most  abundantly  near  Bristol  in  the  red 
marl  formation;  and  crystallized  in  red  sand- 
stone, at  Inverness  in  Scotland. 

Mr.  Gruner  Ober  Berg  of  Hanover  has 
lately  favoured  the  world  with  an  analysis 
of  a  crystallized  celestine,  found  in  the 
neigbourhood  of  that  city,  of  rather  pecu- 
liar composition.  Its  sp.gr.  is  only  3. 59,  and 
yet  it  contains  a  large  proportion  of  sulphate 
of  barytes: 

Sulphate  of  strontites,          73.000 
Sulphate  of  barytes,  26.166 

Ferruginous  clay,  0.213 

Loss,  0.621 

100.000 

Had  the  result  been  75  of  sulphate  of  stron- 
ties  -{-  25  sulphate  of  barytes,  we  should 
have  considered  the  mineral  as  a  compound 
of  4  primes  of  the  first  salt  -}-  1  of  the  se- 
cond. Now  the  analysis,  in  my  opinion,  can- 
not be  confided  in,  within  these  limits;  for 
the  mingled  muriates  of  the  earths  were  se- 
parated by  digestion  in  16  times  th^ir  weight 
of  boiling  alcohol,  of  a  strength  not  named. 
Besides,  the  previous  perfect  conversion  of 
the  sulphates  into  carbonates,  by  merely  fu- 
sing the  mineral  with  thrice  its  weight  of 
carbonate  of  potash,  is,  to  say  the  least, 
problematic?!.  J)r.  Thomson  adapts  M1 
33 


CEM 


CEM 


•her  Bern's  analysis  to  7  atoms  of  sulphate 
of  strontian,  and  2  atoms  of  sulphate  of  ba- 
rytes.* 

CEATEXT.  Whatever  is  employed  to  unite 
or  cement  together  things  of  the  same  or 
different  kinds,  may  be  called  a  cement  In 
this  sense  it  includes  LUTES,  GLUES,  and  SOL 
DEHS  of  every  kind,  which  see;  but  it  is  more 
commonly  employed  to  signify  those  of 
which  the  basis  is  an  earth  or  earthy«alt. 
-See  LIME.  We  shall  here  enumerate, 
chiefly  from  the  Philosophical  Magazine, 
some  cements  that  are  used  for  particular 
purposes. 

Seven  or  eight  parts  of  resin,  and  one  of 
wax,  melted  together,  and  mixed  with  a  small 
quantity  of  plaster  of  Paris,  is  a  very  good 
cement  to  unite  pieces  of  Derbyshire  spar, 
or  other  stone.  The  stone  should  be  made 
hot  enough  to  melt  the  cement,  and  the 
pieces  should  be  pressed  tog-ether  as  close- 
ly as  possible,  so  as  to  leave  as  little  as  may 
be  of  the  cement  between  them.  This  is  a 
general  rule  in  cementing,  as  the  thinner 
the  stratum  of  cement  interposed,  the  firm- 
er it  will  hold. 

Melted  brimstone  used  in  the  same  way 
will  answer  sufficiently  well,  if  the  joining 
be  not  required  to  be  very  strong. 

It  sometimes  happens,  that  jewellers,  in 
setting  precious  stones,  break  off'  pieces  by 
accident;  in  this  case  they  join  them  so  that 
it  cannot  easily  be  seen,  with  gum  mastic, 
the  stone  being  previously  made  hot  enough 
to  melt  it.  By  the  same  medium  cameos  of 
white  enamel  or  coloured  glass  are  often 
joined  to  a  real  stone  as  a  ground,  to  pro- 
duce the  appearance  of  an  onyx.  Mastic  is 
likewise  used  to  cement  false  backs  or  doub- 
lets to  stones,  to  alter  their  hue. 

The  jewellers  in  Turkey,  who  are  gene- 
rally Armenians,  ornament  watch-cases  and 
other  trinkets  with  gems,  by  glueing  them 
on.  The  stone  is  set  in  silver  or  gold,  and 
the  back  of  the  setting  made  flat  to  corres- 
pond with  the  part  to  which  it  is  to  be  ap- 
plied. It  is  then  fixed  on  with  the  follow- 
ing cement.  Isinglass,  soaked  in  v  ater  till 
it  swells  up  and  becomes  soft,  is  dissolved  in 
French  brandy,  or  in  rum,  so  as  to  form  a 
strong  glue.  Two  small  bits  of  gum  gal- 
baiuim,  or  gum  ammoniacum,  are  dissolved 
in  two  ounces  of  this  by  trituration;  and  five 
or  six  bits  of  mastic,  as  big  as  peas,  being 
dissolved  in  as  much  alcohol  as  will  render 
them  fluid,  are  to  be  mixed  with  this  by 
means  of  a  gentle  heat  This  cement  is  to 
be  kept  in  a  phial  closely  stopped;  and  when 
used,  it  is  to  be  liquefied  by  immersing  the 
phial  in  hot  water.  This  cement  resists  mois- 
ture. 

A  solution  of  shell  lac  in  alcohol,  added  to 
a  solution  of  isinglass  in  proof  spirit,  makes 
another  cement  that  will  resist  mo  sture. 

So  does  common  g-lue  melted  without  wa- 
ter, with  half  its  weight  of  resin,  with  the 


addition  of  a  little  red  ochre  to  give  it  a  bu- 
dy.  This  is  particularly  useful  for  cement- 
ing hones  to  their  frames. 

If  clay  and  oxide  of  iron  be  mixed  with 
oil,  according  to  Mr.  Gad  of  Stockholm, 
they  will  form  a  cement  that  will  harden 
under  water. 

A  strong  cement,  insoluble  in  water,  may 
be  made  from  cheese.  The  cheese  should 
be  that  of  skimmed  milk,  cut  into  slices, 
throwing  away  the  rind,  and  boiled  till  it 
becomes  a  strong  glue,  which  however  does 
not  dissolve  in  the  water.  This  water  being 
poured  ofT,  it  is  to  be  washed  in  cold  water, 
and  then  kneaded  in  warm  water.  This  pro- 
cess is  to  be  repeated  several  times.  The 
glue  is  then  to  be  put  warm  on  a  levigating 
stone,  and  kneaded  with  quicklime.  This 
cement  may  be  used  co)d,  but  it  is  better  to 
warm  it;  and  it  will  join  marble,  stone,  or 
earthen-ware,  so  that  the  joining  is  scarcely 
to  be  discovered. 

Boiled  linseed  oil,  litharge,  red  lead,  and 
white  lead,  mixed  together  to  a  proper  con- 
sistence, and  applied  on  each  side  of  a  piece 
of  flannel,  or  even  linen  or  paper,  and  put 
between  two  pieces  of  metal  before  they  are 
brought  home,  or  close  together,  will  make 
a  close  and  durable  joint,  that  will  resist 
boiling  water,  or  even  a  considerable  pivs- 
sure  of  steam.  The  proportions  of  the  in- 
gredients are  not  material,  but  the  more 
the  red  lead  predominates,  the  sooner  the 
cement  will  diy,  and  the  more  the  white 
lead  the  contrary.  This  cement  answers  well 
for  joining  stones  of  any  dimensions. 

The  following  is  an  excellent  cement  for 
iron,  as  in  time  it  unites  with  it  into  one 
mass.  Take  two  ounces  of  muriate  of  am- 
monia, one  of  flowers  of  sulphur,  and  16  of 
cast-iron  filings  or  borings  Mix  them  well 
in  a  mortar,  and  keep  the  powder  dry. 
When  the  cement  is  wanted  for  use,  take 
one  part  of  this  mixture,  twenty  parts  of 
clear  iron  borings  or  filing's,  grind  them  to- 
gether in  a  mortar,  mix  them  with  water  to 
a  proper  consistence,  and  apply  them  be- 
tween the  joints. 

Powdered  quicklime  mixed  with  bullock's 
blood  is  often  used  by  coppersmiths  to  lay 
over  the  rivets  and  edges  of  the  sheets  of 
copper  in  large  boilers,  as  a  security  to  the 
junctures,  and  also  to  prevent  cocks  from 
leaking. 

Six  parts  of  clay,  one  of  iron  filings,  and 
linseed  oil  sufficient  to  form  a  thick  paste, 
make  a  good  cement  for  stopping  cracks  ia 
iron  boilers. 

Temporary  cements  are  wanted  in  cutting, 
grinding,  or  polishing  optical  glasses,  stones, 
and  various  small  articles  of  jewvllery,  which 
it  is  necessary  to  fix  on  blocks,  or  handles, 
for  the  purpose.  Four  ounces  of  resin,  a 
quarter  of  on  ounce  of  wax,  and  four  ounces 
of  whiting  made  previously  red-hot,  form  a 
good  cemment  of  this  kind;  as  any  of  the 


CEM 


CER 


above  articles  may  be  fastened  to  it  by  heat- 
ing them,  and  removed  at  pleasure  in  the 
same  manner,  though  they  adhere  very  firm- 
ly to  it  when  cold.  Pitch,  resin,  and  a  small 
quantity  of  tallow,  thickened  with  brick- 
dust,  is  much  used  at  Birmingham  for  these 
purposes.  Four  parts  of  resin,  one  <?f  bees 
wax,  and  one  of  brick  dust,  likewise  make  a 
good  cement.  This  answers  extremely  well 
for  fixing  knives  and  forks  in  the  ir  halts; 
but  the  manufacturers  of  cheap  articles  of 
this  kind  too  commonly  use  resin  and  brick- 
dust  alone,  On  some  occasions,  in  which  a 
very  tough  cement  is  requisite,  that  will  not 
crack  though  exposed  to  repeated  blows; 
as  in  fastening  to  a  block  metallic  articles 
that  are  to  be  cut  with  a  hammer  and  punch, 
workmen  usually  mix  some  tow  with  the 
cement,  the  fibres  of  which  hold  its  parts 
together. 

*Mr.  Singer  recommends  the  following1 
•omposition  as  a  good  cement  for  electrical 
apparatus:  Five  pounds  of  resin,  one  of  bees 
wax,  one  of  red  ochre,  and  two  table  spoon- 
fuls of  plaster  of  Paris,  all  melted  together. 
A  cheaper  one  for  cementing  voltaic  plates 
into  wooden  troughs  is  made  with  six 
pounds  of  resin,  one  pound  of  red  ochre, 
half  a  pound  of  plaster  of  Paris,  and  a  quar- 
ter of  a  pint  of  linseed  oil.  The  ochre  and 
plaster  of  Paris  should  be  well  dried,  and 
added  to  the  other  ingredients,  in  a  melted 
state.*f 

*  CEMENT,  for  buildings.  See  MOHTAH  CE- 
MENTS.* 

•j-  The  meal  of  oil  cake,  or  the  residuum  of 
flaxseed,  after  the  expression  of  the  oil,  is  a 
good  lute;  and  when  mixed  with  clay  will 
enable  it  to  bear  very  high  temperatures 
without  cracking.  It  acts,  no  doubt,  in  that 
case,  by  creating  pores  in  consequence  of  its 
carbonization. 

Calcined  gypsum,  or  sulphate  of  lime,  when 
powdered  and  made  into  a  paste  with  water, 
sets  in  a  few  minutes.  It  is  more  cleanly  for 
electrical  apparatus,  and  more  easily  applied 
than  the  cements  above  recommended. 

Shell  lac,  in  sticks,  has  been  imposed  up- 
on the  public,  in  Philadelphia,  as  a  new  ce- 
ment of  a  peculiarly  costly  kind;  and  as  much 
has  been  demanded  for  a  stick,  weighing  a 
few  penny  weights,  as  would  buy  a  pound. 

Applied  to  potters*  ware,  or  glass  heated 
above  the  temperature  of  boiling  water,  it  is 
an  excellent  cement. 

The  application  is  much  facilitated,  by  dis- 
solving the  lac  in  its  weight  of  very  strong 
boiling  alcohol,  so  as  to  make  a  thick  paste. 
This  being  smeared  over  the  edges  of  the 
fractured  pieces,  they  must  be  bound  to- 
gether and  subjected  to  the  rays  of  a  fire, 
till  water  will  boil  when  dropped  on  them. 
When  a  crack  is  to  be  mended,  more  spirit 
must  be  used,  so  that  the  solution  may  be 
thin  enough  to  run  in. 


CEMENTATION.  A  chemical  process,  which 
consists  in  surrounding  a  body  in  the  solid 
slate  with  the  powder  of  some  other  bodies, 
and  exposing  the  whole  for  a  time  in  a  clos- 
ed vessel,  to  a  degree  of  heat  not  sufficient 
to  fuse  the  contents.  Thus  iron  is  con- 
verted into  steel  by  cementation  with  char- 
coal; green  bottle  glass  is  converted  into 
porcelain  by  cementation  with  sand  &C, 
See  IRON  and  PORCELAIN. 

*CE.«ASIN.  The  name  given  by  Dr.  John 
of  Berlin  to  those  gummy  substances  which 
swell  in  cold  water,  but  do  not  readily  dis- 
solve in  it.  Cerasin  is  soluble  in  boiling  water, 
but  separates  in  a  jelly  when  the  water  cools. 
Water  acidulated  with  sulphuric,  nitric,  or 
muriatic  acid,  by  the  aid  of  a  gentle  heat, 
forms  a  permanent  solution  of  cerasin.  Gum 
tragacanth  is  the  best  example  of  this  spe- 
cies of  vegetable  product.* 

*CERATE.  The  compound  of  oil  or  lard 
with  bees  wax,  used  by  surgeons  to  screen 
ulcerated  surfaces  from  the  air.* 

*CKRIN.  \  peculiar  substance  which  pre- 
cipitates, on  evaporation,  from  alcohol,  which 
has  been  digested  on  grated  cork,  Suber- 
cerin  would  have  been  a  fitter  name.  Chev- 
reul,  the  discoverer,  describes  this  substance 
as  consisting  of  small  white  needles,  which 
sink  and  merely  soften  in  boiling  water. 
1000  parts  of  boiling  alcohol  dissolve  2.42  of 
cerin,  and  only  2  of  wax.  Nitric  acid  con- 
verts it  into  oxalic  acid  It  is  insoluble  in  an 
alcoholic  solution  of  potash.* 

*CERIN.  The  name  given  by  Dr.  John 
to  the  part  of  common  wax  which  dissolves 
in  alcohol.* 

*CERIN.  A  variety  of  the  mineral  allanr 
tie,  lately  examined  by  Berzelius.  It  con- 
sists of  oxide  of  cerium  28.19,  oxide  of  iron 
2^.72,  oxide  of  copper  0.87,  silica  30.17, 
alumina  11.31,  lime  9.12,  volatile  water  0.40*. 

*CEHITE  The  siliciferous  oxide  of  ce- 
rium. This  rare  mineral  is  of  a  rose -red  or 
flesh-red  colour,  occasionally  tinged  with 
clove-brown.  Its  powder  is  reddish-gray. 
It  is  found  massive  and  disseminated.  In- 
ternal lustre  resinous,  but  scarcely  glim- 
mei-ing.  Its  fracture  is  fine  splintery,  with  in- 
determinate fragments.  It  is  opaque,  scratch- 
es glass,  gives  sparks  with  steel,  is  difficult 
to  break,  scarcely  yields  to  the  knife,  and 
gives  a  grayish-white  streak.  It  is  infusible 
before  the  blow-pipe;  but  heat  changes  the 
gray  colour  of  the  powder  to  yellow.  It  con- 
sists, by  Hisinger's  analysis,  of  18  silica, 
68.59  oxide  of  cerium,  2  oxide  of  iron,  1.25 
lime,  9.6  water  and  carbonic  acid,  and  0.56 
loss,  in  100  parts.  Klaproth  found  54.5  oxide 
of  cerium,  and  34.5  silica,  in  the  hundred 
parts.  It  is  found  only  in  the  copper  mine 
of  Bastuaes  near  Riddarhytta  in  Sweden, 
accompanied  by  the  ores- of  copper,  molyb- 
dena,  and  bismuth.  Its  sp.  BT.  is  from  4,6 
to  4.9.* 


CER 


CHA 


*e'EiftB3r.  The  metal  whose  oxide  exists 
in  the  preceding  mineral.* 

To  obtain  the  oxide  of  the  new  metal,  the 
cerite  is  calcined,  pulverized,  and  dissolved 
in  nitromuriatic  acid.  The  filtered  solution 
being  neutralized  with  pure  potash,  is  to  be 
precipitated  by  tartrate  of  potash,  and  the 
precipitate,  well  washed,  and  afterward  cal- 
cined, is  oxide  of  cerium. 

*The  attempts  to  obtain  the  pure  m*tal, 
by  igniting  the  oxide  purified  from  iron  by 
oxalic  acid,  in  contact  with  tartaric  acid,  oil, 
and  lampblack,  have  in  a  great  measure 
failed.  A  white  brittle  carburet  was  only 
obtained.* 

Cerium  is  susceptible  of  two  stages  of 
oxidation;  in  the  first  it  is  white,  and  this  by 
calcination  becomes  of  a  fallow-red. 

The  white  oxide  exposed  to  the  blow- 
pipe soon  becomes  red,  but  does  not  melt, 
or  even  agglutinate.  With  a  large  proportion 
of  borax  it  fuses  into  a  transparent  globule. 

The  white  oxide  becomes  yellowish  in  the 
open  air,  but  never  so  red  as  by  calcination, 
because  it  absorbs  carbonic  acid,  which  pre- 
vents its  saturating  itself  with  oxygen,  and 
retains  a  portion  of  water,  which  diminishes 
its  colour. 

Alkalis  do  not  act  on  it;  but  caustic  potash 
in  the  dry  way  takes  part  of  the  oxygen 
from  the  red  oxide,  so  as  to  convert  it  into 
the  white  without  altering  its  nature. 

*The  protoxide  of  cerium  is  composed 
by  Hisinger  of  85.17  metal  -{-  14.83  oxygen, 
and  the  peroxide  of  79.3  metal  -f-  -0.7.  The 
protoxide  has  been  supposed  a  binary  com- 
pound of  cerium  5.75-f-  oxygen  l,und  the  per- 
oxide a  compound  of  5.75  X  2  of  cerium 
•4-  3  oxygen.  An  alloy  of  this  metal  with 
iron  was  obtained  by  Vauquelm. 

The  salts  of  cerium  are  white  or  yellow 
coloured,  have  a  sweet  taste,  yield  a  white 
precipitate  with  hydrosulphuret  of  potash, 
but  none  with  sulphuretted  hydrogen;  a 
milk-white  precipitate,  soluble  in  nitric  and 
muriatic  acids,  with  ferroprussiate  of  potash 
and  oxalate  of  ammonia,  none  with  infusion 
of  galls,  and  a  white  one  with  arseniate  of 
potash.* 

Equal  parts  of  the  sulphuric  acid  and  red 
oxide,  with  four  parts  of  water,  unite  by  the 
assistance  of  heat  into  a  crystalline  mass, 
which  may  be  completely  dissolved  by  add- 
ing more  acid,  and  heating  them  together 
a  long  time  This  solution  yields,  by  gen- 
tle evaporation,  small  crystals,  some  of  an 
orange,  others  of  a  lemon  colour.  The  sul- 
phate of  cerium  is  soluble  in  water  only  with 
an  excess  of  acid.  Its  taste  is  acid  and  saccha- 
rine. The  sulphuric  acid  combines  readily 
with  the  white  oxide,  particularly  in  the 
state  of  carbonate.  The  solution  has  a  saccha- 
rine taste,  and  readily  affords  white  crystals. 

Nitric  acid  does  not  readily  dissolve  the 
red  oxide  without  heat.  With  an  excess  of 
acid,  white  deliquescent  crystals  are  formed, 


which  are  decomposable  by  heat.  Their 
tastir  is  at  first  pungent,  afterward  very  su- 
gavy.  The  white  oxide  unites  more  readily 
with  the  acid. 

Muriatic  acid  dissolves  the  red  oxide  with 
effervescence.  The  solution  crystallizes  con- 
fusedly. The  salt  is  deliquescent,  soluble 
in  an  equal  weight  of  cold  water,  and  in 
three  or  four  times  its  weight  of  alcohol. 
The  flame  of  this  solution,  if  concentrated, 
is  yellow  and  sparkling;  if  not,  colourless; 
but  on  agitation  it  emits  white,  red,  and  pur- 
ple sparks. 

Carbonic  acid  readily  unites  with  the  ox- 
ide. This  is  best  done  by  adding  carbo- 
nate of  potash  to  the  nitric  and  muriatic 
solution  of  the  white  oxide,  when  a  light 
precipitate  will  be  thrown  down,  which  on 
drying  assumes  a  shining  silvery  appear- 
ance, and  consists  of  23  acid  -f-  65  oxide  -f 
12  water. 

The  white  oxide  unites  directly  with  tar- 
taric acid,  but  requires  an  excess  to  render 
it  soluble. 


of  the  ear.  It  is  a  yellow  co- 
loured secretion,  which  lines  the  external 
auditory  canal,  rendered  viscid  and  concrete 
by  exposure  to  air.  It  has  a  bitter  taste, 
melts  at  a  low  heat,  and  evolves  a  slightly 
aromatic  odour.  On  ignited  coals,  it  gives 
put  a  white  smoke,  similar  to  that  of  burn- 
ing fat,  swells,  emits  a  fetid  ammoniacal 
odour,  ana  is  converted  into  a  light  coal. 

Alcohol  dissolves  7  of  it,  and  on  evapora- 
tion leaves  a  substance  resembling  the  resin 
of  bile.  The  8  which  remained  are  albumen 
mixed  with  oil,  which  by  incineration  leave 
soda  and  phosphate  of  lime.  Hence,  the 
whole  constituents  are  five;  albumen,  an  in- 
spissated oil,  a  colouring  matter,  soda,  and 
calcareous  phosphate.* 

CERUSE,  or  WHITE  LEAD.     See  LEAD. 

*CKTINB.  The  name  given  by  Chevreul 
to  spermaceti.  According  to  Berard,  who 
analyzed  it  on  M.  Gay-Lussac's  plan,  by  pass- 
ing its  vapour  through  ignited  peroxide  of 
copper,  cetme  consists  of  81  carbon,  6  oxy- 
gen, aud  13  hydrogen,  in  100  parts* 

*  CEYLANITE.    This  mineral,  the  pleonaste 
of  Haiiy,  comes  from  Ceylon,  commonly  in 
rounded  pieces,  but  occasionally  in  crystals. 
The  primitive  form  of  its  crystals  is  a  regu- 
lar octahedron,  in  which  form,  or  with  the 
edges  truncated,  it  frequently  occurs.     Its 
colour   is   indigo-blue,    passing  into  black, 
which  on  minute  inspection  appears  green- 
ish. It  has  a  rough  surface,  with  little  exter- 
nal lustre,   but   splendent   internally.    The 
fracture  is  perfect  fiat  conchoidal,  with  very 
sharp-edged  fragments.  It  scarcely  scratches 
quart  z,  and  is  softer  than  spinell.  It  is  easily 
broken,  has  a  sp.  gr.  of  3.  77,  and  is  infusi- 
ble by  the  blow-pipe.* 

*  CHABASITJE.  This  mineral  occurs  in  crys- 


CHA 


CHA 


tab  whose  primitive  form  is  nearly  a  cube,    considered  them  as  relics  of  alchemistical 

ni,i°      obscurity,  and  have  almost  totally  rejected 
since  the  angle  at  the  summit  is  only  9j?  •    their  use     Very  little  of  system  appears  in 

It  is  found  in  that  form,  and  also  with  6  of  the  ancient  characters  of  chemists:  the  char- 
its  edges  truncated,  and  the  truncatures  acters  of  Bergmann  are  chiefly  grounded  on 
united  3  and  3  at  the  two  opposite  angles,  the  ancient  characters,  with  additions  and 
while  the  other  six  angles  are  truncated,  improvements.  But  the  characters  of  Has- 
It  occurs  also  in  double  six-sided  pyramids,  senfratz  and  Adet  are  systematical  through- 
applied  base  to  base,  having  the  six  angles  out.  The  former  are  exhibited  in  Plate  III. 
at  the  base,  and  the  three  acute  edges  of  and  the  latter  in  Plate  IV. 
each  pyramid  truncated.  It  is  white,  or  CHAHCOAL.  When  vegetable  substances 
with  a  tinge  of  rose  colour,  and  sometimes  are  exposed  to  a  strong  heat  in  the  appara- 
transparent  It  scratches  glass,  fuses  by  the  tus  for  distillation,  the  fixed  residue  is  called 
blow-pipe  into  a  white  spongy  mass,  and  has  charcoal.  For  general  purposes,  wood  is  con- 
a  sp.  gr.  of  2.  72.  Its  constituents  are  43.33  verted  into  charcoal  by  building  it  up  in  a 
silica,  22.66  alumina,  3.34  lime,  9.34  soda  pyramidal  form,  covering  the  pile  with  clay 
and  potash,  water  21.  It  is  found  in  scatter-  Or  earth,  and  leaving  a  few  air-holes,  which 
ed  crystals  in  the  fissures  of  some  trap  rocks,  are  closed  as  soon  as  the  mass  is  well  light- 
and  in  the  hollows  of  certain  geocles,  dissemi-  ed;  and  by  this  means  the  combustion  is  car- 
Dated  in  the  same  rocks.  It  occurs  in  the  ried  on  in  an  imperfect  manner.  In  the  fo- 
quarry  of  Alteberg  near  Oberstein.*  rest  of  Benon,  near  Rochelle,  great  attention 
CHALK.  A  very  common  species  of  cal-  js  paid  to  the  manufacture,  so  that  the  char- 
oareous  earth,  of  an  opaque  white  colour,  coal  made  there  fetches  25  or  30  per  cent 
very  soft,  and  without  the  least  appearance  moi-e  than  any  other.  The  wood  is  that  of 
of  a  polish  in  its  fracture.  Its  specific  gravity  the  black  oak.  It  is  taken  from  ten  to  fif- 
is  from  2.4  to  2.6,  according  to  Kirwan.  It 
contains  a  little  siliceous  earth,  and  about 


teen  years  old,  the  trunk  as  well  as  the 
branches  cut  into  billets  about  four  feet  long, 
two  per  cent  of  clay.    Some  specimens,  and    and  not  split.    The  largest  pieces,  however, 


perhaps  most,  contain  a  little  iron,  and  Berg-  seldom  exceed  six  or  seven  inches  in  dia- 
mann  affirms  that  muriate  of  lime,  or  magne-  meter.  The  end  that  rests  on  the  ground 
sia,  is  often  found  in  it;  for  which  reason  he  is  cut  a  little  sloping,  so  as  to  touch  it  mere- 
directs  the  powder  of  chalk  to  be  several  ly  with  an  edge,  and  they  are  piled  nearly 
times  boiled  in  distilled  water,  before  it  is  upright,  but  never  in  more  than  one  story, 
dissolved  for  the  purpose  of  obtaining  pure  The  wood  is  covered  all  over  about  four  in- 
calcareous  earth.  ches  thick  with  dry  grass  or  fern,  before  it 
*  CHALK  (BLACK).  Drawing  slate.  The  is  enclosed  in  the  usual  manner  with  clay; 
colour  of  this  mineral  is  grayish  or  bluish-  and  when  the  wood  is  charred,  half  a  barrel 
black.  Massive.  The  principal  fracture  is  of  water  is  thrown  over  the  pile,  and  earth 
glimmering  and  slaty,  the  cross  fracture  dull,  to  the  thickness  of  five  or  six  inches  is 
and  fine  earthy.  It  is  in  opaque,  tabular  thrown  on,  after  which  it  is  left  four-and- 
fragments,  stains  paper  black,  streak  glisten-  twenty  hours  to  cool.  The  wood  is  always 
ing,  and  the  same  colour  as  the  surface;  used  in  the  year  in  which  it  is  cut, 
easily  cut  and  broken;  sp.  gr.  2.4;  becomes  In  charring  wood  it  has  been  conjectured, 
red  in  the  fire,  and  falls  to  pieces  in  water,  that  a  portion  of  it  is  sometimes  converted 
It  occurs  in  primitive  mountains,  often  ac-  into  a  pyrophorus,  and  that  the  explosions 
oompanied  by  alum  slate.  It  is  used  in  cray-  that  happen  in  powder-mills  are  sometimes 

f\n  f\t*f*\\r\r\fr    wVi*»«/*.f*  its  nftmf*.^  O  Will  IT  t.O  tills* 

•  Charcoal  is  made  on  the  great  scale,  by 
igniting  wood  in  iron  cylinders,  as  I  have 
described  under  ACETIC  ACID.     When  the 
resulting  charcoal  is  to  be  used  in  the  ma- 
nufacture of  gunpowder,  it  is  essential  that, 
the  last  portion  of  vinegar  and  tar  be  suffer- 
CHALK  (RKD).    This  is  a  clay  coloured  by    ed  to  escape,  and  that  the  reabsorption  of 
the  oxide  of  iron,  of  which  it  contains  from    the  crude  vapours  be  prevented,  by  cutting 
16  to  18  parts  in  the  hundred,  according  to    off  the  communication  between  the  interior 
Rinman.  of  the  cylinders  and  the  apparatus  for  con- 

CHALK  (SPANISH).  The  soap  rock  is  fre-  densing  the  pyrolignous acid,  whenever  the 
quently  distinguished  by  this  name.  fire  is  withdrawn  from  the  furnace.  If  this 

CHARACTERS  (CHEMICAL).  The  chemical  precaution  be  not  observed,  the  gunpowder 
characters  were  invented  by  the  earlier  cue-  made  with  the  charcoal  would  be  of  inferior 
mists,  probably  with  no  other  view  than  to  quality. 

save  time  in  writing  the  names  of  substances  In  the  third  volume  of  Tilloch's  Magazine, 
that  frequently  occurred,  in  the  same  man-  we  have  some  valuable  facts  on  charcoal,  by 
ner  as  we  avoid  repetitions  by  the  use  of  Mr.  Mushet.  He  justly  observes,  that  the 
pronouns.  But  the  moderns  seem  to  have  produce  «f  charcoal  in  the  small  way,  differs' 


on  drawing,  whence  its  name. 

*CnALK  STONES.  Gouty  concretions  whose 
true  nature  was  first  discovered  by  Dr.  VVol- 
laston,  and  described  by  him  in  his  admira- 
ble dissertation  on  urinary  calculi,  published 
in  the  Phil.  Trans,  for  1797.  See  GOUTT 
CONCRETIONS.* 


CHA 


CHE 


from  that  em  the  large  scale,  in  which  the  absolute  quantity  of  carbon  it  contains.  The 

quantity  of  char  depends    more   upon  the  following  is  his  table  of  results,  reduced  to 

hardness,  and  compactness  of  the  texture  of  100  parts,  from  experiments  on  one  pound 

wood,  and  the  skill  of  the  workman  in  ma-  avoirdupois  of  wood, 
the  pyramid  of  faggots,  than  on  the 


Oak, 
As!i, 
Birch, 
Norway  Pine, 

Mahogany, 
Sycamore, 

Holly, 

Scotch  Pine, 

Beech, 

Elm, 

Walnut, 

American  Maple, 


Matte  re 
76.895 
81260 
80.717 
80.441 

73.528 
79.20 

78.92 

83.095 
79.104 
79.655 
78.5*1 
79.331 


Parts  in  100. 


Charcoal.    Ashes. 


22.682 
17.972 
17491 
19.204 

25.492 
19.734 


0.423 
0.768 
1792 
0.355 

0.980 

1.066 


Charcoal  by 
Proust      ft  urn  ford, 
20.  43.00 

17. 


19.918        1.162 


Do.      Black  Beech,      77.512 
Laburnum,  74.234 


Lignum  Vit«, 
Sallow, 

Chesnut, 


72643 
8^.371 


16.456 
19.941 
19.574 
20663 
19.901 

21.445 
245S6 

26.857 
18.497 


0.449 
0.955 
0.761 
0.816 
0.768 

1.033 
1.180 

0.500 
1.132 


20. 
Black  Ash. 

25. 

'  Willow. 

17. 

Heart  of  Oak. 
19. 


44-.  18 


Guaiacum. 


4327 
42.28 


76.304        23.280        0.416 


Poplar. 
43.57 

Lime. 
43.59 


MM.  Clement  and  Desormes  say,  that  wood 
affords  one-half  its  weight  of  charcoal.  I  con- 
sider  the  statements  of  Mr.  Mushet  and  M. 
Proust,  much  more  correct.  They  come -de 
with  the  experiments  to  which  I  have  refer- 
red in  treating  of  the  extraction  of  vinegar 
from  wood.  (See  ACETIC  ACID.)  M.  Proust 
says,  that  good  pit-coals  afford  70,  75,  or  80 
per  cent  of  charcoal  or  coak;  from  which 
only  two  or  three  parts  in  the  humir  d  of 
ashes  remain  after  combustion.  'J'illuch's 
Mag.  vol.  viii.* 

Charcoal  is  black,  sonorous,  and  brittle, 
and  in  general  retains  the  figure  of  the  ve- 
getable it  was  obtained  from.  If,  however, 
the  vegetable  consist  for  the  most  part  of 
water  or  other  fluids,  these  in  their  extrica- 
tion will  destroy  the  connexion  of  the  more 
fixed  parts.  In  this  case  the  quantity  of 
charcoal  is  much  less  than  in  the  former. 
The  charcoal  of  oily  or  bituminous  sub- 
•tances  is  of  a  light  pulverulent  form,  and 
rises  in  soot.  This  charcoal  of  oils  is  called 
lampblack.  A  very  fine  kind  is  obtained 
from  burning  alcohol. 

Turf  or  peat  has  been  charred  lately  in 
France,  it  is  said  by  a  peculiar  process,  and, 
according  to  the  account  given  in  Sonnini's 
Journal,  is  superior  to  wood  for  this  purpose. 
Charcoal  of  turf  kindles  slower  than  that  of 
wood,  but  emits  more  flame,  and  burns  long- 
er. In  a  goldsmith's  furnace  it  fused  eleven 


ounces  of  gold  in  eight  minutes,  while  wood 
charcoal  required  sixteen.  The  malleability 
of  the  gold,  too,  was  preserved  in  the  farm- 
er instance,  but  not  in  the  latter.  Iron  heat- 
ed red-hot  by  it  in  a  forge,  was  rendered 
more  malleable. 

Prom  the  scarcity  of  wood  in  this  country, 
pit-coal  charred,  is  much  used  instead  of  char- 
coal by  the  name  of  Coak.  See  CAHBOX. 

CHAT,  or  <  HAVA-ROOT,  This  is  the  root 
of  the  Oldenlandia  uinbellata,  which  grows 
wild  on  the  coast  of  Coromandel,  and  is 
likewise  cultivated  there  for  the  use  of  the 
dyers  and  calico  printers.  It  is  used  for  the 
same  purposes  as  madder  with  us,  to  which 
it  is  said  to  be  far  superior,  giving  the  beau- 
tiful  red  so  much  admired  in  the  Madras  cot- 
tons. 

CHEESE.  Milk  consists  of  butter,  cheese, 
a  saccharine  matter  called  sugar  of  milk,  and 
a  small  quantity  of  common  salt,  together 
with  much  water. 

If  any  vegetable  or  mineral  acid  be  mix- 
ed with  milk,  the  cheese  separates,  and,  if 
assisted  by  heat,  coagulates  into  a  mass. 
The  quantity  of  cheese  is  less  when  a  mine- 
ral acid  is  used.  Neutral  salts,  and  likewise 
all  earthy  and  metallic  salts,  separate  the 
ch  e  from  the  whey.  Sugar  and  gumara- 
bic  produce  the  same  effect.  Caustic  alka- 
lis will  dissolve  the  curd  by  the  assistance 
of  a  boiling  heat,  and  acids  occasion  a  pre- 


CHE 


CHL 


*pitation  a^a'n.  Vegetable  acids  have  ve- 
ry little  solvent  power  upon  ^nrd.  Tlvs  ac- 
counts tor  a  greater  quantity  of  cur;l  he- 
ing-  obtained  when  a  vegetable  acid  is  used. 
But  what  answers  best  is  rennet,  v.lvch  is 
made  by  macerating  in  water  a  piece  of  the 
last  stomach  of  a  calf,  salted  and  dried  for 
this  purpose. 

Scheele  observed,  that  cheese  has  a  consi- 
derable analogy  to  albumen,  which  it  resem- 
bles in  being  coagiilable  by  fire  and  acids, 
soluble  in  ammonia,  and  affording  the  same 
products  by  distillation  or  treatment  with 
nitric  acid.  There  are,  however,  certain  dif- 
ferences between  them.  Rouelle  observed 
likewise,  a  striking  analogy  betw-en  cheese 
and  the  gluten  of  wheat,  and  that  fouivi  in 
the  fcculae  of  green  vegetables.  By  knead- 
ing the  gluten  of  wheat  with  a  little  salt  and 
a  small  portion  of  a  solution  of  starch,  he 
gave  it  the  taste,  smell,  and  unctuosity  of 
cheese,  so  that  after  it  had  been  kept  a  cer- 
tain time,  it  was  not  to  be  distinguished  from 
the  celebrated  Koch efort  cheese,  of  which  it 
had  all  the  pungency.  This  caseous  substance 
from  gluten,  as  well  as  the  cheese  of  milk, 
appears  to  contain  acetate  of  ammonia,  after 
it  has  been  kept  long-  enough  to  have  under- 
gone the  requisite  fermentation,  as  may  be 
proved  by  examining  it  with  sulphuric  acid, 
and  with  potash.  The  pungency  of  strong 
el-ieese,  too,  is  destroyed  by  alcohol. 

*  In  the  llth  volume  of  Tilloch's  Magazine 
there  is  an  excellent  account  of  the  mode  of 
making  Cheshire  cheese,  taken  from  the 
Agricultural  Report  of  the  county.     "  If  the 
milk,"  says  the  reporter,   "  be  set  together 
very  warm,  the  curd,  as  before  observed,  will 
be  firm;  in  this  case,  the  usual  mode  is  to 
take  a  common  case-knife,  and  make  inci- 
sions across  it,  to  the  full  depth  of  the  knife's 
blade,  at  the  distance  of  about  one  inch;  and 
again  cross  ways  in  the  same  manner,  the  in- 
cisions intersecting  each  other  at  right  an- 
gles.   The  whey  rising  through  these  inci- 
sions is  of  a  fine  pale-green  colour.    The 
cheese-maker  and  two  assistants  then  pro- 
ceed to  break  the  curd;  this  is  performed 
by  their  repeatedly  putting  their  hands  down 
into  the  tub;  the  cheese-maker,  with  the 
skimming  dish  in  one  hand,  breaking  every 
part  of  it  as  they  catch  it,  raising  the  curd 
from  the  bottom,  and  still  breaking  it.  This 
part  of  the  business  is  continued  till  the  whole 
is  broken  uniformly  small;  it  generally  takes 
up  about  40  minutes,  and  the  curd  is  then 
left  covered  over  with  a  cloth  for  about  half 
an  hour  to  subside.     If  the  milk  has  been 
set  cool  together,  the  curd,  as  before  men- 
tioned, will  be  much  more  tender,  the  whey 
will  not  be  so  green,  but  rather  of  a  milky 
appearance."  The  above  account  of  cheese- 
making  is  evidently  at  variance  with  that 
given  by  Dr.  Thomson  in  the  4th  volume  of 
his  system.* 

*  QHKMLSTRY  may  be  defined,  the  science 


which  investigates  the  composition  of  mate- 
rial substances,  and  the  permanent  changes 
of  constitution  which  their  mutual  actions 
produce* 

*  CHKNOPODIUTVT  OT.IDUM.  A  plant  remark- 
able, according  to  MM.  Chevalier  and  Las- 
seigne,  for  containing  uncombined  ammonia, 
which  is  probably  the  vehicle  of  the  remark- 
ably nauseous  odour  which  it  exhales,  strong. 
ly  resembling  that  of  putrid  fish.  When  the 
plant  is  bruised  with  water,  and  the  liquor 
expressed  and  afterwards  distilled,  we  pro- 
cure a  fluid  which  contains  the  subcarbonate 
of  ammonia,  and  an  oily  matter,  which  gives 
the  fluid  a  milky  appearance.     If  the  ex- 
pressed juice  of  the  chenopodium  be  evapo- 
rated to  the  consistence  of  an  extract,  it  is 
found  to  be  alkaline;  there  seems  to  be  ace- 
tic acid  in  it.  Its  basis  is  said  to  be  of  an  al- 
buminous nature.  It  is  stated  also  to  contain 
a  small  quantity  of  the  substance  which  the 
French  call  osmazome,  a  little  of  an  aroma- 
tic resin,  and  a  bitter  matter,  soluble  both  in 
alcohol  and  water,  as  well  as  several  saline 
bodies.     The  following  is  stated  as  the  re- 
sult of  their  analysis,  which,  however,  seems 
somewhat  complex:  1.  Subcarbonate  ofam- 
menia,  2.  Albumen,  3.  Osmazone,  4.  An  aro- 
matic resin,  5.  A  bitter  matter,  6.  Nitrate 
of  potash  in  large  quantity,  7.  Acetate  and 
phosphate  of  potasn,    8.  Tartrate   of  pot- 
ash.    It  is  said  that  100  parts  of  the  dried 
plant  produce  18  of  ashes,  of  which  5£  are; 
potash.* 

*  CHERT.     See  HORXSTONE.* 

*  CHIASTOLITE.     A  mineral  crystallized  in 
four-sided,  nearly  rectangular  prisms.    On 
looking  into  the  end  of  the  prism,  we  per- 
ceive in  the  axis  of  it  a  blackish  prism,  sur- 
rounded by  the  other,  which  is  of  a  grayish, 
yellowish,  or  reddish-white  colour.     From 
each  angle  of  the  interior  prisms,  a  blackish 
line  extends  to  the  corresponding  angle  of 
the  exterior.    In  each  of  these  outer  angles 
there  is  usually  a  small  rhomboidal  space, 
filled  with  the  same  dark  substance  which 
composes  the  central  prism.      The  black 
matter  is  the  same  clay-slate  with  the  rock 
in  which  the  chiastolite  is  imbedded.    Frac- 
ture, foliated  with  double  cleavage.     Trans- 
lucent.    Scratches  glass.     Rubbed  on  seal- 
ing-wax, it  imparts  negative  electricity.    Its 
sp.  gr.  is  2.94.     Before  the  blow-pipe  it  is 
convertible  into  a  whitish  enamel.   The  on- 
ly mineral  with  which  chiastolite  or  macle 
can  be  confounded,  were  it  not  crystallized, 
is  steatite;  but  the  latter  communicates  posi- 
tive electricity  to  sealing-wax.   It  has  been 
found  in  Britanny,  in  the  Pyrenees,  in  the 
valley  of  Barege,  and  in  Galicia  in  Spain, 
near  St.  James  of  Compostella.     The  inte- 
rior black  crystal  is  properly  an  elongated 
four-sided  p>ramid.* 

*  CHLORATES.    Compounds  of  chloric  acid 
with   the  ealifiable   bases.     See   CHLORIC 
ACID.* 


CHL 


CHL 


-"*  €HLOHIC  ACID.     See  ACID  (CHLORIC).* 

*  CHLOTHDKS.  Compounds  of  chlorine  with 
combustible  bodies,     bee  CHLORINE  and  the 
respective  substances.* 

*  CHLORINE.     The   introduction   of  this 
term,  marks  an  era  in  chemical  science.     It 
originated  from  the  masterly  researches  of 
Sir  H.  Davy  on  the  oxymuriatic  acid  gas  of 
the  French  school,  a  substance  which,  j^i'ter 
resisting  the  most   powerful  means  of  de- 
composition which  his  sagacity  could  invent, 
or  his  ingenuity  apply,  he  declared  to  be, 
according  to  the  true  logic  of  chemistry,  an 
elementary  body,  and  not  a  compound  of 
muriatic  acid  and  oxygen,  as  was  previous- 
ly imagined,   and    as  its  name  seemed  to 
denote.     He  accordingly  assigned  to  it  the 
term  chlorine,  descriptive  of  its  colour;  a 
name  now  generally  used.     The  chloridic 
theory  of  combustion,  though  more  limited 
in  its  applications  to  the  chemical  phenome- 
na of  nature,  than  the  antiphlogistic  of  La- 
voisier, may  justly  be  regarded  as  of  equal 
importance  to  the  advancement  of  the  sci- 
ence itself.  When  we  now  survey  the  Trans- 
actions of  the  Royal  Society  for  "l 808,  1809, 
1810,  and  1811,  we  feel  overwhelmed  with 
astonishment  at  the  unparalleled  skill,   la- 
bour, and  sagacity,  by  which  the  great  Eng- 
lish chemist,  in  so  short  a  space,  prodigiously 
multiplied  the  objects  and  resources  of  the 
science,  while  he  promulgated  a  new  code 
of  laws,  flowing  from  views  of  elementary 
action,  equally  profound,  original,  and  su- 
blime.    The   importance  of  the  revolution 
produced  by  his  researches  on  chlorine,  will 
justify  us  in  presenting  a  detailed  account  of 
the  steps  by  which  it  has  been  effected.  How 
entirely  the  glory  of  this  great  work  belongs 
to  Sir  H.  Davy,  notwithstanding  some  inCi- 
dious  attempts  in  this  country,  to  tear  the 
well-earned  laurel  from  his  brow,  and  trans- 
fer it  to  the  French  chemists,  we  may  rea- 
dily judge  by  the  following  decisive  facts. 

The  second  part  of  the  Phil.  Trans,  for 
1809  contains  researches  on  oxymuriatic 
acid,  its  nature  and  combinations*  by  Sir  H. 
Davy,  from  which  I  shall  make  a  few  inter- 
esting extracts. 

«  In  the  Bakerian  lecture  for  1808,"  says 
he,  "  i  have  given  an  account  of  the  action 
oi  potassium  upon  muriatic  acid  gas,  by 
which  more  than  one-third  of  its  volume  of 
hydr>gcn  is  produced;  and  I  have  stated, 
that  uuriatic  acid  can  in  no  instance  be  pro- 
cured from  oxymuriatic  acid,  or  from  dry 
muriates,  unless  water  or  its  elements  be 
present. 

"  In  the  second  volume  of  the  Memoir es 
D'Arcueil,  MM.  Gay-Lussac  and  Thenard 
have  detailed  an  extensive  series  of  facts  up- 
on muriatic  acid,  and  oxymuriatic  acid. 
Some  of  their  experiments  are  similar  to 
those  1  have  detailed  in  the  paper  just  re- 
ferred to;  others  are  peculiarly  their  own, 
and  of  a  very  curious  kind;  their  general 


conclusion  is,  that  muriatic  acid  gas  contains 
about  one  quarter  of  its  weight  of  water; 
and  that  oxymuriatic  acid  is  not  decomposa- 
ble by  any  substances  but  hydrogen,  or  such 
as  can  form  triple  combinations  with  it. 

'«  One  of  the  most  singular  tacts  that  I 
have  observed  on  this  subject,  and  which  I 
have  before  referred  to,  is  that  charcoal, 
even  when  ignited  to  whiteness  in  oxymu- 
riatic or  muriatic  acid  gases,  by  the  voltaic 
battery,  effects  no  change  in  them,  if  it  has 
been  previously  freed  from  hydrogen  and 
moisture,  by  intense  ignition  in  vacua. 

»«  This  experiment,  which  I  have  several 
times  repeated,  led  me  to  doubt  of  the  ex- 
istence of  oxygen  in  that  substance,  which 
has  been  supposed  to  contain  it,  above  all 
others,  in  a  loose  and  active  state;  ana  to 
make  a  more  rigorous  investigation,  than 
had  hitherto  been  attempted  for  its  detec- 
tion.'1 

He  then  proceeds  to  interrogate  nature, 
with  every  artifice  of  experiment  and  rea- 
soning, till  he  finally  extorts  a  confession  of 
the  true  constitution  of  this  mysterious  mu- 
riatic essence.  The  above  paper,  and  his 
Bakerian  lecture,  read  before  the  Royal  So- 
ciety in  Nov.  and  Dec.  1810,  and  published 
in  the  first  part  of  their  transactions  for  1811, 
present  the  whole  body  of  evidence  for  the 
undecompounded  nature  of  oxymuriatic  acid 
gas,  thenceforward  sty  led  chlorine,  and  they 
will  be  studied  in  every  enlightened  age  and 
country,  as  a  just  and  splendid  pattern  of  in- 
ductive Baconian  logic.  These  views  were 
slowly  and  reluctantly  admitted  by  the  che- 
mical philosophers  of  Europe.  The  hypo- 
thesis of  Lavoisier,  that  combustion  was  mere- 
ly the  combination  of  oxygen  with  a  basis, 
had  become  as  favourite  an  idol  with  the 
learned,  as  the  previous  hypothesis  of  Stahl, 
that  one  phlogistic  principle  pervaded  all 
combustible  bodies,  which  was  either  evolved 
in  heat  and  light,  or  quietly  transferred  to  an 
incombustible, imparting  that  inflammability 
to  the  new  substance,  which  its  former  com- 
panion had  secretly  lost.  Stahl's  idea  of  com- 
bustion is  the  more  comprehensive,  and  may 
still  be  true;  Lavoisier's  as  a  general  propo- 
sition, is  certainly  false.f 

In  1812  Sir  H.  Davy  published  his  Ele- 
ments of  Chemical  Philosophy;  containing  a 
systematic  account  of  his  new  doctrines  con- 
cerning the  combination  of  simple  bodies. 

f  It  appears  to  me  that  Stahl's  doctrine  is 
false,  both  as  a  general  and  particular  pro- 
position. According  to  him,  metals  are  com- 
pounds of  their  own  oxides,  now  known  to  be 
compounds  containing  metals  as  ingredients; 
and  this  error  was  extended  to  explain  the 
relation  between  every  combustible,  and 
its  compounds  formed  with  oxygen.  The 
doctrine  of  Stahl  never  can  be  true,  until  it 
ceases  to  be  an  axiom,  that  the  less  earmot 
contain  the  greater. 


CHL 


CHL 


Chlorine  is  there  placed  in  the  same  rank  muriatic  gas  as  a  compound  body."  Thi» 

with  oxygen,  and  finally  removed  from  the  pressure  of  public  opinion  becomes  conspi- 

class  of  acids.     In  18  i3,  M.  Thenard  pub-  cuous  at  the  end  of  the  rolume.  Among  the 

lished  the  first  volume  of  his  Traitf  de  Chi-  additions,  we  have  the  following  decisive 

mie  Elementaire  Theorique  et  Pratique.    This  evidence,  of  the  lingering  attachment  to  the 

distinguished  chemist,  the  fellow-labourer  of  old  theory  of  Lavoisier  and  Berthollet .--"  A 

M.  Gay-Lussac,  in  those  able  researches  on  pretty  considerable  number  of  persons  who 
the  alkalis  and  oxymurialic  acid,  which  form 
the  honourable  rivalry  of  the  French  school 
to  the  brilliant  career  of  Sir  H.  Davy,  states 
at  page  584.  of  the  above  volume,  the  com- 
position ofoxymuriatic  acid  as  follows:  "  Corn- 


have  subscribed  for  this  work,  desiring  a  de 
tailed  explanation  of  the  phenomena,  which 
oxygenated  muriatic  gas  presents,  on  the 
supposition  that  this  gas  is  a  simple  body, 
we  are  now  going  to  explain  these  pheno- 
mena, on  this  supposition,  by  considering 
them  attentively.  The  oxygenated  muriatic 

-  ,,    -       -.-  x  ..  .      gas  will  take  the  name  of  chlorine;  its  com- 
rnunatic  acid.     It  thence  tollows,  that  it  is    "•     L- _..-^i      i    __• _._i_i ~.,..«^ 


position.  The  oxygenated  muriatic  i^as,  con- 
tains the  half  of  its  volume  of  oxygen  gas, 
not  including  that  which  we  may  suppose  in 


formed  of  1.9183  of  muriatic  acid,  and  0.5517 
of  oxygen;  for  the  specific  gravity  of  oxyge- 
nated muriatic  gas  is  2.47,  and  that  of  oxy- 
gen gas,  1.1034."  "  M.  Chenevix  first  de- 
termined the  proportion  of  its  constituent 
principles.  MM.  Gay-Lussac  and  Thenard 
determined  it  more  exactly,  and  showed  that 
we  could  not  decompose  the  oxygenated 
muriatic  gas,  but  by  putting  it  in  contact 
with  a  body  capable  of  uniting  with  the  two 
elements  of  this  gas,  or  with  muriatic  acid. 
They  announced  at  the  same  time,  that  they 


binations  with  phosphorus,  sulphur,  azote, 
metals,  will  be  called  chlorures;  the  muriatic 
acid,  which  results  from  equal  parts  in  vol- 
ume of  hydrogen  and  oxygenated  muriatic 
gases,  will  be  hydrochloric  add;  the  super- 
oxygcnated  muriatic  acid,  will  be  chlorous 
acid;  and  the  hyperoxygenated  muriatic, 
chloric  acid;  the  first,  comparable  to  the 
h)driodic  acid,  and  the  last  to  the  iodic 
acid."  In  fact,  therefore,  we  evidently  see, 
that  so  far  from  the  chloridic  theory  origin- 
ating in  France,  as  has  been  more  than 


insinuated,  it  was  only  the  researches  on 

could  explain  all  the  phenomena  which  it    iodine>  so  admirably  conducted  by  M.  Gay- 
presents,  by  considering  it  as  a  simple,   or    Lussac    that  by  their  auxiliary  attack  of  the 

'  oxygen  hypothesis,  eventually  opened  the 
minds  of  its  adherents,  to  the  evidence  long 
ago  advanced  by  Sir  H.  Davy.  It  will  be 
peculiarly  instructive,  to  give  a  general 
outline  of  that  evidence,  which  has  been 
mutilated  in  some  systematic  works  on  che- 
mistry, or  frittered 'away  into  fragments. 


as  a  compound  body.  However,  this  last 
opinion  appeared  more  probable  to  them. 
M.  Davy  on  the  contrary,  embraced  the  first, 
admitted  it  exclusively,  and  sought  to  fortify 
it,  by  experiments  which  are  peculiar  to 
him."  P.  585. 

In  the  second  volume  of  M.  Thenard's 
work,  published  in  1814,  he  explains  the  mu- 
tual action  of  chlorine  and  ammonia  gases 
solely  on  the  oxygenous  theory.  "  On  peut 


Sir  H.  Davy  subjected  oxymuriatic  gas, 
to  the  action  of  many  simple  combustibles, 
as  well  as  metals,  and  from  the  compounds 


•  •     j          .  /  i  '  i  <*a  wen  as  mc».wi»,  uuu.  iiuiii    v.uc    ijwuiuwuuu* 

demontrer  par  ce  dernier  proceue    que    e  fopmed    endeavoured  to  eliminate  oxygen, 

gas   munatique   oxtgene  doit  contemn  14  by  the  most  energetic  powers  of  affinity  and 

moitie   de   son   volume  doxigene,  um   a  ^u.,;f,  ^i«Ptwr.;+v.  K..t  unthmit  ci.o^ss.  an 


1'acide  muriatique."  P.  147. — In  the  4th 
volume  which  appeared  in  1816,  we  find 
the  following  passages:  "  Oxygenated  mu- 
riatic gas.  Oxyg'enated  muriatic  gas,  in 
combining  with  the  metals,  gives  ris< 
the  neutral  muriates.  Now,  107.6  of  oxide 


voltaic  electricity,  but  without  success, 
the  following  abstract  will  show. 

If  oxymuriatic  acid  gas  be  introduced  in- 
to a  vessel  exhausted  of  air,  containing  tin; 
and  the  tin  be  gently  heated,  and  the  gas  in 


combining  with  the  metals,  gives  rise  to  sufficient  quantity,  the  tin  and  the  gas  dis- 

the  neutral  muriates.  Now,  107.6  of  oxide  aopear.  and  a  limpid  flujd>   precisely  the 

of  silver,  contain  7.6  of  oxygen,  and  absorb  same  as  Libavius's  liquor  is  formed:  If  this 

26.4  of  muriatic  acid,  to  pass  to  the^state  substance  is  a  combination  of  muriatic  acid 

of  neutral  muriate.  Of  consequence,  348  of  and  oxjde  of  tin,  oxide  of  tin  ought   to  be 

this  last  acid  supposed  dry,  and  100  of  oxy-  separated  from  it  by  means  of  ammonia.— 

gen,  form  this  gas.  But  the  sp.  gr.  of  oxy-  jje  admitted  ammoniacal  gas  over  mei-cury 

gen  is  1.1034,  and  that  of  oxygenated  mu-  to  a  small  quantity  of  the  liquor  of  Libavius; 

riatic  gas  is  2.47;  hence,  this  contains  the  it  was  absorbed  with  great  heat,  and  no  gas 


:  gas 
half  of  its  volume  of  oxygen."  P.  52. 

The  force  of  Sir  H.  Davy's  demonstra- 
tions, pressing  for  six  years  on  the  public 
mind  of  the  French  philosophers,  now  be- 
gins to  transpire  in  a  note  to  the  above 

passage. "  We   reason   here,"  says    M. 

Thenard,   "obviously,  on  the  hypothesis, 
which   consists   in  regarding  oxygenated 
VOL.  I. 


-  „  .  gas 

was  generated;  a  solid  result  was  obtained, 
which  was  of  a  dull  white  colour:  some  of 
it  was  heated,  to  ascertain  if  it  contained 
oxide  of  tin;  but  the  whole  volatilized,  pro- 
ducing dense  pungent  furnes. 

Another  experiment  of  the  same  kind, 
made  with  great  care,  and  in  which  the  am- 
monia was  used  in  great  excess,  proved  that 
36 


CHL 


CHL 


the  liquor  of  Libavius  cannot  be  decom- 
pounded by  ammonia;  but  that  it  forms  a 
new  combination  with  this  substance. 

He  made  a  considerable  quantity  of  the 
solid  compound  of  oxymuriatic  acid  and 
phosphorus  by  combustion,  and  saturated  it 
with  ammonia,  by  heating  it  in  a  proper  re- 
ceiver filled  with  ammoniacal  gas,  on  which 
it  acted  with  great  energy,  producing  much 
heat;  and  they  formed  a  white  opaque  pow- 
der. Supposing  that  this  substance  was 
composed  of  the  dry  muriates  and  phos- 
phates of  ammonia;  as  muriate  of  ammonia 
is  very  volatile,  and  as  ammonia  is  driven  off 
from  phosphoric  acid,  by  a  heat  below  red- 
ness, he  conceived  that,  by  igniting  the  pro- 
duct obtained,  he  should  procure  phosphoric 
acid;  he  therefore  introduced  some  of  the 

it  to  redness,  out  of  the  contact  of  air,  by  a 
spirit  lamp;  but  found,  to  his  great  surprise, 
that  it  was  not  at  all  volatile  nor  decomposa- 
ble at  this  degree  of  heat,  and  that  it  gave 
off  no  gaseous  matter. 

The  circumstance,  that  a  substance  com- 
posed principally  of  oxymuriatic  acid,  and 
ammonia,  should  resist  decomposition^  or 
change  at  so  high  a  temperature,  induced 
him  to  pay  particular  attention  to  the  pro- 
perties of  this  new  body. 

It  has  been  said,  and  taken  for  granted  by 
many  chemists,  that  when  oxymuriatic  acid 
and  ammonia  act  upon  each  other,  water  is 
formed;  he  several  times  made  the  experi- 
ment, and  was  convinced  that  this  is  not  the 
case. 

He  mixed  together  sulphuretted  hydrogen 
in  a  high  degree  of  purity,  and  oxymuriatic 
acid  gas,  both  dried,  in  equal  volumes.  In 

this  instance  the  condensation   was  not 

40; 

sulphur,  which  seemed  to  contain  a  little 
oxymuriatic  acid,  was  formed  on  the  sides  of 
the  vessel;  no  vapour  was  deposited;  and 

19 

the  residual  gas  contained  aboui^  of  muri. 

atic  acid  gas,  and  the  remainder  was  inflam- 
mable. 

When  oxymuriatic  acid  is  acted  upon  by 
nearly  an  equal  volume  of  hydrogen,  a  com- 
bination takes  place  between  them,  and  mu- 
riatic acid  gas  results.  When  muriatic  acid 
gas  is  acted  on  by  mercury,  or  any  other 
metal,  the  oxymuriatic  acid  is  attracted  from 
the  hydrogen,  by  the  stronger  affinity  of  the 
metal;  and  an  oxymuriate,  exactly  similar  to 
that  formed  by  combustion,  is  produced. 

The  action  of  water  upon  those  com- 
pounds, which  have  been  usually  considered 
as  muriates,  or  as  dry  muriates,  but  which 
are  properly  combinations  of  oxymuriatic 
acid  with  inflammable  bases,  may  be  easily 
explained,  according  to  these  views  of  the 
subject.  When  water  is  added  in  certain 
quantities  to  Libavius's  liquor,  a  solid  crys- 
tallized mass  is  obtained,  from  which  oxide 


of  tin  and  muriate  of  ammonia  can  fre  pro- 
cured by  ammonia.  In  this  case,  oxygen 
may  be  conceived  to  be  supplied  to  the  tin, 
and  hydrogen  to  the  oxymuriatic  acid. 

The  compound  formed  by  burning  phos- 
phorus in  oxymuriatic  acid,  is  in  a  similar 
relation  to  water.  If  that  substance  be  add- 
ed to  it,  it  is  resolved  into  two  powerful 
acids;  oxygen,  it  may  be  supposed,  is  fur- 
nished to  the  phosphorus  to  form  phosphoric 
acid,  hydrogen  to  the  oxymuriatic  acid  to 
form  common  muriatic  acid  gas. 

He  caused  strong  explosions  from  an 
electrical  jar  to  pass  through  oxymuriatic 
gas,  by  means  of  points  of  platina,  for  several 
hours  in  succession;  but  it  seemed  not  to 
undergo  the  slightest  change. 

He  electrized  the  oxymuriates  of  phos. 
phorus  and  sulphur  for  some  hours,  by  the 
power  of  the  voltaic  apparatus  of  1000  dou- 
ble plates.  No  gas  separated,  but  a  minute 
quantity  of  hydrogen,  which  he  was  inclined 
to  attribute  to  the  presence  of  moisture  in 
the  apparatus  employed;  for  he  once  ob- 
tained hydrogeTi  from  Libavius's  liquor  by 
a  similar  operation.  But  he  ascertained  that 
this  was  owing  to  the  decomposition  of  wa- 
ter adhering  to  the  mercury;  and  in  some 
late  experiments  made  with  2000  double 
plates,  in  which  the  discharge  was  from  pla- 
tina wires,  and  in  which  the  mercury  used 
for  confining  the  liquor  was  carefully  boiled, 
there  was  no  production  of  any  permanent 
elastic  matter. 

Few  substances,  perhaps,  have  less  claim 
to  be  considered  as  acid,  than  oxymuriatic 
acid.  As  yet  we  have  no  right  to'  say  that 
it  has  been  decompounded;  and  as  its  ten- 
dency of  combination  is  with  pure  inflam- 
mable matters,  it  may  possibly  belong  to  the 
same  class  of  bodies  as  oxygen. 

May  it  not  in  fact  be  a  peculiar  acidifying 
and  dissolving  principle,  forming  compounds 
with  combustible  bodies,  analogous  to  acids 
containing  oxygen,  or  oxides,  in  their  proper- 
ties and  powers  of  combination;  but  differ- 
ing from  them,  in  being  for  the  most  part 
decomposable  by  water?  On  this  idea  mu- 
riatic acid  may  be  considered  as  having  hy- 
drogen for  its  basis,  and  oxymuriatic  acid  for 
its  acidifying  principle.  And  the  phosphoric 
sublimate  as  having  phosphorus  for  its  basis, 
and  oxymuriatic  acid  for  its  acidifying  matter. 
And  Libavius's  liquor,  and  the  compounds  of 
arsenic  with  oxymuriatic  acid,  may  be  regard- 
ed as  analogous  bodies.  The  combinations 
of  oxymuriatic  acid  with  lead,  silver,  mer- 
cury, potassium,  and  sodium,  ia  this  view, 
would  be  considered  as  a  class  of  bodies  re- 
lated more  to  oxides  than  acids,  in  their 
powers  of  attraction. — Hak.  Lee.  1809. 

On  the  Combinations  of  the    Common  Metals 
icith  Oxygen  and  Oxymuriatic  Gas. 

Sir  H.  used  in  all  cases  small  retorts  of 


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•green  glass,  containing  from  three  to  six  cu- 
bical inches,  furnished  with  stop-cocks.  The 
metallic  substances  were  introduced,  the  re- 
tort exhausted  and  filled  with  the  gas  to  be 
acted  upon,  heat  was  applied  by  means  of  a 
spirit  lamp,  and  after  cooling,  the  results 
were  examined,  and  the  residual  gas  ana- 
lyzed. 

All  the  metals  he  tried,  except  silver, 
lead,  nickel,  cobalt,  and  gold,  when  heated, 
burnt  in  the  oxymuriatic  gas,  and  the  vola- 
tile metals  with  fLtme.  Arsenic,  antimony, 
tellurium,  and  zinc,  with  a  white  flame, 
mercury  with  a  red  flame.  Tin  became 
ignited  to  whiteness,  and  iron  and  copper  to 
redness;  tungsten  and  manganese  to  dull 
redness;  platina  was  scarcely  acted  upon  at 
the  heat  effusion  of  the  glass. 

The  product  from  mercury  was  corrosive 
sublimate.  That  from  zinc  was  similar  in 
colour  to  that  from  antimony,  but  was  much 
less  volatile. 

Silver  and  lead  produced  horn-silver  and 
horn-lead;  and  bismuth,  butter  of  bismuth. 

In  acting  upon  metallic  oxides  by  oxy- 
muviatic  gas,  he  found  that  those  of  lead, 
silver,  tin,  copper,  antimony,  bismuth,  and 
tellurium,  were  decomposed  in  a  heat  below 
redness,  but  the  oxides  of  the  volatile  metals 
more  readily  than  those  of  the  fixed  ones. 
The  oxides  of  cobalt  and  nickel  were  scarcely 
acted  upon  at  a  dull  red  heat.  The  red 
oxide  of  iron  was  not  affected  at  a  strong 
red  heat,  whilst  the  black  oxide  was  readily 
decomposed  at  a  much  lower  temperature; 
arsenical  acid  underwent  no  change  at  the 
greatest  heat  that  could  be  given  it  in  the 
glass  retort,  whilst  the  white  oxide  readily 
decomposed. 

In  cases  where  oxygen  was  given  off,  it 
was  found  exactly  the  same  in  quantity  as 
that  which  has  been  absorbed  by  the  metal^ 
Thus  two  grains  of  red  oxide  of  mercury  ab* 
sorbed-— -of  a  cubical  inch  of  oxymuriatic 
gas,  and  afforded  0.45  of  oxygen.  Two 
grains  of  dark  olive  oxide  from  calomel  de- 
composed by  potash,  absorbed 

of  oxymuriatic  gas,  and  afforded  —  of  oxy. 
gen,  and  corrosive  sublimate  was  produced 
in  both  cases. 

In  the  decomposition  of  the  white  oxide 
of  zinc,  oxygen  was  expelled  exactly  equal 
to  half  the  volume  of  the  oxymuriatic  acid 
absorbed.  In  the  case  of  the  decomposition 
of  the  black  oxide  of  iron,  and  the  white 
oxide  of  arsenic,  the  changes  that  occurred 
were  of  a  very  beautiful  kind;  no  oxygen 
was  given  off'  in  either  case,  but  butter  of 
arsenic  and  arsenical  acid  formed  in  one  in- 
stance, and  the  ferruginous  sublimate  and 
red  oxide  of  iron  in  the  other. 

General  Conclusions   and   Observations,  illus- 
trated by  Experiments. 
Oxymuriatic  gas   combines  with  inflam- 


about-£ 


mable  bodies,  to  form  simple  binary  com- 
pounds; and  in  these  cases,  when  it  acts 
upon  oxides,  it  either  produces  the  expulsion 
of  their  oxygen,  or  causes  it  to  enter  into 
new  combinations. 

If  it  be  said  that  the  oxygen  arises  from 
the  decomposition  of  the  oxymuriatic  gas, 
and  not  from  the  oxides,  it  may  be  asked, 
why  it  is  always  the  quantity  contained  in 
the  oxide?  and  why  in  some  cases,  as  those 
of  the  peroxides  of  potassium  and  sodium,  it 
bears  no  relation  to  the  quantity  of  gas? 

If  there  existed  any  acid  matter  in  oxy- 
muriatic gas,  combined  with  oxygen,  it 
ought  to  be  exhibited  in  the  fluid  compound 
of  one  proportion  of  phosphorus,  and  two  of 
oxymuriatic  gas;  for  this,  on  such  an  as- 
sumption, should  consist  of  muriatic  acid 
(on  the  old  hypothesis,  free  from  water) 
and  phosphorous  acid;  but  tin's  substance 
has  no  effect  on  litmus  paper,  and  does  not 
act  under  common  circumstances  on  fixed 
alkaline  bases,  such  as  dry  lime  or  magne- 
sia. Oxymuriatic  gas,  like  oxygen,  must 
be  combined  in  large  quantity  with  pecu- 
liar inflammable  matter,  to  form  acid  mat- 
ter. In  its  union  with  hydrogen,  it  instantly 
reddens  the  driest  litmus  paper,  though  a 
gaseous  body.  Contrary  to  acids,  it  expels 
oxygen  from  protoxides;  and  combines 
with  peroxides. 

When  potassium  is  burnt  in  oxymuriatic 
gas,  a  dry  compound  is  obtained.  If  potas- 
sium combined  with  oxygen  is  employed, 
the  whole  of  the  oxygen  is  expelled,  and 
the  same  compound  formed.  It  is  contrary 
to  sound  logic  to  say,  that  this  exact  quan- 
tity of  oxygen  is  given  off  from  a  body  not 
known  to  be  compound,  when  we  are  cer- 
tain of  its  existence  in  another;  and  all  the 
cases  are  parallel. 

Scheele  explained  the  bleaching  powers 
of  the  oxymuriatic  gas,  by  supposing  that 
it  destroyed  colours  by  combining  with 
phlogiston.  Berthollet  considered  it  as  act- 
ing by  supplying  oxygen.  He  made  an  ex- 
periment, which  seems  to  prove  that  the 
pure  gas  is  incapable  of  altering  vegetable 
colours,  and  that  its  operation  in  bleaching 
Depends  entirely  upon  its  property  of  de- 
composing water,  and  liberating  its  oxygen. 

He  filled  a  glass  globe,  containing  dry 
powdered  muriate  of  lime,  with  oxymuri- 
atic gas.  He  introduced  some  dry  paper 
tinged  with  litmus  that  had  been  just  heat- 
ed, into  another  globe  containing  dry  mu- 
riate of  lime;  after  some  time  this  globe 
was  exhausted,  and  then  connected  with 
the  globe  containing  the  oxymuriatic  gas, 
and  by  an  appropriate  set  of  stop-cocks, 
the  paper  was  exposed  to  the  action  of  the 
gas.  No  change  of  colour  took  place,  and 
after  two  days  there  was  scarcely  a  per- 
ceptible alteration. 

Some  similar  paper  dried,  introduced  in- 


CHL 


CHL 


to  gas  that  had  not  been  exposed  to  mu- 
riate of  lime,  was  instantly  rendered  white. 
It  is  generally  stated  in  chemical  books, 
that  oxymuriatic  gas  is  capable  of  being 
condensed  and  crystallized  at  a  low  tem- 
perature. He  found  by  several  experiments 
that  this  is  not  the  case.  The  solution  of  oxy- 
muriatic gas  in  water  freezes  more  readi- 
ly than  pure  water,  but  the  pure  gas  dnjed 
by  muriate  of  lime  undergoes  no  change 
•whatever,  at  a  temperature  of  40  below  0° 
of  Fahrenheit.  The  mistake  seems  to  have 
arisen  from  the  exposure  of  the  gas  to  cold 
in  bottles  containing  moisture. 

He  attempted  to  decompose  boracic  and 
phosphoric  acids  by  oxymuriatic  gas,  but 
without  success;  from  which  it  seems  pro- 
bable, that  the  attractions  of  boracium  and 
phosphorus  for  oxygen  are  stronger  than 
for  oxymuriatic  gas.  And  from  the  experi- 
ments already  detailed,  iron  and  arsenic 
are  analogous  in  this  respect,  and  proba- 
bly some  other  metals. 

Potassium,  sodium,  calcium,  strontium, 
barium,  zinc,  mercury,  tin,  lead,  and  proba- 
bly silver,  antimony,  and  gold,  seem  to 
have  a  stronger  attraction  for  oxymuriatic 
gas  than  for  oxygen. 

"  To  call  a  body  which  is  not  known  to 
contain  oxygen,  and  which  cannot  contain 
muriatic  acid,  oxymuriatic  acid,  is  contrary 
to  the  principles  of  that  nomenclature  in 
which  it  is  adopted;  and  an  alteration  of  it 
seems  necessary  to  assist  the  progress  of 
discussion,  and  to  diffuse  just  ideas  on  the 
subject.  If  the  great  discoverer  of  this  sub- 
stance had  signified  it  by  any  simple  name, 
it  would  have  been  proper  to  have  recur- 
red to  it;  but  dephlogisticated  marine  acid 
is  a  term  which  can  hardly  be  adopted  in 
the  present  advanced  era  of  the  science. 

After  consulting  some  of  the  most  emi- 
nent chemical  philosophers  in  this  country, 
it  has  been  judged  most  proper  to  suggest 
a  name  founded  upon  one  of  its  obvious  and 
characteristic  properties — its  colour,  and 
to  call  it  chlorine,  or  chloric  gas. 

Should  it  hereafter  be  discovered  to  be 
compound,  and  even  to  contain  oxygen,  this 
name  can  imply  no  error,  and  cannot  neces- 
sarily require  a  change. 

Most  of  the  salts  which  have  been  called 
muriates,  are  not  known  to  contain  any  mu- 
riatic acid,  or  any  oxygen.  Thus  Libavius's 
liquor,  though  converted  into  a  muriate  by 
water,  contains  only  tin  and  oxymuriatic 
gas;  and  horn-silver  seems  incapable  of  be- 
ing converted  into  a  true  muriate." — Eak. 
Lee.  1811. 

We  shall  now  exhibit  a  summary  view 
of  the  preparation  and  properties  of  chlo- 
rine. 

Mix  in  a  mortar  3  parts  of  common  salt 
and  1  of  black  oxide  of  manganese.  Intro- 
duce them  into  a  glass  retort,  and  add  2 
parts  of  sulphuric  acid.  Gas  will  issue, 


which  must  be  collected  in  the  water-pneu- 
matic trough.  A  gentle  heat  will  favour  its 
extrication.  In  practice,  the  above  pasty  - 
consistenced  mixture  is  apt  to  boil  over  in- 
to the  neck.  A  mixture  of  liquid  muriatic 
acid  and  mang'anese  is  therefore  more  con- 
venient for  the  production  of  chlorine.  A 
very  slight  heat  is  adequate  to  its  expul- 
sion from  the  retort.  Instead  of  manganese, 
red  oxide  of  mercury,  or  puce-coloured  ox- 
ide of  lead,  may  be  employed. 

This  gas,  aa  we  have  already  remarked, 
is  of  a  greenish-yellow  colour,  easily  recog- 
nized by  day-light,  but  scarcely  distinguish- 
able by  that  of  candles.  Its  odour  and  taste 
are  disagreeable,  strong,  and  so  charac- 
teristic, that  it  is  impossible  to  mistake  it 
for  any  other  gas.  When  we  breathe  it,  even 
much  diluted  with  air,  it  occasions  a  sense 
of  strangulation,  constriction  of  the  thorax, 
and  a  copious  discharge  from  the  nostrils. 
If  respired  in  larger  quantity,  it  excites 
violent  coughing,  with  spitting  of  blood, 
and  would  speedily  destroy  the  individual, 
amid  violent  distress.  Its  specific  gravity 
is  2.4733.  This  is  better  inferred  from  the 
specific  gravities  of  hydrogen  and  muriatic 
acid  gases,  than  from  the  direct  weight  of 
chlorine,  from  the  impossibility  of  confin- 
ing it  over  mercury.  One  volume  of  hydro- 
gen, added  to  one  of  chlorine,  form  two 
of  the  acid  gas.  Hence,  if  from  twice 
the  specific  gravity  of  muriatic  gas  = 
2  5427,  we  subtract  that  of  hydrog-en  = 
0.0694,  the  difference  2-4733  is  the  speci- 
fic gravity  of  chlorine.  100  cubic  inches  at 
mean  pressure  and  temperature  weigh  75£ 
grains.  See  GAS. 

In  its  perfectly  dry  state,  it  has  no  effect 
on  dry  vegetable  colours.  With  the  aid  of 
a  little  moisture,  it  bleaches  them  into  a 
yellowish-white.  Scheele  first  remarked 
this  bleaching  property;  Berthollet  applied 
it  to  the  art  of  bleaching  in  France,  and 
from  him  Mr.  Watt  introduced  its  use  into 
Great  Britain. 

If  a  lighted  wax  taper  be  immersed  ra- 
pidly into  this  gas,  it  consumes  very  fast, 
with  a  dull  reddish  flame,  and  much  smoke. 
The  taper  will  not  burn  at  the  surface  of 
the  gas.  Hence,  if  slowly  introduced,  it  is 
apt  to  be  extinguished.  The  alkaline  me- 
tals, as  well  as  copper,  tin,  arsenic,  zinc, 
antimony,  in  fine  laminae  or  filings,  spon- 
taneously burn  in  chlorine.  Metallic  chlo- 
rides result.  Phosphorus  also  takes  fire  at 
ordinary  temperatures,  and  is  converted 
into  a  chloride.  Sulphur  may  be  melted  in 
the  gas  without  taking  fire.  It  forms  a  li- 
quid chloride,  of  a  reddish  colour.  When 
dry,  it  is  not  altered  by  any  change  of  tem- 
perature. Enclosed  in  a  phial  with  a  little 
moisture,  it  concretes  into  crystalline  nee- 
dles, at  40°  Fahr. 

According  to  M.  Thenard,  water  con- 
denses, at  the  temperature  of  68°  Fahr. 


CHL 


CHL 


and  at  29.92  barom.  1£  times  its  volume  of 
chlorine,  and  forms  aqueous  chlorine,  for- 
merly called  liquid  oxymuriatic  acid.  This 
combination  is  best  made  in  the  second 
bottle  of  a  Woulfe's  apparatus,  the  first  be- 
ing- charged  with  a  little  water,  to  inter- 
cept the  muriatic  acid  gas,  while  the  third 
bottle  may  contain  potash-water  or  milk 
of  lime,  to  condense  the  superfluous  gas. 
M.  Thenard  says,  that  a  kilogramme  of 
salt  is  sufficient  for  saturating  from  10  to 
12  litres  of  water.  These  measures  corres- 
pond to  2  and  l-3d  libs,  avoirdupois,  and 
from  21  to  25  pints  English.  There  is  an 
ingenious  apparatus  for  making  aqueous 
chlorine,  described  in  Berthollet's  Ele- 
ments of  Dyeing,  vol.  i.;  which,  however, 
the  happy  substitution  of  slaked  lime  for 
water,  by  Mr.  Charles  Tennent  of  Glasgow, 
has  superseded,  for  the  purposes  of  manu- 
facture. It  congeals  by  cold  at  40°  Fahr. 
and  affords  crystallized  plates,  of  a  deep 
yellow,  containing  a  less  proportion  of 
water  than  the  liquid  combination.  Hence 
when  chlorine  is  passed  into  water  at  tem- 
peratures under  40°,  the  liquid  finally  be- 
comes a  concrete  mass,  which  at  a  gentle 
heat  liquefies  with  effervescence,  from  the 
escape  of  the  excess  of  chlorine.  When 
steam  and  chlorine  are  passed  together 
through  a  red-hot  porcelain  tube,  they  are 
converted  into  muriatic  acid  and  oxygen. 
A  like  result  is  obtained  by  exposing  aque- 
ous chlorine  to  the  solar  rays;  with  this  dif- 
ference, that  a  little  chloric  acid  is  formed. 
Hence  aqueous  chlorine  should  be  kept  in 
a  dark  place.  Aqueous  chlorine  attacks  al- 
most all  the  metals  at  an  ordinary  tempe- 
rature, forming  muriates  or  chlorides,  and 
heat  is  evolved.  It  has  the  smell,  taste,  and 
colour  of  chlorine;  and  acts  like  it,  on  ve- 
getable and  animal  colours.  Its  taste  is 
somewhat  astringent,  but  not  in  the  least 
degree  acidulous. 

When  we  put  in  a  perfectly  dark  place 
at  the  ordinary  temperature,  a  mixture  of 
chlorine  and  hydrogen,  it  experiences  no 
kind  of  alteration,  even  in  the  space  of  a 
great  many  days.  But  if,  at  the  same  low 
temperature,  we  expose  the  mixture  to  the 
diffuse  light  of  day,  by  degrees  the  two 
gases  enter  into  chemical  combination,  and 
form  muriatic  acid  gas.  There  is  no  change 
in  the  volume  of  the  mixture,  but  the  change 
of  its  nature  may  be  proved,  by  its  rapid  ab- 
sorbability by  water,  its  not  exploding  by 
the  lighted  taper,  and  the  disappearance  of 
the  chlorine  hue.  To  produce  the  complete 
discoloration,  we  must  expose  the  mixture 
finally  for  a  few  minutes  to  the  sunbeam. 
If  exposed  at  first  to  this  intensity  of  light, 
it  explodes  with  great  violence,  and  instant- 
ly forms  muriatic  acid  gas.  The  same  ex- 
plosive combination  is  produced  by  the 
electric  spark  and  the  lighted  taper.  M. 
Thenard  says,  a  heat  of  392°  is  sufficient 


to  cause  the  explosion.  The  proper  pro, 
portion  is  an  equal  volume  of  each  gas 
Chlorine  and  nitrogen  combine  into  a  re-, 
markable  detonating  compound,  by  expos- 
ing the  former  gas  to  a  solution  of  an  am- 
moniacal  salt.  See  NITROGEN.  Chlorine 
is  the  most  powerful  agent  for  destroying 
contagious  miasmata.  The  disinfecting  phi- 
als of  Morveau  evolve  this  gas.  See  CHLO- 
ROUS OXIDE.*  f 

*  CHLORITE  is  a  mineral  usually  friable 
or  very  easy  to  pulverize,  composed  of  a 
multitude   of  little    spangles,   or   shining 
small  grains,  falling  to  powder  under  the 
pressure  of  the  fingers.    There  are  four 
sub-species.     1.   Chlorite  earth.     In  green, 
glimmering  and  somewhat  pearly  scales, 
with  a  shining  green  streak.   It  adheres  to 
the  skin,  and  has  a  greasy  feel.  Sp.  gr.  2.6. 
It  consists  of  50  silica,  26  alumina,  1.5  lime, 
5  oxide  of  iron,  17.5  potash.  This  mineral 
is  found  chiefly  in  clay-slate,  in  Germany 
and  Switzerland.  At  Altenberg,  in  Saxony, 
it  is  intermingled  with  sulphurets  of  iron 
and  nrsenic;  and  amphibole  in  mass.  2  Com- 
mon chlorite.  A  massive  mineral  of  a  black- 
ish-green colour,  a  shining  lustre,  and  a  fo- 
liated fracture  passing  into  earthy.  Streak 
is  lighter  green;  it  is  soft,  opaque,  easily 
cut  and  broken,. and  feels  greasy.     Sp.  gr. 
2.83.     Its  constituents  are  26  silica,    18.5 
alumina,  8  magnesia,  4;>  oxide  of  iron,  and 
2  muriate  of  potash.     3.  Chlorite  slate.     A 
massive,  blackish-green  mineral,  with  re- 
sinous lustre,  and  curve  slaty  or  scaly-foli- 
ated fracture.  Double  cleavage.  Easily  cut. 
Feels  somewhat  greasy.    Sp    gr    2.82.    It 
occurs  particularly  along  with  clay-slate, 
and  is  found  in  Corsica,  Fahlun  in  Sweden, 
and  Norway.     4.  Foliated  chlorite      Colour 
between     mountain     and    black ish-green. 
Massive;  but  commonly  crystallized  in  six- 
sided  tables,  in  cylinders  terminated  by  two 
cones,  and  in  double  cones  with  the  bases 
joined.    Surface  streaked.    Lustre  shining 
pearly;  foliated  fracture,  translucent  on  the 
edges;  soft,  sectile,  and  folia  usually  flexi- 
ble.   Feels  rather  greasy.    Sp.  gr.  2.82.    It 
is  found  at  St.  Gothard,  in  Switzerland,  and 
in  the  island  of  Java.     Us  constituents  are 
35  silica,  18  alumina,    29.9  magnesia,  9.7 
oxide  of  iron,  27  water.* 

* CHLOROPHANE  A  violet  fuor  spar, 
found  in  Siberia.* 

*  CHLORO-CARBONOUS  ACID.  The  term 

f  It  is  surprising,  that  I  have  no  where 
met  with  any  mention  of  one  of  the  most 
distinctive  and  obvious  properties  of  this 
gas.  When  the  exterior  air  was  about  the 
temperature  of  60°,  and  a  mercurial  ther- 
mometer detected  no  difference  between 
the  temperature  of  the  chlorine  and  that 
of  the  surrounding  medium,  the  hand,  im- 
mersed in  it,  would  experience  a  sensa- 
tion of  warmth,  indicating  80  or  90°. 


CHL 


CHL 


chloro-carbonic  which  has  been  given  to 
this  compound  is  incorrect,  leading-  to  the 
belief  of  its  being  a  compound  of  chlorine 
and  acidified  charcoal,  instead  of  being-  a 
compound  of  chlorine  and  the  pi-otoxide 
of  charcoal.  Chlorine  has  no  immediate  ac- 
tion on  carbonic  oxide,  when  they  are  ex- 
posed to  each  other  in  common  day-light 
over  mercury;  not  even  when  the  electric 
spark  is  passed  through  them.  Experiments 
made  by  Dr.  John  Davy,  in  the  presence  of 
his  brother  Sir  H.  Davy,  prove  that  they 
combine  rapidly  when  exposed  to  the  di- 
rect solar  beams,  and  one  volume  of  each 
is  condensed  into  one  volume  of  the  com- 
pound. The  resulting-  gas  possesses  very 
curious  properties,  approaching  to  those 
of  an  acid.  From  the  peculiar  potency  of 
the  sunbeam  in  effecting  this  combination, 
Dr.  Davy  called  it  phosgene  gas.  The  con- 
stituent gases,  dried  over  muriate  of  lime, 
ought  to  be  introduced  from  separate  re- 
servoirs into  an  exhausted  globe,  perfectly 
dry,  and  exposed  for  fifteen  minutes  to 
bright  sunshine,  or  for  twelve  hours  to 
day-light.  The  colour  of  the  chlorine  dis- 
appears, and  on  opening  the  stop-cock  be- 
longing to  the  globe  under  mercury  re- 
cently boiled,  an  absorption  of  one-half  the 
gaseous  volume  is  indicated.  The  resulting 
gas  possesses  properties  perfectly  distinct 
from  those  belonging  to  either  carbonic 
oxide  or  chlorine. 

It  does  not  fume  in  the  atmosphere.  Its 
odour  is  different  from  that  of  chlorine, 
something  like  that  which  might  be  ima- 
gined to  result  from  the  smell  of  chlorine 
combined  with  that  of  ammonia.  It  is  in 
fact  more  intolerable  and  suffocating  than 
chlorine  itself,  and  affects  the  eyes  in  a 
peculiar  manner,  producing  a  rapid  flow 
of  tears,  and  occasioning  painful  sensations. 

It  reddens  dry  litmus  paper;  and  con- 
denses four  volumes  of  ammonia  into  a 
white  salt,  while  heat  is  evolved.  This  am- 
moniacal  compound  is  neutral,  but  has  no 
odour,  but  a  pungent  saline  taste;  is  deli- 
quescent, decomposable  by  the  liquid  mi- 
neral acids,  dissolves  without  effervescing 
in  vinegar,  and  sublimes  unaltered  in  mu- 
riatic, carbonic,  and  sulphurous  acid  gases. 
Sulphuric  acid  resolves  it  into  carbonic  and 
muriatic  acids,  in  the  proportion  of  two 
in  volume  of  the  latter,  and  one  of  the 
former.  Tin,  zinc,  antimony,  and  arsenic, 
heuted  in  chloro-carbonous  acid,  abstract 
the  chlorine,  and  leave  the  carbonic  oxide 
expanded  to  its  original  volume.  There  is 
neither  ignition  nor  explosion  takes  place, 
though  the  action  of  the  metals  is  rapid. 
Potassium  acting  on  the  compound  gas 
produces  a  solid  chloride  and  charcoal. 
White  oxide  of  zinc,  with  chloro-carbonous 
acid,  gives  a  metallic  chloride,  and  carbo- 
nic acid.  Neither  sulphur,  phosphorus,  oxy- 
gen, nor  hydrogen,  though  aided  by  heat, 


produce  any  change  on  the  acid  gas.  But 
oxygen  and  hydrogen  together,  in  due  pro- 
portions, explode  in  it;  or  mere  exposure 
to  water,  converts  it  into  muriatic  and  car- 
bonic acid  gases. 

From  its  completely  neutralizing  ammo- 
nia, which  carbonic  acid  does  not;  from  its 
separating  carbonic  acid  from  the  subcar- 
bonate  of  this  alkali,  while  itself  is  not  se- 
parable by  the  acid  gases,  or  acetic  acid; 
and  its  reddening  vegetable  blues,  there 
can  be  no  hesitation  in  pronouncing  the 
chloro-carbonous  compound  to  be  an  acid. 
Its  saturating  powers  indeed  surpass  every 
other  substance.  None  condenses  so  large 
a  proportion  of  ammonia. 

One  measure  of  alcohol  condenses  twelve 
of  chloro-carbonous  gas  without  decompos- 
ing it;  and  acquires  the  peculiar  odour  and 
power  of  affecting  the  eyes. 

To  prepare  the  gas  in  a  pure  state,  a 
good  air  pump  is  required,  perfectly  tight 
stop-cocks,  dry  gases,  and  dry  vessels.  Its 
specific  gravity  may  be  inferred  from  the 
specific  gravity  of  its  constituents,  of  which 
it  is  the  sum.  Hence  2.4733  -f  0.9722  = 
3.4455,  is  the  specific  gravity  of  chloro- 
carbonous  gas;  and  100  cubic  inches  weigh 
105.15.  grains.  It  appears  that  when  hydro- 
gen, carbonic  oxide,  and  chlorine,  mixed 
in  equal  volumes,  are  exposed  to  light, 
muriatic  and  chloro-carbonous  acids  are 
formed,  in  equal  proportions,  indicating 
an  equality  of  affinity. 

The  paper  in  the  Phil.  Trans,  for  1812, 
from  which  the  preceding  facts  are  taken, 
does  honour  to  the  school  of  Sir  H.  Davy. 
MM.  Gay-Lussac  and  Thenard,  as  well  as 
Dr.  Murray,  made  controversial  investiga- 
tions on  the  subject  at  the  same  time,  but 
without  success.  M.  Thenard  has,  however, 
recognized  its  distinct  existence  and  pro- 
perties, by  the  name  of  carbo -muriatic  acid, 
in  the  2d  volume  of  his  System,  published 
in  1814,  where  he  considers  it  as  a  com- 
pound of  muriatic  and  carbonic  acids,  re- 
suiting  from  the  mutual  actions  of  the  oxy- 
genated muriatic  acid,  and  carbonic  oxide.* 

*  CHLOROUS  and  CHLORIC  OXIDES,  or 
the  protoxide  and  deutoxide  of  chlorine. 

Both  of  these  interesting  gaseous  com- 
pounds were  discovered  by  Sir  H.  Davy. 

1st,  The  experiments  which  led  him  to 
the  knowledge  of  the  first,  were  instituted 
in  consequence  of  the  difference  he  had 
observed  between  the  properties  of  chlo- 
rine, prepared  in  different  modes.  The  pa- 
per describing  the  production  and  proper- 
ties of  the  chlorous  oxide,  was  published 
in  the  first  part  of  the  Phil.  Trans,  for  1811. 
To  prepare  it,  we  put  chlorate  of  potash 
into  a  small  retort,  and  pour  in  twice  as 
much  muriatic  acid  as  will  cover  it,  diluted 
with  an  equal  volume  of  water.  By  the  ap- 
plication of  a  gentle  heat,  the  gas  is  evolved. 
It  must  be  collected  over  mercury. 


CHL 


CHL 


Its  tint  is  much  more  lively,  and  more 
yellow  than  chlorine,  and  hence  its  illus- 
trious discoverer  named  it  euchlorine.  Its 
smell  is  peculiar,  and  approaches  to  that 
of  burnt  sugar.  It  is  not  respirable.  It  is 
soluble  in  water,  to  which  it  gives  a  lemon 
colour.  \Vater  absorbs  8  or  10  times  its  vo- 
lume of  this  gas.  Its  specific  gravity  is  to 
that  of  common  air  nearly  as  2.40  to  1;  for 
100  cubic  inches  weigh,  according  to  Sir 
H.  Davy,  between  74  and  75  grains.  If  the 
compound  gas  result  from  4  volumes  of 
chlorine  -j-  2  of  oxygen,  weighing  12.1154, 
which  undergo  a  condensation  of  one-sixth, 
then  the  specific  gravity  comes  out  2.42.), 
in  accordance  with  Sir  H.  Davy's  expe- 
riments. He  found  that  50  measures  deto- 
nated in  a  glass  tube  over  pure  mercury, 
lost  their  brilliant  colour,  and  became  60 
measures;  of  which  40  were  chlorine,  and 
20  oxygen.  Dr.  Thomson  states  2.407  for 
the  sp.  gr.,  though  his  own  data,  when 
rightly  calculated  upon,  give  2.444. 

This  gas  must  be  collected  and  examined 
with  much  prudence,  and  in  very  small 
quantities.  A  gentle  heat,  even  that  of  the 
hand,  will  cause  its  explosion,  with  such 
force  as  to  burst  thin  glass.  From  this  fa- 
cility of  decomposition,  it  is  not  easy  to 
ascertain  the  action  of  combustible  bodies 
upon  it.  None  of  the  metals  that  burn  in 
chlorine  act  upon  this  gas  at  common  tem- 
peratures; but  when  the  oxygen  is  sepa- 
rated, they  then  inflame  in  the  chlorine. 
This  may  be  readily  exhibited  by  first  in- 
troducing into  the  protoxide  a  little  Dutch 
foil,  which  will  not  be  even  tarnished;  but 
on  applying  a  heated  glass  tube  to  the  gas 
in  the  neck  of  the  bottle,  decomposition 
instantly  takes  place,  and  the  foil  burns 
with  brilliancy.  When  already  in  chemical 
union,  therefore,  chlorine  has  a  stronger 
attraction  for  oxygen  than  for  metals;  but 
when  insulated,  its  affinity  for  the  latter  is 
predominant.  Protoxide  of  chlorine  has  no 
action  on  mercury,  but  chlorine  is  rapidly 
condensed  by  this  metal  into  calomel.  Thus 
the  two  gases  may  be  completely  separated. 
When  phosphorus  is  introduced  into  the 
protoxide,  it  instantly  burns,  as  it  would 
do  in  a  mixture  of  two  volumes  of  chlorine 
and  one  of  oxygen;  and  a  chloride  and  acid 
of  phosphorus  result.  Lighted  taper  and 
burning1  sulphur  likewise  instantly  decom- 
pose it.  When  the  protoxide  freed  from 
water  is  made  to  act  on  dry  vegetable  co- 
lours, it  gradually  destroys  them,  but  first 
gives  to  the  blues  a  tint  of  red;  from  which, 
from  its  absorbability  by  water,  and  the 
strongly  acrid  taste  of  the  solution  ap- 
proaching to  sour,  it  may  be  considered  as 
approximating  to  an  acid  in  its  nature. 
Since  2  volumes  of  chlorine  weigh  (2  X 
2.4733)  4.9466,  and  1  of  oxygen  1.1111;  we 
have  4.45  -f-  1.  =  5.45  for  the  prime  equi- 
valent Of  chlorous  oxide,  on  {lie  oxygen 


scale.  The  proportion  by  weight  in  100 
parts  is  81.65  chlorine  -{-  18.35  oxygen. 

2d,  Deut  oxide  of  Chlorine,  or  Chloric  Ox- 
ide.  "  On  Thursday  the  4th  May,  a  paper 
by  Sir  H.  Davy  was  read  at  the  Royal  So- 
ciety, on  the  action  of  acids  on  hyper-oxy- 
muriate  of  potash.  When  sulphuric  acid  is 
poured  upon  this  salt  in  a  wine-glass,  very 
little  effervescence  takes  place,  but  the 
acid  gradually  acquires  an  orange  colour, 
and  a  dense  yellow  vapour,  of  a  peculiar 
and  not  disagreeable  smell,  floats  on  the 
surface.  These  phenomena  led  the  author 
to  believe,  that  the  substance  extricated 
fi  oin  the  salt  is  held  in  solution  by  the  acid. 
After  various  unsuccessful  attempts  to  ob- 
tain this  substance  in  a  separate  state,  he 
at  last  succeeded  by  the  following  method: 
About  60  grains  of  the  salt  are  triturated 
with  a  little  sulphuric  acid,  just  sufficient 
to  convert  them  into  a  very  solid  paste. 
This  is  put  into  a  retort,  which  is  heated 
by  means  of  hot  water.  The  water  must 
never  be  allowed  to  become  boiling  hot, 
for  fear  of  explosion.  The  heat  drives  off 
the  new  gas,  which  may  be  received  over 
mercury.  This  new  gas  has  a  much  more 
intense  colour  than  euchlorine.  It  does  not 
act  on  mercury.  Water  absorbs  more  of  it 
than  of  euchlorine.  Its  taste  is  astringent. 
It  destroys  vegetable  blues  without  red- 
dening them.  When  phosphorus  is  intro- 
duced into  it,  an  explosion  takes  place. 
When  heat  is  applied,  the  gas  explodes 
with  more  violence,  and  producing  more 
light  than  euchiorine.  When  thus  exploded, 
two  measures  of  it  are  converted  into 
nearly  three  measures,  which  consist  of  a 
mixture  of  one  measure  chlorine,  and  two 
measures  oxygen.  Hence,  it  isfcomposed  of 
one  atom  chlorine  and  four  atoms  oxygen." 

I  have  transcribed  the  above  abstract  of 
Sir  II.  Davy's  paper  from  the  number  of 
Dr.  Thomson's  Annuls  for  June  1815,  in  or- 
der to  confront  it  with  the  following-  state- 
ment in  his  System,  5th  edition,  vol.  i,  page 
189:  "  The  deutoxide  of  chlorine  was  dis- 
covered about  the  same  time  by  Sir  Hum- 
phry Davy  and  Count  Von  Stadion  of  Vi- 
enna; but  Davy's  account  of  it  was  publish- 
ed sooner  than  that  of  Count  Von  Stadion. 
Davy's  account  is  published  in  the  F'hiloso- 
phical  Transactions  for  1815,  p.  214.  Count 
Von  Stadion's  in  Gilbert's  Annalen  der  Phy- 
sick,  52.  179.  published  in  February,  1816." 

Sir  H.  Davy's  paper  bears  date  "  Rome, 
February  15th,  1815."  There  is  therefore 
an  interval  of  fully  twelve  months  between 
the  transmission  of  Sir  H.  Davy's  discovery 
for  publication,  and  the  promulgation 
of  Count  Von  Stadion's  paper;  and  an  in- 
terval of  nine  months  between  the  actual 
publication  of  the  first,  by  the  reading  of 
it  before  the  Royal  Society  of  England, 
and  the  appearance  of  the  second,  in  Gil- 
bert's Annalen.  I  do  not  wish  to  insinuate 


CHL 


CHR 


that  the  Count  copied  from  the  English 
philosopher;  but  1  maintain,  that  according 
to  every  principle  of  literary  justice,  the 
reputation  of  the  discovery  entirely  belongs 
to  Sir  H.  Davy. 

Even  the  volume  of  the  Transactions  for 
1815,  which  one  is  left  to  infer  might  come 
forth  only  in  1816,  must  have  been  pub- 
lished earlier,  for  Tilloch's  Magazine  ^for 
December  1815,  contains  the  whole  of  Sir 
H.  Davy's  paper. 

The  preceding  abstract,  circulated  over 
Europe  seven  or  eight  months  before  the 
52d  volume  of  Gilbert's  Annalen  appeared 
is  so  copious  as  to  require  few  additions. 

Deutoxide  of  chlorine  has  a  peculiar  aro- 
matic odour,  unmixed  with  any  smell  of 
chlorine.  A  little  chlorine  is  always  ab- 
sorbed by  the  mercury  during  the  explo- 
sion of  the  gas.  Hence  the  small  deficiency 
of  the  resulting  measure  is  accounted  for. 
At  common  temperatures  none  of  the  sim- 
ple combustibles  which  Sir  H  Davy  tried, 
decomposed  the  gas,  except  phosphorus. 
The  taste  of  the  aqueous  solution  is  ex- 
tremely astringent  and  corroding,  leaving 
for  a  long  while  a  very  disagreeable  sensa- 
tion. The  action  of  liquid  nitric  acid  on  the 
chlorate  of  potash  affords  the  same  gas, 
and  a  much  larger  quantity  of  this  acid 
may  be  safely  employed  than  of  the  sul- 
phuric. But  as  the  gas  must  be  procured 
by  solution  of  the  salt,  it  is  always  mixed 
with  about  one-fifth  of  oxygen. 

Since  two  measures  of  this  gas,  at  212°, 
explode  and  form  three  measures  of  min- 
gled gases,  of  which  two  are  oxygen  and 
one  chlorine;  its  composition  by  weight  is 
Oxygen,  2.2222  4  primes,  4.00  47,33 
Chlorine,  2.4733  1  do.  4.45  52.67 

8.45  100.00 

Its  specific  gravity  is  2.3477;  and  hence  100 
cubic  inches  of  it  weigh  about  77  grains. 

Having  completed  the  account  of  this  in- 
teresting compound,  it  may  be  worth  while 
to  copy  a  note  from  the  190th  page  of  Dr. 
Thomson's  1st  volume,  to  show  the  con- 
sistency of  his  opinions,  in  one  leaf  of  his 
System.  "  According  to  Count  Von  Stadion, 
its  constituents  are  two  volumes  chlorine, 
and  three  volumes  oxygen.  This  would 
make  it  a  compound  of  one  atom  chlorine, 
and  three  atoms  oxygen.  But  the  proper- 
ties of  the  substance  described  by  the 
Count  differ  so  much  from  those  of  the  gas 
examined  by  Davy,  that  it  is  probable  they 
are  distinct  substances."  So  that  after  all, 
Count  Von  Stadion  has  got  a  deutoxide  of 
chlorine  to  himself,  without  interfering 
with  Sir.  H.  Davy's  property.  We  shall  leave 
him  to  enjoy  it,  with  the  following  intima- 
tion by  his  commentator: — "  The  reader 
will  find  an  account  of  the  properties  of  the 
deutoxide  of  chlorine  of  Count  Von  Stadion, 
in  the  Annals  of  Philosophy,  vol.  ix.  p.  22." 


CHLOROPHILE.  The  name  lately  given 
by  MM.  Pelletier  and  Caventou  to  the 
green  matter  of  the  leaves  of  plants.  They 
obtained  it,  by  pressing  and  then  washing 
in  water,  the  substance  of  many  leaves,  and 
afterwards  treating  it  with  alcohol.  A  mat- 
ter was  dissolved,  which  when  separated 
by  evaporation,  and  purified  by  washing  in 
hot  water,  appeared  as  a  deep  green  resin- 
ous substance.  It  dissolves  entirely  in  alco- 
hol, ether,  oils,  or  akalis;  it  is  not  altered 
by  exposure  to  air;  it  is  softened  by  heat, 
but  does  not  melt;  it  burns  with  flame,  and 
leaves  a  bulky  coal.  Hot  water  slightly  dis- 
solves it.  Acetic  acid  is  the  only  acid  that 
dissolves  it  in  great  quantity-  If  an  earthy 
or  metallic  salt  be  mixed  with  the  alco- 
holic solution,  and  then  alkali  or  alkaline 
subcarbonate  be  added,  the  oxide  or  earth 
is  thrown  down  in  combination  with  much 
of  the  green  substance,  forming  a  lake. 
These  lakes  appear  moderately  permanent 
when  exposed  to  the  air.  It  is  supposed  to 
be  a  peculiar  proximate  principle. 

The  above  learned  term  should  be  spel- 
led with  a  y,  chiorophyle,  to  signify  the 
green  of  leaf,  or  leaf-green:  chlorophile, 
with  an  z,  has  a  different  etymology,  and 
a  different  meaning.  It  signifies  fond  of 
green. 

CHOLESTERINE.  The  name  given  by  M. 
Chevreul  to  the  pearly  substance  of  human 
biliary  calculi.  It  consists  of  72  carbon, 
6.66  oxygen,  and  21.33  hydrogen,  by  Be- 
rard. 

CHOLESTERIC  ACID.  By  heating  choles- 
terine  with  its  own  weight  of  strong  nitric 
acid  until  it  ceases  to  give  off  nitrous  gas, 
MM.  Pelletier  and  Caventou  obtained  a 
yellow  substance,  which  separated  on  cool- 
ing, and  was  scarcely  soluble  in  water. 
When  well  washed,  this  is  cholesteric  acid. 
It  is  soluble  in  alcohol,  and  may  be  crystal- 
lized by  evaporation.  It  is  decomposed  by 
a  heat  above  that  of  boiling  water,  and 
gives  products  having  oxygen,  hydrogen, 
and  charcoal,  for  their  elements.  It  com- 
bines with  bases,  and  forms  salts.  Those  of 
soda,  potash,  and  ammonia,  are  very  solu- 
ble; the  rest  are  nearly  insoluble. 

*  CHROMIUM.  This  rare  metal  may  be 
extracted  either  from  the  native  chromate 
of  lead  or  of  iron.  The  latter  being  cheap- 
est and  most  abundant,  is  usually  employ- 
ed. 

The  brown  chromate  of  iron  is  not  acted 
upon  by  nitric  acid,  but  most  readily  by  ni- 
trate of  potash,  with  the  aid  of  a  red  heat. 
A  chromate  of  potash,  soluble  in  water, 
is  thus  formed.  The  iron  oxide  thrown  out 
of  combination  may  be  removed  from  the 
residual  part  of  the  ore  by  a  short  diges- 
tion in  dilute  muriatic  acid.  A  second  fu- 
sion with  ^th  of  nitre,  will  give  rise  to  a 
new  portion  of  chromate  of  patash.  Having 
decomposed  the  whole  of  the  ore,  we  satu- 


CHR 


CHE, 


rate  the  alkaline  excess  with  nitric  acid, 
evaporate  and  crystallize.  The  pare  crys- 
tals dissolved  in  water,  are  to  be  added  to 
a  solution  of  neutral  nitrate  of  mercury; 
whence  by  complex  affinity,  red  chromate 
of  mercury  precipitates.  Moderate  ignition 
expels  the  mercury  from  the  chromaie, 
and  the  remaining'  chromic  acid  may  be  re- 
duced to  the  metallic  state,  by  being1  ex- 
posed, in  contact  of  the  charcoal  from  su- 
gar, to  a  violent  heat. 

Chromium  thus  procured,  is  a  porous 
mass  of  agglutinated  grains.  It  is  very  brit- 
tle, and  of  a  grayish-white,  intermediate 
between  tin  and  steel.  It  is  sometimes  ob- 
tained in  needleform  crystals,  which  cross 
each  other  in  all  directions.  Its  sp.  gravity 
is  5.9.  It  is  susceptible  of  a  feeble  magnet- 
ism. It  resists  all  the  acids  except  nitro- 
muriatic,  which,  at  a  boiling  heat,  oxidizes 
it  and  forms  a  muriate.  M.  Thenard  de- 
scribes only  one  oxide  of  chromium;  but 
there  are  probably  two,  besides  the  acid 
already  described. 

1.  The  protoxide  is  green,  infusible,  in- 
decomposable by  heat,  reducible  by  voltaic 
electricity,  and  not  acted  on  by  oxygen  or 
air.   When  heated  to  dull  redness  with  the 
half  of  its  weight  of  potassium  or  sodium, 
it  forms  a  brown  matter,  which,  cooled  and 
exposed  to  tiie  air,  burns  with  fhime,  and 
is  transformed  into  chromate  of  potash  or 
soda,  of  a  canary-yellow  colour.  It  is  this 
oxide  which  is  obtained  by  calcining  the 
chromate   of  mercury  in  a  small  earthen 
retort  for  about  £  of  an  hour.  The  beak  of 
the  retort  is  to  be  surrounded  with  a  tube 
of  wet  linen,  and  plunged  into  water,  to  fa- 
cilitate the   condensation  of  the  mercury. 
The  oxide,  newly  precipitated  from  acids, 
has  a  dark  green  colour,  and  is  easily  re- 
dissolved;  but  exposure  to  a  dull  red  heat 
ignites  it,  and  renders  it  denser,  insoluble, 
and  of  a  light  green  colour.  This  change 
arises  solely  from  the  closer  aggregation 
of  the   particles,  for  the  weight  is  not  al- 
tered. 

2.  The  deutoxide  is  procured  by  expos- 
ing- the  protonitrate  to  heat,  till  the  fumes 
of  nitrous  gas  cease  to  issue.    A  brilliant 
brown    powder,    insoluble    in    acids,    and 
scarcely   soluble  in  alkalis,  remains.    Mu- 
riatic acid  digested  on  it,  exhales  chlorine, 
showing  the  increased  proportion  of  oxy- 
gen in  this  oxide. 

3.  The  tritoxide  has  been  already  descri- 
bed among  the  acids.  It  may  be  directly 

i  procured  by  adding  nitrate  of  lead  to  the 
'above  nitrochromate  of  potash,  and  digest- 
ing the  beautiful  orange  precipitate  of 
chromate  of  lead  with  moderately  strong 
muriatic  acid,  till  its  power  of  action  be  ex- 
hausted. The  fluid  produced  is  to  he  pass- 
ed through  a  filter,  and  a  little  oxide  of 
'  silver,  very  gradually  added,  till  the  whole 
VOL.  1. 


solution  becomes  of  a  deep  red  tint.  This 
liquor,  by  slow  evaporation,  depositcs  small 
ruby-red  crystals,  which  are  the  hydrated 
chromic  acid.  The  prime  equivalent  of 
chromic  acid  deduced  from  the  chromates 
of  barytes  and  lead  by  Berzelius,  is  6.544, 
if  we  suppose  them  to  be  neutral  salts.  Ac- 
cording to  this  chemist,  the  acid  contains 
double  the  oxygen  that  the  green  oxide 
does.  But  if  these  chromates  be  regarded 
as  subsalts,  then  the  acid  prime  would  be 
13.088,  consisting  of  6  oxygen  -f  7.088, 
metal;  while  the  protoxide  would  consist 
of  3  oxygen-J-7  088  metal;  and  the  deutox- 
ide, of  an  intermediate  proportion.* 

*  CHRYSOBERYL.    Cymophcwt:  of  Hatty. 
This  mineral  is  usually  got  in  round  pieces 
about  the  size  of  a  pea,  but  it  is  found  crys- 
tallized in  eight-sided  prisms,  terminated 
by  six-sided  summits.  Colour,  asparagus 
green;  lustre,  vitreous;  fracture,  conchoi- 
dal;  it  is  semi-transparent,  and  brittle,  but 
scratches  quartz  and  beryl.  Sp.  gr  3.76.  It 
is  infusible   before   the   blow-pipe.   It  has 
double  refraction,  and  becomes  electric  by 
friction.  Its  primitive  form  is  a  rectangular 
parallelopiped.  Its  constituents,  according 
to  Klaproth,  are  71   alumina,  18  silica,  6 
lime,  and  1£  oxide  of  iron. 

The  summits  of  the  p:isms  of  chrysobe- 
ryl,  are  sometimes  so  cut  into  facettes, 
that  the  solid  acquires  28  faces  It  is  found 
at  Brazil,  Ceylon,  Connecticut,  and  perhaps 
Nertschink  in  Siberia.  This  mineral  has  no- 
thing to  do  with  the  chrysoberyl  of  Pliny, 
which  was  probably  a  variety  of  beryl  of  a 
greenish-yellow  colour.* 

CHRYSOCOLLA.  The  Greek  name  for 
borax. 

*CHRYSOLITE.  Peridot  of  Hatty.  Topaz 
of  the  ancients,  while  our  topaz  is  their 
chrysolite.  Chrysolite  is  the  least  hard  of 
all  the  gems.  It  is  scratched  by  quartz  and 
the  file.  Its  crystals  are  well  formed  com- 
pressed prisms,  of  eight  sides  at  least,  ter- 
minated by  a  wedged  form  or  pyramidal 
summit,  truncated  at  the  apex.  Its  primi- 
tive form  is  a  right  prism,  with  a  rectan- 
gular base.  It  has  a  strong  double  refrac- 
tion, which  is  observed  in  looking  across 
one  of  the  large  sides  of  the  summit,  and 
the  opposite  face  of  the  prism  The  lateral 
planes  are  longitudinally  streaked.  The  co- 
lour is  pistachio  green,  and  other  shades. 
External  lustre  splendent.  Transparent; 
fracture,  conchoidal.  Scratches  feldspar. 
Brittle.  Sp  gr.  3.4.  With  borax,  it  fuses  in- 
to a  pale  green  glass.  Its  constituents  are 
39  silica,  43.5  magnesia,  19  of  oxide  of  iron, 
according  to  Klaproth;  but  Vauquelin  found 
38,  50.5,  and  9.5.  Chrysolite  comes  from 
Egypt,  where  it  is  found  in  alluvial  strata. 
It  has  also  Ixen  found  in  Bohemia,  and  in 
the  circle  of  Bunzlau.* 

*  CHRYSOPRASE.  A  variety  of  calcedony. 

57 


CHY 


CIN 


It  is  either  of  an  apple  or  leek-green  colour. 
Its  fracture  is  even,  waxy,  sometimes  a  lit- 
tle splintery.  Translucent,  with  scarcely  any 
lustre.  Softer  than  calcedony,  and  rather 
tough.  Sp.  gr.  2.5.  A  strong  heat  whitens 
it.  It  consists  of  96.16  silica,  0.08  alumina, 
0.83  lime,  0.08  oxide  of  iron,  and  1  oxide 
of  nickel,  to  which  it  probably  owes  its  co- 
lour. It  has  been  found  hitherto  only*  at 
Kosemiitz  in  Upper  Silesia.  The  mountains 
which  enclose  it,  are  composed  chiefly  of 
serpentine,  potstone,  talc,  snd  other  unctu- 
ous rocks  that  almost  all  contain  magnesia. 
It  is  found  in  veins  or  interrupted  beds  in 
the  midst  of  a  green  earth  which  contains 
nickel.  It  is  used  in  jewellery.* 

*  CHUSITE.  A  mineral  found  by  Saus- 
sure  in  the  cavities  of  porphyries  in  the 
environs  of  Limbourg.  It  is  yellowish  or 
greenish   and  translucent;  its  fracture  is 
sometimes  perfectly  smooth,  and  its  lustre 
greasy;  at  other  times  it  is  granular.  It  is 
very  brittle.  It  melts  easily  into  a  translucid 
enamel,  enclosing  air  babbles.  It  dissolves 
entirely  and  without  effervescence  in  acids.* 

*  CHYLE.  By  the  digestive  process  in  the 
stomach  of  animals,  the  food  is  converted 
into  a  milky  fluid,  called  chyme,  which  pass- 
ing into  the  intestines  is  mixed  with  pan- 
ereatic  juice  and  bile,  and  thereafter  re- 
solved into  chyle  and  feculent  matter.  The 
former  is  taken  up  by  the  lacteal  absorbent 
vessels  of  the  intestines,  which  coursing 
along  the  mesenteric  web,  terminate  in  the 
thoracic  duct.  This  finally  empties  its  con- 
tents into  the  vena  cava. 

Chyle  taken  soon  after  the  death  of  an 
animal,  from  the  thoracic  duct,  resembles 
milk  in  appearance.  It  has  no  smell,  but  a 
slightly  acido-saccharine  taste;  yet  it  blues 
reddened  litmus  paper,  by  its  unsaturated 
alkali.  Soon  after  it  is  drawn  from  the  duct, 
it  separates  by  coagulation  into  a  thicker 
and  thinner  matter.  l.The  former,  or  curd, 
seems  intermediate  between  albumen  and 
fibrin.  Potash  and  soda  dissolve  it,  with  a 
slight  exhalation  of  ammonia.  Water  of 
ammonia  forms  with  it  a  reddish  solution. 
Dilute  sulphuric  acid  dissolves  the  coagu- 
lum; and  very  weak  nitric  acid  changes  it 
into  adipocere.  By  heat,  it  is  converted  in- 
to a  charcoal  of  difficult  incineration,  which 
contains  common  salt  and  phosphate  of 
lime,  with  minute  traces  of  iron.  2.  From 
the  serous  portion,  heat,  alcohol,  and  acids, 
precipitate  a  copious  coagulum  of  albumen. 
If  the  alcohol  be  hot,  a  little  matter  analo- 
gous to  the  substance  of  brain  is  subse- 
quently deposited.  By  evaporation  and  cool- 
ing, Mr.  Brande  obtained  crystals  analo- 
gous to  the  sugar  of  milk.  Dr.  Marcet 
found  the  chyle  of  graminivorous  animals 
thinner  and  darker,  and  less  charged  with 
albumen,  than  that  of  carnivorous.  In  the 
former,  the  weight  of  the  fluid  part  to  that 
of  the  coagulum  was  nearly  2  to  1;  but  a 


serous  matter  afterwards  oozed  out,  which 
reduced  the  clot  to  a  very  small  volume.* 

*  CHYME.   Dr.  Marcet  examined  chyme 
from  the  stomach  of  a  turkey.  It  was  a  ho- 
mogeneous, brownish  opaque  pulp,  having 
the  smell  peculiar  to  poultry.  It  was  nei- 
ther acid  nor  alkaline,  and  left  one-fifth  of 
solid  matter  by  evaporation.  It  contained 
albumen.  From  the   incineration  of  1000 
parts,    12   parts  of  charcoal  resulted,   in 
which  iron,  lime,  and  an  alkaline  muriate 
were  distinguished.     See  DIGESTION.* 

ClMOLITK,  Or  ClMGT.IAN  EARTH.  The 

cimolia  of  Pliny,  which  was  used  both  me- 
dicinally and  for  cleaning  cloths  by  the 
ancients,  and  which  has  been  confounded 
with  fullers'  earth  and  tobacco-pipe  clay, 
has  lately  been  brought  from  Argentiera, 
the  ancient  Cimolus  by  Mr.  Hawkins,  and 
examined  by  Klaproth. 

It  is  of  a  light  grayish-white  colour,  ac- 
quiring superficially  a  reddish  tint  by  ex- 
posure to  the  air;  massive;  of  an  earthy, 
uneven,  more  or  less  slaty  fracture;  opaque; 
when  shaved  with  a  knife,  smooth  and  of  a 
greasy  lustre;  tenacious,  so  as  not  without 
difficulty  to  be  powdered  or  broken;  and 
adhering  pretty  firmly  to  the  tongue.  Its 
specific  g'ravitv  is  2.  It  is  immediately  pe- 
netrated by  water,  and  deve'opes  itself  into 
thin  laminae  of  a  curved  slaty  form.  Tritu- 
rated with  water  it  forms  a  pappy  mass; 
and  100  grains  will  give  three  ounces  of 
water  the  appearance  and  consistence  of  a 
thick ish  cream.  If  left  to  dry  after  being 
thus  ground,  it  detaches  itself  in  hard 
bands,  somewhat  flexible,  and  still  more 
difficult  to  pulverize  than  before. 

It  appeared  on  analysis  to  consist  of  si- 
lex  63,  alumina  23,  oxide  of  iron  1.25,  wa- 
ter 12. 

Ground  with  water,  and  applied  to  silk 
and  woollen,  greased  with  oil  of  almonds, 
the  oil  was  completely  discharged  by  a 
slight  washing  in  water,  after  the  stuffs  had 
been  hung  up  a  day  to  dry,  without  the  least 
injury  to  the  beauty  of  the  colour.  Mr. 
Klaproth  considers  it  as  superior  to  our  best 
fullers'  earth;  and  attributes  its  properties 
to  the  minutely  divided  state  of  the  silex, 
and  its  intimate  combination  with  the  alu- 
mina. It  is  still  used  by  the  natives  of  Ar- 
gentiera for  the  same  purposes  as  of  old. 

According  to  Olivier  the  island  of  Argen- 
tiera is  entirely  volcanic,  and  the  cimolian 
earth  is  produced  by  a  slow  and  gradual 
decomposition  of  the  porphyries,  occasion, 
ed  by  subterranean  fires.  He  adds,  that  he 
collected  specimens  of  it  in  all  the  states 
through  which  it  passes. 

*  CINCHONA.  The  quinquina  and  kina of 
the  French,  is  the  bark  of  several  species 
of  cinchona,  which  grow  in  South  America. 
Of  this  bark  there  are  three  varieties,  the 
red,  the  yellow,  and  the  pale. 

1.  The  red  is  in  large,  easily  pulverized 


CIN 


pieces,  which  furnish  a  reddish-brown  pow- 
der, having  a  bitter  astringent  taste.  The 
watery  infusion  reddens  vegetable  blues, 
from  some  free  citric  acid.  It  contains  also 
muriates  of  ammonia  and  lime.  The  bark 
contains  extractive,  resin,  bitter  principle, 
and  tannin.  2.  The  yellow  Peruvian  burk,was 
first  brought  to  this  country  about  the  year 
1790;  and  it  resembles  pretty  closely  in 
composition,  the  red  species,  only  it  yields 
a  good  deal  of  kinate  of  lime  in  plates.  3 
The  pale  cinchona  is  that  generally  em- 
ployed in  medical  practice,  as  a  tonic  and 
febrifuge.  M.  Vauquelin  made  infusions  of 
all  the  varieties  of  cinchona  he  could  pro- 
cure, using  the  same  quantities  of  the  barks 
and  water,  and  leaving  the  powders  infus- 
ed for  the  same  time.  He  observed,  1.  That 
certain  infusions  were  precipitated  abun- 
dantly by  infusion  of  galls,  by  solution  of 
glue,  and  tartar  emetic.  2.  That  some  were 
precipitated  by  glue,  but  not  by  the  two 
other  reagents;  and  3.  That  others  were,  on 
the  contrary,  by  nutgalls  and  tartar  emetic, 
without  being  affected  by  glue.  4.  And  that 
there  were  some  which  yielded  no  precipi- 
tate by  nutgalls,  tannin,  or  emetic  tartar. 
The  cinchonas  that  furnished  the  first  infu- 
sion were  of  excellent  quality;  those  that 
afforded  the  fourth  were  not  febrifuge, 
while  those  that  gave  the  second  and  third, 
were  febrifuge,  but  in  a  smaller  degree 
than  the  first.  Besides  mucilage,  kinate  of 
lime,  and  woody  fibre,  he  obtained  in  his 
analyses,  a  resinous  substance,  which  ap- 
pears not  to  be  identic  in  all  the  species  of 
bark.  It  is  very  bitter;  very  soluble  in  alco- 
hol, in  acids  and  alkalis;  scarcely  soluble 
in  cold  water,  but  more  soluble  in  hot.  It  is 
this  body  which  gives  to  infusions  of  cin- 
chona, the  property  of  yielding  precipitates 
by  emetic  tartar,  galls,  gelatin;  and  in  it, 
the  febrifuge  virtue  seems  to  reside.  It  is 
this  substance  in  part,  which  falls  down, 
on  cooling  decoctions  of  cinchona,  and  from 
concentrated  infusions.  A  table  of  precipi- 
tations by  glue,  tannin,  and  tartar  emetic, 
from  infusions  of  different  barks,  has  been 
given  by  M.  Vauquelin;  but  as  the  particu- 
lar species  are  difficult  to  define,  we  shall 
not  copy  it.* 

CINCHONIN.   See  the  preceding  article. 

CINNABAR.  An  ore  of  mercury,  consist- 
ing of  that  metal  united  with  sulphur. 

*  CINNAMON  STONE.  The  colours  of 
this  rare  mineral  are  blood-red,  and  hya- 
cinth-red, passing  into  orange-yellow.  It  is 
found  always  in  roundish  pieces;  lustre 
splendent;  fracture  imperfect  conchoidal; 
fragments  angular;  transparent  and  semi- 
transparent;  scratches  quartz  with  difficul- 
ty; somewhat  brittle;  sp.  gr.  3.53;  fuses  in- 
to a  brownish-black  enamel.  Its  constitu- 
ents are  38.8  silica,  21.2  alumina,  31.25 
lime,  and  6.5  oxide  of  iron.  It  is  found  in 
the  sand  of  rivers,  in  Ceylon.* 


CLA 

CIPOLIN.  The  cipolin  from  Rome  is  a 
green  marble  with  white  zones:  it  gives 
fire  with  steel,  though  difficultly.  One  hun- 
dred parts  of  it  contain  67.8  of  carbonate 
of  lime;  25  of  quartz;  8  of  schistus;  0.2  of 
iron,  beside  the  iron  contained  in  the  schis- 
tus. The  cipolin  from  Autun,  83  parts  car- 
bonate of  lime,  12  of  green  mica,  and  one 
of  iron. 

*CISTIC  OXIDE  A  peculiar  animal  pro- 
duct, discovered  by  Dr.  Wollaston.  It  con- 
stitutes a  variety  of  urinary  CALCULUS, 
which  see.* 

*  CITRIC  ACID.  Acid  of  limes.  It  has 
been  found   nearly    unmixed,   with  other 
acids,   not   only   in   lemons,    oranges  and 
limes,  but  also  in  the  berries  of  vaccinium 
oxycoccns,  or  cranberry,  vaccinhtm  vitisidteat 
or  red  whortleberry,  of  birdcherry,  night- 
shade, hip,  in  unripe  grapes  and  tamarinds. 
Gooseberries,    currants,   bilberries,  beam- 
berries,   cherries,   strawberries,  cloudber- 
ries,  and  raspberries,   contain   citric  acid 
mixed  with  an  equal  quantity  of  malic  acid. 
The  onion  yields  citrate  of  lime.  See  ACID 
(CITRIC).* 

CIVET  is  collected  betwixt  the  anus  and 
the  organs  of  generation  of  a  fierce  carni- 
vorous quadruped  met  with  in  China  and 
the  East  and  West  Indies,  called  a  civet- 
cat,  but  bearing  a  greater  resemblance  to 
a  fox  or  marten  than  a  cat. 

Several  of  these  animals  have  been 
brought  into  Holland,  and  afford  a  consi- 
derable branch  of  commerce,  particularly 
at  Amsterdam.  The  civet  is  squeezed  out, 
in  summer  every  other  day,  in  winter  twice 
a  week:  the  quantity  procured  at  once  is 
from  two  scruples  to  a  drachm  or  more. 
The  juice  thus  collected  is  much  purer  and 
finer  than  that  which  the  animal  sheds 
against  shrubs  or  stones  in  its  native  cli- 
mates 

Good  civet  is  of  a  clear  yellowish  OP 
brownish  colour,  not  fluid,  nor  hard,  but 
about  the  consistence  of  butter  or  honey, 
and  uniform  throughout;  of  a  very  strong 
smell;  quite  offensive  when  undiluted;  but 
agreeable  when  only  a  small  portion  of 
civet  is  mixed  with  a  large  one  of  other 
substances. 

*  Civet  unites  with  oils,  but  not  with 
alcohol.     Its  nature  is  therefore  not  resin- 
ous.* 

CLARIFICATION  is  the  process  of  free- 
ing a  fluid  from  heterogeneous  matter  or 
feculencies,  though  the  term  is  seldom  ap- 
plied to  the  mere  mechanical  pi-ocess  of 
straining,  for  which  see  FILTRATION. 

Albumen,  gelatin,  acids,  certain  salts, 
lime,  blood,  and  alcohol,  in  many  cases 
serve  to  clarify  fluids,  that  cannot  be 
freed  from  their  impurities  by  simple  per- 
colation. 

Albumen  or  gelatin,  dissolved  in  a  small 
portion  of  water,  is  commonly  used  for 


CLA 


CLA 


fining  vinous  liquors,  as  it  inviscates  the 
feculent  matter,  and  gradually  subsides 
with  it  to  the  bottom  Albumen  is  parti- 
cularly used  for  fluids,  with  which  it  will 
combine  when  cold,  as  sirups;  it  being-  co- 
agulaied  by  the  heat,  and  then  rising  in  a 
scum  with  the  dregs. 

Heat  alone  clarifies  some  fluids,  as  the 
juices  of  plants,  in  which  however  the  aflbu 
men  they  contain  is  probably  the  agent. 

A  couple  of  handful*  of  marl,  thrown 
into  the  press,  will  clarify  cyder,  or  water- 
cyder. 

CLAY  (PURE)      See  ALUMINA. 

*  CLAY.  The  clays  being  opaque  and 
non  crystallized  bodies,  of  dull  fracture, 
afford  no  good  principle  for  determining 
their  species;  yet  as  they  are  extensively 
distributed  in  nature,  and  are  used  in 
many  arts,  they  deserve  particular  atten- 
tion. The  argillaceous  minerals  are  all  suf- 
ficiently soft  to  be  scratched  by  iron;  they 
have  a  dull  or  even  earthy  fracture;  they 
exhale,  when  breathed  on,  a  peculiar  smell 
called  argillaceous.  The  clays  form  with 
water  a  plastic  paste,  possessing  considera- 
ble tenacity,  which  hardens  with  heat,  so  as 
to  strike  fire  with  steel.  Marls  and  chalks 
also  soften  in  water,  but  their  paste  is  not 
tenaceous,  nor  docs  it  acquire  a  siliceous 
hardness  in  the  fire.  The  affinity  of  the 
clays  for  moisture  is  manifested  by  their 
sticking  to  the  tongue,  and  by  the  intense 
heat  necessary  to  make  them  perfectly  dry. 
The  odour  ascribed  to  clays  breathed  upon, 
is  due  to  the  oxide  of  iron  mixed  with 
them.  Absolutely  pure  clays  emit  no  smell. 

1.  Porcelain  earth,  the  kaolin  of  the  Chi- 
nese— This  mineral  Is  friable,  meagre  to 
the  touch,  and,  when  pure,  forms  with 
difficulty  a  paste  with  water.  It  is  infusible 
in  a  porcelain  furnace.  It  is  of  a  pure 
white,  verging  sometimes  upon  the  yellow 
or  flesh-red.  Some  present  particles'of  mi- 
ca, which  betray  their  origin  to  be  from 
feldspar  or  graphic  granite.  It  scarcely  ad- 
heres to  the  tongue.  Sp.  gr.  2.J.  It  is 
found  in  primitive  mountains,  amid  blocks 
of  granite,  forming  interposed  strata.  Ka- 
olins are  sometimes  preceded  by  beds  of 
a  micaceous  rock  of  the  texture  of  gneiss, 
but  red  and  very  friable.  This  remarkabe 
disposition  has  been  observed  in  the  kaolin 
quarries  of  China,  in  those  of  Alenc_on,  and 
of  Saint  Yriex  near  Limoges.  The  consti- 
tuents of  kaolin  are  52  silica,  47  alumina, 
O.j.3  oxide  of  iron;  but  some  contain  a  not- 
able proportion  of  water  in  their  recent 
state.  The  Chinese  and  Japanese  kaolins 
are  whiter  and  more  unctuous  to  the  touch 
than  those  of  Europe.  The  Saxon  has  a 
slight  tint  of  yellow  or  carnation,  which  dis- 
appears in  the  fire,  and  therefore  is  not  ow- 
ing  to  metallic  impregnation.  At  Saint 
Yriex  the  kaolin  is  in  a  stratum  and  also 
in  a  vein,  amid  blocks  of  granite,  or  rather 


the  feldspar  rock,  which  the  Chinese  call 
petuntze.  The  Cornish  kaolin  is  very  white 
and  unctuous  to  the  touch,  and  obviously 
is  formed  by  the  disintegration  of  the  feld- 
spar of  granite. 

2.  Potters'  clay,  or  plastic  clay — The  clays 
of  this  variety  are  compact,   smooth,   and 
almost  unctuous  to  the  touch,  and  may  be 
polished  by  the  finger  when  they  are  dry. 
They  have  a  great  affinity  for  water,  form 
a  tenacious  paste,  and  adhere  strongly  to 
the  tongue.     The  paste  of  some   is  even 
slightly  transparent.     They  acquire   great 
solidity,  but  are  infusible  in  the  porcelain 
furnace.  This  property  distinguishes  them 
from  common  clays,  employed  for   coarse 
earthen  ware.  Some  of  them  remain  white, 
or  become  so  in  a  high  heat;   others  turn 
red.     Sp.  gr.  2.     The  slaty  potters'  clay  of 
Werner  has  a  dark  ash-gray  colour;  prin- 
cipal fracture  imperfectly  conchoidal,  cross 
fracture  earthy;  fragments  tabular,  rather 
light,  and  feels  more  greasy  than  common 
potters'  clay.     Vauquelin's  analysis  of  the 
plastic  clay  of  Forge s-les-Eaux,  employed 
for   making  glass-house  pots,  as  well  as 
pottery,  gave  16  alumina,  63  silica,  1  lime, 
8  iron,  and  10  water.     Another   potters' 
clay  gave  33  2  and  43.5  of  alumina  and  si- 
lica, with  3.5  lime. 

3.  Loam. — This  is  an  impure  potters'  clay 
mixed  with  mica  and  iron  ochre.     Colour 
yellowish-gray,  often    spotted   yellow  and 
brown.     Massive,  with  a  dull  glimmering 
lustre  from  scales  of  mica.  Adheres  pretty 
strongly  to  the  tongue,  and  feels   slightly 
greasy.     Its  density  is  inferior  to  the  pre- 
ceding. 

4.  Variegated  clay. — Ts  striped  or  spotted 
with  white,  red,  or  yellow  colours.     Mas- 
sive, with  an  earthy  fracture,  verging  on 
slaty.     Shining  streak.     Very  soft,  some- 
times even  friable.     Feels  slightly  greasy, 
and  adheres  a  little  to  the  tongue.   Sectile. 
It  is  found  in  Upper  Lusatia. 

5.  Slate  clay. — Colour  gray,  or  grayish- 
yeliow.    Massive.    Dull  or  glimmering  lus- 
tre, from  interspersed  mica.  Slaty  fracture, 
approaching  sometimes  to  earthy.     Frag- 
ments tabular.     Opaque,  soft,  sectile,   and 
easily  broken.    Sp.  gr.  2.6.    Adheres  to  the 
tongue,  and  breaks  down  in  water.     It  is 
found  along  with  coal,  and  in  the  floetz 
trap  formation. 

6.  Claystone. Colour  gray,  of  various 

shades,    sometimes    red,   and    spotted    or 
striped.   Massive.     Dull  lustre,  with  a  fine 
earthy  fracture,  passing  into  fine  grained 
uneven,  slaty  or   splintery.     Opaque,  soft, 
and  easily  broken.    Does  not  adhere  to  the 
tongue,  and   is  meagre  to  the  touch.     It 
has  been  found  on  the  top  of  the  Pentium! 
hills  in  Scotland,  and  in  Germany. 

7.  Adhesive  slate—  Colour  light  greenish- 
gray.     Internal  lustre  dull;  fracture  in  the 
large,  slaty;  in  the  small,  fine  earthy.   Frag- 


CLA 


CLI 


merits  slaty.  Opaque.  Shining-  streak.  Sec- 
tile.  K,asily  broken  or  exfoliated.  Adheres 
strongly  to  the  tongue,  and  absorbs  water 
rapidly  with  the  emission  of  air  bubbles, 
and  a  crackling-  sound.  It  is  found  at  Mont- 
martre  near  Paris,  between  blocks  of  im- 
pure gypsum,  in  larg-e  straight  plates  like 
sheets  of  pasteboard.  It  is  found  also  at 
Menil  Montant,  enclosing  menilite.  K lap- 
roth's  analysis  is  62.5  silica,  8  magnesia, 
0.5  alumina,  0.25  lime,  4  oxide  of  iron,  22 
water,  and  0.75  charcoal.  Its  sp.  gr.  is  2.08. 

8.  Polishing  slate  of  Werner. Colour, 

cream-yellow,  in   alternate   stripes.     Mas- 
sive.    Lustre  dull.     Slaty  fracture.     Frag- 
ments tabular.     Very  soft,  and  adheres  to 
the  tongue.     Smooth,   but  meagre  to  the 
touch.     Sp.  gT.  in  its  dry  state   0.6;   when 
imbued   with   moisture    1.9.     It   has   been 
found  orily  in  Bohemia.     Its   constituents 
are  79  silica,  1  alumina,   1    lime,  4  oxide 
of  iron,  and  14  water. 

9.  Common  clay  may  be  considered  to  be 
the  same  as  foam — Besides  the  above,   we 
have  the  analyses  of  some  pure  clays,   the 
results  of  which  show  a  verv  minute  quan- 
tity of  silica,   and  a  large  quantity  of  sul- 
phuric acid.    Thus,  in  one  analyzed  by  Hu- 
cholz,  there  was  1  silica,   31    alumina,  0.5 
lime,  0.5  oxide  of  iron,  21.5  sulphuric  acid, 
45  water,  and  0.5  loss.    Simon  found   1935 
sulphuric  acid  in  100  parts.     We  must  re- 
gard these  clays  as   sub-sulphates   of  alu- 
mina. 

CLAY  SLATE.  Argillaceous  Schistus — 
the  Argillite  of  Kirwan.  Colour, bluish-gray, 
and  grayish  black  of  various  shades.  Mas- 
sive. Internal  lustre  shining  or  pearly.  Frac- 
ture foliated.  Fragments  tabular.  Streak, 
greenish-white.  Opaque.  Soft.  Sectile.  Ea- 
sily broken.  Sonorous,  when  struck  with 
a  hard  body.  Sp.  gr.  2.7.  Its  constituents 
are  48.6  silica,  23.5  alumina,  1.6  magnesia, 
11.3  peroxide  of  iron,  0.5  oxide  of  manga- 
nese, 4.7  potash,  0.3  carbon,  0.1  sulphur, 
7.6  water  and  volatile  matter.  Clay-slate 
melts  easily  by  the  blow-pipe  into  a  shining- 
scoria.  This  mineral  is  extensively  distri- 
buted, forming  a  part  of  both  primitive  and 
transition  mountains.  The  great  beds  of 
it  are  often  cut  across  by  thin  seams  of 
quartz  or  carbonate  of  lime,  which  divide 
them  into  rhomboidal  masses.  Good  slates 
should  not  imbibe  water.  If  they  do,  they 
soon  decompose  by  the  weather. 

*  CLAY  IRON  STONE.  See  ORES  OF 
IRON.* 


*  CLIMATE.  The  prevailing  constitu- 
tion of  the  atmosphere,  relative  to  heat, 
wind,  and  moisture,  peculiar  to  any  region. 
This  depends  chiefly  on  the  latitude  of  the 
place,  its  elevation  above  the  level  of  the 
sea,  and  its  insular  or  continental  position. 
Springs  which  issue  from  a  considerable 
depth,  and  caves  about  iO  feet  under  the 
surface,  preserve  a  uniform  temperature 
through  all  the  vicissitudes  of  the  season. 
This  is  the  mean  temperature  of  this  coun- 
try From  a  comparison  of  observations, 
Professor  Mayer  constructed  the  following 
empirical  rule  for  finding  the  relation  be- 
tween the  latitude  and  the  mean  tempera- 
ture, in  centesimal  degrees,  at  the  level  of 
the  sea. 

Multiply  the  square  of  the  cosine  of  the 
latitude  by  the  constant  number  29,  the  pro- 
duct is  the  temperature.  The  variation  of 
temperature  for  each  degree  of  latitude  is 
hence  denoted  centesimal ly  with  very 
great  precision,  by  half  the  sine  of  double- 
the  latitude. 


Mean 

Height  of  curve 

Latitude. 

temperature*. 

of  congelation 

Cent.      Fahr. 

in  feet. 

C° 

2G°         84.2° 

15207 

5 

28.78      83.8 

15095 

10 

28.13      82.6 

14764 

15 

27.06      80.7 

14220 

20 

25.61      78.1 

13478 

25 

2.3.82      74.9 

12557 

30 

21.75      71.1 

11484 

35 

19.46      67. 

10287 

40 

17.01      62.6 

9001 

45 

14.50      58  1 

7671 

50 

11.98      536 

6334 

55 

9.54      49.2 

5034 

60 

7.25      45.0 

3818 

65 

5.18      41.3 

2722 

70 

339      38.1 

1778 

75 

1.94      35.5 

1016 

80 

0.86      33.6 

457 

85 

0.22      32.4 

117 

90 

0.0        32.0 

00 

The  following  table  represents  the  re- 
sults of  some  interesting  observations  made 
under  the  direction  of  Mr.  Ferguson  of 
Raith,  at  Abbotshall  in  Fife,  about  50  feet 
above  the  level  of  the  sea,  in  latitude  56° 
10'.  The  large  and  strong-  bulbs  of  the 
thermometers  were  buried  in  the  ground 
at  various  depths,  while  the  stems  rose 
above  the  surface,  for  inspection. 


CLI 


CLI 


1816. 


1817. 


I  foot. 

2  feet. 

3  feet. 

4  feet. 

I  foot.   2  feet 

3  feet. 

4  feet. 

January, 

33°     i  36.3° 

-*U.7°     43° 

35.6 

38.7 

40.5 

45.1 

February, 

33.7 

36 

390 

42 

37.0 

40.0 

41.6 

42.7 

March, 

35 

36.7 

39.6 

42.3 

39.4 

40.2 

41.7 

42.5 

April, 

39.7 

38.4 

41.4 

43.8 

45.0       424 

42.6 

42.6 

May, 

44.0 

43.3 

46.4 

44.0 

46.8       44.7 

44.6 

44.2 

.'une, 

51.6 

50.0 

47.1 

45.8 

51.1    !  49.4 

47.6 

47.8 

July, 

54.0 

52.5 

55.4 

47.7 

55.2    |  55.0 

51.4 

49.6 

August, 

50.0 

52.5 

50.6 

49.4 

53.4 

53.9 

52.0 

50.0 

September, 

51.6 

51.3 

51.8 

50.0 

53.0 

52.7 

52.0 

50.7 

October, 

47.0 

49.3 

49.7 

49.6 

45.7 

49.4 

49.4 

49.8 

November, 

10.8 

43.8 

46.3 

45.6 

41.0 

44.7    1  47.0 

47.6 

December, 

35.7 

40.0 

43.0 

46.0 

37.9    i  40.8    :  44.9 

46.4 

.             ,. 

iMean  ot 

whole  year. 

43.8 

44.1 

45.1 

46. 

44.9      45.9       46.2 

46.6 

Had  the  thermometers  been  sunk  deep- 
er, they  would  undoubtedly  have  indicated 
47.7,  which  is  the  mean  temperature  of  the 
place,  as  is  shown  by  a  copious  spring. 

The  lake  of  Geneva,  at  the  depth  of  1000 
feet,  was  found  by  Saussure  to  be  42°;  and 
below  160  feet  from  the  surface  there  is  no 
monthly  variation  of  temperature.  The  lake 
of  Thun,  at  370  of  depth,  and  Lucerne  at 
640,  had  both  a  temperature  of  41°,  while 
the  waters  at  the  surface  indicated  respec- 
tively 64°  and  68£°  Fahr.  Barlocci  observ- 
ed, that  the  Lago  Sabatino,  near  Rome,  at 
the  depth  of  490  feet,  was  only  44^°,  while 
the  thermometer  stood  on  its  surface  at 
77°.  Mr.  Jardine  has  made  accurate  obser- 
vations on  the  temperatures  of  some  of  the 
Scottish  lakes,  by  which  it  appears,  that 
the  temperature  continues  uniform  all  the 
year  round,  about  20  fathoms  under  the 
surface.  In  like  manner,  the  mine  of  Dan- 
nemora  in  Sweden,  which  presents  an  im- 
mense excavation,  200  or  300  feet  deep, 
was  observed  at  a  period  when  the  work- 
ing1 was  stopped,  to  have  great  blocks  of 
ice  lying  at  the  bottom  of  it.  The  bottom 
of  the  main  shaft  of  the  silver  mine  of 
Kongsberg  in  Norway,  about  300  feet  deep, 
is  covered  with  perpetual  snow.  Hence, 
likewise,  in  the  deep  crevices  on  JEina.  and 
the  Pyrenees,  the  snows  are  preserved  all 
the  year  round.  It  is  only,  however,  in  such 
confined  situations  that  the  lower  strata  of 
air  are  thus  permanently  cold.  In  a  free 
atmosphere,  the  gradation  of  temperature 
is  reversed,  or  the  upper  regions  are  cold- 
er, in  consequence  of  the  increased  capaci- 
ty for  heat  of  the  air,  by  the  diminution  of 
the  density.  In  the  milder  climates,  it  will 
be  sufficiently  accurate,  in  moderate  eleva- 
tions, to  reckon  an  ascent  of  540  feet  for 
each  centesimal  degree,  or  100  yards  for 
each  degree  on  Fahrenheit's  scale,  of  di- 
minished temperature.  Dr.  Francis  Bu- 
chanan found  a  spring  at  Chitlong,  in  the 
lesser  valley  of  Nepal,  in  Upper  India, 


which  indicated  the  temperature  of  14.7 
centesimal  degrees,  which  is  8.1°  below 
the  standard,  for  its  parallel  of  latitude, 
27°  38'.  Whence,  8.1  X  540  =  4374  feet, 
is  the  elevation  of  that  valley.  At  the  height 
of  a  mile  this  rule  would  give  about  33 
feet  too  much.  The  decrements  of  tem- 
perature augment  in  an  accelerated  pro- 
gression as  we  ascend. 

Ben  Nevis,  the  highest  mountain  in  Great 
Britain,  stands  in  latitude  57°,  where  the 
curve  of  congelation  reaches  to  4534  feet. 
But  the  altitude  of  the  summit  of  the  moun- 
tain is  no  more  than  4380  feet;  and  there- 
fore, during  two  or  three  weeks  in  July, 
the  snow  disappears.  The  curve  of  conge- 
lation must  evidently  rise  higher  in  sum- 
mer, and  sink  lower  in  winter,  producing  a 
zone  of  fluctuating  ice,  in  which  the  gla- 
ciers are  formed. 

In  calculating  the  mean  temperature  of 
countries  at  different  distances  from  the 
equator,  the  warmth  has  been  referred 
solely  to  the  sun.  But  Mr.  Bald  has  pub- 
lished,  in  the  first  number  of  the  Edin- 
burgh Philosophical  Journal,  some  facts 
apparently  incompatible  with  the  idea  of 
the  interior  temperature  of  the  earth  being- 
deducible  from  the  latitude  of  the  place, 
or  the  mean  temperature  at  the  surface. 
The  following  table  presents,  at  one  view, 
the  temperature  of  air  and  water,  in  the 
deepest  coal-mines  in  Great  Britain. 

Whitehaven  Colliery t  county  of  Cumberland. 
Air  at  the  surface,    - 
A  spring  at  the  surface,    • 
Water  at  the  depth  of  480  feet, 
Air  at  same  depth,    ... 
Air  at  depth  of  600  feet,  - 
Difference  between  water  at  surface 
and  at  480  feet,  11 

Workington  Colliery,  county  of  Cumberland. 
Air  at  the  surface,  56 

A  spring  at  the  surface,    -        -        48 


55°  F. 

49 

60 

63 

66 


GLI 


CLI 


Water  180  feet  down,        -        -        50°  F. 

Water  504  feet  under  the  level  of  the 
ocean,  and  immediately  beneath 
the  Irish  sea,  ...  60 

Difference  between  water  at  surface 
and  bottom,  ....  12 

Teem  Colliery,  county  of  Durham. 
Air  at  pit  bottom,  444  feet  deep,        68 
Water  at  same  depth,  61 

Difference  between  the  mean  tempe- 
rature of  water  at  surface  =  49*, 
and  444  feet  down,  -  -  12 

Percy  Main  Colliery,  county  of  Northum- 
berland. 

Air  at  the  surface,  42 

Water  about  900  feet  deeper  than  the 
level  of  the  sea,  and  under  the  bed 
of  the  river  Tyne,         -         -         68 
Air  at  the  same  depth,  70 

At  this  depth  Leslie's  hygrometer  in- 
dicated dryness  =  83°. 
Difference  between  mean  tempera- 
ture of  water  at  surface  =  49°, 
and  at  900  feet  down,    -        -          19 

Jarrow  Colliery,  county  of  Durham. 
Air  at  surface,  49£ 

Water  882  feet  down,  -  -  68 
Air  at  same  depth,  ...  70 
Air  at  pit  bottom,  64 

Difference  between  the  mean  tempe- 
rature of  water  at  surface  =  49°, 
and  882  feet  down,  -  -  19 
The  engine-pit  of  Jarrow  is  the  deep- 
est perpendicular  shaft  in  Great 
Britain,  being  900  feet  to  the  foot 
of  the  pumps. 

Killing-worth  Colliery,  county  of  Northum- 
berland. 

Air  at  the  surface,    ...         48 
Air  at  bottom  of  pit,  790  feet  down,  51 
Air  at  depth  of  900  feet  from  the 
surface,  after  having  traversed  a 
mile  and  a  half  from  the  bottom 
of  the  downcast  pit,      -         -         70 
Water  at  the  most  distant  forehead 
or  mine,  and  at  the  great  depth  of 
1200  feet  from  the  surface,  74 

Air  at  the  same  depth,      -         -         77 
Difference  betwixt  the  mean  tempe- 
rature of  the  water  at  the  surface 
=  49*,  and  water  at  the  depth  of 
1200  feet,       ....         25 
Distilled  water  boils  at  this  depth  at  213 
Do.          do.     at  surface,        -         210$ 

M.  Humboldt  has  stated,  that  the  tem- 
perature of  the  silver  mine  of  Valenciana 
in  New  Spain  is  11°  above  the  mean  tem- 
perature of  Jamaica  and  Pondicherry,  and 
that  this  temperature  is  not  owing  to  the 
miners  and  their  lights,  but  to  local  and 
geological  causes.  To  the  same  local  and 


geological  causes  we  must  ascribe  the  ex- 
traordinary elevation  of  temperature  ob- 
served by  Mr.  Bald.  He  further  remarks, 
that  the  deeper  we  descend,  the  drier  we 
find  the  strata,  so  that  the  roads  through 
the  mines  require  to  be  watered,  in  order 
to  prevent  the  horsedrivers  from  being  an- 
noyed  by  the  dust.  This  fact  is  adverse  to 
the  hypothesis  of  the  heat  proceeding  from 
the  chemical  action  of  water  on  the  strata 
of  coal.  As  for  the  pyrites  intermixed  with 
these  strata,  it  does  not  seem  to  be  ever 
decomposed,  while  it  is  in  situ.  The  per- 
petual circulation  of  air  for  the  respiration 
of  the  miners,  must  prevent  the  lights  from 
having  any  considerable  influence  on  the 
temperature  of  the  mines. 

The  meteorological  observations  now 
made  and  published  with  so  much  accura- 
cy and  regularity  in  various  parts  of  the 
world,  will  soon,  it  is  hoped,  make  us  bet- 
ter acquainted  with  the  various  local  causes 
which  modify  climates,  than  we  can  pre- 
tend to  be  at  present.  The  accomplished 
philosophical  traveller,  M.  de  Humboldt, 
published  an  admirable  systematic  view  of 
the  mean  temperatures  of  different  places, 
in  the  third  volume  of  the  Memoirs  of  the 
Society  of  Arcueil.  His  paper  is  entitled, 
of  Isothermal  Lines  (lines  of  the  same  tem- 
perature), and  the  Distribution  of  Heat 
over  the  Globe.  By  comparing  a  great  num- 
ber of  observations  made  between  46°  and 
48°  N.  lat.,  he  found,  that  at  the  hour  of 
sun-set  the  temperature  is  very  nearly  the 
mean,  of  that  at  sun-rise  and  two  hours  af- 
ter noon.  Upon  the  whole,  however,  he 
thinks,  that  the  two  observations  of  the 
extreme  temperatures,  will  give  us  more 
correct  results. 

The  difference  which  we  observe  in  cul-- 
tivated  plants,  depends  less  upon  mean  tem- 
perature, than  upon  direct  light,  and  the 
serenity  of  the  atmosphere;  but  \vhcat  will 
not  ripen  if  the  mean  temperature  descend 
to  47.6°. 

Europe  may  be  regarded  as  the  western 
part  of  a  great  continent,  and  subject  to  all 
those  influences,  which  make  the  western 
sides  of  all  continents  warmer  than  the  eas- 
tern. The  same  difference  that  we  observe 
on  the  two  sides  of  the  Atlantic,  exists  on 
the  two  sides  of  the  Pacific.  In  the  north 
of  China,  the  extremes  of  the  seasons  are 
much  more  felt  than  in  the  same  latitudes 
in  New  California,  and  at  the  mouth  of  the 
Columbia.  On  the  eastern  side  of  North 
America,  we  have  the  same  extremes  as  in 
China;  New-York  has  the  summer  of  Rome, 
and  the  winter  of  Copenhagen;  Quebec  has 
the  summer  of  Paris,  and  the  winter  of 
Petersburgh.  And  in  the  same  way  in 
Pekin,  which  has  the  mean  temperature  of 
Britain;  the  heats  of  summer  are  greater 
than  those  at  Cairo,  and  the  cold  of  winter, 
as  severe  as  that  at  Upsal.  This  analogy 


CLI 


CLI 


between  the  eastern  coasts  of  Asia  and  of 
America,  sufficiently  proves,  that  the  in- 
equalities of  the  seasons,  depend  upon  the 
prolongation  and  enlargement  of  the  conti- 
nents towards  the  pole,  and  upon  the  fre- 
quency of  N.  W.  winds,  and  not  upon  the 
proximity  of  any  elevated  tracts  of  coun- 
try. 

Ireland,  says  Humholdt,  presents  orft  of 
the  most  remarkable  examples  of  the  com- 
bination of  very  mild  winters  with  cold 
summers;  the  mean  temperature  in  Hunga- 
ry for  the  month  of  Ausrust  is  71.6°;  while 
in  Dublin  it  is  only  60.t>°.  In  Belgium  and 
Scotland,  the  winters  are  milder  than  at 
Milan. 

In  the  article  Climate,  Supplement  to  the 
Encyclopaedia  Britannica,  the  following  ve- 
ry simple  rule  is  given,  for  determining  the 
change  of  temperature  produced  by  sudden 
rarefaction  or  condensation  of  air.  Multi- 
ply 25  by  ihe  difference  between  the  density 
of  air,  and  its  reciprocal,  the  product  will  be 
the  difference  of  temperature  o?i  the  centigrade 
scale.  Thus,  if  the  density  be  twice,  or  one 
half  25°  X  (2—2)  —  37i°  cent.  =  67.5° 
Fahr.  indicates  the  change  of  temperature 
by  doubling  the  density  or  rarity  of  air. 
Were  it  condensed  30  times,,  then,  by  this 
formula,  we  have  749°  for  the  elevation  of 
temperature,  or  25°  (30  —  TV).  But  M. 
Gay-Lussac  says,  that  a  condensation  of  air 
into  one-fifth  of  its  volume,  is  sufficient  to 
ignite  tinder;  a  degree  of  heat  which  he 
states  at  300°  centigrade  =  572°  Fahr. 
(Journal  of  Science,  vol.  vii.  p.  177).  This 
experimental  result  is  incompatible  with 
Professor  Leslie's  Formula,  which  gives 
only  112.6°,  for  the  heat  produced  by  a 
condensation  into  one-fifth. 

It  appears  very  probable,  that  the  cli- 
mates of  European  countries  were  more 
severe  in  ancient  times  than  they  are  at 
present.  Caesar  says,  that  the  vine  could 
not  be  cultivated  in  Gaul,  on  account  of  its 
winter-cold.  The  rein-deer,  now  found  on- 
ly in  the  zone  of  Lapland,  was  then  an  in- 
habitant of  the  Pyrenees.  The  Tiber  was 
frequently  frozen  over,  and  the  ground 
about  Rome  covered  wilh  snow  for  several 
weeks  together,  which  almost  never  hap- 
pens in  our  times.  The  Rhine  and  the  Dan- 
ube, in  the  reign  of  Augustus,  were  gene- 
rally frozen  over,  for  several  months  of 
winter.  The  barbarians  who  overran  the 
Roman  empire  a  few  centuries  afterwards, 


transported  their  armies  and  wagons  across 
the  ice  of  these  rivers.  The  improvement 
that  is  continually  taking  place  in  the  cli- 
mate of  America,  proves,  that  the  power 
of  man  extends  to  phenomena,  which  from 
the  magnitude  and  variety  of  their  causes, 
seemed  entirely  beyond  his  controul.  At 
Guiana,  in  South  America,  within  five  de- 
grees of  the  line,  the  inhabitants  living 
amid  immense  forests,  a  century  ago,  were 
obliged  to  alleviate  the  severity  of  the 
cold,  by  evening  fires.  Even  the  duration 
of  the  rainy  season  has  been  shortened 
by  the  clearing  of  the  country,  and  the 
warmth  is  so  increased,  that  a  fire  now 
would  be  deemed  an  annoyance.  It  thun- 
ders continually  in  the  woods,  rarely  in  the 
cultivated  parts. 

Drainage  of  the  ground,  and  removal 
of  forests,  however,  cannot  be  reckoned 
among  the  sources  of  the  increased  warmth 
of  the  Italian  winters.  Chemical  writers 
have  omitted  to  notice  an  astronomical 
cause  of  the  progressive  amelioration  of 
the  climates  of  the  northern  hemisphere. 
In  consequence  of  the  apogee  -portion  of 
the  terrestrial  orbit  being  contained  be- 
tween our  vernal  and  autumnal  equinox,  our 
summer  half  of  the  year,  or  the  interval 
which  elapses  between  the  sun's  crossing- 
the  equator  in  spring  and  in  autumn,  is 
about  seven  days  longer  than  our  winter 
half  year.  Hence  also,  one  reason  for  the 
relative  coldness  of  the  southern  hemis- 
phere.* 

Isothermal  Sands,  and  Distribution  of  Heat, 

over  the  Globe. 

The  temperatures  are  expressed  in  de- 
grees of  Fahrenheit's  thermometer;  the  lon- 
gitudes are  counted  from  east  to  west,  from 
the  first  meridian  of  the  observatory  of 
Paris.  The  mean  temperature  of  the  sea- 
sons has  been  calculated,  so  that  the 
months  of  December,  January,  and  Feb- 
ruary, form  the  mean  temperature  of  the 
winter.  The  mark  *  is  prefixed  to  those 
places,  the  mean  temperatures  of  which 
have  been  determined  with  the  most  pre- 
cision, generally  by  a  mean  of  8000  obser- 
vations. The  isothermal  curves  having  a 
concave  summit  in  Europe,  and  two  con- 
vex summits  in  Asia  and  Eastern  America, 
the  climate  is  denoted  to  which  the  indivi- 
dual places  belong1:— 


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*  CLINKSTONE.    A  stone  of  an  imper- 
fectly slaty  structure,  which  rings  like  me- 
tal when  struck  with  a  hammer.     Its  co- 
lour is  gray  of  various  shades;  it  is  brittle; 
as  hard  as  feldspar,  and  translucent  on  the 
edges.     It  occurs  in  columnar  and  tabular 
concretions.  Sp.  gr.  2.57.     Fuses  easily  in- 
to  a  nearly   colourless  glass.     Its  consti- 
tuents are  57.25  silica,  25.5  alumina,  2.75 
lime,  8.1   soda,  3.25  oxide  of  iron,  0.25 
oxide  of  manganese,   and  3   of  water. — 
Klaproth.     This  stone  generally  rests  on 
basalt.     It  occurs  in  the  Ochil  and  Pent- 
land   hills,  the   Bass-rock,  the  islands    of 
Mull,  Lamlash,  and  Islay,  in  Scotland;  the 
Breidden  hills  in  Montgomeryshire,  and  in 
the  Devis  Mountain,  in  the  county  of  An- 
trim.    It  is  found  in  Upper  Lusace  and  Bo- 
hemia.* 

*  CLINOMETER.     An    instrument    for 
measuring  the  dip  of  mineral  strata.     It 
Was  originally  invented  by  R.  Griffith,  Esq. 
Professor  of  Geology  to  the  Dublin  Society, 
and  subsequently  modified  by  Mr.  Jardine 
and  Lord  Webb  Seymour.     See  a  descrip- 
tion and  drawing  by  the  latter,  in  the  third 
volume    of  the   Geological    Transactions. 
Lord  Webb's  instrument  was  a  very  per- 
fect one.     It  was  made  by  that  unrivalled 
artist,  Mr.  Troughton.' 

*  CLOUD.     A  mass  of  vapour,  more  or 
less  opaque,  formed  and  sustained  at  con- 
siderable heights  in  the  atmosphere,  pro- 
bably  by  the  joint  agencies  of  heat  and 
electricity.     The  first  successful  attempt 
to  arrange  the  diversified  forms  of  clouds, 
under  a  few  general   modifications,   was 
made  by  Luke   Howard,  Esq.     We   shall 
give  here  a  brief  account  of  his  ingenious 
classification. 

The  simple  modifications  are  thus  named 
and  defined.  1.  Cirrus.  Parallel,  flexu- 
ous,  or  diverging  fibres,  extensible  in  any 
or  in  all  directions.  2.  Cumulus.  Convex 
or  conical  heaps,  increasing  upwards  from 
a  horizontal  base.  3.  Stratus.  A  widely 
extended,  continuous  horizontal  sheet,  in- 
creasing from  below. 

The  intermediate  modifications  which 
require  to  be  noticed  are,  4.  Cirro-cumulus. 
Small  well-defined  roundish  masses,  in 
close  horizontal  arrangement.  5.  Cirro- 
stratus.  Horizontal,  or  slightly  inclined 
masses,  attenuated  towards  a  part  or  the 
whole  of  their  circumference,  bent  down- 
ward, or  undulated,  separate  or  in  groups, 
consisting  of  small  clouds  having  these 
characters. 

The  compound  modifications  are,  6.  Cu- 
mulo-stratus.  The  cirro-stratus,  blended 
with  the  cumulus,  and  either  appearing  in- 
termixed with  the  heaps  of  the  latter,  or 
superaddirig  a  wide-spread  structure  to  its 
base. 

7.  Cumulo-cirro-stratus,  vel  Nimbus.  The 
rain  cloud.  A  cloud  or  system  of  clouds 


from  which  rain  is  falling.  It  is  a  hori- 
zontal sheet,  above  which  the  cirrus 
spreads,  while  the  cumulus  enters  it  la- 
terally  and  from  beneath. 

The  cirrus  appears  to  have  the  least 
density,  the  greatest  elevation,  the  great- 
est  variety  of  extent  and  direction,  and  to 
appear  earliest  on  serene  weather,  being 
indicated  by  a  few  threads  pencilled  on  the 
sky.  Before  storms  they  appear  lower  and 
denser,  and  usually  in  the  quarter  oppo- 
site to  that  from  which  the  storm  arises. 
Steady  high  winds  are  also  preceded  and 
attended  by  cirrus  streaks,  running  quite 
across  the  sky  in  the  direction  they  blow 
in. 

The  cumulus  has  the  densest  structure, 
is  formed  in  the  lower  atmosphere,  and 
moves  along  with  the  current  next  the 
earth.  A  small  irregular  spot  first  appears 
and  is  as  it  were  the  nucleus  on  which  they 
increase.  The  lower  surface  continues  ir- 
regularly plane,  while  the  upper  rises  into 
conical  or  hemispherical  heaps;  which  may 
afterwards  continue  long  nearly  of  the  same 
bulk,  or  rapidly  rise  into  mountains.  They 
will  begin,  in  fair  weather,  to  form  some 
hours  after  sunrise,  arrive  at  their  max- 
imum in  the  hottest  part  of  the  afternoon, 
then  go  on  diminishing  and  totally  dis- 
perse about  sunset.  Previous  to  rain,  the 
cumulus  increases  rapidly,  appears  lower 
in  the  atmosphere,  and  with  its  surface 
full  of  loose  fleeces  or  protuberances.  The 
formation  of  large  cumuli  to  leeward  in  a 
strong  wind,  indicates  the  approach  of  a 
calm  with  rain.  When  they  do  not  disap- 
pear or  subside  about  sunset  but  continue 
to  rise,  thunder  is  to  be  expected  in  the 
night.  The  stratus  has  a  mean  degree  of 
density,  and  is  the  lowest  of  clouds,  its  in- 
ferior surface  commonly  resting  on  the 
earth  or  water.  This  is  properly  the  cloud 
of  night,  appearing  about  sunset.  It  com- 
prehends all  those  creeping  mists  which 
in  calm  weather  ascend  in  spreading-  sheets 
(like  an  inundation  of  water),  from  the 
bottom  of  valleys,  and  the  surfaces  of  lakes 
and  rivers.  On  the  return  of  the  sun,  the 
level  surface  of  this  cloud  begins  to  put  on 
appearance  of  cumulus,  the  whole  at  the 
same  time  separating  from  the  ground. 
The  continuity  is  next  destroyed,  and  the 
cloud  ascends  and  evaporates,  or  passes 
off  with  the  appearance  of  the  nascent  cu- 
mulus. This  has  long  been  experienced 
as  a  prognostic  of  fair  weather. 

1  he  cirrus  having  continued  for  some 
time  increasing  or  stationary,  usually 
passes  either  to  the  cirro-cumulus  or  the 
cirro-stratus,  at  the  same  time  descending 
to  a  lower  station  in  the  atmosphere  This 
modification  forms  a  very  beautiful  sky;  is 
frequent  in  summer,  an  attendant  on  warm 
and  dry  weather.  The  cirro-stratus,  when 
seen  in  the  distance,  frequently  gives  the 


COA 


COA 


idea  of  shoals  of  fish.  It  precedes  wind 
and  rain;  is  seen  in  the  intervals  of  storms; 
and  sometimes  alternates  with  the  cirro- 
cumulus  in  the  same  cloud,  when  the  dif- 
ferent evolutions  form  a  curious  spectacle. 
A  judgment  may  be  formedof  the  weather 
likely  to  ensue  by  observing'  which  modifi- 
cation prevails  at  last.  The  solar  and  lu- 
nar halos,  as  well  as  the  parhelion  and 
paraselene,  (mock  sun  and  mock  moon), 
prognostics  of  foul  weather,  aiv  occasioned 
by  this  cloud.  The  cumulo-stratus  pre- 
cedes, and  the  nimbus  accompanies  rain. 
See  RAIN. 

Mr.  Howard  gives  a  view  of  the  origin 
of  clouds,  which  will  be  found,  accompa- 
nied with  many  useful  remarks,  in  the  I6ih 
and  17th  volumes  of  the  Philos.  Magazine.* 

CI.YSSUS.  A  word  formerly  used  to  de- 
note the  vapour  produced  by  the  detona- 
tion of  nitre  with  any  inflammable  sub- 
stance. 

COAK.  Coal  is  charred  in  the  same  man- 
ner as  wood  to  convert  it  into  charcoal.  An 
oblong-  square  hearth  is  prepared  by  beat- 
ing the  earth  to  a  firm  flat  surface,  and 
puddling  it  over  with  clay.  On  this,  the 
pieces  of  coal  are  piled  up,  inclining  to- 
ward one  another,  and  those  of  the  lower 
strata  are  set  up  on  their  acutest  angle, 
so  as  to  touch  the  ground  with  the  least 
surface  possible.  The  piles  are  usually 
from  30  to  50  inches  high,  from  9  to  16 
feet  broad,  and  contain  from  40  to  100 
tons  of  coal.  A  number  of  vents  are  left, 
reaching  from  top  to  bottom,  into  which 
the  burning  fuel  is  thrown,  and  they  are 
then  immediately  closed  with  small  pieces 
of  coal  beaten  hard  in.  Tims  the  kindled 
fire  is  forced  to  creep  along  the  bottom, 
and  when  that  of  all  the  vents  is  united,  it 
rises  gradually,  and  bursts  out  on  every 
side  at  once.  If  the  coal  contain  pyrites, 
the  combustion  is  allowed  to  continue  a 
considerable  time  after  the  disappearance 
of  the  smoke,  to  extricate  the  sulphur,  part 
of  which  will  be  found  in  flowers  on  the 
surface:  If  it  contain  none,  the  fire  is  cover- 
ed up  soon  after  the  smoke  disappears,  be- 
ginning- al  thi-  bottom,  and  proceeding  gra- 
dually to  the  top.  In  50,  60,  or  70  hours, 
the  fire  is  in  general  completely  covered 
"with  the  ashes  of  char  formerly  made,  and 
in  12  or  14  days  the  coak  muv  be  removed 
for  iiv.".  in  this  way  a  ton  of  coals  com- 
monly produces  liom  700  to  11.00  pounds 
of  coak. 

In  this  way  the  volatile  products  of  the 
coal,  however,  which  might  be  turned  to 
good  account,  are  lost:  but  some  years 
ago,  Lord  Lhuvionuhl  conceived  and  car- 
ried into  effect,  a  plan  for  saving  them.  By 
burning  the  coal  in  a  range  of  18  or  20 
stoves,  with  as  little  access  of  air  as  may 
be,  at  the  bottom;  and  conducting  the 
smoke,  through  proper  horizontal  tunnels, 


to  a  capacious  close  tunnel  100  yards  or 
more  in  length,  built  of  brick,  supported 
on  brick  arches,  and  covered  on  the  top 
by  a  shallow  pond  of  water;  the  bitumen  is 
condensed  in  the  form  of  tar:  120  tons  of 
coal  yield  about  3^  of  tar,  though  some 
coals  are  said  to  be  so  bituminous  as  to 
afford  l-8th  of  their  weight.  Part  of  the 
tar  is  inspissated  into  pitch,  21  barrels  of 
which  are  made  of  28  of  tar;  and  the  vola- 
tile parts  arising  in  this  process  are  con- 
densed into  a  varnish,  used  for  mixing 
with  colours  for  out-door  pain' ing  chiefly. 
A  quantity  of  ammonia  too  is  collected, 
and  used  for  making  sal  ammoniac.  The 
cakes  thus  made  are  likewise  of  superior 
quaii  ty. 

*COAL.  This  very  important  order  of 
combustible  minerals,  is  divided  by  Pro- 
fessor Jameson  into  the  following  species 
and  sub-species: 

Species  1.  Brown  coal,  already  described. 

Species  2.  Black  coal,  of  which  there  are 
four  sub-species,  slate  coal,  cannel  coal, 
foliated  coal,  and  coarse  coal. 

1.  Slate  coal.     Its  colour  is  intermediate 
between   velvet-black,   and  dark    grayish- 
black.     It  has    sometimes    a   peacock-tail 
tarnish.     It  occurs  massive,  and  in  colum- 
nar and  egg-shaped  concretions.     It  has  a 
resinous  lustre.     Principal  fracture   slaty; 
cross  fracture,  imperfect  conchoidal.  Hard- 
er than  gypsum,  but  softer  than  calcareous 
spar.     Brittle.     Sp.    gr.    1.26   to    1.38     It 
burns  longer  than  cannel  coal;  cakes  more 
or  less,  and  leaves  a  slag.     The   constitu- 
ents of  the   slate  coal  of  Whitehaven,  by 
Kirwan,  are  56.8  carbon,  with  43.2  mixture 
of  asphalt  and  maltha,  in  which  the  former 
predominates.     This  coal  is  found  in   vast 
quantities  at   Newcastle;    in  the  coal   for- 
mation  which    stretches  from   Bolton,   by 
Al'onby  and  Workington,  to  Whitehaven. 
In  Scotland,  in  the  river   district  of  Forth 
and  Clyde;  at  Cannoby,  Sanquhar,  and  Kir- 
connel,    in    Dumfries-shire;   in    Thuring-ia, 
Saxony,  and  many  other  countries  of  Ger- 
manv.     It    sometimes   passes   into  cannel 
and  foliated  coal. 

2.  Cannel  coal.     Colour  between  velvet 
and  grayish-black.    Massive     Resinous  lus- 
tre.    Fracture,    flat-conchoidal,    or   even. 
Fragments    trapezoidal.     Hardness    as    in 
the    preceding    sub-species.     Brittle.     Sp. 
gr.  1.23  to  1.27.     It  occurs  along  with  the 
preceding.     It  is  found  near  Whitehaven, 
at  Wig  An,  in  Lancashire,  Brosely,  in  Shrop- 
shire, near  Sheffield;   in    Scotland,  at   Gil- 
merton  and    Muirkirk,  where  it  is  called 
parret  coal.     It    has   been   wor-'.ed   on   the 
lathe  into  drinking  vessels,  snuff-boxes,  &c. 

3.  Foliated   coal.     Its    colour   is    velvet- 
black,  sometimes  with  iridescent  tarnish. 
Massive,  and  in  lamellar  concretions.     Re- 
sinous or  splendent  lustre;  uneven  fracture, 
fragments  approaching  to  trapezoidal.  Soft- 


COA 


COA 


er  than  cannel  coal;  between  brittle  and 
sectile.  Easily  broken.  Sp.  gr.  1.34  to  1.4. 
The  Whitehaven  variety  consists,  by  Kir- 
wan,  of  57  carbon,  41.3  bitumen;  and  1.7 
ashes.  It  occurs  in  the  coal  formations  of 
this  and  other  countries.  It  is  distinguish- 
ed by  its  lamellar  concretions,  splendent 
lustre,  and  easy  frangibility. 

4.  Coarse  coal.  Colour  dark,  grayish- 
black,  inclining  to  brownish-black.  Mas- 
sive, and  in  granular  concretions.  Glisten- 
ing  lustre.  Fracture  imperfect  scaly.  Frag- 
ments indeterminate  angular.  Hardness 
as  above.  Easily  frangible  Sp.  gr.  1.454 
It  occurs  in  the  German  coal  formations. 
To  the  above,  Professor  Jameson  has  ad- 
ded soot-coal}  which  has  a  dark  grayish- 
black  colour;  is  massive;  with  a  dull  semi- 
metallic  lustre.  Fracture  uneven;  some- 
times earthy.  Shining  streak;  soils;  is  soft, 
light,  and  easily  frangible.  It  burns  with 
a  bituminous  smell,  cakes,  and  leaves  a 
small  quantity  of  ashes.  It  occurs  along 
with  slate-coal  in  West-Lothian  and  the 
Forth  district;  in  Saxony  and  Silesia. 

Species  3d.  Glance-coal,  of  which  the 
Professor  gives  two  sub-species,  pitch-coal, 
and  glance-coal.  1.  Pitch-coal.  Colour  vel- 
vet-black. Massive,  or  in  plates  and  bo- 
trioidal  branches,  with  a  woody  texture. 
Splendent  and  resinous.  Fracture,  large 
perfect  conchoidal.  Fragments  sharp-edged 
and  indeterminate  angular;  opaque;  soft; 
streak  brown  coloured.  Brittle.  Does  not 
soil.  Sp.  gr.  1.3.  It  burns  with  a  greenish 
flame.  It  occurs  along  with  brown  coal  in 
beds,  in  floetz,  trap,  and  limestone  rocks, 
and  in  bituminous  shale.  It  is  found  in  the 
Isles  of  Sky  and  Faroe;  in  Hessia,  Bavaria, 
Bohemia,  and  Stiria.  It  is  used  for  fuel, 
and  for  making  vessels  and  snufF-boxes.  It 
is  called  black  amber  in  Prussia,  and  is 
cut  into  rosaries  and  necklaces.  It  is  dis- 
tinguished by  its  splendent  lustre  and  con- 
choidal fracture.  It  was  formerly  called 
jet,  from  the  river  Gaga  in  Lesser  Asia. 

2.  Glance-coal,-  of  which  we  have  four 
kinds,  conchoidal,  slaty,  columnar,  and  fi- 
brous. The.  conchoidal  has  an  iron -black 
colour,  inclining  to  brown,  with  sometimes 
a  tempered  steel-varnish.  Massive  and  ve- 
sicular. Splendent,  shining-  and  imperfect 
metallic  lustre.  Fracture  flat -conchoidal; 
fragments  sharp-edged.  Hardness  as  above. 
Brittle,  and  easily  frangible.  In  thin  pieces, 
it  yields  a  ringing  sound.  It  burns  without 
flame  or  smell,  and  leaves  awhile  coloured 
ash.  Its  constituents  are  S6  r"6  infla-Mma- 
ble  matter,  2  alumina,  and  1.38  silica  and 
iron.  Jt  occurs  in  beds  in  clay-slate,  gray- 
wacke,  and  alum-slate;  but  it  is  more  abun- 
dant in  secondary  rocks,  as  in  coal  and 
trap  formations,  'it  occurs  in  beds  in  the 


coal  formations  of  Ayrshire,  near  Cumnock 
and  Kilmarnock;  in  the  coal  district  of  the 
Forth;  and  in  Staffordshire.  It  appears  to 
pass  into  slaty  glance-coal. 

Slaty  glance-coal.  Colour  iron-black. 
Massive.  Lustre  shining,  and  imperfect 
metallic.  Principal  fracture  slaty;  coarse 
fracture  imperfect  conchoidal.  Fragments 
trapezoidal.  Softer  than  conchoidal  glance- 
coal.  Easily  frangible;  between  sectile  and 
brittle.  Sp.  gr.  1.50.  It  burns  without 
flame  or  odour.  It  consists,  by  Dolomieu, 
of  72.05  carbon,  13.19  silica,  3.29  alumina, 
3.47  oxide  of  iron,  and  8  loss.  It  occurs  in. 
beds  or  veins  in  different  rocks  In  Spain, 
in  gneiss;  in  Switzerland,  in  mica-slate  and 
clay-slate;  in  the  trap  rock  of  the  Calton- 
hili,  Edinburgh;  in  the  coal  formations  of 
the  Forth  district.  It  is  found  also  in  the 
floetz  districts  of  Westcraigs,  in  West  Lo- 
thian, Dunfermline,  Cumnock,  Kilmarnock, 
and  Arran;  in  Brecknock,  Caermarthen- 
shire,  and  Pembrokeshire,  in  England;  and 
at  Kilkenny,  Ireland;  and  abundantly  in  the 
United  States.  In  this  country  it  is  called 
blind  coal. 

Columnar  glance-coal  Colour  velvet -black 
and  grayish-black.  Massive,  disseminated, 
and  in  prismatic  concretions.  Lustre 
glistening,  and  imperfect  metallic.  Frac- 
ture conchoidal.  Fragments  sharp-edged. 
Opaque.  Brittle.  Sp.  gr.  1.4.  It  burns 
without  flame  or  smoke.  It  forms  a  bed 
several  feet  thick  in  the  coal-field  of  San- 
quhar,  in  Dumfries-shire;  at  Saltcoats,  in 
Ayrshire,  it  occurs  in  beds  and  in  green- 
stone; in  basaltic  columnar  rows  near  Cum- 
nock, in  Ayrshire. 

Fibrous  coal.  Colour  dark  grayish-black. 
Massive,  in  thin  layers,  and  in  fibrous  con- 
cretions. Lustre  glimmering,  or  pearly. 
It  soils  strongly.  It  is  soft,  passing  into 
friable.  It  burns  without  flame;  but  some 
varieties  scarcely  yield  to  the  most  intense 
heat.  It  is  met  with  in  the  different  coal- 
fields of  Great  Britain.  Its  fibrous  concre- 
tions and  silky  hibtre  distinguish  it  from 
all  the  other  kinds  of  coal. 

It  is  not  certain  that  this  mineral  is 
wood  mineralized.  Several  of  the  varieties 
may  be  original  carbonaceous  matter,  crys- 
tallized in  fibrous  concretions. — Jameson. 

Parts.  Charcoal.  Earth. 

100  Kilkenny  coal  contain      97.3         3.7 

Anthracite,  90.0       10.0 

Ditto,          -          -  72.0       20.0 

Ditto,  -  -         97.25      2.7 

Coal  of  Notre  Dame  de  Vaux,  78.5       20 

The  following  table  exhibits  the  results 
of  Mr.  Mushot's  experiments  on  the.  car- 
bonization and  incineration  of  coals: 


COA 


COA 


Volatile 
matter 

Char- 
coal. 

Jlshes. 

Sp.  gr. 

of  coal. 

Sp.  gr.  of 
coak. 

Welsh  furnace  coal,  .... 
Alfreton  do.       do.    -     -     -     , 
Butterly  do.       do.    .... 
Welsh  stone       do.    -     -     -     - 
Welsh  slaty        do     -     -     -     -   * 

8.50 
45.50 
42.83 
8.00 
9.10 
47.00 
4.25 
16.66 
13.00 
56.57 
13.80 
9.10 
10.30 
33.37 
80.00 

88.068 
52.456 
52.882 
89.700 
84.175 
48.362 
92.877 
69.74 
80.475 
39.430 
82.960 
87.491 
86.560 
54.697 
19.500 

3.432 
2.044 
4.288 
2.300 
6.725 
4.638 
2.873 
13.600 
6.525 
4.000 
3.240 
3.409 
3.140 
11.933 
0.500 

1.337 
1.235 

1.264 
1.368 
1.409 
1.278 
1.602 

1.445 

1.436 
1.403 
1.403 
1.150 

1. 

ess  than  1. 
1.1 
1.39 

1.657 

1.596 
1.656 

1.622 

Derbyshire  cannel  do.    .     -     - 

Stone-coal  found  under  basalt, 
Kilkenny  slaty  coal,       ... 

Bonlarooneen  do.      -      "^ 
Corgee  coal,     -     -     -      V  Irish. 
Queen's  County,  No.  39.  j 
Stone-wood,  Giant's  Causeway, 

It  was  remarked  long  ago  by  Macquer, 
that  nitre  detonates  with  no  oily  or  in- 
flammable matter,  until  such  matter  is 
reduced  to  coal,  and  then  only  in  propor- 
tion to  the  carbonaceous  matte  L  it  contains. 
Hence  it  occurred  to  Mr.  Krrwan,  that  as 
coals  appear  in  distillation  to  be  for  the 
most  part  merely  compounds  of  carbon  and 
bitumen,  it  should  follow,  that  by  the  de- 
composition of  nitre,  the  quantity  of  car- 
bon in  a  given  quantity  of  every  species 
of  coal  may  be  discovered,  and  the  pro- 
portion of  bitumen  inferred.  This  cele- 
brated chemist  accordingly  projected  on 
a  certain  portion  of  nitre  in  a  state  of  fu- 
sion, successive  fragments  of  various  kinds 
of  coal,  till  the  deflagration  ceased.  Coal, 
when  in  fine  powder,  was  thrown  out  of 
the  crucible.  The  experiments  seem  to 
have  been  judiciously  performed,  and  the 
results  are  therefore  entitled  to  as  much 
confidence  as  the  method  permits.  Lavoi- 
sier and  Kirwan  state,  that  about  13  parts 
of  dry  wood-charcoal  decompose  100  of 
nitre. 

100  parts.  Charcoal.  Bitumen.  Earth  Sp.  ^r. 
Kilkenny  coal,  97.3  0  3.7  1.526 

Comp. cannel,  75.2  21  68  maltha  3.1  1.232 
Swansey,  73.53  23.14  mixt.  3.331.357 
Leitrim,  71.43  23.37  do.  5.20  1.351 

Wigan,  61.73  36.7     do.      1.57  1.268 

Newcastle,  58.00  40.0  do.  —  1.271 
Whitehaven  57-0  41.3  1.7  1.257 

Slaty -cannel,  47.62  32.52  mal.  20.01.426 
Asphalt,  31.0  63.0  bitumen  — 1.117 
Maltha,  8.0  —  2.07 

100  parts  of  the  best  English   coal   give, 

of  coak,     -         -         63.  by  Mr.  Jars. 
100       do,         -         -         73.  Hielm. 
100       do.  Newcastle  do.  58.  Dr.  Watson. 
Mr.  Kirwan  says  he  copied  the  result,  for 
Newcastle  coal,  from  Dr.  Watson. 

The  foliated  or  cubical  coal,  and  slate 
coal,  are  chiefly  used  as  fuel  in  private 
houses;  the  caking  coals,  for  smithy  forges; 
the  slate  coal,  from  its  keeping  open,  an- 


swers  best  for  giving  great  heats  in  a  wind 
furnace,  as  in  distillation  on  the  great 
scale;  and  glance  coal  is  used  for  drying 
grain  and  malt.  The  coals  of  South  Wales 
contain  less  volatile  matter  than  either  the 
English  or  the  Scotch;  and  hence,  in  equal 
weight,  produce  a  double  quantity  of  cast 
iron  in  smelting  the  ores  of  this  metal.  It 
is  supposed  that  3  parts  of  good  Newcas- 
tle coals,  are  equivalent  as  fuel  to  4  parts 
of  good  Scotch  coals. 

Werner  has  ascertained  three  distinct 
coal  formations,  without  including  the  beds 
of  coal  found  in  sandstone  and  limestone 
formations.  The  first  or  oldest  formation, 
he  calls  the  independent  coal  formation, 
because  the  individual  depositions  of  which 
it  is  composed,  are  independent  of  each 
other,  and  are  not  connected.  The  second, 
is  that  which  occurs  in  the  newest  floetz- 
trap  formation;  and  the  third  occurs  in  al- 
luvial land.  Werner  observes,  that  a  fourth 
formation  mig-ht  be  added,  which  would 
comprehend  peat  and  other  similar  sub- 
stances; so  that  we  would  have  a  beautiful 
and  uninterrupted  series,  from  the  oldest 
formation  to  the  peat,  which  is  daily  form- 
ing under  the  eye. 

The  independent  formation  contains  ex- 
clusively coarse  coal,  foliated  coal,  cannel 
coal,  slate  coal,  a  kind  of  pitch  coal,  and 
slaty  glance  coal.  The  latter  was  first 
found  in  this  formation  in  Arran,  Dum- 
fries-shire, Ayrshire,  and  at  Westcraigs, 
by  Professor  Jameson.  The  formation  in 
the  newest  floetz-trap  contains  distinct 
pitch  coal,  columnar  coal,  and  conchoidal 
glance  coal.  The  alluvial  formation  con- 
tains almost  exclusively  earth  coal  and 
bituminous  wood.  The  first  formation  be- 
sides coal,  contains  three  rocks  which  are 
peculiar  to  it;  these  are  a  conglomerate, 
which  is  more  or  less  coarse-grained;  a 
friable  sandstone,  which  is  always  mica- 
ceous; and  lastly,  slate -clay.  But  besides 
these,  there  occur  also  beds  of  harder  sand- 


COA 


COA 


stone,  marl,  limestone,  porphyritic  stone,  which  the  arts  of  life  have  ever  derived 
bituminous  shale,  clay -ironstone;  and  as  dis-  from  philosophical  research  and  sagacity, 
covered  by  Professor  Jameson,  greenstone,  jn  the  year  1798,  Mr.  Murdoch,  after  se 
amygdaloid,  and  graphite.  The  slate-clay 
is  well  characterized,  by  the  great  variety 


of  vegetable  impressions  of  such  plants  as 


veral  trials  on  a  small  scale  five  years  be- 
fore, constructed  at  the  Foundry  of  Messrs. 
Bolton  and  Watt,  an  apparatus  upon  a  large 


flourish  in  marshes  and  woods.  The  scale,  which  during  many  successive  nights 
smaller  plants  and  reeds  occur  in  casts  or  was  applied  to  the  lighting  of  their  prin- 
impressions  always  laid  in  the  direction  of  cipal  building;  and  various  new  methods 
the  strata;  but  the  larger  arborescent  plants  were  practised  of  washing  and  purifying 

the  gas.  In  the  year  1805,  the  cotton  mill 
of  Messrs.  Philips  and  Lee,  reckoned  the 
most  extensive  in  the  kingdom,  was  partly 
lighted  by  gas  under  Mr  Murdoch's  di- 


often  stand  erect,  and  their  stems  are  fil- 
led with  the  substance  of  the  superincum- 
bent strata,  which  seems  to  show  that  these 
stems  are  in  their  original  position.  The 
leaves  and  stems  resemble  those  of  palms  rection;  and  the  light  was  soon  extended 


and    ferns.      The    central,    northern    and  over  the  whole  manufactory.     In  the  same 

western  coal  mines  of  England;  the  river  year,  I  lighted  up  the  large  lecture-room 

coal  districts  of  the  Forth  and  the  Clyde,  of  Anderson's   Institution    with   coal-gas, 

and  the  Ayrshire,  and  in   part  the  Dum-  generated  in  the  laboratory;  and  continued 


fries-shire  coals,  belong  to  this  formation 
as  well  as  the  coals  in  the  northern  and 
western  parts  of  France. 

By  far  the  most  valuable  and  extensive 
beds  of  coal  which  have  been  found  and 
wrought,  are  in  Great  Britain.  The  gene- 
ral form  of  our  great  independent  coal- 
beds,  is  semi-circular,  or  semi-elliptical, 
being  the  segment  of  a  great  basin.  The 
strata  have  a  dip  or  declination  to  the 
horizon  of  from  1  in  5,  to  1  in  20.  They 
are  rarely  vertical,  and  seldom  perfectly 


the  illumination  every  evening  through 
that  and  the  succeeding  winter.  Hence  I 
was  induced  to  pay  particular  attention  to 
the  theory  and  practice  of  its  production 
and  use. 

If  coal  be  put  into  a  cold  retort,  and 
slowly  exposed  to  heat,  its  bitumen  is 
merely  volatilized  in  the  state  of  conden- 
sible  tar.  Little  gas,  and  that  of  inferior 
illuminating  power,  is  produced.  This  dis- 
tillatory temperature  may  be  estimated  at 
about  600°  to  700°  F.  If  the  retort  be 


horizontal    to     any    considerable    extent.    previously  brought  to  a  bright  cherry-red 
Slips  and  dislocations  of  the   strata,  how-    heat)  then  tlle  coals,the  instant  after  their 

supply 


ever,  derange   more  or  less   the  general 


form  of  the  basin. 

Those  who  wish  to  understand  the  most 
improved  modes  of  working  coal  mines, 


introduction,  yield  a  copious  supply  of 
good  gas,  and  a  moderate  quantity  of  tarry 
and  ammoniacal  vapour.  But  when  the  re- 
tort is  heated  vo  nearly  a  white  incandes- 


will  be   amply  gratified   by  consulting,  A    cence}  tne  part  of  the  gas  richest  in  light, 

J?/»/i/i9*y*    />7»      tht>      J  .piTiQtpY*     f^.nnl      T\i&tv*irt       Tiv       •  *       i    •  -A  „£•  1  — X*~...;~«         . ..-,  I'.  +  .r 


Report  on  the  Leinster  Coal  District,  by 
Richard  Griffith,  Esq.  Professor  of  Ge- 
ology, and  Mining  Engineer  to  the  Dublin 
Society.  The  author  has  given  a  most  lu- 
minous view  of  Mr.  Buddie's  ingenious 


is  attenuated  into  one  of  inferior  quality, 
as  I  have  shown  in  detailing  Berthollet's 
experiments  on  CARBURETTED  HYDRO- 
GEN. A  pound  of  good  cannel  coal,  pro- 
perly treated  in  a  small  apparatus,  will 


system  of  working  and  ventilating,  in  which     yieic[  five  cuijic  feet  Of  ffas,  equivalent  in 

f <r  OiU_   4^    n  irui,~  ~c   *.v._   ...u,-.i_ i      r,,         .         .  u          *TI 

illuminating  power  to  a  mould  candle,  six 
in  the  pound.     See  CANDLE. 

On  the  great  scale,  however,  3^  cubic 
feet  of  good  gas  are  all  that  should  be  ex- 
pected from  1  pound  of  coal.  A  gas  jet, 


from  7-8ths  to  9-10ths  of  the  whole  coal 
may  be  raised;  instead  of  only  £,  which 
was  the  proportion  obtained  in  the  former 
modes.  Mr.  Griffith  has  since  published 
some  other  reports,  the  whole  constituting 
an  invaluable  body  of  mining  information.* 
*  COAL  GAS.  When  coal  is  subjected 
in  close  vessels  to  a  red  heat,  it  gives  out 
a  vast  quantity  of  gas,  which  being  col- 
lected and  purified,  is  capable  of  affording 
a  beautiful  and  steady  light,  in  its  slow 
combustion  through  small  orifices.  Dr. 
Clayton  seems  to  have  been  the  first  who 
performed  this  experiment,  with  the  view 
of  artificial  illumination,  though  its  appli- 
cation to  economical  purposes  was  unac- 
countably neglected  for  about  60  years. 
At  length  Mr.  Murdoch  of  the'Soho 
Foundry,  instituted  a  series  of  judicious 
experiments  on  the  extraction  of  gas  from 


which  consumes  half  a  cubic  foot  per  h< 
affords  a  steady  light  equal  to  that  of  the 
above  candle. 

According  to  Mr.  Murdoch's  statement, 
presented  to  the  Royal  Society,  2500  cu- 
bic feet  of  gas  were  generated  in  Mr.  Lee's 
retort  from  7  cwt.=784  Ibs.  of  cannel  coal. 
This  is  nearly  3j  cubic  feet  for  every 
pound  of  coal,  and  indicates  judicious 
management.  The  price  of  the  best  Wi- 
gan  cannel  is  13^d.  per  cwt.  (22s.  6d-  per 
ton)  delivered  at  Mr.  Lee's  mill  at  Man- 
chester; or  about  8s.  for  the  seven  hundred 
weight.  About  -j  of  the  above  quantity  of 


ignited  coal;  and  succeeded  in  establishing    of  good  common  coal  at  10s.  per  ton,  is 
<?ne    of  the  most  capital  improvements    required  for  fuel  to  heat  the  retorts.  Near- 


COA 


COA 


Jy  •§•  of  the  weight  of  the  coal  remains  in 
the  retort  in  the  form  of  coak,  which  is 
sold  on  the  spot  at  1*.  4d.  per  cwt.  The 
quantity  of  tar  produced  from  each  ton  of 
cannel  coal,  is  from  11  to  12  ale  gallons. 

The  economical  statement  for  one  year 
is  given  by  Mr.  Murdoch  thus: 
Cost  of  110  tons  of  cannel  coal,  4125 

Ditto  of  40  tons  of  common  ditto,  20 


Deduct  the  value  of  70  tons  of  coak, 


145 

93 


The  annual  expenditure  in  coal,  with- 
out allowing  any  thing  for  tar,  is  52 

And  the  interest  of  capital,  and  wear 
and  tear  of  apparatus,  -  -  350 

Making  the  total  annual  expense  of 
gas  apparatus  about  -  -  600 

That  of  candles  to  give  the  same  light,  2000 

If  the  comparison  had  been  made  upon 
an  average  of  three  hours  per  day, 
instead  of  two  hours,  (all  the  year 
round),  then  the  cost  from  gus 
would  be  only  ...  650 

Ditto  candles,         ....      3000 

The  peculiar  softness  and   clearness   of 
this  light,  with  its  almost  unvarying  inten- 


sity, soon  brought  it  into  great  favour  with 
the  work-people.  And  its  being  free  from 
the  inconvenience  and  danger,  resulting 
from  the  sparks  and  frcquvnt  snuffing  of 
candles,  is  a  circumstance  of  material  im- 
portance, tending  to  diminish  the  hazard 
of  fire,  and  lessening  the  high  insurance 
premium  on  cotton-mills.  The  cost  of  the 
attendance  upon  candles  would  be  fully 
more  than  upon  the  gas  apparatus;  and 
upon  lamps  greatly  more,  in  such  an  es- 
tablishment as  Mr.  Lee's.  The  preceding 
statements  are  of  standard  authority,  far 
above  the  suspicion  of  empiricism  or  ex- 
aggeration, from  which  many  subsequent 
statements  by  gas-book  compilers  are  by 
no  means  exempt. 

At  the  same  manufactory,  Dr.  Henry  has 
lately  made  some  useful  experiments  on 
the  quality  of  the  gas  disengaged  from  the 
same  retort  at  different  periods  of  the  de- 
composition. I  have  united  in  the  follow- 
ing- table,  the  chief  part  of  his  results.  He 
collected  in  a  bladder  the  gas,  as  it  issued 
from  an  orifice  in  the  pipe,  between  the 
retorts  and  the  tar  pit;  and  purified  it  af- 
terwards by  agitation  in  contact  of  quick- 
lime and  water.  Ten  cwt.  or  1120  Ibs.  of 
coal  were  contained  in  the  retorts. 


100  measures 

100  measures  of  :    100  measures 

100  combustible 

Hours 

of  impure  gas 

purified  gas              of  purified 

gas,  exclusive 

from  com- 

contain, 

contain,                       gas 

of  azote, 

5 

B 
tt 

mencement. 

Su'ph. 
hydr. 

Carb. 
acid. 

Olef. 

Other 
infi. 
gases. 

Con- 
JLzote      sume 

oxyg. 

Give 
car.  ac. 

Take 
oxygen 

Carb. 
acid. 

O 

I 

0* 

si 

16     !  64 

20     i      180 

94 

225 

118 

&J3 

1 

3 

3* 

18     I  77i 

4f 

210 

112 

220 

117 

£ 

3 

2£ 

2* 

15     ;  80 

5 

200 

108 

210 

114 

5 

2* 

2* 

13       72 

15      !    176 

94 

206 

108 

7 

2 

2* 

9     :  76 

15      !     170 

83 

200 

98 

i 

9 

ft* 

8        ;    77 

15          150 

73 

176 

85 

10* 

0 

2 

6       74 

20      '    120 

54 

150 

70 

12 

0 

0* 

4 

76 

20     !       82 

36 

103 

45 

o  5 

1 

3 

3 

10        90 

0 

164 

91 

164          91 

3 

2 

2 

9 

91 

0 

168 

93 

168 

93 

c  ~ 

5 

3 

2 

6 

94 

0 

132 

70 

132 

70 

p  ° 

7 

1 

3 

5 

80 

15 

120 

64 

140 

75 

i  i 

9 

1 

2* 

2 

89 

9 

112 

60 

123 

66 

3* 

11 

1 

1 

0 

85 

15            90 

43 

106     '     50 

Dr.  Henry  conceives  that  gas  to  have  the 
greatest  illuminating  power,  which,  in  a 
given  volume,  consumes  the  largest  quan- 
tity of  oxygen;  and  that  hence  the  gas  of 
cannel  coal  is  one  third  better,  than  the 
gas  from  common  coal.  3500  cubic  feet 
of  gas  were  collected  from  1120  ponnds  of 
the  cannel  coal;  and  only  3000  from  the 
same  weight  of  the  Clifton  coal. 

From  the  preceding  table,  we  see  also 
that  the  gas  which  issues  at  the  third  hour 
Contains,  in  100  parts,  of  sulphuretted  hy- 


drogen and  carbonic  acid,  each  2^,  of  azote 
4if,  olefiant  gas  14-i,  and  of  other  inflam- 
mable gases  76  parts. 

A  cubic  foot  of  carbonic  acid  weighs  800 
gr.  A  cubic  foot  of  sulphuretted  hydro- 
gen weighs  620.  The  first  takes  about  1026 
gr.  of  lime  for  its  saturation;  the  second 
about  1070;  and  hence  1050,  the  quantity 
assigned  by  Dr.  Henry  for  either,  is  suffi- 
ciently exact.  100  cubic  feet  of  the  above 
impure  gas,  containing  5  cubic  feet  of  these 
two  gases,  will  require  at  least  2100  grains 


COA 


COA 


of  lime,  oi'  about  5  oz.  avoirdupois  for  their 
complete  condensation. 

The  proportion  employed  by  Mr.  Lee,  is 
5  pounds  of  fresh  burned  lime  to  200  cu- 
bic feet  of  gas.  The  lime,  after  being- 
sluked,  is  sifted,  and  mixed  with  a  cubic 
foot  (7.48  wine  gallons)  of  water.  This 
quantity  of  cream  of  lime,  is  adequate  to 
the  ordinary  purification  of  the  gas.  Yet 
it  will  still  slightly  darken  a  card,  coated 
with  moistened  white  lend. .  A  second  ex- 
posure to  lime  makes  it  absolutely  pure. 

Jlcfixiires.                          Oxvzen.  Carb.  acid. 

100  crude  gas,  consume  190  give  108 

100  gas,  once  washed,      175  100 

100  do.  twice  washed,       175  100 

What  is  separated  by  the  first  washing 
is  probably  vapour  of  bitumen  or  petrole- 
um, which   would  injure  the   pipes  by  its 
deposition,  more  than  it  would  profit,   by 
any  increased  quantity  of  light.     Though 
we  thus  see  that  the  second  washing  in  the 
above  experiment  condensed  none   of  the 
olcfiant  gas,  it  is  prudent  not  to  use  unne- 
cessary agitation  in  a  large  body  of  water. 
The  carbonate  of  lead  precipitated  from 
a  cold  solution  of  the  acetate,  by  carbonate 
of  ammonia,  washed  with  water,  and  mixed 
with  a  little  of  that  liquid  into  the  consist- 
ence of  cream,  is  well  adapted  to  the  sepa- 
ration of  sulphuretted  hydrogen  from  coal 
gas.    The  carbonic  acid  may  then  be  with- 
drawn from  the  residuary  g'as,  by  a  little 
water  of  potash.    We  must  now  determine 
the  azote  present,  which  is  easily  done   by 
firing  a  volume  of  this  gas  with  thrice   its 
volume  of  pure  oxygen.     What  remains  af- 
ter agitation  with  water  of  potash,  is  a  mix- 
ture of  azote  and  oxygen.    Explode  it  with 
hydrogen;  one-third  of  the  diminution   of 
volume  shows  the  oxygen;  the  rest  is  azote. 
We  have  now  to  eliminate  three   quanti- 
ties, viz.  the  volume  of  olefiant  gas,  that,  of 
common  carburetted  hydrogen,  and  that  of 
carbonic  oxide.     Mr.  Faraday  has   proved 
that  chlorine  acts  pretty   speedily  on  the 
second   species   of  carburetted   hydrogen, 
and  therefore  it  cannot  be  employed  with 
the  view  of  condensing  merely  the  first 
species.     In  contact  with  moisture,  chlo- 
rine acts  also  rapidly  on   carbonic   oxide, 
giving  birth  to  muriatic  and  carbonic  acids. 
If  we  be  therefore  deprived  of  all   known 
means  of  chemical  elimination,  we  shall  find 
a  ready  and  successful  resource  in  the  doc- 
trines of  specific  gravity.     In  any  mixture 
of  two  solids,  two  liquids,  or  two   gases, 
whose  specific  gravities   are  known,  it  is 
easy  to  infer  from  the   specific   gravity   of 
the  compound  (when  the  mixture  is  effect- 
ed without  change  of  volume)  the  relative 
"weights   of  the  two  constituents.     Thus  if 
we  apply  to  an  alloy  of  gold  and  zinc,  the 
old  problem  of  Archimedes,  we  shall  de- 
VOL.  I. 


termine  exactly  the  proportion  of  each  me- 
tal present,  because  the  volume  of  the  al- 
loy is  very  nearly  the  sum  of  the  volumes 
of  its  ingredients.  I  have  long  applied  this 
problem  to  gaseous  mixtures,  and  found  it 
a  very  convenient  means  of  verification  on 
many  occasions,  particularly  in  examining 
the  nature  of  the  residuary  air  in  the  lungs 
of  the  galvanized  criminal,  of  which  an  ac- 
count is  given  in  the  12th  Number  of  the 
Journal  of  Science. 

PROBLEM. — In  100  measures  of  mixed 
gases,  consisting,  for  example,  of  olefiant  gas, 
carbonic  oxide,  and  subcarburettedhydrogent 
in  unknoton  proportions,  to  determine  the  quan- 
tity of  each.  The  first  step  is  to  find  the 
quantity  of  the  two  denser  gases,  which 
have  the  same  specific  gravity  =  0.9720. 

RULE. — Multiply  by  100,  the  difference 
between  the  specific  gravity  of  the  mixture, 
and  that  of  the  lighter  gas.  Divide  that 
number,  by  the  sum  of  the  differences  of 
the  sp.  gr.  of  the  mixture,  and  that  of  the 
denser  and  lighter  gas;  the  quotient  is  the 
per-centage  of  the  denser  See  Gregory's 
^Mechanics,  vol.  1.  p.  364. 

EXAMPLE. — A  mixture  of  olefiant  gas, 
carbonic  oxide,  and  subcarburcttcd  hydro- 
gen, has  a  sp.  gr.  of  0.638. 

What  is  the  proportion  per  cent  of  the 
first  two? 

Sp.  gr.  of  subcarb.  hydrogen,  is  0.555; 
0.638—0.55-5  =  0.083  .'.  100  X  °-083  = 
8.3. 


difference  0.332 
difference  0.083 


sum  =  0.415 


And  o-8v-YT  —  20  —  volume  of  the  two  hear 
vier  gases;  and  therefore  there  are  80  of  the 
lighter  gas.  Hence,  having  fired  the  whole 
with  oxygen,  we  must  allow  160  of  oxygen, 
for  saturating  the  80  measures  of  the  sub- 
carburetted  hydrogen.  Then  let  us  sup- 
pose 35  cubic  inches  more  oxygen  to  have 
been  consumed  We  know  that  the  satu- 
rating power  of  olefiant  gas,  and  of  carbonic 
oxide  with  oxygen,  is  in  the  ratio  of  3  to 
0.5.  Therefore,  the  quantity  of  olef.  gas  = 
35— (20  X  0.5)  25 

3—0.5  ~     ~  2~3  ~  10  measures. 

We  see  now,  that  a  gas  of  sp.  gr.  0.638 
consists  of 

0.8  measures  subcarb.  hydrogen  =  0.444 
0.1  do.  olefiant  gas  =  0.097 

0.1       po.      carb.  oxide  =      0.097 

0.638 

For  further  details  see  GAS. 
Dr.  Henry  gives,  at  the  end  of  his  expe- 
riments, (Manchester  Men  oirs,  vol.  iii.  se- 
cond series),  some  hypothetical  represent- 
ations of  the  constitution  of  coal  gases,  in 
one  of  which  he  assigns, 
39 


COA 


COA 


2  of  carburetted  hydrogen, 
2  of  carbonic  oxide, 

and  15  of  pure  hydrogen,  in  18§  mea- 
sures. 

With  mixtures  of  three  gaseous  bodies, 
the  problem  of  eliminating  the  proportion 
of  the  constituents,  by  explosion  with  oxy- 
gen, becomes  complex,  and  several  Hypo- 
thetical proportions  may  be  proposed.  But 

1  can  hardly  imagine,  that  pure  hydrogen 
should  be  disengaged  from   ignited   coal. 
There  is  no  violation  of  the   doctrine  of 
multiple  proportions,  in  conceiving  a  com- 
pound  to  exist  in   which  three   or  more 
atoms  of  hydrogen  may  be  united  with  one 
of  carbon.     Berthollet's  experiments  ren- 
der this  view  highly  probable,    if  the  above 
hypothetical  numbers  were  altered  to   1.6; 
2.4;  and  15;  their  accordance  with  Dr.  Hen- 
ry's experiments  would  be  improved.  Now, 
this  is  a  considerable  latitude   of  adjust- 
ment. 

The  principles  laid  down  at  the  com- 
mencement of  this  article  show,  that  the 
more  uniformly  the  coal  undergoes  igneous 
decomposition,  the  richer  is  the  gas.  The 
retorts,  if  cylindrical,  should  not  exceed, 
therefore,  12  or  14  inches  diameter,  and  six 
or  seven  feet  in  length.  Compressed  cy- 
linders, whose  length  is  44  feet,  breadth 

2  feet,  and  inside  vertical  diameter  about 
10  inches,  have  been  found  to  answer  well 
at  Glasgow.     The  cast  iron  of  which  they 
are  composed,  must  be  screened  from  the 
direct  impulse  of  the  fire,  by  a  case  of  fire- 
brick. 

On  the  maximum  quantity  of  gas  pro- 
curable from  coal,  it  is  difficult  to  acquire 
satisfactory  information,  at  the  great  gas 
establishments.  Exaggeration  seems  to  be 
the  prevailing  foible.  Mr.  Accum  gives  the 
following  tables,  as  the  maximum  results 
of  his  own  experiments,  made  at  the  Royal 
Mint  gas-works;—  Cubic  feet 

of  gas. 

Scotch  cannel  coal,          -  19.890 

Lancashire  Wigan  cannel,          -         19.608 

Yorkshire  cannel,  Wakefield,      -      18.860 

Staffordshire  coal,    1st  variety,      -     9.748 

By  experim.  at}       2d       do.       -      10.223 

Birmingham  C      3d       do.       -      10.866 

gas  works,    J       4tn      do.       -        9.796 

Gloucester  coal,  High  Delph,       -      16.584 

Do.  Low  Delph,        -       12.852 

Do.  Middle  Delph,     -     12.096 

Newcastle  coal,  Hartley,          -  16.120 

Cowper's  High  Main,15.876 

Tanfield  Moor,     -     16.920 

Pontops,  15.112 

The  following  varieties  of  coal,  accord- 
ing to  Mr.  Accum,  contain  a  less  quantity 
of  bitumen,  and  a  larger  quantity  of  car- 
bon than  the  preceding.  They  soften,  swell, 
and  cake  on  the  fire,  and  are  well  calcu- 
lated for  the  production  of  coal  gas: — 


One  chaldron  produces, 
Newcastle  coal,  Russel's  Wall's-end,  16.876 
Bewicke  and  Cras- 

tor's  Wall's-end,  16.897 
Heaton  Main,  -  15.876 
Bleyth,  -  -  12.096 
Eden  Main,  -  9.600 
Primrose  Main,  -  8.348 

Concerning  the  duration  of  the  decom- 
position of  a  retort-charge  of  one  cwt.,  va- 
rious opinions  are  maintained.  Mr.  Peck- 
ston's  experiments  at  the  gas  light  and 
couk  company's  works,  Westminster  sta- 
tion, seem  to  prove,  that  decided  advan- 
tages attend  the  continuance  of  the  process 
for  eight  hours,  in  preference  to  six,  or 
any  shorter  period.  The  average  product 
of  gas,  from  one  chaldron  of  Newcastle 
coals,  at  six  hours'  charges,  he  states  at 
8,300  cubic  feet,  and  at  those  of  eight  hours, 
at  10,000.  On  76  retorts,  worked  for  a 
week  at  the  latter  rate,  he  gives  a  state- 
ment to  prove,  that  there  is  a  saving  of 
77/.  18*.  above  the  former  rate  of  working. 
Two  men,  one  by  day,  and  one  by  night, 
can  attend  nine  or  ten  retorts,  at  eight 
hours  charges,  of  100  pounds  of  coal  each. 
Scotch  cannel  yields  its  gas  most  rea- 
dily, or  ....  i.oo 
Newcastle  coal,  -  -  1.04 
Gloucester  Low  Delph,  -  -  1.08 
Newcastle.  Brown's  Wall's-end,  -  1.18 
Warwickshire,  -  1.65 
Hence,  the  latter  kinds  afford  good  gas, 
long  after  the  former  are  exhausted. 

The  following  table  by  Mr.  Peckslon 
exhibits  the  ratio  at  which  the  gcis  is 
evolved  from  Bewicke  and Crastor's  Wall's- 
end  coal,  when  the  retorts  are  worked  at 
eight  hours'  charges: — 

Cubic  feet.   Sum. 
During  the  1st  hour  are  ge- 
nerated,      2000 
2d,  1495      3495 

3d,  1387      4882 

4th,  1279      6161 

5th,  1189      7350 

6th,  991       8341 

7th,  884      9225 

8th,  775    10000 

We  have  already  explained  the  princi- 
ples of  purifying  gas  by  milk  of  lime.  But 
previous  to  its  agitation  with  that  liquid, 
it  should  be  made  to  traverse  a  series  of 
refrigeratory  pipes  submersed  under  cold 
water.  A  vast  variety  of  apparatus,  some 
very  ingenious, but  many  absurd,  have  been 
contrived  within  these  few  years,  for  ex- 
posing gas  to  lime  in  the  liquid  or  dry 
state.  Mr.  Accum  and  Mr.  Peckston  have 
been  at  much  pains  in  describing  several 
of  them.  The  gas  holder  is  now  generally 
preferred  of  a  cylindrical  shape,  like  an  im- 
mense drum,  open  at  bottom;  and  flat,  or 
slightly  conical  at  top.  The  diameter  is  from 


COA 


COA 


S3  to  45  feet  in  the  large  establishments, 
and  the  height  from  18  to  24.  The  average 
capacity  is  from  15000  to  20000  cubic  feet. 
It  is  suspended  in  a  tank  of  water  by  a 
strong  iron  chain  fixed  to  the  centre  of  its 
summit,  which  passing  round  a  pulley, 
bears  the  counter-weight.  When  totally  im- 
mersed in  water,  the  sheet-iron,  of  which  the 
gas  holder  is  composed,  loses  hydrostatical- 
ly  about  -j-2y  of  its  weight;  or  if  equipoised 
when  immersed,  it  becomes  -j-%  heavier 
when  in  air,  minus  the  buoyancy  of  the  in- 
cluded gas.  The  mean  sp.  gr.  of  well  pu- 
rified coal-gas  by  Dr.  Henry's  late  experi- 
ments may  be  computed  at  0.676,  to  air 
called  1.000;  or  in  round  numbers,  its  den- 
sity may  be  reckoned  two-thirds  of  that  of 
air.  One  cubic  foot  of  air  weighs  527  gr., 
one  cubic  foot  of  gas  weighs  351  gr.;  the 
difference  is  176  gr.  Hence,  40  cubic  feet 
have  a  buoyancy  of  one  pound  avoirdupois. 

The  hydrostatic  compensation  is  obtain- 
ed by  making  the  weight  of  that  length  of 
the  suspending  chain  which  is  between  the 
top  of  the  immersed  gasometer  and  the 
tangential  point  of  the  pulley-wheel,  equal 
to  one-fifteenth  the  weight  of  the  gasometer 
in  pounds,  minus  its  capacity  in  cubic  feet, 
divided  by  twice  40,  or  80.  Thus,  if  its 
weight  be  4  tons,  or  8960  Ihs.;  and  its  capa- 
city 15000  cubic  feet,  a  length  of  chain  equal 
to  the  height  of  the  gasometer,  or  to  its 
vertical  play,  should  weigh  597  Ibs.  with- 
out allowing  for  buoyancy.  In  this  case, 
the  gasometer,  when  out  of  water,  would 
have  the  buoyancy  of  that  liquid,  replaced 
by  the  passage  of  these  597  Ibs.  to  the  op- 
posite side  of  the  wheel-pulley,  so  that 
twice  that  weight  =  1194  Ibs.  would  then 
be  added  to  the  constant  counterpoise. 
When  the  gasometer  again  sinks,  and  loses 
its  weight  by  the  displacement  of  the  li- 
quid, successive  links  of  the  chain  come 
over  above  it,  augmenting  its  weight,  and 
diminishing  that  of  the  counterpoise,  by  a 
twofold  operation,  as  in  taking  a  weight 
out  of  one  scale,  and  putting  it  in  the  other. 

But  we  must  now  introduce  the  correc- 
tion for  the  buoyancy  of  the  combustible 
gas.  Tn  ordinary  cases,  we  must  regard  it 
as  holding  a  portion  of  petroleum  vapour 
diffused  through  it,  and  cannot  fairly  esti- 
mate its  specific  gravity  at  less  than  0.750; 
whence  nearly  50  cubic  feet  have  a  buoy- 
ancy of  one  pound  over  the  same  bulk  of 
atmospheric  air.  If  we  divide  15000  by  50, 
the  quotient  =  300  is  the  double  of  what 
must  be  deducted  in  pounds  weight  from 
the  hydrostatic  compensation.  Thus,  597 
—  150  =  447,  is  the  weight  of  the  above 
portion  of  chain.  When  the  gasometer  at- 
tains its  greatest  elevation,  these  447  Ibs. 
hang  on  the  opposite  side  of  the  wheel, 
constituting  an  increased  counterpoise  of 
twice  447  =  894,  to  which,  if  we  add  the 
total  buoyancy  of  the  included  gas  —  300 


Ibs.  we  have  the  sum  1194,  equal  to  the 
total  increase  of  the  weight  of  the  iron  ves- 
sel on  its  suspension  in  air. 

f  The  following  plan  for  suspending  ga- 
someters was  devised  by  me  several  years 
ago,  and  published  in  the  Analeclic  Maga- 
zine of  this  city  for  May  1817. 

"  Account  of  an   improved   mode  of  sus- 
pending gasometers;  by  Dr.  Hare. 

"It  is  well  known  to  all  who  are  con- 
versant in  gas  light  apparatus,  that  no 
mode  has  been  heretofore  devised  to  ren- 
der gasometers  accurately  equiponderant 
at  all  points  of  their  immersion  in  the  wa- 
ter; a  circumstance  so  indispensable  to  their 
action.  The  mode  adopted  in  the  large 
London  establishments,  and  which  appears 
to  be  the  most  approved,  is  that  of  the  gas- 
ometer chain.  This  is  costly;  difficult  to 
execute  well,  and  not  susceptible  of  cor- 
rection, when  erroneously  proportioned  to 
the  desired  effect;  especially  after  the  ap- 
paratus is  in  operation.  From  all  these 
faults,  the  method  of  suspension  on  a  beam, 
like  that  in  the  following  cut,  is  entirely 
free.  In  practice  it  has  answered  perfectly: 
and,  when  we  have  described  the  mode  of 
constructing  such  a  beam,  we  think  the  ra- 
tionale of  its  operation  will  become  self- 
evident. 


Find  (by  trial,  if  possible;  if  not,  by  cal- 
culation) the  weight  of  the  gasometer  when 
sunk  so  low,  as  that  the  top  will  be  as  near 
as  possible  to  the  water,  without  touching 
it.  In  the  same  way  find  the  weight  of  the 
gasometer  at  the  highest  point  of  immer- 
sion, to  which  it  is  to  rise,  when  in  use. 
Then,  as  the  weight  in  the  last  case,  is  to 
the  weight  in  the  first;  so  let  the  length  of 
the  arm  A,  be  <o  the  length  of  the  arm  B. 
From  the  centre  D,  with  the  radius  A,  de- 
scribe a  circle;  on  which  set  off  an  arch  C, 
equal  to  the  v.'lv^e  height  through  which 
the  gasometer  is  to  move.  Divide  this  into 
as  many  parts  as  there  are  spaces  in  it, 
equal  each  to  one-sixth  of  the  radius  or 
length  of  arm  A.  Through  the  points  thus 
found,  draw  as  many  diameters;  which  will, 


COA 


C-OA 


of  course,  form  a  corresponding  number  of 
radii  and  divisions,  on  the  opposite  sids  of 
the  circle.  Divide  the  difference  between 
the  length  of  A  and  B,  by  the  sum  of 
these  divisions:  and  let  the  quotient  be  q. 
From  the  centre  D  towards  the  sid^  E,  on 
radius  2,  set  off  a  distance  equal  to  the 
length  of  the  arm  A,  less  the  quotient  or 
q.  On  radius  3,  set  off  a  distance  equal  to 
A,  less  2  g,  or  twice  the  quotient;  and  so 
set  off  distances  on  each  of  the  radii;  the 
last  being'  always  less  than  the  preceding1, 
by  the  value  of  q.  A  curve  line  bounding 
the  distances  thus  found,  will  be  that  of 
the  arch  head  E.  The  beam  being  sup- 
ported on  a  gudgeon  at  D,  let  the  gasome- 
ter be  appended  at  G;  and  let  a  weight  be 
appended  at  F,  adequate  to  balance  it  at 
any  one  point  of  immersion.  This  same 
weight  will  balance  it  at  all  other  points  of 
its  immersion — provided  the  quantity  of 
water  displaced  by  equal  sections  of  the 
gasometer  be  equal.  But  as  the  weights 
on  which  A  and  B  were  predicated,  may 
not  be  quite  correct,  and  as,  in  the  con- 
struction of  large  vessels,  equability  of 
thickness  and  shape  cannot  be  sufficiently 
attained — the  consequent  irregular  buoy- 
ancy is  compensated  by  causing  the  weight 
to  hang  nearer  to,  or  farther  from  the  cen- 
tre, at  any  of  the  points  taken  in  making 
the  curve.  This  object  is  accomplished 
by  varying  the  sliders  seen  opposite  to  the 
figures  1,  2,  3,  4,  5,  6.  When  they  are 
properly  adjusted,  they  are  made  firm  by 
the  screws  of  which  the  heads  are  visible 
in  the  diagram. 

The  drawing  is  of  a  beam  twelve  feet 
in  length;  and  of  course  the  length  of  the 
arm  A  is  six  feet — that  of  B,  four  feet — 
their  difference  two  feet;  which  divided  by 
6,  the  number  of  points  taken  in  making 
the  curve  E,  gives  four  inches  for  the  quo- 
tient q.  Hence  the  distance  on  radius  2, 
was  five  feet  eight  inches — on  radius  3,  five 
feet  four  inches — on  radius  4,  five  feet — on 
radius  5,  four  feet  eight  inches — on  radius 
6,  four  feet  four  inches — and  lastly  four 
feet. 

The  iron  gudgeon,  where  it  enters  the 
beam,  is  square.  The  projecting  parts  are 
turned  true,  and  should  be  bedded  in  brass 
or  steel  dies;  placed,  of  course,  on  a  com- 
petent frame.  The  sixth  part  of  a  revolu- 
tion of  the  portions  of  the  gudgeon  thus 
supported,  is  the  only  source  of  friction 
to  which  this  beam  is  subject  during  the 
whole  period  of  the  descent  of  the  gasom- 
eter;— which,  in  large  ones,  does  not  ordi- 
narily take  place  in  less  than  six  hours.'  f 

The  principles  of  the  distribution  of  gas 
are  exhibited  in  the  following  table,  given 
bv  Mr.  Pcckston.  The  gas  holder  is  work- 
ed at  a  pressure  of  one  vertical  inch  of  wa- 
ter, and  each  argand  burner  consumes  five 
cubic  feet  per  hjur. 


*•  ~» 

s  -S  . 

iii 

t£.2 

|^ 

Cubic  feet 
passing1  per 
hour. 

Burners 
supplied. 

2 

¥ 

20 

4 

3 
f 

50 

10 

4 
•g- 

90 

18 

% 

160 

32 

6 

•f 

250 

50 

7 
•g- 

380 

76 

500 

100 

2 

2000 

400 

3 

4500 

900 

4 

8000 

1600 

5 

12500 

2500 

6 

18000 

3600 

7  . 

24500 

4900 

8 

32000 

6400 

9 

40500 

8100 

10 

50000 

10000 

12 

72000 

14400 

14 

98000 

19600 

16 

128000 

25600 

18 

162000 

32400 

The  following  statement  is  given  by  Mr. 
Accum.  An  argand  burner,  which  mea- 
sures in  the  upper  rim  half  an  inch  in  dia- 
meter between  the  holes  from  which  the 
gas  issues,  when  furnished  with  five  aper- 
tures l-25th  part  of  an  inch  diameter,  con- 
sumes two  cubic  feet  of  gas  in  an  hour, 
when  the  gas  flame  is  one  and  a  half  inch 
high.  The  illuminating  power  of  this  burner 
is  equal  to  three  tallow  candles  eight  in  the 
pound. 

An  argand  burner  three-fourths  of  an 
inch  in  diameter  as  above,  and  perforated 
with  holes  l-30th  of  an  inch  diameter  (what 
number?  probably  15)  consumes  three  cu- 
bic feet  of  gas  in  an  hour  when  the  flame 
is  2$  inches  high,  giving  the  light  of  four 
candles  eight  to  the  pound.  And  an  argand 
burner  seven-eighths  of  an  inch  diameter 
as  above,  perforated  with  18  holes  l-32d 
of  an  inch  diameter,  consumes,  when  the 
flame  is  three  inches  high,  four  cubic  feet 
of  gas  per  hour,  producing  the  light  of  six 
tallow  candles  eight  to  the  pound'.  Increas- 
ed length  of  flame  makes  imperfect  com- 
bustion, and  diminished  intensity  of  light. 
And  if  the  holes  be  made  larger  than  l-25th 
of  an  inch,  the  gas  is  incompletely  burnt. 
The  height  of  the  glass  chimney  should 
never  be  less  than  five  inches. 

The  argand  burner  called  No.  4,  when 
burnt  in  shops  from  sunset  till  nine  o'clock, 
is  charged  three  pounds  a-year.  The  dia- 
meter of  its  circle  of  holes  is  five-eighths 
of  an  inch,  and  of  each  hole  l-32d  of  an 
inch.  It  is  drilled  with  12  holes,  5-32ds  of 
an  inch  from  the  centre  of  one  to  the  ceu. 


COB 


tre  o£  another.    Height  of  this  burner  1 J 
inches. 

No.  6,  argand  burner.  15  apertures  of 
I -32d  of  an  inch;  diameter  of  their  circle 
three-fourths  of  an  inch;  height  of  burner 
two  inches;  charge  per  ann.  four  guineas. 

According  to  Mr.  Accum,  one  gas  lamp, 
consuming  4  cubic  feet  of  gas  in  an  hour, 
if  situated  20  feet  distant  from  the  main, 
which  supplies  the  gas,  requires  a  tube  not 
less  than  a  quarter  of  an  inch  in  the  bore; 
2  lamps,  3  feet  distance,  require  a  tube 
three-eighths  of  an  inch;  3  lamps,  30  feet 
distance,  require  a  tube  three-eighths:  4 
lamps  at  40  feet,  one -half  inch  bore;  10 
lamps,  at  100  feet  distance,  require  a  tube 
three-fourths  of  an  inch;  and  20,  150  feet 
distant,  1%  inch  bore. 

We  have  seen  that  the  average  product 
in  London  from  1  pound  of  coal  in  8  hours, 
is  3^  cubic  feet.  In  the  Glasgow  coal  gas 
establishment,  which  is  conducted  by  en- 
gineers skilled  in  the  principles  of  che- 
mistry and  mechanics,  fully  4  cubic  feet 
of  gas  are  extracted  from  every  pound  of 
coal  of  the  splent  kind  in  4  hour  charges, 
from  retorts  containing  each  120  Ibs;  which 
is  about  two-thirds  of  their  capacity.  The 
decomposing  heat  is  much  the  same  as  that 
used  in  London,  but  the  retorts  are  com- 
pressed cylinders,  a  little  concave  below. 
Hence  in  8  hours,  fully  double  the  London 
quantity  of  gas,  is  obtained  from  a  retort 
in  Glasgow. 

An  ingenious  pupil  of  mine,  lately  em- 
ployed by  a  projected  gas  company  in  Glas- 
gow to  visit  the  principal  factories  of  gas  in 
England,  made  a  series  of  accurate  experi- 
ments on  its  illuminating  quality  in  the  dif- 
ferent towns.  For  this  purpose,  he  carried 
along  with  him  a  mould  candle,  six  in  the 
pound,  and  a  single-jet  gas-nozzle.  By  at- 
taching this  to  a  gas-pipe,  and  producing 
a  flame  of  determinate  length,  (three 
inches),  he  could  then,  by  the  method  of 
shadows,  compare  the  flame  of  the  gas 
with  that  of  his  candle,  and  ascertain  their 
relative  proportions  of  light.  He  found 
that  the  average  illuminating  power  of  the 
gas  in  the  English  establishments,  was  to 
that  of  the  Glasgow  company,  as  four  to 
five;  the  worst  being  so  low  as  three  to 
five,  and  the  best  as  five  to  six.  If  we 
therefore  multiply  this  ratio,  into  the  dou- 
ble product  of  gas  obtained  in  the  Glasgow 
gas-work,  we  shall  have  the  proportion  of 
light  generated  here,  anil  in  London,  from 
an  equal  sized  retort,  in  an  equal  time,  as 
luO  to  40.  This  result  merits  entire  con- 
fidence. In  the  sequel  of  the  article 
LIGHT,  in  this  Dictionary,  instructions 
will  be  given  how  to  calcullte  the  relative 
illuminating  powers  of  different  flames. 

When  the  tar  is  passed  through  ignited 
iron  pipes,  it  yields  from  10  to  15  cubic 
feet  of  gas  per  pound.  The  deposite  of  re- 


fractory asphaltum,  however,  is  very  apt  to 
obstruct  the  pipes;  and  the  light  afforded 
is  perhaps  of  inferior  quality.  Hence  tar 
is  decomposed  in  very  few  establishments. 

The  film  of  petroleum,  which  floats  on 
the  water  of  the  gasometer  tank,  and  that 
procured  from  the  tar  by  distillation,  have 
been  used  instead  of  oil  for  street-lamps. 
The  lamp  fountain  is  kept  on  the  outside 
of  the  glass  lantern,  and  the  flame  is  made 
small,  to  prevent  an  explosion  of  the  vapo- 
rized naphtha. 

1430  Ibs.  of  tar  by  boiling  yield  9  cwt. 
of  good  pitch.  From  a  chaldron  of  New- 
castle coal  about  200  Ibs.  of  ammoniacal 
liquor  are  obtained;  a  solution  chiefly  of 
the  carbonate  and  sulphate.  The  strongest 
liquor  comes  from  the  caking  coal.  A  gal- 
lon, or  8£  Ibs.  usually  requires  for  satura- 
tion from  fifteen  to  sixteen  ounces  of  oil  of 
vitriol,  sp.  gr.  1.84.  To  obtain  subcarbo- 
nate  of  ammonia,  125  Ibs.  of  calcined  gyp- 
sum in  fine  powder  are  added  to  108  gal- 
lons of  the  ammoniacal  liquor.  The  mix- 
ture is  stirred,  and  the  cask  containing  it, 
is  then  closed  for  three  or  four  hours.  Six- 
teen ounces  of  sulphuric  acid  are  now  mix- 
ed in;  and  the  whole  allowed  to  remain  at 
rest  for  four  or  six  hours.  The  superna- 
tant sulphate  of  ammonia  is  next  evaporat- 
ed till  it  crystallize.  One  hundred  weight 
of  the  dry  crystals  is  mixed  with  one-fourth 
of  their  weight  of  dry  •  halk  in  powder,  and 
sublimed  from  a  cylindrical  iron  retort  into 
a  barrel-shaped  receiver  of  lead.  A  charge 
of  120  Ibs.  of  the  mixture,  is  usually  de- 
composed in  the  course  of  twenty-four 
hours.  One  hundered  weight  of  dry  sul- 
phate of  ammonia,  is  said  to  produce  from 
sixty  to  sixty-five  pounds  of  solid  subcar- 
bonate  of  ammonia.  If  the  sulphate  of  am- 
monia, mixed  with  common  salt,  is  expos- 
ed to  a  subliming  heat,  sal  ammoniac  is  ob- 
tained. For  oil  gas,  sec  OIL.* 

COATING,  or  LORICATION.  Chaptal 
recommends  a  soft  mixture  of  marly  earth, 
first  soaked  in  water,  and  then  kneaded 
with  fresh  horse-dung,  as  a  very  excellent 
coating. 

The  valuable  method  used  by  Mr.  Willis 
of  Wapping  to  secure  or  repair  his  retorts 
used  in  the  distillation  of  phosphorus,  de- 
serves to  be  mentioned  here.  The  retorts 
are  smeared  with  a  solution  of  borax,  to 
which  some;  slaked  Ume  has  been  added, 
and  when  dry,  they  are  again  smeared  with 
a  thin  paste  of  slaked  lime  and  linseed  oil. 
This  paste  being  made  somewhat  thicker, 
is  applied  with  success,  during  the  distil- 
lation, to  mend  such  retorts  as  crack  by 
the  fire. 

*  COB  ALT.  A  brittle,  somewhat  soft,  but 
difficultly  fusible  metal,  of  a  reddish-gray 
colour,  of  little  lustre,  and  a  sp.  trr.  of  8.6. 
Its  melting  point  is  said  to  be  130°  Wedge- 
wood.  It  is  generally  associated  in  its  ores 


COB 


COB 


nickel,  arsenic,  iron,  and  copper;  and 
the  cobalt  of  commerce  usually  contains  a 
proportion  of  these  metals.  To  separate 
them,  calcine  with  4  parts  of  nitre,  and 
Wash  away,  with  hot  water,  the  soluble  ar- 
senite  of  potash.  Dissolve  the  residuum  in 
dilute  nitric  acid,  and  immerse  a  plate  of 
iron  in  the  solution,  to  precipitate  the  Cop- 
per. Filter  the  liquid  and  evaporate  to 
dryness.  Digest  the  mass  with  water  of  am- 
monia, which  will  dissolve  only  the  oxides 
of  nickel  and  cobalt.  Having1  expelled  the 
excess  of  alkali  by  a  gentle  heat  from  the 
clear  ammoniacal  solution,  add  cautious- 
ly water  of  potash,  which  will  precipitate 
the  oxide  of  nickel.  Filter  immediately,  and 
boil  the  liquid,  which  will  throw  down  the 
pure  oxide  of  cobalt.  It  is  reduced  to  the 
metallic  state  by  ignition  in  contact  with 
lampblack  and  oil.  Mr.  Laugier  treats 
the  above  ammoniacal  solution  with  oxalic 
acid.  He  then  redissolves  the  precipitated 
oxalates  of  nickel  and  cobalt  in  concentrat- 
ed water  of  ammonia,  and  exposes  the  so- 
lution to  the  air.  As  the  ammonia  exhales, 
oxalate  of  nickel,  mixed  with  ammonia, 
is  deposited.  The  nickel  is  entirely  sepa- 
rated from  the  liquid  by  repeated  crystal- 
lizations. There  remains  a  combination  of 
oxalate  of  cobalt  and  ammonia,  which  is 
easily  reduced  by  charcoal  to  the  metallic 
state.  The  small  quantity  of  cobalt  re- 
maining in  the  precipitated  salt  of  nickel, 
is  separated  by  digestion  in  water  of  am- 
monia. 

Cobalt  is  susceptible  of  magnetism,  but 
in  a  lower  degree  than  steel  and  nickel. 

Oxygen  combines  with  cobalt  in  two  pro- 
portions; forming  the  dark  blue  protoxide, 
and  the  black  deutoxide.  The  first  dis- 
solves in  acids  without  effervescence.  It  is 
procured  by  igniting  gently  in  a  retort  the 
oxide  precipitated  by  potash, from  the  nitric 
solution.  Proust  says,  the  first  oxide  con- 
sists of  100  metal  -f  19.8  oxygen;  and  Ro- 
thoff  makes  the  composition  of  the  deutox- 
ide 100  -j-  36.77.  If  we  call  the  first  18.5 
and  the  second  37;  then  the  prime  equiva- 
lent of  cobalt  will  be  5.4;  and  the  two  ox- 
ides will  consist  of 

fOobult,     5.4          100         84.38 
Protox.  >0          18.5         15<62 


Deutox     [Cobalt»      5A 
Deutox.    [oxygen,   2.0 


100.00 

100  73 

37  27 

100 

The  precipitated  oxide  of  cobalt,  wash- 
ed and  gently  heated  in  contact  with  air, 
passes  into  the  state  of  black  peroxide. 

When  cobalt  is  heated  in  chlorine,  it 
takes  fire,  and  forms  the  chloride.  The 
iodide,  phosphuret,  and  sulphuret  of  this 
metal  have  not  been  much  examined. 


The  salts  of  cobalt  are  interesting-  from 
the  remarkable  changes  of  colour  which 
they  can  exhibit. 

Their  solution  is  red  in  the  neutral  state, 
but  green,  with  a  slight  excess  of  acid;  the 
alkalis  occasion  a  blue  coloured  precipitate 
from  the  salts  of  pure  cobalt,  but  reddish- 
brown  when  arsenic  acid  is  present;  sul- 
phuretted hydrogen  produces  no  precipi- 
tate, but  hydrosulphurets  throw  down  a 
black  powder,  soluble  in  excess  of  the  pre- 
cipitant; tincture  of  galls  gives  a  yellow- 
ish-white precipitate;  oxalic  acid  throws 
down  the  red  oxalate.  Zinc  does  not  pre- 
cipitate this  metal. 

The  sulphate  is  formed  by  boiling  sul- 
phuric acid  on  the  metal,  or  by  dissolving 
the  oxide  in  the  acid.  By  evaporation,  the 
salt  may  be  obtained  in  acicular  rhomboi- 
dal  prisms  of  a  reddish  colour.  These 
are  insoluble  in  alcohol,  but  soluble  in  24 
parts  of  water.  It  consists,  by  the  analy- 
sis of  Bucholz,  of; 


Expert.  Theory. 

Acid,  26    or  1  prime  5.0  24.4 

Protoxide,       30          1  do.       6.4  31.4 

Water,  44          8  do.       9.  44.2 


100 


20.4 


Dr.  Thomson's  hypothetical  synthesis 
differs  widely  from  the  experimental,  in 
consequence  of  his  assuming  3.625  for  an 
atom  of  the  metal,  and  4.625  for  that  of  its 
oxide.  He  gives  28.57  acid  +  26.43  pro- 
toxide -f-  45  water. 

The  nitrate  forms  prismatic  red  deliques- 
cent crystals.  It  is  decomposable  by  gen- 
tle ignition.  The  muriate  is  easily  formed 
by  dissolving  the  oxide  in  muriatic  acid. 
The  neutral  solution  is  blue  when  concen- 
trated, and  red  when  diluted;  but  a  slight 
excess  of  acid  makes  it  green.  According 
to  Klaproth,  a  solution  of  the  pure  muriate 
forms  a  sympathetic  ink,  whose  traces  be- 
come blue  when  the  paper  is  heated;  but 
if  the  salt  be  contaminated  with  iron,  the 
traces  become  green.  I  find  that  the  addi- 
tion of  a  little  nitrate  of  copper  to  the  so- 
lution forms  a  sympathetic  ink,  which  by 
heat  gives  a  rich  greenish-yellow  colour. 
When  a  small  quantity  of  muriate  of  soda, 
of  magnesia,  or  of  lime  is  added  to  the  ink, 
its  traces  disappear  very  speedily  on  re- 
moval from  the  fire;  showing  that  the  vivid 
green,  blue,  or  yellow  colour,  is  owing  to 
the  concentration  of  the  saline  traces  by 
heat,  and  their  disappearance,  to  the  re  ab- 
sorption of  moisture.  At  a  red  heat,  the 
greater  part  of  the  muriate  sublimes  in  a 
gray  coloured  chloride.  The  acetate 
forms  a  sympathetic  ink,  whose  traces  be- 
ing heated,  become  of  a  dull  blue  colour. 
The  arseniate  of  cobalt  is  found  native  in 
a  fine  red  efflorescence,  and  in  crystals. 
See  ORES  of  Cobalt.  A  cream-tartrate  o 


COG 


COF 


cobalt  may  be  obtained  in  large  rhomboi- 
dal  crystals,  by  adding-  the  tart  rate  of  pot- 
ash to  cobaltic  solutions,  and  slow  evapo- 
ration. An  ammonia-nitrate  of  cobalt  may 
be  formed  in  red  cubical  crystals,  by  add- 
ing- ammonia  in  excess  to  the  nitric  solu- 
tion, and  evaporating  at  a  very  gentle  h«.-at. 
They  have  a  urinous  taste,  and  are  perma- 
nent in  the  air.  The  red  oxalate  is  soluble 
in  an  excess  of  oxalic  acid,  and  hence  neu- 
tral oxalate  of  potash  is  the  proper  reagent 
for  precipitating  cobalt.  The  phosphate 
may  be  formed  by  double  decomposition. 
It  is  an  insoluble  purple  powder,  which, 
heated  along  with  eight  parts  of  gelatinous 
alumina,  produces  a  beautiful  blue  pig- 
ment, a  substitute  for  ultra-marine.  The 
colouring  power  of  oxide  of  cobalt  on  vitri- 
tiable  mixtures,  is  greater  perhaps  than 
that  of  any  other  metal.  One  grain  gives 
a  full  blue  to  240  grains  of  glass.  Zafire 
is  a  mixture  of  flint  powder  and  an  impure 
oxide  of  cobalt,  prepared  by  calcination  of 
the  ores.  Smalt  and  azure  blue  are  mere- 
ly cobaltic  glass  in  fine  powder.  See 
GLASS.* 

*  COBALUS.  The  demon  of  mines,  which 
obstructed  and  destroyed  the  miners.  The 
church  service  of  Germany  formerly  con- 
tained a  form  of  prayer  for  the  expulsion 
of  the  fiend.     The  ores  of  the  preceding 
metal  being  at   first  mysterious    and    in- 
tractable, were  nicknamed  cobalt.* 

*  COCCOLITE.     A  mineral  of  green  co- 
lour of  various  shades,  which  occurs,  mas- 
sive; in  loosely  aggregated  concretions;  and 
crystallized  in  six-sided  prtsms,  with  two 
opposite  acute  lateral  edges,  and  bevelled 
on    the    extremities,    with   the    bevelled 
planes  set  on  the  acute  lateral  edges;  or  in 
four-sided  prisms.     The  crystals  are  gene- 
rally rounded  on  the  angles   and  edges. 
The  internal  lustre  is  vitreous.     Cleavage, 
double  oblique  angular.    Fracture  uneven. 
Translucent  on    the   edges.    It    scratches 
apatite,  but  not  feldspar.  Is  brittle.  Sp.  gr. 
3.3.  It  fuses  with  difficulty  before  the  blow- 
pipe.    Its  constituents  are  silica  50,  lime 
24,   magnesia   10,    alumina   1.5,  oxide  of 
iron  7,  oxide  of   manganese  3,  loss  4.5. 
Vauquclin. 

It  occurs  along  with  granular  limestone, 
garnet  and  magnetic  ironstone,  in  beds 
subordinate  to  the  trap  formation.  It  is 
found  at  Arendal  in  Norway,  Nericke  in 
Sweden,  Barkas  in  Findland,  the  Hartz, 
Lower  Saxony,  and  Spain.* 

COCHINEAL,  was  at  first  supposed  to  be 
a  grain,  which  name  it  still  retains  by  way 
of  eminence  among  dyers,  but  naturalists 
soon  discovered  that  it  was  an  insect.  It 
is  brought  to  us  from  Mexico,  where  the 
insect  lives  upon  different  species  of  the 
opuntia. 

Fine  cochineal,  which  has  been  well 
dried  and  properly  kept,  ought  to  be  of  a 


gray  colour  inclining  to  purple.  The  gray 
is  owing  to  a  powder  which  covers  it  na- 
turally, a  part  of  which  it  still  retains:  the 
purple  tinge  proceeds  from  the  colour  ex- 
tracted by  the  water  in  which  it  has  been 
killed.  Cochineal  will  keep  a  long  time  in 
a  dry  place.  Hellot  says,  that  he  tried 
some,  one  hundred  and  thirty  years  old, 
and  found  it  produced  the  same  effect  a» 
new. 

*  MM.  Pelletier  and  Caventou  have  lately 
found  that  the  very  remarkable  colouring 
matter  which  composes  the  principal  part 
of  cochineal,  is  mixed  with  a  peculiar  ani- 
mal matter,  a  fat  like  common  fat,  and 
with  different  salts.  The  fat  having  been 
separated  by  ether,  and  the  residuum 
treated  with  boiling  alcohol,  they  allowed 
the  alcohol  to  cool  as  they  gently  evapora- 
ted it,  and  by  this  means  they  obtained  the 
colouring  matter;  but  still  mixed  with  a 
little  fat  and  animal  matter.  These  were 
separated  from  it,  by  again  dissolving  it 
in  cold  alcohol,  which  left  the  animal  mat- 
ter untouched,  and  by  mixing  the  solution 
with  ether,  and  thus  precipitating  the  co- 
louring matter  in  a  state  of  great  purity, 
which  they  have  called  car  minium.  It  melts 
at  122°  F*ahr.  becomes  puffy,  and  is  de- 
composed, but  does  not  yield  ammonia.  It 
is  very  soluble  in  water,  slightly  in  alcohol, 
and  not  at  all  in  ether,  unless  by  the  in- 
termediation of  fat.  Acids  change  it  from 
crimson,  first  to  bright  red,  and  then  to 
yellow;  alkalis,  and,  generally  speaking,  all 
protoxides  turn  it  to  violet;  alumina  takes 
it  from  water.  Lake  is  composed  of  car- 
minium  and  alumina.  Carmine  is  a  triple 
compound  of  an  animal  matter,  carminhim, 
and  an  acid  which  enlivens  the  colour. 
The  action  of  muriatic  acid  in  changing 
the  crimson  colour  of  cochineal  into  a  fine 
scarlet,  is  similar. 

Dr.  John  calls  the  red  colouring  matter 
cochenilin.    He  says,  the  insect  consists  of 
Cochenilin,  50.0 

Jelly,  10.5 

Waxy  fat,  10.0 

Gelatinous  mucus,  14.0 
Shining  matter,  14.0 
Salts,  1.5 

100.0 

COFFEE.  The  seeds  of  the  co/ea  ara- 
bica  are  contained  in  an  oval  kernel,  enclo- 
sed in  a  pulpy  berry,  somewhat  like  a 
cherry.  The  ripe  fruit  is  allowed  slightly 
to  ferment,  by  which  the  pulp  is  more 
easily  detached  from  the  seeds.  These 
are  afterwards  washed,  carefully  dried  in 
the  sun,  and  freed  from  adhering  mem- 
branes by  winnowing.  Besides  the  pecu- 
liar bitter  principle,  which  we  have  de- 
scribed under  the  name  caffbin,  coffee  con- 
tains several  other  vegetable  products. 
According  to  Cadet,  64  parts  of  raw  coffee 


COH 


COH 


consist  of  8  gum,  1  resin,  1  extractive  and 
bitter  principle,  3.5  gallic  acid,  0.14  albu- 
men, 43.5  fibrous  insoluble  matter,  and 
6.86  loss.  Hermann  found  in  1920  grains 
of 

Levant  Coffee.     Mart.  Coffee. 
Resin,  74  68 

Extractive,  320  310. 

Gum,  130 

Fibrous  matter,    1335  1386 

Loss,  61  12 


1920  1920  Craigleith  stone, 

The  nature  of  the  volatile  fragrant  prin- 
ciple, developed  in  coffee  by  roasting,  has 
not  been  ascertained.  The  Dutch  in  Su- 
rinam improve  the  flavour  of  their  coffee 
by  suspending  bags  of  it,  for  two  years,  in 
a  dry  atmosphere.  They  never  use  new 
coffee.* 

Coffee  is  diuretic,  sedative,  and  a  cor- 
rector of  opium.  It  should  be  given  as 
medicine  in  a  strong  infusion,  and  is  best 
cold.  In  spasmodic  asthma  it  has  been  par- 
ticularly serviceable;  and  it  has  been  re- 
commended in  gangTfne  of  the  extremities 
arising  from  hard  drinking. 

*  COHESION,  or  attraction  of  cohesion, 
is  that  power  by  which  the  particles  of  bo- 
dies are  held  together.  The  absolute  co- 
hesion of  solids  is  measured  by  the  force 
necessary  to  pull  them  asunder.  Heat  is 
excited  "at  the  same  lime.  At  the  iron 
cable  manufactory  of  Captain  Brown,  a 
cylindrical  bar  of  iron,  14  inch  diameter, 
was  drawn  asunder  by  a  force  of  43  tons. 
Before  the  rupture,  the  bar  lengthened 
jtbout  5  inches,  and  the  section  of  fracture 
was  reduced  nearly  -|  of  an  inch.  About 
this  part,  a  degree  of  heat  was  generated, 
which,  according  to  Mr.  Barlow  of  Wool- 
wich, rendered  it  unpleasant,  if  not  in  a 
slight  degree  painful,  to  grasp  the  bar  in 
the  hand."  The  same  thing  is  shown  in  a 
greater  degree  in  wire -drawing.  When 
the  force  is  applied  to  compress  the  body, 
it  becomes  shorter  in  the  direction  of  the 
force,  which  is  called  the  compression;  and 
the  area  of  its  section  at  right  angles  to 
the  force,  expands.  The  cohesion,  calcu- 
lated from  the  transverse  strength,  is  as 
near,  or  perhaps  nearer,  the  real  cohesion, 
than  that  obtained  by  pulling  the  body 
asunder.  The  cohesive  force  of  metals  is 
much  increased  by  wire-drawing,  rolling, 
and  hammering  them.  In  the  elaborate 
tables  of  cohesion  drawn  up  by  Mr.  Thomas 
Tredgold,  and  published  in  the  50th  vol. 
of  Tilloch's  Magazine,  the  specific  cohe- 
sion of  plate  glass  (a  pretty  uniform  body)  cast  iron, 
is  denoted  by  unity.  Cast  copper, 

The  following  table  is  the  result  of  ex-    Fine  yellow  brass, 
periments  by   George   Rennie,   .Fun.  Esq.    Wrought  copper, 
published  in   the  first  part  of  the  Phil.    Cast  tin, 
Transactions  for  1818.  Cast  lead, 


Mr.  Rennie  found  a  cubical  inch  of  the 
following  bodies  crushed  by  the  following- 
weights:  Ibs.  ov. 
Elm, 

American  pine,  ...         1606 

White  deal,         ....         1928 
English  oak,       .... 
Ditto  of  five  inches  long,  slipped  with,  2572 
Ditto  of  four  inches,  ditto,  -         5147 

A  prism  of  Portland  stone,  two  inches 

long, 
Ditto  statuary  marble,  3216 


8688 


Cubes  of  l£  inch. 


sp.  gr. 

Chalk,         ....       —        1127 

Brick  of  a  pale  red  colour,       2.085     1265 

Roe-stone,  Gloucestershire,        —        1449 

Red  brick,  mean  of  two  trials,  2.168     1817 

Yellow  face  baked  Hammer- 
smith paviors,  three  times,    —        2254 

Burnt  ditto,  mean  of  two  trials,  —        3243 

Stourbridge,  or  fine  brick,          —        3864 

Derby  grit,  a  red  friable  sand- 
stone, -         -     2.316     7070 

Derby  grit  from  another  quar- 
ry, -         -     2.428    9776 

Kilialy   white    freestone,   not 

stratified,         -          -         -     2.42,1  10264 

Portland,  -          -         -     2.428  10284 

Craigleith,  white  freestone,      2.452  12346 

Yorkshire    paving,    with   the 

strata,  -          -         -     2.507  12856 

Ditto,  against  the  strata,  2.507  12856 

White  'statuary   marble,   not 

veined,  *-          -         -     2.760  13632 

Bramley-Fall  sandstone,  near 

Leeds,  with  strata,         -        2.506  13632 

Ditto,  against  strata,          -        2.506  13632 

Cornish' granite,  2.662  14302 

Dundee  Sandstone,  or  breccia, 

two  kinds,       -  2.530  14918 

A  two  inch  cube  of  Portland,  2.423  14918 

Craigleith,  with  strata,  2.452  15560 

Devonshire  red  marble,  varie- 
gated, —     16712 

Compact  limestone,  -       2.584  17354 

Peterhead  granite, hard  close- 
grained, 

Black  compact  limestone,  Li- 
merick,         -  2.598  19924 

Purbeck,  -  2.599  20610 

Black  Brabant  marble,  2.697  20742 

Very  hard  freestone, 

White  Italian  veined  marble,  2.726  21 783 
Aberdeen  granite,  blue  kind,  2.625  24556 

Cubes  of  different  metals  of  £th  inch  were 
crushed  by  the  following  weights. 

9773 
7318 

-       •  -      10304 
6440 
966 


COL 


COL 


Bars  of  different  metals,  six  inches  long, 
and  a  quarter  of  an  inch  square,  were 
suspended   by  nippers,  and  broken  by 
the  following  weights: 
Cast  iron,  horizontal,            -        -         1166 
Di  to,  vertical,              -         -         -         1218 
CjiSt  steel,  previously  tilted,         -         8o91 
Blistered  steel,  reduced  by  the  ham- 
mer, 8322 
Shear  steel  ditto,          -         -         -         7977 
Swedish  iron  ditto,               -         -         4504 
English  iron  ditto,        -  3492 
Hard  gun  metal,  mean  of  two  trials,  2273 
Wrought  copper,  reduced  by  ham- 
mer,          2112 

Cast  copper,  ....  1192 
Fine  yellow  brass,  -  -  .  1123 
Cast,  tin,  .....  296 
Cast  lead,  ....  114 

For  the  experiments  on  the  twist  of  bars 
We  must  refer  to  the  paper. 

The  strengths  of  Swedish  and  English  iron 


do  not  bear  the  same  proportion  to  each  other 
in  these  experiments,  that  they  do  when  we 
compare  the  trials  of  Count  S'rckingen  with 
those  made  at  Woolwich,  of  which  an  ac- 
count was  given  in  the  Annals  of  Philosophy, 
vii.  320.  From  that  comparison,  the  propor- 
tional strengths  were  as  follows: 


English  iron, 
Swedish  iron, 


348.38 
549.25 


But  from  Mr.  Rennie's  experiments,  the  pro- 
portional strengths  are: 


English  iron, 
Swedish  iron, 


348.38 
449.34 


A  very  material  difference,  which  ought  to 
be  attended  to. 

The  following  Table  contains  a  view  of 
some  former  experiments,  on  the  cohesive 
strengths  or  tenacities  of  bodies. 


A  wire        inch  of  zinc  breaks  with  26  pounds.    Mechenbroek. 


Do. 
Do. 
Do. 
Do. 
Do. 
Do. 
Do. 


lead 

tin 

copper 

brass 

silver 

iron 

gold 


A  cylinder  1  inch  iron 

According  to  Sickingeu,  the  relative  co- 
hesive strengths  of  the  metals  are  as  fol- 
lows: 


Gold, 
Silver, 
Platina, 
Copper, 
Soft  iron, 
Hard  iron, 


150955 
190771 
262361 
304696 
362927 
559880 


A  wire  of  iron  0.078  or  j~  of  an  inch,  will 
just  support  549.25  pounds.  Emerson's 
number  for  gold  is  excessively  incorrect.  In 
general,  iron  is  about  4  times  stronger  than 
oak,  and  6  times  stronger  than  deal.* 

*  COHOBATION  The  continuous  redistil- 
lation of  the  same  liquid,  from  the  same  ma- 
terials.* 

COLCOTHAR.  The  brown-red  oxide  of  iron, 
which  remains  after  the  distillation  of  the  acid 
from  sulphate  of  iron:  it  is  used  for  polishing 
glass  and  other  substances  by  artists,  who 
eall  it  crocus,  or  crocus  martis. 

COLD.  The  privation  of  heat.  See  C  Ato- 
nic, CONGELATION,  and  TEMPERATURE. 

COLOPHONY.  Colophony,  or  black  resin, 
is  the  resinous  residuum  after  the  distilla- 
tion of  the  light  oil,  and  thick  dark  reddish 
balsam,  from  turpentine. 


49* 
299J 
360 
370 
450 
500 
63320 


Emerson. 

do. 

do. 

do. 

do. 

do. 

do. 
Rumford. 


*CoLUMBruM.  If  the  oxide  of  columbium 
described  under  ACID  (COLUMBIC)  be  mixed 
with  charcoal,  and  exposed  to  a  violent  heat 
in  a  charcoal  crucible,  the  metal  columbium 
will  be  obtained.  It  has  a  dark  gray  colour; 
and  when  newly  abraded,  the  lustre  nearly 
of  iron.  Its  sp.  gr.,  when  in  agglutinated 
particles,  was  found  by  Dr.  Wollaston  to  be 
5.61.  These  metallic  grains  scratch  glass, 
and  are  easy  pulverized.  Neither  nitric,  mu- 
riatic, nor  nitro-muriatic  acid  produces  any 
change  in  this  metal,  though  digested  on  it 
for  several  days.  It  has  been  alloyed  with 
iron  and  tungsten.  See  ACID  (COLUMBIC.)* 

*COLCHICUM  ArTUMNALE.  A  medicinal 
plant,  the  vinous  infusion  of  whose  root  has 
been  shown  by  Sir  E.  Home  to  possess  spe- 
cific powers  of  alleviating  gout,  similar  to 
those  of  the  empirical  preparation  called 
Eau  medicinale  D'Husson.  The  sediment  of 
the  infusion  ought  to  be  removed  by  filtra- 
tion, as  it  occasions  gripes,  sickness,  and 
vomiting.* 

*  COLOFHONITE.  A  mineral  of  a  blackish, 
or  yellowish -brown,  or  orange -red  colour; 
of  a  resino-adamantine  lustre;  and  conchoi- 
dal  fracture.  Its  sp.  gr.  is  4.0.  It  consists  of 
silica  35,  alumina  13.5,  lime  29.0,  magnesia 
6.5,  oxide  of  iron  7.5,  oxide  of  manganese 
4.75,  and  oxide  of  titanium  0.5.  It  occurs 
massive,  in  angulo-granular  concretions,  and 
40 


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in  rhomboidal  dodecahedrons,  whose  sur- 
faces have  a  melted  appearance.  It  is  the 
resinous  garnet  of  Haiiy  and  Jameson.  It 
is  found  in  magnetic  ironstone  at  Arendal 
in  Norway.  It  occurs  also  in  Piedmont  and 
Ceylon.* 

*  COMBINATION.     The  intimate   union   of 
the  particles  of  different  substances  by  che- 
mical attraction,  so  as  to  form  a  compound 
possessed  of  new  and  peculiar  properties. 
See  ATTRACTION,  EQUIVALENT,  and  GAS.* 

*  COMBUSTIBLE.     A    body    which,    in    its 
rapid  union  with  others,  causes  a  disengage- 
ment of  heat  and  light.     To  determine  this 
rapidity  of  combination,  or  intensity  of  che- 
mical action,  a  certain  elevation  of  tempera- 
ture is  necessary,  which  differs  for  every  dif- 
ferent combustible.    This  difference  thrown 
into  a  tabular  form,  would  constitute  their 
scale  of  accendibility,  or  degree  of  accension. 

Stahl  adopted,  and  refined  on  the  vulgar 
belief  of  the  heat  and  light  com.ng  from  the 
combustible  itself;  Lavoisier  advanced  the 
opposite  and  more  limited  doctrine,  that  the 
heat  and  light  proceeded  from  the  oxy- 
genous gas,  in  air  and  other  bodies,  which 
lie  regarded  as  the  true  pabulum  of  fire. 
Stahl's  opinion  is  perhaps  more  just  than 
Lavoisier's;  f-r  man}  combustibles  burn  to- 
getlivr,  without  the  presence  of  oxygen  or 
of  any  analogous  fancied  supporters;  us 
chlorine,  and  the  adjuncts  to  oxvgen,  have 
bten  iMiphilosophically  called.  Sulphur,  hy- 
dros.;; n,  carbon,  and  azote,  are  as  much 
entitled  to  be  styled  supporters,  as  oxygen 
and  chlorine;  for  potassium  burns  vividly  in 
sulphuretted  hydrogen,  and  in  pruss'me,  and 
most  of  the  metals  burn  with  sulphur  alone. 
lit  at  and  light  are  disengaged,  with  a  change 
of  properties,  and  reciprocal  saturation  of 
the  combining  bodies.  All  the  combustible 
gases  are  certainly  capable  of  affording  heat, 
to  the  degree  of  incandescence,  as  is  shown 
by  their  mechanical  condensation. 

Sound  logic  would  justify  us  in  regard- 
ing oxygen,  chlorine,  and  iodine,  to  be  in 
reality  combustible  bodies;  perhaps  more  so, 
than  those  substances  vulgarly  called  com- 
bustibie.  Experiments  with  the  condensing 
syringe,  and  the  phenomena  of  the  decom- 
pusiuon  of  euchlorine,  prove  that  light  as 
well  as  heat,  tuuy  be  afforded  by  oxygen  and 
chlorine.  If  the  body,  therefore,  which  emits, 
or  can  emit,  light  and  heat  in  copious  streams, 
by  its  action  on  others,  be  a  combustible, 
then  chlorine  and  oxygen  merit  that  desig- 
nation, as  much  as  charcoal  and  sulphur. 
Azote  is  declared  by  the  expounders  of  the 
Lavcusierian  creed,  to  be  a  simple  incombus- 
tible. Ytt  its  mechanical  condensation  proves 
that  it  can  afford,  from  its  own  resources,  an 
incandescent  hea  ;  and  with  chlorine,  iodine, 
and  metallic  oxides,  all  incombustibles  on 
the  antiphlogistic  notion,  it  forms  com- 
pounds possessed  of  combustible  properties, 
in  a  pre-eminent  and  a  tremendous  degree 


of  concentration.  It  is  melancholy  to  reflect 
with  what  easy  credulity,  the  fictions  of  the 
Lavoisierian  faith  have  been  received  and 
propagated  by  chemical  compilers,  some- 
times sufficiently  incredulous  on  subjects  of 
rational  belief.  See  the  next  article. 

The  electric  polarities  unquestionably  show, 
what  no  person  can  wish  to  deny,  that  be- 
tween oxygen,  chlorine,  iodine,  on  one  hand, 
and  hydrogen,  charcoal,  sulphur,  phospho- 
rus, and  the  metals,  on  the  other,  there 
exist  striking  differences.  The  former  are 
attracted  by  the  positive  pole,  the  latter  by 
the  negative,  in  voltaic  arrangements.  But 
still  nothing  definitive  can  be  inferred  from 
this  fact;  because  in  the  actions  of  what  are 
called  combustibles,  on  each  other,  without 
the  presence  of  the  other  class,  we  have  an 
exhibition  of  opposite  electrical  polarities. 
Sulphur  and  metallic  plates,  by  mutual 
friction  or  mere  contact,  produce  electrical 
changes,  which  apparently  prove  that  sul- 
phur should  be  ranked  along  with  oxygen, 
chlorine,  and  acids,  apart  from  combusti- 
bles, whose  polarities  are  negative.  Sul- 
phuretted hydrogen  in  its  electrical  relations 
to  metals,  ranks  also  with  oxygen  and  acids. 
How  vague  and  fallacious  a  rule  of  classifi- 
cation electrical  polarity  would  afford,  may 
be  judged  of  from  the  following  unquestion- 
able facts;  "  Among  the  substances  that 
combine  chemically,  all  those,  the  electrical 
energies  of  which  are  well  known,  exhibit 
opposite  states;  thus  copper  and  zinc,  gold 
and  quicksilver,  sulphur  and  the  metals,  the 
acid  and  alkaline  substances,  afford  opposite 
instances.  In  the  voltaic  combination  of 
diluted  nitrous  acid,  zinc  and  copper,  as  is 
well  known,  the  side  of  the  zinc  exposed  to 
the  acid  is  positive.  But  in  combinations  of 
zine,  water,  and  diluted  nitric  acid,  the  sur- 
face exposed  to  the  acid  is  negative;  though 
if  the  chemical  action  of  the  acid  on  the 
zinc  had  been  the  cause  of  the  effect,  it 
ought  to  be  the  same  in  both  cases."  On 
sc'ine  chemical  agencies  of  electricity  by  Sir  H. 
Davy,  Phil.  Trims.  1807. 

Combustibles  have  been  arranged  into 
sin  pie  and  compound.  The  former  consist 
cf  hydrogen,  carbon,  boron,  sulphur,  phos- 
phorus, and  nitrogt  n,  besides  all  the  metals. 
The  kuter  class  comprehends  the  hydrurets, 
carburets,  sulphurets,  phosphurets,  metallic 
alloys,  and  organic  products.* 

*COMBISTION.  The  disengagement  of 
heat  and  light  which  accompanies  chemical 
combination.  It  is  frequently  made  to  be 
synonymous  with  inflammation,  a  term  which 
might'  be  restricted,  however,  to  that  peou- 
liar  species  of  combustion,  in  which  gaseous 
matter  is  burned.  Ignition  is  the  incandes- 
cence of  a  body,  produced  by  extrinsic 
means,  without  change  of  its  chemical  con- 
stitution. 

Beccher  and  Stahl,  feeling  daily  the  neces- 
sity of  tire  to  human  existence, 


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ed  with  the  metamoiyhoses  which  this  power 
seemed  to  cause  charcoal,  sulphur,  and  me- 
tals to  undergo,  came  to  regard  combustion 
as  the  single  phenomenon  <»f  chemistry.  I  n- 
der  this  impression  Stahl  framed  his  chemi- 
cal system,  the  Theoria  C/iemix  Df'gmuticte, 
a  title  characteristic  of  the  dogmatic  spirit 
with  which  it  was  inculcated  by  chemical 
piofessors,  as  the  infallible  code  of  their 
science  for  almost  a  century.  When  the  dis- 
coveries of  Scheele,  Cavendish,  and  Priest- 
ley, had  fully  demonstrated  the  essential 
par<.  which  air  played,  in  many  instances  of 
combustion,  the  French  school  made  a  small 
modification  of  the  German  hypothesis.  In- 
stead of  supposing-,  with  Stahl,  that  the  heat 
and  light  were  occasioned  by  the  emission  of 
a  common  inflammable  principle  from  the 
combustible  itself,  Lavoisier  and  his  asso- 
ciates dexterously  availed  themsehes  of 
Black's  hypothesis  of  latent  heat,  and  main- 
tained, that  the  heat  and  light  emanated 
from  the  oxygenous  air,  at  the  moment  of 
its  union  or  fixation  with  the  inflammable 
basis.  How  thoroughly  the  chemical  mind 
has  been  perverted  by  these  conjectural 
notions,  all  our  existing  systems  of  chemis- 
try, with  one  exception,  abundantly  prove. 

Dr.  Robison,  in  his  preface  to  Black's 
lectures,  after  tracing  with  perhaps  super- 
fluous zeal,  the  expanded  ideas  of  Lavoi- 
sier, to  the  neglected  germs  of  Hooke  and 
Mayhow,  says,  "This  doctrine  concerning 
combustion,  the  great,  the  characteristic 
phenomenon  of  chemical  nature,  has  at 
last  received  almost  universal  adoption, 
though  not  till  after  considerable  hesitation 
and  opposition;  and  it  has  made  a  complete 
revolution  in  chemical  science."  The  French 
theory  of  chemistry,  as  it  was  called,  or 
hypothesis  of  combustion,  as  it  should  have 
been  named,  was  for  some  time  classed  in 
certainty  with  the  theory  of  gravitation. — 
Alas!  it  is  vanishing  with  the  luminous 
phantoms  of  the  day,  but  the  sound  logic, 
the  pure  candour,  the  numerical  precision 
of  inference,  which  characterize  Lavoisier's 
elements,  will  cause  his  name  to  be  held  in 
everlasting  admiration- 

It  was  the  rival  logic  of  Sir  H.  Davy, 
aided  by  his  unrivalled  felicity  ^of  investiga- 
tion, which  first  recalled  chemistry  from  the 
pleasing  labyrinths  of  fancy,  to  the  more 
arduous  but  far  more  profitable  and  pro- 
gressive career  of  reason.  His  researches 
on  combustion  and  flame,  already  rich  in 
blessings  to  mankind,  would  alone  place 
him  in'the  first  rank  of  scientific  genius.  I 
shall  give  a  pretty  copious  account  of  them, 
since  by  some  fatality  it  has  happened,  that 
in  our  best  and  largest  system,  where  so 
many  pages  are  devoted  to  the  reveries  of 
ancient  chemists,  the  splendid  and  useful 
truths,  made  known  by  the  great  chemist 
*f  England,  have  been  totally  overlooked. 
Whenever  the  chemical  "ferces,  which 


determine  either  combination  or  decompo- 
sition, are  energetically  exercised,  the  phe- 
nomena of  combustion,  or  incundesence 
with  a  change  of  properties,  are  displayed.' 
The  distinction,  therefore,  between  sup- 
porters of  combustion  and  combustibles,  on 
which  some  late  systems  are  arranged,  is 
frivolous  and  partial.  In  fact,  one  substance 
frequently  acts  in  both  capacities,  being  a 
supporter  apparently  at  one  time,  anil  a 
combustible  at  another.  But  in  both  cases 
the  heat  and  light  depend  on  the  same 
cause,  and  merely  indicate  the  energy  and 
rapidity  with  which  reciprocal  attractions 
are  exerted. 

Thus,  sulphuretted  hydrogen  is  a  com- 
bustible with  oxygen  and  chlorine;  a  sup- 
porter with  potassium.  Sulphur,  with 
chlorine  and  oxxgen,  has  been  called  a 
combustible  basis;  with  metals  it  acts  the 
part  of  a  supporter;  for  incandescence  and 
reciprocal  saturation  result.  In  like  man- 
ner,  potassium  unites  so  powerfully  with 
arsenic  and  tellurium  as  to  produce  the  phe- 
nomena of  combustion.  Nor  can  we  as- 
cribe the  phenomena  to  extrusion  of  latent 
heat,  in  consequence  of  condensation  of 
volume.  The  protoxide  of  chlorine,  a  bo- 
dy destitute  of  any  combustible  constitu- 
ent, at  the  instant  of  decomposition,  evolves 
light  and  heat  with  explosive  violence;  and 
its  volume  becomes  one-half  greater.  Chlo- 
ride and  iodide  of  azote,  compounds  alike 
destitute  of  any  inflammable  matter,  ac- 
cording to  the  ordinary  creed,  are  resolved 
into  their  respective  elements  with  tremen- 
dous force  of  inflammation;  and  the  first 
expands  into  more  than  600  times  its  bulk. 
Now,  by  the  prevailing  hypothesis  of  latent 
heat,  instead  of  heat  and  light,  a  prodigious 
cold  ought  to  accompany  such  an  expansion. 
The  chlorates  and  nitrates,  in  like  manner, 
treated  with  charcoal,  sulphur,  phosphorus, 
or  metals,  deflagrate  or  detonate,  while  the 
volume  of  the  combining  substances  is 
greatly  enlarged.  The  same  thing  may  be 
said  of  the  nitrogurets  of  gold  and  silver. 
In  truth,  the  combustion  of  gunpowder,  a 
phenomenon  toofamiliar  to  mankind,  should 
have  been  a  bar  to  the  reception  of  Lavoi- 
sier's hypothesis  of  combustion.  The  sub- 
terfuges which  have  been  adopted,  and  ad- 
mitted, in  order  to  reconcile  them,  are  un- 
worthy to  be  detailed. 

From  the  preceding  facts  it  is  evident 
1st,  That  combustion  is  not  necessarily  de- 
pendent on  the  agency  of  oxygen;  2d,  That 
the  evolution  of  the  heat  is  not  to  be  as- 
cribed simply  to  a  gas  parting  with  its  la- 
tent store  of  that  ethereal  fluid,  on  its  fixa- 
tion, or  combustion;  and,  Sclly:  That  "no 
peculiar  substance  or  form  of  matter  is  ne- 
cessary for  producing  the  effect,  but  that  it 
is  a  general  result  of  the  actions  ot  any  sub- 
stances possessed  of  strong  chemical  at- 
tractions^ or  different  electrical  rdhitioas* 


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and  that  it  takes  place  in  all  cases  in  which 
an  intense  and  violent  motion,  can  be  con- 
ceived to  be  communicated  to  the  corpus- 
cles of  bodies." 

All  chemical  phenomena  indeed  may  be 
justly  ascribed  to  motions  among  the  ulti- 
mate particles  of  matter,  tending  to  change 
the  constitution  of  the  mass. 

It  was  fashionable  for  a  while,  to  attribute 
the  caloric  evolved  in  combustion  to  a  di- 
minished capacity  for  heat  of  the  resulting 
substance.     Some  phenomena,  inaccurately 
observed,  gave  rise  to  this  generalization. 
On  this  subject  I  shall  content  myself  with 
stating  the  conclusions  to  which  M  M.   Du- 
long  and  Petit   have  come,  in  consequence 
of  their  own  recent  researches  on  the   laws 
of  heat,  and  those  of  Berard  and  Delaroche. 
"We  may  likewise,"  say  these  able  chemists, 
"deduce  from  our  researches  another  very 
important  consequence  f  >r  the  general  the- 
ory of  chemical  action,  that  the  quantity  of 
heat  developed  at  the  instant  of  the  combi- 
nation of  bodies,  has  no  relation  to  the  ca- 
pacity   of  the   elements,  and  that  in  the 
greatest  number  of  cases,  this   loss   of  heat 
is  not  followed  by  any  diminution  in  the  ca- 
pacity of  the  compounds  formed.    Thus, 
for  example,   the    combination  of  oxygen 
and  hydrogen,   or  of  sulphur  and     lead, 
which" produces  so  great  a  quantity  of  heat, 
occasions  no  greater  alteration  in  the   capa- 
city of  water,  or  of  sulphuret  of  lead,  than 
the   combination  of  oxygen    with   copper, 
lead,  silver,  or  of  sulphur  with  carbon,  pro- 
duces  in   the  capacities    of  the  oxides    of 
these  metals,  or  of  carburet  of  sulphur." — 
"  We  conceive  that  the  relations  which  we 
have  pointed  out  between  the  specific  heats 
of  simple  bodies,  and  of  those  of  their  com- 
pounds, prevent  the  possibility   of  suppos- 
ing, that   the  heat  developed  in  chemical 
actions,  owes  its  origin  merely  to  the   heat 
produced  by  change  of  state,  or  to  that  sup- 
posed to  be  combined    with  the    material 
molecules;"  Jlnnaks  deChimie  et  Physique,  x. 
Mr.  Dalton,  in  treating  ot  the  constitution 
of  elastic  fluids,  lays  it  down  as   an  axiom, 
that  diminution  of  volume  is  the   criterion 
of  chemical  affinity    being    exercised;  and 
hence  maintains,  that  the  atmospheric  air  is 
a  mere  mixture.    Thus,  also,  the  extrication 
of  heat  from  chemical  union,  has  been  usu- 
ally referred  to  the  condensation  of  volume. 
The  following  examples  will  show  the  falla- 
cy of  such  crude   hypotheses.    1.  Chlorine 
and  hydrogen  mixed,  explode  by   the  sun- 
beam, electric  spark,  or  inflamed  taper  with 
the  disengagement  of  much  heat  and  light; 
and  the  volume  of  the   mixture,   which    is 
greatly  enlarged  at  the  instant  of  combination, 
suffers  no  condensation  afterwards.     Muri- 
atic acid  gas,  having  the  mean  densily  of  its 
components,   is  produced.     2-  When   one 
voiume  of  olefiant  gas  and  one  of  oxygen 
are  detonated  together,  three  and  a  halt  ga- 


seous volumes  result,  the  greater  part  of  the 
hydrogen  remains  untouched,  and  a  volume 
and  a  half  of  carbonic  oxide  is  formed, 
with  about  1-lOth  of  carbonic  acid.  3.  The 
following  experiments  of  M.  Gay-Lussac  on 
liquid  combinations  are  to  the  same  purpose. 
1.  A  saturated  solution  of  nitrate  of  ammo- 
nia, at  the  temperature  of  61°,  and  of  the 
density  1.3J2,  was  mixed  with  water  in  the 
proportion  of  44.05.  to  33.76.  The  tempe- 
rature of  the  mixture  sank.  8.9°;  but  the 
density  at  61°  was  1159,  while  the  mean 
density  was  only  1.-51.  2.  On  adding  wa- 
ter to  the  preceding  mixture,  in  the  pro- 
portion of  33.64  to  39  28,  the  temperature 
sank  3  4°,  while  the  density  continued  000.3 
above  the  mean.  Other  saline  solutions  pre- 
sented the  same  result,  though  none  to  so 
great  a  degree. 

That  the  internal  motions  which  accom- 
pany the  change  in  the  mode  of  combination, 
independent  of  change  of  form,  occasion  the 
evolution  of  heat  and  light,  is  evident  from 
the  following  observations  of  Berzelius: — 
In  the  year  1811,  when  he  was  occupied  with 
examining  the  combinations  of  antimony, 
he  discovered,  accidentally,  that  several  me- 
talline antimoniutes,  when  they  begin  to 
grow  red-hot,  exhibit  a  sudden  appearance 
of  fire,  and  then  the  temperature  again 
sinks  to  that  of  the  surrounding  combusti- 
bles. He  made  numerous  experiments  to 
elucidate  the  nature  of  this  appearance,  and 
ascertained  that  the  weight  of  the  salt  was 
not  altered,  and  that  the  appearance  to-;k 
place  without  the  presence  of  oxygen.  Be- 
fore the  appearance  of  fire,  these  salts  are 
very  easily  decomposed,  but  afterwards  they 
are  attacked  neither  by  acids  nor  alkaline 
leys — a  proof  that  their  constituents  are  now 
held  together  by  a  stronger  affinity,  or  that 
they  are  more  intimately  combined.  Since 
that  time  he  has  observed  these  appearances 
in  many  other  bodies,  as,  for  example,  in 
green  oxide  of  chromium,  the  oxides  of  tan- 
talum and  rhodium  (See  CHROMIUM.) 

Mr.  Edmund  Davy  found,  that  when  a 
neutral  solution  of  platinum  was  precipitat- 
ed by  hydro-suiphuret  of  potash,  and  the 
precipitate  dried  in  air  deprived  of  oxygen, 
a  black  compound  was  obtained,  which 
when  heated  out  of  the  contact  of  air,  gave 
out  sulphur,  and  some  sulphuretted  hydro-- 
gen gas,  while  a  combustion  similar  to  that 
in  the  formation  of  the  metallic  sulphurets 
appeared,  and  common  sulphuret  of  plati- 
num remained  behind.  When  we  heat  the 
oxide  of  rhodium,  obtained  from  the  soda- 
muriate,  water  first  comes  over;  and  on  in- 
creasing the  temperature,  combustion  takes 
place,  oxygen  gas  is  suddenly  disengaged, 
and  a  suboxide  of  rhodium  remains  behind 
The  two  last  cases  are  analogous  to  that  of 
the  protoxide  of  chlorine,  the  euc/ilorine  of 
Sir  il.  Davy.  Gadolinite,  the  sihcuite  of 
>  ttria,  was  first  observed  by  Dr.  Wolluston 


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to  display  a  similar  lively  incandescence. — 
The  variety  of  this  mineral  with  a  glassy 
fracture,  answers  better  than  the  splintery 
variety,  It  is  to  be  heated  before  tht  blow- 
pipe, so  that  the  whole  piece  becomes  equal- 
ly hot.  At  a  red-heat  it  catches  fire.  The 
colour  becomes  greenish-gray,  and  the  so- 
lubility in  acids  is  destroyed.  Two  small 
pieces  of  gadolinite,  one  of  which  liad  been 
heated  to  redness,  were  put  in  aqua  regia; 
the  first  was  dissolved  in  a  few  hours;  the 
second  was  not  attacked  in  two  months.  Fi- 
nally, Sir  H.  Davy  observed  a  similar  phe- 
nomenon on  heating  hydrate  of  zirconia. 

The  verbal  hypothesis  of  thermoxygen  by 
Brugnatelli,  with  Dr.  Thomson's  supporters, 
partial  supporters,  andsemicombustion,  need 
not  detain  us  a  moment  from  the  substantial 
tacts,  the  noble  truths,  first  revealed  by  Sir 
H  Davy,  concerning  the  mysterious  process 
of  combustion.  Of  the  researches  winch 
brought  them  to  light,  it  has  been  said,  with- 
out any  hyperbole,  that  "  it  Bacon  were  to 
revisit  the  earth,  this  is  exactly  such  a  case 
as  we  should  chuse  to  place  before  him,  in 
order  to  give  him,  in  a  small  compass,  an 
idea  of  the  advancement  which  philosophy 
has  made  since  the  time,  when  he  had  point- 
ed out  to  her  the  route  which  she  ought  to 
pursue." 

The  coal  mines  of  England,  alike  essen- 
tial to  the  comfort  of  her  population  and  her 
financial  resources,  had  become  infested  with 
fire-damp,  or  inflammable  air,  to  such  a  de- 
gree as  to  render  the  mutilation  and  destruc- 
tion of  the  miners,  by  frequent  and  tremen- 
dous explosions,  subjects  ot  sympathy  and  dis- 
may te  the  whole  nation.  By  a  late  explo- 
sion in  one  of  the  Newcastle  collieries,  no 
less  than  one  hundred  and  one  persons  per- 
ished in  an  instant;  and  the  misery  heaped 
on  their  forlorn  families,  consisting  of  more 
than  three  hundred  persons,  is  inconceivable. 
To  subdue  this  gigantic  power  was  the  task 
which  Sir  H.  Davy  assigned  to  himself;  and 
which,  had  his  genius  been  baffled,  the  king- 
dom could  scarcely  hope  to  see  achieved  by 
another.  But  the  stubborn  forces  of  nature 
can  only  be  conquered,  as  Lord  Bacon  just- 
ly pointed  out,  by  examining  them  in  the 
nascent  state,  and  subjecting  them  to  expe- 
rimental interrogation,  under  every  diver- 
sity of  circumstance  and  form.  It  was  this 
in*  c  sligation,  which  first  laid  open  the  hi- 
therto unseen  and  inaccessible  sanctuary  of 
Fire. 

As  some  invidious  attempts,  however,  have 
been  made,  to  insinuate  that  Sir  H.  Davy 
Stole  the  germ  of  his  discoveries  from  the 
late  Mr.  Tennant,  it  may  be  proper  to  pre- 
face the  account  of  them  by  the  following 
extract  from  "Resolution  of  a  Meeting  held 
for  considering  the  facts  relating  to  the  Dis- 
covery of  the  Lamp  of  Safety." 

«  Soho  Square,  JVbu.  20,  1817. 
« ,3d— That  Sir  H.  Davy  net  only  disco- 


vered, independently  of  all  ethers,  and  with- 
out any  knowledge  ot  the  unpublished  expe- 
riments of  the  late  Mr.  Tennant  on  Flame, 
the  principle  of  the  non-communication  of 
explosions  through  SJT  all  apertures,  but  that 
he  has  also  the  sole  rn^rit  of  having  first  ap- 
plied it  to  the  very  important  purpose  of  a 
safeiy-lamp,  which  has  evidently  been  imi- 
tated in  the  latest  lamps  of  Mr.  George  Ste- 
phenson. 

(Signed)  Joseph  Banks,  P.  R.  S. 

William  .1.  Brande, 
Charles  Hatchett, 
William  Hyde  Wollaston, 
Thomas  Young." 

See  the  whole  document  in  Tilloch's  Maga- 
zine, vol.  50.  p.  387. 

The  phenomena  of  combustion  may  be 
conveniently  considered  under  six  Heads: 
1st.  The  temnerature  necessary  to  inflame 
different  bodies.  '2d,  The  nature  of  flame, 
and  the  relation  between  the  light  and  heat 
which  compose  it.  3d.  The  heat  disengaged 
by  different  combustibles  in  burning.  4th, 
The  causes  which  modify  and  extinguish 
combustion,  and  of  the  safe-lamp,  5th, 
Invisible  combustion  6th,  Practical  Infe- 
rences. 

1st  Of  the  temperature  necessary  to  inflame 
different  bodies.  1st.  A  simple  experiment 
shows  the  successive  combustibilities  of 
different  bodies.  Into  a  long  bottle  with  a 
narrow  neck,  introduce  a  lighted  taper,  and 
let  it  burn  till  it  is  extinguished.  Carefully 
stop  the  bottle  and  introduce  another  light- 
ed taper.  It  will  be  extinguished,  before  it 
reaches  the  bottom  of  the  neck.  Then  in- 
troduce a  small  tube,  containing  zinc  and 
dilute  sulphuric  acid,  at  the  aperture  of 
which  the  hydrogen  is  inflamed.  The  hy- 
drogen will  be  found  to  burn  in  whatever 
part  of  the  bottle  the  tube  is  placed.  After 
the  hydrogen  is  extinguished,  introduce 
lighted  sulphur.  This  will  burn  for  some 
time;  and  after  its  extinction  phosphorus 
will  be  as  luminous  as  in  the  air,  and,  if 
heated  in  the  bottle,  will  produce  a  pale 
yellow  flame  of  considerable  density. 

Phosphorus  is  said  to  take  fire  when  heat- 
ed to  150°  and  sulphur  to  550°.  Hydrogen 
inflames  with  chlorine  at  a  lower  tempera- 
ture than  with  oxygen.  By  exposing  oxygen 
and  hydrogen,  confined  in  glass  tubes,  to  a 
very  dull  red  (about  800  F.)  they  explode. 
When  the  heat  was  about  700  F.  they  com- 
bine rapidly  with  a  species  of  silent  com- 
bustion. A  mixture  of  common  air  and  hy- 
drogen was  introduced  into  a  small  copper 
tube,  having  a  stopper  not  quite  tight;  the 
copper  tube  was  placed  in  a  charcoal  fire; 
before  it  became  visibly  red-hot  an  explo- 
sion took  place,  and  the  stopper  was  driven 
out.  We  see,  therefore,  that  the  inflaming 
temperature  is  independent  of  compression 
or  rarefaction. 


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The  ratio  of  the  combustibility  of  the  dif- 
ferent gaseous  matters,  is  likewise  to  a  cer- 
tain extent,  as  the  masses  of  heated  matters 
required  to  inflame  them.  Thus,  an  iron 
wire  l-40th  of  an  inch,  heated  cherry-red, 
will  not  inflame  oleh'ant  gas,  but  it  will  in- 
flame hydrogen  gas.  A  wire  of  l-8th,  heat- 
ed to  the  same  degree,  will  inflame  oleh'ant 
g-as.  But  a  wire  -i-  of  an  inch,  must  be  Tic  at- 
ed  to  whiteness  to  inflame  hydrogen,  though 
at  a  low  red-heat  it  will  inflame  bi-phosphu- 
retted  gas.  Yet  wire  of  1 -40th,  heated  even 
to  whiteness,  will  not  inflame  mixtures  of 
h're-damp.  Carbonic  oxide  inflames  in  the 
atmosphere  when  brought  into  contact  with 
an  iron  wire  heated  to  dull  redness;  whereas 
carburetted  hydrogen  is  not  inflammable, un- 
less the  iron  i's  heated  to  whiteness,  so  as  to 
burn  with  sparks. 

These  circumstances  will  explain,  why  a 
mesh  of  wire,  so  much  finer  or  smaller,  is 
required  to  prevent  the  explosion  from  hy- 
drogen and  oxygen, from  passing;  and  why 
»o  course  a  texture  and  wire  are  suflicient 
to  prevent  the  explosion  of  the  fire-damp, 
fortunately  the  least  combustible  of  all  the 
Inflammable  gases  known.  The  flame  of  sul- 
phur, which  kindles  at  so  low  a  temperature, 
will  exist  under  refrigerating  proc<  sst  s, 
which  extinguish  the  flame  of  hydrogen  and 
all  carburetted  gases. 

Let  the  smallest  possible  flame  be  made 
by  a  single  thread  of  cotton  immersed  in 
oil,  and  burning  immediately  upon  the  sur- 
face of  the  oil.  it  will  be  found  to  yield  a 
flame  about  l-30th  of  an  inch  in  diameter. 
Let  a  fine  iron  wire  of  —^  of  an  inch,  made 

into  a  ring  of  1  -10th  of  an  inch  diameter,  be 
brought  over  the  flame.  Though  ut  such 
a  distance,  it  will  instantly  extinguish  the 
flame,  if  it  be  cold;  but  if  it  be  held  above 
the  flame,  so  as  to  be  slightly  heated,  the 
flame  may  be  passed  through  it  without  be- 
ing extinguished.  That  f  he  effect  depends 
entirely  on  the  pov  er  of  the  metal  to  ab- 
stract the  heat  of  flame,  is  shown  by  bring- 
ing a  glass  capillary  ring*  of  the  same  diame- 
ter and  size  over  the  flame.  This  being  a 
much  worse  conductor  of  heat,  will  not,  even 
when  cold,  extinguish  it.  If  its  size,  how- 
ever, be  made  greater,  and  its  circumference 
smaller,  it  will  act  like  the  metallic  wire,  and 
require  to  be  heated  to  prevent  it  from  ex- 
tinguishing the  flame.  Now,  a  flame  of  sul- 
phur may  be  made  much  smaller  than  that 
of  hydrogen;  one  of  hydrogen  may  be  made 
much  smaller  than  that  of  a  wick  fed  with 
oil;  and  that  of  a  wick  fed  with  oil  smaller 
than  that  of  carburetted  hydrogen.  A  ring 
of  cool  wire,  which  instantly  extinguishes 
the  flame  of  carburetted  hydrogen,  diminish- 
es but  slight ly  the  size  of  a  flame  of  sulphur, 
of  the  same  dimensions. 

By  the  following  simple  contrivance,  we 
may  determine  the  relative  facility  of  burn- 


ing, among-  different  combustibles.  Prepare 
a  series  of  metallic  globules  o!  different  sizes, 
by  fusion  at  the  end  of  iron  wires,  and  light 
a  series  of  very  minute  flames  of  different 
"bodies  all  of  one  size.  If  a  globule  -20th 
of  an  inch  diameter  be  brought  near  an  oil 
flame  of  1-3  Jth  in  diameter,  it  will  extinguish 
it,  when  cold,  at  the  distance  of  a  diameter. 
The  size  of  the  spherule,  adequate  to  the 
extinction  of  the  particular  flame,  will  be  a 
measure  of  its  combustibility.  If  the  glo- 
bule be  heated,  however,  the  distance  will 
diminish  at  which  it  produces  extinction.  At 
a  white  heat,  the  globule,  in  the  above  in- 
stance, does  not  extinguish  it  by  actual  con- 
tact, though  at  a  dull  red-heat  it  immediately 
produces  the  effect. 

2d  Of  the  nature  of  fame,  and  of  the  rela- 
tion between  the  light  mid  the.  heat  which  cwn- 
P'ise  it.  The  flume  of  combustible  bodies 
may  in  all  cases  be  considered,  as  the  com- 
bustion of  an  explosive  mixture  of  inflammable 
gus,  or  vapour,  with  air.  It  cannot  be  re- 
garded as  a  mere  combustion,  at  the  surface 
of  contact,  of  the  inflammable  matter.  Tin's 
fact  is  proved  by  holding  a  taper,  or  a  piece 
of  burning  phosphorus,  within  a  large  flame 
made  by  the  combustion  of  alcohol.  The 
flame  of  the  taper,  or  of  the  phosphorus,  will 
appear  in  the  centre  of  the  other  flame, 
proving  that  there  is  oxygen  even  in  its  in- 
terior part.  When  a  wire-gauze  safe-lamp 
is  made  to  burn  in  a  very  explosive  mixture 
of  coal-gas  and  air,  the  light  is  feeble  and  of 
a  pale  colour.  Whereas  the  flame  of  a  cur- 
rent of  coal  gas  burnt  in  the  atmosphere,  as 
is  well  known  by  the  phenomena  of  the  gas 
lights,  is  extremely  brilliant.  It  becomes, 
therefore,  a  problem  of  some  interest,  ''•  Why 
the  combustion  of  explosive  mixtures,  under 
different  circumstances,  should  produce  such 
different  appearances?"  In  reflecting  on  the 
circumstances  of  these  two  species  of  com- 
bustion, Sir  H.  Davy  was  led  to  imagine  that 
the  cause  of  the  superiority  of  the  light  of 
the  stream  of  coal  gas,  might  be  owing  to  the 
decomposition  of  a  part  of  the  gas,  towards  the 
interior  of  the  flame,  where  the  air  w-as  in 
the  smallest  quantity,  and  the  deposition  of 
solid  charcoal,  which  first  by  its  ignition,  and 
afterwards  by  its  combustion,  increased,  in  a 
high  degree,  the  intensity  of  the  light.  The 
following  experiments  show,  that  this  is  the 
true  solution  of  the  problem* 

If  we  hold  a  piece  of  wire -gauze,  of  about 
900  apertures  to  the  square  inch,  over  a 
stream  of  coal  gas  issuing  from  a  small  pipe, 
and  if  we  inflame  the  gas  above  the  wire- 
gauze,  left  almost  in  contact  with  the  orifice 
of  the  pipe,  it  burns  with  its  usual  bright 
light.  On  raising  the  wire-gauze  so  as  to 
cause  the  gas  to  be  mixed  with  more  air  he- 
fore  it  inflames,  the  light  becomes  feebler, 
and  at  a  certain  distance  the  flame  assumes 
the  precise  character  of  that  of  an  explo- 
sive mixture  burning  within  the  lamp.  But 
though  the  light  is  so  feeble  in  this  case,  tfce 


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be  at  is  greater  than  when  the  Fight  is  much 
more  vivid.  A  piece  of  wire  of  platina,  held 
in  this  feeble  blue  flame,  becomes  instantly 
white-hot. 

On  reversing  the  experiment  by  inflaming 
a  stream  of  coal-gas,  and  passing  a  piece  of 
wire  gauze  gradually  from  th  summit  of 
the  flame  to  the  orifice  of  the  pipe,  the  re- 
sult is  still  more  instructive.  It  is  found 
that  the  apex  of  the  flame,  intercepted  by 
the  wire-gauze,  affords  no  solid  charcoal; 
but  in  passing  it  downwards,  solid  charcoal 
is  given  off  in  considerable  quantities,  and 
prevented  from  burning  by  the  cooling  agen- 
cy of  the  wire-gauze.  At  die  bottom  of 
the  flame,  where  the  gas  burned  blue,  in  its 
immediate  contact  with  the  atmosphere,  char- 
coal ceased  to  be  deposited  in  visible  quan- 
tities. 

The  principle  of  the  increase  of  the  brilli- 
ancy and  density  of  flame,  by  the  production 
and  ignition  of  solid  matter,  appears  to  ad- 
mit of  many  applications.  Thus,  olefiant 
gas  gives  the  most  brilliant  white  light  of  all 
combustible  gases,  because,  as  we  learn 
from  Bei  thollet's  experiments,  related  under 
carburetted  hydrogen,  at  a  very  high  tem- 
perature, it  deposites  a  very  large  quantity 
of  solid  carbon-  Phosphorus,  which  rises  in 
vapour  at  common  temperatures,  and  the 
vapour  of  which  combines  with  oxygen  at 
those  temperatures,  is  always  luminous;  for 
each  particle  of  acid  formed,  must,  there  is 
every  reason  to  believe,  be  white-hot.  So 
few  of  these  particles,  however,  exist  in  a 
given  space,  that  they  scarcely  raise  the  tem- 
perature of  a  solid  body  exposed  to  them, 
though,  as  in  the  rapid  combustion  of  phos 
phorus,  where  immense  numbers  are  exist- 
ing in  a  small  space,  they  produce  a  most 
intense  heat. 

The  above  principle  readily  explains  the 
appearances  of  the  different  parts  of  the 
flames  of  burning  bodies,  and  of  flame  urged 
by  the  blow-pipe.  The  point  of  the  inner 
blue  flame,  where  the  heat  is  greatest,  is  the 
point  where  the  whole  of  the  charcoal  is 
burned  in  its  gaseous  combinations,  without 
previous  deposition. 

It  explains  also  the  intensity  of  the  light 
of  those  fames  in  which  Jixed  solid  matter  is 
produced  in  combustion,  such  as  the  flame 
of  phosphorus  and  of  zinc  in  oxygen,  &c. 
and  of  potassium  in  chlorine,  and  the  feeble- 
ness of  the  light  of  those  flames  in  which 
gaseous  and  volatile  matter  alone  is  pro- 
duced, such  as  those  of  hydrogen  and  of  sul- 
phur in  oxygen,  phosphorus  in  chlorine,  &c. 

It  offers  means  of  increasing  the  light  of 
certain  burning  substances,  by  placing  in 
their  flames  even  incombustible  substances. 
Thus  the  intensity  of  the  light  of  burning 
sulphur,  hydrogen,  carbonic  oxide,  &c.  is 
wonderfully  increased  by  throwing  into  them 
oxide  of  zinc,  or  by  placing  in  them  very 
fine  amianthus  or  metallic  gauze. 


It  leads  to  deductions  concerning  the 
chemic  1  nature  of  bodies,  and  various  phe- 
nomena of  their  decomposition.  Thus  ether 
burns  with  a  flame,  which  seems  to  indicate 
the  presence  of  olefiant  gas  in  that  substance. 
Alcohol  burns  with  a  flame  similar  to  that 
of  a  mixture  of  carbonic  oxide  and  hydro- 
gen. Hence  the  first  is  probably  a  binary 
compound  of  olefiant  gas  and  water,  and  the 
second  of  carbonic  oxide  and  hydrogen. 
When  protochloride  of  copper  is  introduced 
into  the  flame  of  a  candle  or  lamp,  it  affords 
a  peculiar  dense  and  brilliant  red  light, 
tinged  with  green  and  blue  towards  the 
edges,  which  seems  to  depend  upon  the 
chlorine  being  separated  from  the  copper 
by  the  hydrogen,  and  the  ignition  and  com- 
bustion of  the  solid  copper  and  charcoal. 

Similar  explanations  may  be  given  of  the 
phenomena  presented  by  the  action  of  other 
combinations  of  chlorine  on  flame;  and  it 
is  probable,  in  many  of  those  cases,  when 
the  colour  of  flame  is  changed  by  the  intro* 
duction  of  incombustible  compounds,  that 
the  effect  depends  on  the  production,  and 
subsequent  ignition  or  combustion  of  in- 
flammable matter  from  them.  Thus  the 
rose-coloured  light  given  to  flame  by  the 
compounds  of  strontium  and  calcium,  and 
the  yellow  colour  given  by  those  of  barium, 
and  the  green  by  those  of  boron,  may  de- 
pend upon  a  temporary  production  of  these 
bases,  by  the  inflammable  matter  of  the  flame , 
Dr.  Clarke's  experiments  on  the  reduction 
of  barytes,  by  the  hydroxygen  lamp,  is  fa 
vourable  to  this  idea,  ftor  should  any  sup- 
posed inadequacy  of  heat  in  ordinary  flame, 
prevent  us  from  adopting  this  conclusion. 
Flame,  or  gaseous  matter  heated  so  highly 
as  to  be  luminous,  possesses  a  temperature 
beyond  the  white  heat  of  solid  bodies,  as  is 
shown  by  the  circumstance,  that  air  not 
luminous  will  communicate  this  degree  of 
heat.  This  is  proved  by  a  simple  experi- 
ment. Hold  a  fine  wire  of  plantinum  about 
l-2Gth  of  an  inch  from  the  exterior  of  the 
middle  of  the  flame  of  a  spirit-lamp,  and 
conceal  the  flame  by  an  opaque  body.  The 
wire  will  become  white -hot  in  a  space,  where 
there  is  no  visible  light.  The  real  tem- 
perature of  visible  flame  is  perhaps  as  high 
as  any  we  are  acquainted  with.  Mr.  Ten- 
nant  used  to  illustrate  this  position,  by  fusing 
a  small  filament  of  platinum,  in  the  flame  of 
a  common  candle. 

These  views  will  probably  offer  illustra« 
tions  of  electrical  light.  The  voltaic  arc  of 
flame  from  the  great  battery,  differs  in  co» 
lour  and  intensity,  according  to  the  substan- 
ces employed  in  the  circuit,  and  is  infinitely 
more  brilliant  and  dense  with  charcoal  than 
with  any  other  substance.  May  not  this  de- 
pend, says  Sir  H.  Davy,  upon  particles  of 
the  substances  separated  by  the  electrical 
attractions?  And  the  particles  of  charcoal, 
being  the  lightest  among  solid  bodies  (as 


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their  prime  equivalent  shows),  and  the  least 
coherent,  would  be  separated  in  the  largest 
quantities. 

The  heat  of  flames  may  be  actually  dimi- 
nished by  increasing  their  light  (at  least  the 
heat  communicable  to  other  matter)  and  vice 
versa.  The  flame  from  combustion,  which 
produces  the  most  intense  heat  amongst 
those  which  have  been  examined,  is  that  of  a 
mixture  of  oxygen  and  hydrogen  compressed 
in  Newman's  blow-pipe  apparatus.  (Si-e 
BLOW-PIPE).  This  flame  is  hardly  visible 
in  bright  day-light,  yet  it  instantly  fuses  the 
most  refractory  bodies;  and  the  light  from 
solid  bodies  ignited  in  it,  is  so  vivid  as  to  be 
painful  to  the  eye.  This  application  cer- 
tainly originated  from  Sir  H.  Davy's  dis- 
covery, that  the  explosion  from  oxygen  and 
hydrogen  would  not  communicate  through 


very  small  apertures,  and  he  himself  first' 
tried  the  experiment  with  a  fine  glass  capil- 
lary tube.  The  flame  was  not  visible  at  the 
end  of  this  tube,  being  overpowered  by  the 
brilliant  star  of  the  glass,  ignited  at  the 
aperture. 

3.  Of  the  heat  disengaged  by  different  com- 
bustibles in  the  act  of  burning. 

Lavoisier,  Crawford,  Dalton,  and  Rum- 
ford,  in  succession,  made  experiments  to  de- 
termine the  quantity  of  heat  evolved  in  the 
combustion  of  various  bodies.  The  appa- 
ratus used  by  the  last  was  perfectly  simple, 
and  perhaps  the  most  precise  of  the  whole. 
The  heat  was  conducted  by  flattened  pipes 
of  metal,  into  the  heart  of  a  body  of  water, 
and  was  measured  by  the  temperature  im- 
parted. The  following  is  a  general  table  of 
results: — 


Substances  burned,  1  Ib. 

Oxygen 
consumed 
inlbs. 

Ice  melted  in  Ibs. 

Lavoisier. 

Crawford 

Dalton. 

Ruraford. 

Hydrogen, 

7.5 

<^J.O 

48U 

3^0 

Car!  >ure  tted  hydrogen, 
Olefiant  gas, 

4 
3.50 

85 
88 

Carbonic  oxide, 

0.58 

25 

Olive  oil, 

3.00 

149 

89 

104 

94.07 

Rape  oil, 

3.0 

124.10 

Wax,      - 

3.0 

133 

97 

104 

12624 

Tallow, 

3.0 

96 

104 

111.58 

Oil  of  turpentine, 

60 

Alcohol,     - 

2.0? 

58 

67.47 

E-..'u-r  sulphuric, 

3 

62 

107.03 

Naphtha,     - 

97.83 

Phosphorus, 
Charcoal, 

1.33 
2.66 

100 
96.5 

69 

60 
40 

Sulphur, 

1.00 

20 

Camphur, 

70 

Caoutchouc, 

42 

The  discrepancies  in  the  preceding  table, 
are  sufficient  to  show  the  necessity  of  new 
experiments  on  the  subject.  Count  Rum- 
ford  made  a  series  of  experiments  on  the 
heat  given  out  during  the  combustion  of  dif- 
ferent woods.  He  found  that  one  pound  of 
wood  by  burning,  produced  as  much  heat  as 
would  have  melted  from  about  34  to  54 
pounds  of  ice.  The  average  quantity  is 
about  40.  MM.  Clement  and  Desormes  find 
that  woods  give  out  heat  in  the  ratio  of  their 
respective  quantities  of  carbon;  which  they 
state  to  be  equal  to  one  half  of  their  total 
weight.  Hence  they  assign  48  pounds  as  the 
quantity  of  ice  melted,  in  burning  one  of 
wood.  In  treating  of  acetic  acid  and  carbon, 
I  have  already  taken  occasion  to  state,  that 
they  appear  greatly  to  overrate  the  propor. 
tion  of  carbon  in  woods. 

The  preceding  table  is  incorrectly  given 
in  several  respects  by  our  systematic  writers} 


Dr.  Thomson,  for  example,  states,  that  1 
pound  of  hydrogen  consumes  only  6  pounds 
of  oxygen,  though  the  saturating  proportion 
assigned  by  him  is  8  pounds.  The  propor- 
tions of  oxygen  consumed  by  olive  oil,  phos- 
phorus, charcoal,  and  sulphur,  are  all  in  like 
manner  erroneous. 

In  vol.  i  p.  184.  of  Dr.  Black's  lectures,  we 
have  the  following1  notes.  "  100  pounds  weight 
of  the  best  Newcastle  coal,  when  applied  by 
the  most  judiciously  constructed  furnace,  will 
convert  about  i£  wine  hogsheads  of  water, 
into  steam  that  supports  the  pressure  of  the 
atmosphere."  1%  hogsheads  of  water,  weigh 
about  790  pounds.  Hence  1  part  of  coal  will 
convert  nearly  8  parts  of  water  into  steam. 
Count  Rumford  says,  that  the  heat  generated 
in  the  combustion  of  1  pound  of  pit  coal, 

would  make  36  ~  pounds  of  ice-cold  water 
boil.  But  we  know  that  it  requires  fully  51 


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times  as  much  heat  to  convert  the  boiling 
water  into  steam.  Therefore,  3~  •=-  6|-,  is 

the  weight  of  water  that  would  be  converted 
into  steam  by  one  pound  of  coal. 

Mr.  Watt  found,  that  it  requires  8  feet 
surface  of  boiler  to  be  exposed  to  fire  to  boil 
oft'  one  cubic  foot  of  water  per  hour,  and 
lhat  a  bushel,  or  84  pounds  of  Newcastle 
coal  so  applied,  will  boil  off  from  8  to  12  cu- 
bic feet.  He  rated  the  heat  expended  in  boil- 
ing off  a  cubic  foot  of  water,  to  be  about  six 
times  as  much  as  would  bring1  it  to  a  boiling- 
heat  from  the  medium  temperature  (5.5°), 
in  this  climate.  The  mean  quantity  is  10  cu- 
bic feet,  which  weigh  625  pounds.  Hence 
1  pound  of  coal  burnt,  is  equivalent  to  boil 
off  in  steam,  nearly  7£  Ibs.  of  water,  at  the 
temperature  of  55°. 

In  situations  where  wood  was  employed 
for  fuel  to  Mr.  Watt's  engines,  he  allowed 
three  times  the  weight  of  it,  that  he  did  of 
Kewcastle  coal.  The  cubical  coal  of  the 
Glasgow  coal  district,  is  reckoned  to  have 
only  |  the  calorific  power  of  the  Newcastle 
«oal;  and  the  small  coal  or  culm,  requires  to 
be  used  in  double  weight,  to  produce  an 
equal  heat  with  the  larger  pieces.  A  bushel 
of  Newcastle  coal  is  equivalent  to  a  hundred 
weight  of  the  Glasgow. 

1  shall  now  describe  the  experiments  re- 
cently made  on  this  subject  by  Sir  H.  Davy, 
subservient  to  his  researches  on  the  nature 
of  flame.  A  mercurial  gas-holder,  furnished 
with  a  system  of  stop-cocks,  terminated  in  a 
strong  tube  of  platinum,  having  a  minute 
aperture.  Above  this,  was  fixed  a  copper 
cup  filled  with  olive  oil,  in  which  a  thermo- 
meter was  placed.  The  oil  was  heated  to 
212°,  to  prevent  any  difference  in  the  com- 
munication of  heat,  by  the  condensation  of 
aqueous  vapour;  the  pressure  was  the  same 
for  the  different  gases,  and  they  were  con- 
sumed as  nearly  as  possible  in  the  same  time, 
and  the  flame  applied  to  the  same  point  of 
the  copper  cup,  the  bottom  of  which  was 
wiped  after  each  experiment.  The  results 
were  as  follows: — 

Substances-.  Rise  of  therm.  Osyj^en  "Ratios  of 

from  212°  to  consumed*   heat. 
Olefiantgas,  270°  6.0  9.66 

Hydrogen,  238  1.0         26.0 

Sulph.  hydrogen,      232  3.0          6.66 

Coal  gas,  .     236  4.0  6,00 

Carbonic  oxide,         218  1.0          6.00 

The  data  on  which  Sir  H.  calculates  the 
ratios  of  heat,  are  the  elevations  of  tempera- 
ture, and  the  quantities  of  oxygen  consumed 
conjointly.  We  see  that  hydrogen  produces 
more  heat  in  combustion  than  any  of  its  com- 
pounds, a  fact  accordant  with  Mr.  Dalton's 
results  HI  the  former  table;  only  Sir  H. 
Davy's  ratio  is  more  than  double  that  of  Mr. 
Dalton's,  as  to  hydrogen,  and  carburetted 
Hydrogen.  On  thts  point,  howcvcn-,  Sir  W. 

VOJ..  !•» 


with  his  usual  sagacity  remarks,  that  it  wili 
be  useless  to  reason  upon  the  ratios  as  exact, 
for  charcoal  was  deposited  from  both  the 
olefiant  gas  and  coat  gas  during  the  experi- 
ment, and  much  sulphur  was  deposited  from 
the  sulphuretted  hydrogen.  It  confirms, 
however,  the  general  conclusions,  and  proves 
that  hydrogen  stands  at  the  head  of  the  scale, 
and  carbonic  oxide  at  the  bottom.  It  might 
at  first  view  be  imagined,  that,  according  to 
this  scale,  the  flame  of  carbonic  oxide  ought 
to  be  extinguished  by  rarefaction  at  the  same 
degree  as  that  of  carburetted  hydrogen;  but 
it  must  be  remembered,  as  has  been  already 
shown,  that  carbonic  oxide  is  a  much  more 
easily  kindled,  a  more  accendible  gas. 

4  Of  the  causes  which  modify  or  extinguish 
combustion  or  flame. 

The  earlier  experimenters  upon  the  Boy- 
lean  vacuum  observed,  that  flame  ceased  in 
highly  rarefied  air;  but  the  degree  of  rare- 
faction necessary  for  this  effect  has  been 
differently  stated.  On  this  point,  Sir  H.  Da- 
vy's investigations  are  peculiarly  beautiful 
and  instructive.  When  hydrogen  gas,  slow- 
ly produced  from  a  proper  mixture,  was  in- 
flamed at  a  fine  orifice  of  a  glass  tube,  as  in 
Priestley's  philosophical  candle,  so  as  to 
make  a  jet  of  flame  of  about  l-6th  of  an 
inch  in  height,  and  introduced  under  the 
receiver  of  an  air-pump,  containing  from 
200  to  300  cubical  inches  of  air,  the  flame 
enlarged  as  the  receiver  became  exhausted; 
and  when  the  gauge  indicated  a  pressure, 
between  4  and  5  times  less  than  that  of  the 
atmosphere,  was  at  its  maximum  of  size;  it 
then  gradually  diminished  below,  but  burn- 
ed above,  till  its  pressure  was  between  7 
and  8  times  less:  when  it  became  extin- 
guish ed 

To  ascertain  whether  the  effect  depended 
upon  the  deficiency  of  oxygen,  he  used  a 
larger  jet  with  the  same  apparatus,  when  the 
flame  10  his  surprise,  burned  longer;  even 
when  the  atmosphere  was  rarefied  10  times; 
and  this  in  repeated  trials.  When  the  larger 
and  this  isin  repeated  trials.  \Vhenthelarger 
jet  came  white-hot,  and  continued  red-hot  till 
the  flame  was  extinguished.  It  immediately 
occurred  to  him,  that  the  heat  communicat- 
ed to  the  gas  by  this  tube,  was  the  cause 
that  the  combustion  continued  longer  in  the 
last  trials  when  the  larger  flame  was  used; 
and  the  following  experiments  confirmed 
the  conclusion.  A  piece  of  v;ire  of  plati- 
num was  coiled  round  the  top  of  the  tube, 
so-asto  reach  into  and  above  the  flame. — 
The  jet  of  gas  of  l-6th  of  an  inch  in  height 
WHS  lighted,  and  the  exhaustion  made. — 
The  wire  of  platinum  soon  became  white- 
hot  in  the  centre  of  the  flame,  and  a  small 
point  of  wire  near  the  top  fused.  It  contin- 
ued white-hot,  till  the  pressure  was  6  times 
less.  When  it  was  10  times,  it  continued 
red-hot  at  the  upper  part,  and  as  long  as  it 
WOT  d'lfl  red,  the  gas,  though  certainly  ex» 
41 


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ting-dished  below,  continued  to  bum  in  con- 
tact with  the  hot  wire,  and  the  combustion 
did  not  cease,  until  the  pressure  was  re- 
duced 13  times 

It  appears  from  this  result,  that  the  flame 
of  hydrogen  is  extinguished  in  rarefied  at- 
mospheres, only  when  the  heat  it  produces 
is  insufficient  to  keep  up  the  combustion: 
which  appears  to  be  when  it  is  incapsftle  of 
communicating  visible  ignition  to  metal;  and 
as  this  is  the  temperature  required  for  the 
inflammation  of  hydrogen,  (see  section  1st,) 
at  common  pressure,  it  appears  that  its  com- 
bustibility is  neither  diminished  nor  increased 
by  rarefactidn  from  the  removal  of  pressure. 
Arc-Tcling  to  this  view,  with  respect  to 
hydrogen,  it  should  follow,  that  those  a- 
mo)i(yst  other  combustible  bodies,  which  re- 
quire less  heat  for  their  accension,  ought  to 
burn  in  more  rarefied  air  than  those  that  re- 
quirt  more  heat;  and  those  which  produce 
much  heat  in  their  combustion  ought  to  burn, 
other  circumstances  being  the  same,  in  more 
rarefied  air,  than  those  that  produce  little 
j(eat.  Every  experiment  since  nude,  con- 

.  iis  these  conclusions.     Thus  olofumt  gas, 

i-.ich  approaches  nearly  to  hydrogt  n,  in  the 
.  inerature  produced  by  its  combust'on, 
•vhich  does  not  require  a  much  higher 
temperature  for  its  accension,  when  its  flame 
was  made  by  a  jet  of  gas  from  a  bladder 
connected  with  a  small  tube,  furnished  with 
a  wire  of  plantinum,  under  the  same  circum- 
stances as  hydrogen,  ceased  to  burn  when 
the  pressure  was  diminished  between  10  and 
11  times.  And  the  flames  of  alcohol  and  of 
thr  wax  taper,  which  require  a  greater  con- 
sumption of  caloric  for  the  volatili  zation  and 
decomposition  of  their  combustible  matter, 
were  extinguished  when  the  pressure  was  5 
or  6  times  less  without  the  wire  of  platinum, 
a;,d  7  or  8  times  less  when  the  wire  was 
kept  in  the  flame.  Light  carburetted  hydro- 
gen, which  produces,  as  we  have  seen,  less 
heat  in  combustion  than  any  of  the  common 
coinbusuble  gases,  except  carbonic  oxide, 
and  which  requires  a  higher  temperature  for 
its  sicceusion  than  any  other,  has  its  flame 
extinguished,  even  though  the  tube  was  fur- 
nished with  the  wire  when  the  pressure  was 
below  l-4th. 

Tin-  flame  of  carbonic  oxide,  which  though 
it  produces  little  heat  in  combustion,  is  as 
ace' ndible  as  hydrogen,  burned  when  the 
wire  was  used,  the  pressure  being  l-6th. 

The  flame  of  sulphuretted  hydrogen,  the 
heat  of  which  is  in  some  measure  carried  off 
by  the  sulphur,  produced  by  its  decomposi- 
tion during  its  combustion  in  rare  air,  when 
burned  in  the  same  apparatus  as  the  defiant 
and  orher  gases,  was  extinguished  when  the 
pressure  was  l-7th. 

Sulphur,  which  requires  a  lower  tempera- 
ture for  its  accension,  than  any  common  in- 
ibie    substance,    except   phosphorus, 
burned  with  a  very  feeble  blue  flame  in  air 


rarefied  15  times ;  and  at  this  pressure  the 
flame  heated  a  wire  of  plantinum  to  dull  red- 
ness; nor  was  it  extinguished  till  the  pres- 
sure was  reduced  to  l-20th.  From  the  pre- 
ceding experimental  facts  we  may  infer,  that 
the  taper  would  be  extinguished  at  a  height 
of  between  9  and  10  miles,  hydrogen  be- 
tween 12  and  13;  and  sulphur  between  15 
and  16. 

Phosphorus,  as  has  been  shown  by  M. 
Van  Marum,  burns  in  an  atmosphere  rare- 
fied 60  times.  Sir  H.  Davy  found,  that 
phosphuretted  hydrogen  produced  a  flash  of 
light  when  admitted  into  the  best  vacuum 
that  could  be  made,  by  an  excellent  pump 
pf  Nairn's  construction. 

Chlorine  and  hydrogen  inflame  at  a  much 
lower  temperature,  than  oxygen  and  hydro- 
gen. Hence  the  former  mixture  explodes 
when  rarefied  24  times;  the  latter  ceases  to 
explode  when  rarefied  18  times.  Heat  ex- 
trinsically  applied,  carries  on  combustion, 
when  it  would  otherwise  be  extinguished. 
Camphor  in  a  thick  metallic  tube,  which 
disperses  the  heat,  ceases  to  burn  in  air  rare- 
fied 6  times;  in  a  glass  tube  which  becomes 
ignited,  the  flame  of  camphor  exists  under  a 
ninefold  rarefaction.  Contact  with  a  red- 
hot  iron,  makes  naphtha  glow  with  a  lam- 
bent flame  at  a  rarefaction  of  30  times; 
though  without  foreign  heat,  its  flame  dies 
at  an  atmospheric  rarefaction  of  6.  If  the 
mixture  of  oxygen  and  hydrogen  expanded 
to  its  non-explosive  tenuity;  be  exposed  to 
the  ignition  of  a  glass  tube,  the  electric  spark 
will  then  cause  an  explosion,  at  least  in  the 
heated  portion  of  the  gases. 

We  shall  now  detail  briefly  the  effects  of 
rarefaction  by  heat  on  combustion  and  ex- 
plosion. Under  CALORIC  we  have  shown, 
that  air  by  being  heated  from  32°  to  212° 
expands  —  ^  or  8  parts  become  11 ;  hence 
the  expansion  of  one  volume  of  air  at  212" 
into  2  £,  or  the  augmentation  of  1.5  =»  ^ 
which  Sir  H.  Davy  found  to  take  place  when 
the  enclosing  glass  tube  began  to  soften  with 
ignition,  will  indicate  932°.  For  -2-  :  180° :  : 
~  :  720°,  to  which  if  we  add  212°,  the  sum 
is  932°.  One  of  air  at  212  becoming  2^,  as 
took  place  in  the  other  experiment  of  Sir 
H.  Davy,  will  give  us  (180°  X  ~)  -f-  2l2a 
«=»  812°,  forthe  heat  of  fusible  metal  lumin- 
ous in  the  shade.  I  believe  these  experi- 
ments to  be  much  more  accurate  than  a  iy 
hitherto  given,  relative  to  the  temperature 
of  incandescence.  This  philosopher,  whose 
ingenuity  of  research  is  usually  guided  by 
the  most  rigorous  arithmetic,  estimates  the 
first  temperature  from  the  above  data  of 
Gay-Lussac,  at  1035°  FarenheSt.  I  there- 
fore hesitate  to  offer  a  discordant  computa- 
tion. One  volume  of  air  at  212°,  should  be- 
come at  a  temperature  «f  1035°,  accord- 


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ing  to  the  rule  I  use,  2.715  parts,  instead  of 
2.5. 

Sir  H.  introduced  into  a  small  glass  tube 
over  well  boiled  mercury,  a  mixture  of  two 
parts  of  hydrogen  and  one  of  oxygen,  and 
heated  the  tube  by  a  spirit  lamp,  till  the 
volume  of  the  gas  was  increased  from  1  to 
2.5.  By  means  of  a  blow-pipe  and  another 
lamp,  he  made  the  upper  pait  of  the  tube 
red-hot,  when  an  explosion  instantly  took 
place.  This  experiment  refutes  the  notions 
of  M.  de  Groithus,  on  the  non-explosiveness 
of  that  mixture,  when  expanded  by  heat. — 
He  introduced  into  a  bladder  a  mixture  of 
oxygen  and  hydrogen,  and  connected  this 
bladder  with  a  thick  glass  tube  of  about  one- 
sixth  of  an  inch  in  diameter,  and  three  feet 
long,  curved  so  that  it  could  be  gradually 
heated  in  a  charcoal  furnace ;  two  spirit- 
lamps  were  placed  under  the  tube,  where  it 
entered  the  charcoal  fire,  and  the  mixture 
was  very  slowly  passed  through.  An  ex- 
plosion took  place,  before  the  tube  was  red- 
hot.  This  fine  experiment  shows,  that  ex- 
pansion by  heat,  instead  of  dim.nishing  the 
accendibility  of  g-ases,  enables  them,  on  the 
contrary,  to  explode  apparently  at  a  lower 
temperature ;  which  seems  perfectly  reason- 
able, as  a  part  of  the  heat  communicated  by 
any  ignited  body,  must  be  lost  in  gradually 
raising  the  temperature. 

M.  de  Grotthus  has  stated,  that  if  a  glow- 
ing coal  be  brought  into  contact  with  a  mix- 
ture of  oxygen  and  hydrogen,  it  only  rare- 
fies them,  but  does  not  explode  them.  This 
depends  on  the  degree  of  heat  communica- 
ted by  the  coal.  If  it  is  red  in  day-light, 
and  free  from  ashes,  it  uniformly  explodes 
the  mixture.  If  its  redness  be  barely  visi- 
ble in  the  shade,  it  will  not  explode  them, 
but  cause  their  slow  combination.  The  gen- 
eral phenomenon  is  wholly  unconnected  with 
rarefaction;  as  is  shown  by  the  following  cir- 
cumstance :  When  the  heat  is  greatest,  and 
before  the  invisible  combination  is  comple- 
ted, if  an  iron  wire,  heated  to  whiteness,  be 
placed  upon  the  coal  within  the  vessel,  the 
mixture  instantly  explodes. 

Subcarburetted  hydrogen,  or  fire-damp,  as 
has  been  shown,  requires  a  very  strong  heat 
for  its  inflammation.  It  therefore  offered  a 
good  substance  for  an  experiment,  on  the 
effect  of  high  degrees  of  rarefaction,  by  heat 
on  combustion.  One  part  of  this  gas,  and 
eight  of  air,  were  mixed  together,  and  in- 
troduced into  a  bladder  furnished  with  a 
capillary  tube.  This  tube  was  heated  till  it 
began  to  melt.  The  mixture  was  then  pass- 
ed through  it,  into  the  flame  of  a  spirit-lamp, 
when  it  took  fire,  and  burned  with  its  own 
peculiar  explosive  light,  beyond  the  flame  of 
the  lamp ;  and  when  withdrawn,  though  the 
Aperture  was  quite  white-hot,  it  continued 
to  burn  vividly. 

That  the  compression  in  one  part  of  an 
explosive  mixture,  produced  by  the  sudden 


expansion  of  another  part  by  heat,  or  the 
electric  spark,  is  not  the  cause  of  combus- 
tion, as  has  been  supposed  by  Mr.  Higgins, 
M.  Berthollet,  and  others,  "appears  to  be 
evident  from  what  has  been  stated,  and  is 
rendered  still  more  so  by  the  following  facts : 
A  mixture  of  bi-phosphuretted  hydrogen 
gas  and  oxygen,  which  explode  at  a  heut  a 
little  above  that  of  boiling  water,  was  con- 
fined by  mercury,  and  very  gradually  heated 
on  a  sand  bath.  When  the  temperature  of 
the  mercury  was  242°,  the  mixture  explo- 
ded. A  similar  mixture  was  placed  in  a  re- 
ceiver communicating  with  a  condensing 
syringe,  and  condensed  over  mercurv  till 
it  occupied  only  one-fifth  of  its  original  vo- 
lume. No  explosion  took  place,  and  no  che- 
mical change  had  occurred;  for  when  its 
volume  was  restored  it  was  instantly  explo- 
ded by  the  spirit-lamp. 

It  would  appear  then  that  the  heat  given 
out  by  the  compression  of  gases,  is  the  real 
cause  of  the  combustion  which  it  produces; 
and  that  at  certain  elevations  of  temperature, 
whether  in  rarefied  or  compressed  atmos- 
pheres, explosion  or  combustion  occurs ; 
that  is,  bodies  combine  with  the  production 
of  heat  and  light. 

Since  it  appears  that  gaseous  matter  ac- 
quires a  double,  triple,  quadruple,  Sec.  bulk, 
by  the  successive  increments  of  480°  F.  2 
X  480°,  3  X  480°,  &c.  we  may  gain  ap- 
proximations to  the  temperature  of  flame, 
by  measuring  the  expansion  of  a  gaseous 
mixture  at  the  instant  of  explosion,  provided 
the  resulting  compound  gus  occupy,  alter 
cooling,  the  same  bulk  as  the  sum  of  its  con- 
stituents. Now  this  is  the  case  with  chlo- 
rine and  hydrogen,  and  with  prussine  and 
oxygen.  The  latter  detonated  in  the  pro- 
portion of  one  to  two,  in  a  tube  of  about 
two-fifths  of  an  inch  diameter,  displaced  a 
quantity  of  water,  which  demonstrated  an. 
expansion  of  15  times  their  original  btdk. 
Hence  15  x  480°  =  7200°  of  Fahr.  and  the 
real  temperature  is  probably  much  higher; 
for  heat  must  be  lost  by  communication  to 
the  tube  and  the  water.  The  heat  of  the 
gaseous  carbon  in  combustion  in  this  gus, 
appears  more  intense  than  that  of  hydro- 
gen ;  for  it  was  found  that  a  filament  ot  pla- 
tinum was  fused  by  a  flame  of  prussine  (cy- 
anogen) in  the  air,  which  was  not  fused  by 
a  similar  flame  of  hydrogen, 

We  have  thus  detailed  the  modifications 
produced  in  combustion  by  rarefaction,  me- 
chanical and  calorific.  It  remains  on  this 
head  to  state  the  effects  of  the  mixture  of 
different  gases,  and  those  of  different  cool- 
ing orifices,  on  flame. 

In  Sir  H.  Davy's  first  paper  on  the  fire- 
damp of  coal  mines,  he  mentioned  that  car- 
bonic acid  had  a  greater  influence  in  de- 
stroying the  explosive  power  of  mixtures  of 
firedamp  ana  air,  than  azote;  and  he  sup- 
pose litfl  t cause  to  be  its  greater  density  and 


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oapacity  for  heat,  in  consequence  of  which 
it  might  exert  a  greater  cooling  agency,  and 
thus  prevent  the  temperature  of  the  mixture 
from  being  raised  to  that  degree  necessary 
for  combustion.  He  subsequently  made  a 
series  of  experiments  with  the  view  of  de- 
termining how  far  this  idea  is  correct,  and 
for  the  purpose  of  ascertaining  the  general 
phenomena,  of  the  effects  of  the  mixture  of 
easeous  substances  upon  explosion  and  com- 
bustion. 

Prevented  by 

Of  hydrogen,  8 

Oxygen,  9 

Nitrous  oxide,  11 

Subcarburetted  hydrogen,  1 

Sulphuretted  hydrogen,  2 

Olefiant  gas,  £ 

Muriatic  acid  gas,  2» 

Chlorine,      ...... 


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He  took  given  volumes,  of  a  mixture  of' 
two  parts  of  hydrogen  and  one  part  of  oxy- 
gen by  measure,  and  diluting  them  with 
various  quantities  of  different:  elastic  flu;ds, 
he  ascertained  at  what  degree  of  dilution, 
the  power  of  inflammation  by  a  strong  spark 
from  a  Leyden  phial  was  destroyed.  He 
found  that  for  one  of  the  mixture,  inflamma= 
tion  was 


Pennitted  with. 
6 
7 
10 


Cdoline;  power,  air  — 
2.66 
1.12 

0.75  (the  mean) 
2.18  (coal  gas) 

1.6 


0.66 


Silicated  fluoric  gas, 

Azote, 

Carbonic  acid, 


-   1.33 
.  0.727 


The  first  column  of  the  preceding  table 
shows,  that  other  causes,  besides  density  and 
capacity  for  heat,  interfere  with  the  pheno- 
mena. Thus  nitrous  oxide,  which  is  nearly 
one-third  denser  than  oxygen,  and  which, 
according  to  Delaroche  and  Berard,  has  a 
greater  capacity  for  heat,  in  the  ratio  of 
1.3503  to  0.9765  by  volume,  has  lower  pow- 
ers of  preventing  explosion.  Hydrogen  al- 
so, which  is  fifteen  1  mes  lighter  than  oxy- 
gen, and  which  in  equal  volumes  1ms  a  small- 
er capacity  for  heat,  certainly  has  a  higher 
power  of  preventing  explosion;  and  oleft- 
ant  gas  exceeds  all  other  gaseous  substan- 
ces, in  a  much  higher  ratio  than  could 
liave  been  expected,  from  its  density  and 
capacity. 

I  have  deduced  the  third  column,  from  Sir 
H.  Davy's  experiments  on  the  relative  times 
in  which  a  thermometer,  heated  to  160°, 
when  plunged  into  a  volume  of  21  cubic 
inches  of  the  respective  gases  at  52°,  took 
to  cool  down  to  106°.  Where  an  elastic 
fluid  exerts  a  cooling  influence  on  a  solid 
surface,  the  effect  must  depend  principally 
upon  the  rapidity  with  which  its  particles 
•change  their  places  ;  but  where  the  cooling 
particles  are  mixed  throughout  a  mass  with 
other  gaseous  particles,  their  effect  must 
depend  principally  upon  the  power  they 
possess  of  rapidly  abstracting  heat  from  the 
contiguous  particles  ;  and  this  will  depend 
probably  upon  two  causes,  the  simple  ab- 
stracting power  by  which  they  become 
quickly  heated,  and  their  capacity  for  heat, 
which  is  great  in  proportion  as  their  tempe- 
ratures are  less  raised  by  this  abstraction.  — 
The  power  of  elastic  fluids  to  abstract  heat 
from  solids,  appears  from  the  above  experi- 
ments to  be  in  some  inverse  ratio  to  their 
3:!y  j  and  there  seems  to  be  something 


in  the  constitution  of  the  light  gases,  whick 
enables  them  to  carry  off'  heat  from  solid 
surfaces  in  a  different  manner  from  that  in 
which  they  would  abstract  it  in  gaseous  mix- 
tures, depending  probably  on  the  mobility 
of  their  parts.  Those  particles  which  are 
lightest  must  be  conceived  most  capable  of 
changing  place,  and  would  therefore  cool 
solid  surfaces  most  rapidly;  in  the  cooling 
of  gaseous  mixtures,  the  mobility  of  the  par- 
ticles can  be  of  little  consequence. 

Whatever  be  the  cause  of  the  different 
cooling  powers  of  the  different  elastic  fluids 
in  preventing  inflammation,  very  simple  ex- 
periments show  that  they  operate  uniformly 
with  respect  to  the  different  species  of  com- 
bustion; and  that  those  explosive  mixtures, 
or  inflammable  bodies,  which  require  least 
heat  for  their  combustion,  require  larger 
quantities  of  the  different  gases  to  prevent 
the  effect,  and  vice  versa.  Thus  one  of  chlo- 
rine and  one  of  hydrogen  still  inflame  when 
mixed  with  eighteen  times  their  bulk  of  oxy- 
gen; whereas  a  mixture  of  carburetted  hy- 
drogen and  oxygen,  in  the  proper  propor- 
tions (one  and  t\vo)  for  combination,  have 
their  inflammation  prevented  by  less  than 
three  times  their  volume  of  oxygen.  A  wax 
taper  was  instantly  extinguished  in  air  mixed 
with  one-tenth  of  silicuted  fluoric  acid,  and 
in  air  mixed  with  one-sixth  of  muriatic  acid 
gns;  but  the  flame  of  hydrogen  burned  rea- 
dily in  those  mixtures;  arid  in  mixtures  which 
extinguished  the  flame  of  hydrogen,  the  flame 
of  sulphur  burned.  (See  the  beginning  of  sec- 
tion 1st.) 

In  cases,  however,  in  which  the  heat  re- 
quired for  chemical  union  is  very  small,  as 
in  the  instance  of  hydrogen  and  chlorine,  a 
mixture  which  prevents  inflammation  will 
«ot  prevent  combination,  that  is,  the 


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'wiH  combine  without  any  flash.  If  two  vo- 
lumes of  carburetted  hydrogen  be  added  to 
a  mixture  of  one  of  chlorine  with  one  of 
hydrogen,  muriatic  acid  is  formed  through- 
out the  mixture  and  heat  produced,  as  was 
evident  from  the  expansion  when  the  spark 
passed,  and  the  rapid  contraction  afterwards, 
but  the  heat  was  so  rapidly  carried  off  by 
the  quantity  of  carburetted  hydrogen,  that 
no  flash  was  visible. 

Experiments  on  combustion  in  condensed 
air,  to  see  if  the  cooling  power  was  much 
increased  thereby,  show  that,  as  rarefaction 
does  not  diminish  considerably  the  heat  of 
flame  in  atmospherical  air,  so  neither  does 
condensation  considerably  increase  it;  a  cir- 
cumstance of  great  importance  in  the  con- 
stitution of  our  atmosphere,  which  at  all 
heights  or  depths,  at  which  man  can  exist, 
still  preserves  the  same  relations  to  combus- 
tion. 

It  may  be  concluded  from  the  general 
law,  that  at  high  temperatures,  gases  not 
concerned  in  combustion  will  have  less 
power  of  preventing  that  operation,  and 
likewise  that  steam  and  vapours,  which  re- 
quire a  considerable  heat  for  their  formation, 
will  have  less  effect  in  preventing  combus- 
tion, particularly  of  those  bodies  requiring 
low  temperatures,  than  gases  at  the  usual 
heat  of  the  atmosphere.  Thus,  a  very  large 
quantity  of  steam  is  required  to  prevent  sul- 
phur from  burning.  A  mixture  of  oxygen 
and  hydrogen  will  explode  by  the  electric 
spark,  though  diluted  with  five  times  its  vo- 
lume of  steam ;  and  even  a  mixture  of  air 
and  carburetted  hydrogen  gas,  the  least  ex- 
plosive of  all  mixtures,  requires  a  third  of 
steam  to  prevent  its  explosion,  whereas  one- 
fifth  of  azote  will  produce  that  effect.  These 
trials  were  made  over  mercury.  Heat  was 
applied  to  water  over  the  mercury,  and  37. 5 

for  100  parts  — -j-  was  regarded  as  the  cor- 
rection for  the  expansion  of  the  gases. 

We.  shall  now  treat  »f  the  effects  of  cooling 
drificcs  on  fame.  The  knowledge  of  the 
cooling  power  of  elastic  media,  in  preventing 
the  explosion  of  the  fire-damp,  led  the  illus- 
trious English  chemist,  to  those  practical 
researches,  which  terminated  in  his  grand 
discovery  of  the  wire-gauze  safe-lamp.  The 
general  investigation  of  ihe  relation  and  ex- 
tent of  those  powers,  serves  to  elucidate  the 
operation  of  wire-gauze  and  other  tissues  or 
systems  of  apertures,  permeable  to  light  and 
air,  in  intercepting  flame,  and  confirms  the 
views  originally  given  of  this  marvellous 
phenomenon.  We  have  seen  that^awe  is 
gaseous  matter,  heated  so  highly  as  to  be 
luminous,  and  that  to  a  degree  of  tempera- 
ture beyond  the  white  heat  of  solid  bodies; 
for  air  not  luminous  will  communicate  this 
degree  of  heat.  When  an  attempt  is  made 
to  pass  flame  through  a  very  fine  mesh  of 
wire-gauze  of  the  common  temperature,  the 


gauze  cools  each  portion  of  the  elastic  mat-  - 
ter  that  passes  through  it,  so  as  to  reduce  its 
temperature  below  that  degree  at  which  it  is 
luminous.  This  diminution  of  temperature 
is  proportional  to  the  smallness  of  the  mesh, 
and  to  the  mass  of  the  metal.  The  power 
of  a  metallic  or  other  tissue  to  prevent  ex- 
plosion, will  depend  upon  the  heat  required 
to  produce  the  combustion,  as  compared 
with  that  acquired  by  the  tissue.  Hence, 
the  flame  of  the  most  inflammable  sub- 
stances, and  of  those  that  produce  most 
heat  in  combustion,  will  pass  through  a 
metallic  tissue,  that  will  interrupt  the  flame 
of  less  inflammable  substances,  or  those  that 
produce  little  heat  in  combustion.  Or  the 
tissue  being  the  same,  and  impermeable  to  all 
flames  at  common  temperatures,  the  flames 
of  the  most  combustible  substances,  and  of 
those  which  produce  most  heat,  will  most 
readily  pass  through  it,  when  it  is  heated, 
and  each  will  pass  through  it  at' a  different 
degree  of  temperature  In  short,  all  the 
circumstances  which  apply  to  the  effect  of 
cooling  mixtures  upon  flame,  will  apply  to 
cooling,  perforated  surfaces.  Thus,  the  flame 
of  phosphuretted  hydrogen,  at  common  tem- 
peratures, will  pass  through  a  tissue  suffi- 
ciently large,  not  to  be  immediately  choaked 
up  by  the  phosphoric  acid  formed,  and  the 
phosphorus  deposited.  If  a  tissue,  contain- 
ing above  700  apertures  to  the  square  inch, 
be  held  over  the  flame  of  phosphorus  or 
phosphuretted  hydrogen,  it  does  not  trans- 
mit the  flame  till  it  is  sufficiently  heated  to 
enable  the  phosphorus  to  pass  through  it  in 
vapour.  Pnosphuretted  hydrogen  is  decom- 
posed by  flame,  and  acts  exactly  like  phos- 
phorus. In  like  manner  a  tissue  of  108 
apertures  to  the  square  inch,  made  of  a  wire 

of  TxF*  will>  at  comrn°n  temperatures,  inter- 
cept the  flame  of  a  spirit-lamp,  but  not  that 
of  hydrogen.  But  when  strongly  heated,  it 
no  longer  arrests  the  flame  of  alcohol.  A 
tissue  which  will  not  interrupt  the  flame  of 
hydrogen  when  red-hot,  will  still  intercept 
that  of  olefiani  gas;  and  a  heated  tissue, 
which  would  communicate  explosion  from  a 
mixture  of  olefiant  gas  and  air,  will  stop  an 
explosion  from  a  mixture  of  fire-damp,  or 
carburetted  hydrogen.  The  latter  gas  re- 
quires a  considerable  mass  of  heated  metal 
to  inflame  it,  or  contact  with  an  extensive 
heated  surface.  An  iron  wire  of  l-20th  or" 
an  inch,  and  eight  inches  long,  red-hot, 
when  held  perpendicularly  in  a  stream  of 
coal  gas,  did  not  inflame  it;  nor  did  a  short 
wire  of  one-sixth  of  an  inch  produce  the 
effect,  when  held  horizontally.  But  wire  of 
the  latter  size,  when  six  inches  of  it  were 
red-hot,  and  when  it  was  held  perpendicu- 
larl),  in  a  bottle  containing  an  explosive 
mixture,  so  that  heat  was  communicated 
successively  to  portions  of  the  gas,  produced 
its 


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The  scale  of  gaseous  accension,  given  in 
the  first  section,  explains,  why  so  fine  a 
mesh  of  wire  is  required  to  hinder  the  ex- 
plosion from  hydrogen  and  oxygen,  to  pass; 
and  why  so  coarse  a  texture  and  wire,  con- 
troul  the  explosion  of  fire-damp.  The  ge- 
neral doctrine,  indeed,  of  the  operation  of 
wire-gauze,  cannot  be  better  elucidated, 
than  in  its  effects  upon  the  flame  of  sulphur. 
When  wire -gauze,  of  600  or  700  apertures 
to  the  square  inch,  is  held  over  the  flame, 
fumes  of  condensed  sulphur  immediately 
come  through  it,  and  the  flame  is  intercept- 
ed. The  fumes  continue  for  some  instants, 
but  on  the  increase  of  the  heat,  they  dimi- 
nish; and  at  the  moment  when  they  disap- 
pear, which  is  long  before  the  gauze  be- 
comes red-hot,  the  flame  passes;  the  tem- 
perature at  which  sulphur  burns  being  that 
at  vrhich  it  is  gaseous. 

Where  rapid  currents  of  explosive  mix- 
tures, however,  are  made  to  act  upon  wire- 
gauze,  it  is  of  course  much  more  rapidly 
heated:  and  therefore,  the  same  mesh  which 
arrests  the  flames  of  explosive  mixtures  at 
rest,  will  suffer  them  to  pass  when  in  rapid 
motion.  Hut,  by  increasing  the  cooling  sur- 
face, by  diminishing  the  apertures  in  size,  or 
increasing  their  depth,  all  fames,  however 
rapid  their  motion,  may  be  arrested.  Pre- 
cisely the  same  law  applies  to  explosions 
acting  in  close  vessels.  Very  minute  aper- 
tures, when  they  are  only  few  in  number, 
will  permit  explosions  to  pass,  which  are 
arrested  by  much  larger  apertures  when  they 
Mil  a  whole  surface.  A  small  aperture  was 
drilled  at  the  bottom  of  a  wire-gauze  lamp, 
itt  the  cylindrical  ring,  which  confines  the 

gauze.      This,  though   less  than  -i-  of  an 

inch  in  diameter,  transmitted  the  flame,  and 
tired  the  external  atmosphere,  in  conse- 
q/uence  of  the  whole  force  of  the  explosion 
of  the  thin  stratum  of  the  mixture,  included 
within  the  cylinder,  driving  the  flame  through 
the  aperture.  Had  the  whole  ring,  however, 
been  composed  of  such  apertures  separated 
by  wires,  it  would  have  been  perfectly  safe. 
Nothing  can  demonstrate  more  decidedly, 
-.huii  these  simple  facts  and  observations, 
that  the  interruption  of  flame,  by  solid  tis- 
sues, permeable  to  light  and  air,  depends 
opon  no  recondite  or  mysterious  cause,  but 
»MI  their  cooling  powers,  simply  considered 
as  such.  When  a  light,  included  in  a  cage 
of  wire -gauze,  is  introduced  into  an  explo- 
sive atmosphere  of  fire-damp  at  rest,  the 
maximum  of  heat  is  soon  obtained ;  the  ra- 
diating power  of  the  wire,  and  the  cooling 
eiJ'ectof  the  atmosphere,  more  efficient  from 
the  admixture  of  inflammable  air,  prevent 
it  from  ever  arriving  at  a  temperature  equal 
to- that  of  dull  redness.  In  rapid  currents 
of  explosive  mixtures  of  fire-damp,  which 
feeat  common  gauze  to  a  higher  tempera- 
ture, twilled  gauze,  in  which  the  radiating 
surface  is  considerably  greater,  and  the  cir- 


culation of  air  less,  preserves  an  equable 
temperature.  Indeed,  the  heat  communi- 
cated to  the  wire  by  combustion  of  the  fire- 
damp in  wire-gauze  lamps,  is  completely  in 
the  power  of  the  manufacturer.  By  diminish- 
ing the  apertures,  and  increasing  the  mass 
of  metal,  or  the  radiating  surface,  it  may  be 
diminished  to  any  extent.  Thick  twilled 

gauze,  made  of  wires  -i-   16   to    the   warp, 

and  30  to  the  weft,  ri vetted  to  the  screw,  to 
prevent  the  possibility  of  displacement,  forms 
a  lamp  cage,  which,  from-  its  flexibility,  can- 
not be  broken,  and  from  its  strength  cannot 
be  crushed,  except  by  a  very  violent  blow. 
The  lamp  which  has  been  found  most  con- 
venient for  the  miner,  is  that  composed  of 
a  cylinder  of  strong  wire-gauze,  fastened 
round  the  flame  by  a  screw,  and  in  which 
the  wick  is  trimmed  by  a  wire  passing 
through  a  safe  aperture.  Such  have  now 
been  used  for  many  years,  in  the  most  dan- 
gerous mines  of  England,  without  any  acci- 
dent. Whatever  explosive  disasters  have 
happened  since,  may  be  imputed  to  the  ne- 
glect, or  gross  and  culpable  mismanagement, 
of  that  infallible  protector.  See  LAMP. 

When  the  fire-dump  is  inflamed  in  the 
wire-gauze  cylinders,  coal  dust  thrown  into 
the  lamp,  burns  with  strong  flushes  and  scin- 
tillations. The  miners  were  at  first  alarmed 
by  an  effect  of  this  kind,  produced  by  the 
dust  naturally  raised  during  the  working  of 
the  coals. 

But  Sir  H.  Davy  showed,  by  decisive  ex- 
periments, that  explosion  could  never  be 
communicated  by  them,  to  the  gas  of  any 
mine.  He  repeatedly  threw  coal  dust,  pow- 
dered rosin,  and  witch-meal,  through  lamps 
burning  in  more  explosive  mixtures,  than 
ever  occur  in  coal  mines;  and  though  he 
kept  these  substances  floating  in  the  explo- 
sive atmosphere,  and  heaped  them  upon  the 
top  of  the  lamp  when  it  was  red-hot,  no  ex- 
plosion could  ever  be  communicated.  Phos- 
phorus or  sulphur,  are  the  only  substances 
which  can  produce  explosion,  by  being  ap- 
plied to  the  outside  of  the  lamp ;  and  sul- 
phur, to  produce  the  effect,  must  be  appli- 
ed in  large  quantities,  and  fanned  by  a  cur- 
rent of  fresh  air.  He  has  even  blown  re- 
peatedly, fine  coal  dust  mixed  with  minute 
quantities  of  the  finest  dust  of  gunpowder, 
through  the  lamp  burning  in  explosive  mix- 
tureSj  without  any  communication  of  explo- 
sion. The  most  timorous  female  might 
traverse  an  explosive  coal  mine,  guided  by 
the  light  of  the  double  cylinder  lamp,  with- 
out feeling  the  slightest  apprehension. 

5.  We  have  now  arrived  at  the  most  cu- 
rious of  all  Sir  H.'s  discoveries  relative  to 
fire,  namely,  invisible  combustion. 

On  passing  mixtures  of  hydrogen  and 
oxygen  through  tubes  heated  below  redness, 
steam  appeared  to  be  formed  without  any 
combustion.  This  led  him  to  expose  mix- 
tures of  oxygen  and  hydrogen  to  heat,  i» 


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tubes,  in  which  they  were  confined  by  fluid 
fusible  metal.  He  found,  that,  by  carefully 
applying  a  heat  between  the  boiling  point 
of  mercury,  which  is  not  sufficient  for  the 
effect,  and  a  heat  approaching  to  the  great- 
est heat  that  can  be  given  without  making 
glass  luminous  in  darkness,  the  combina- 
tion was  effected  without  any  violence,  and 
without  any  light;  and  commencing  with 
212,  the  volume  of  steam  formed  at  the 
point  of  combination,  appeared  exactly 
equal  to  that  of  the  original  gases.  So  that 
the  first  effect  in  experiments  of  this  kind, 
is  an  expansion,  afterwards  a  contraction, 
and  then  the  restoration  of  the  primitive 
volume. 

When  this  change  is  going  on,  if  the 
heat  be  quickly  raised  to  redness,  an  ex- 
plosion takes  place.  With  small  quantities 
of  gas,  the  invisible  combustion  is  complet- 
ed in  less  than  a  minute.  It  is  probable 
that  the  slow  combination  without  combus- 
tion, long  ago  observed  with  respect  to  hy- 
drogen and  chlorine,  oxygen  and  metals, 
will  happen  at  certain  temperatures  with 
most  substances  that  unite  by  heat.  On 
trying  charcoal,  he  found,  that  at  a  tempe- 
rature which  appeared  to  be  a  little  above 
the  boiling  point  of  quicksilver,  it  convert- 
ed oxygen  pretty  rapidly  into  carbonic 
acid,  without  any  luminous  appearance; 
and  at  a  dull  red-heat,  the  elements  of 
olefiant  gas  combined  in  a  similar  manner 
with  oxygen,  slowly  and  without  explo- 
sion. The  effect  of  the  slow  combination 
of  oxygen  and  hydrogen  is  not  connected 
with  their  rarefaction  by  heat,  for  it  took 
place  when  the  gases  were  confined  in  a 
tube  by  fusible  metal,  rendered  solid  at 
its  upper  surface;  and  certainly  as  rapidly, 
and  without  any  appearance  of  light. 

As  the  temperature  of  flame  has  been 
shown  to  be  infinitely  higher  than  that  ne- 
cessary for  the  ignition  of  solid  bodies,  it 
appeared  probable,  that  in  these  silent 
combinations  of  gaseous  bodies,  when  the 
increase  of  temperature  may  not  be  suffi- 
cient to  render  the  gaseous  matters  them- 
selves luminous,  yet  it  still  might  be  ade- 
quate to  ignite  solid  matters  exposed  to 
them. 

Sir  H.  Davy  had  devised  several  experi- 
ments on  this  subject.  He  had  intended  to 
expose  fine  wires  to  oxygen  and  olefiant 
g-as,  and  to  oxygen  and  hydrogen,  during 
their  slow  combination  under  different  cir- 
cumstances, when  he  was  accidentally  led 
to  the  knowledge  of  the  fact,  and  at  the 
same  time  to  the  discovery  of  a  new  and 
curious  series  of  phenomena. 

He  was  making  experiments  on  the  in- 
crease of  the  limits  of  the  combustibility 
of  gaseous  mixtures  of  coal-gas  and  air,  by 
increase  of  temperature.  For  this  pur- 
pose, a  small  wire-gauze  safe-lamp,  with 
fine  wire  of  platinum  fixed  above  the 


flame,  was  introduced  into  a  combustible 
mixture,  containing  the  maximum  of  coal- 
gas.  When  the  inflammation  had  taken 
place  in  the  wire-gauze  cylinder,  he  threw 
in  more  coal-gas,  expecting  that  the  heat 
acquired  by  the  mixed  gas,  in  passing 
through  the  wire-gauze,  would  prevent  the 
excess  from  extinguishing  the  flame.  The 
flame  continued  for  two  or  three  seconds 
after  the  coal  gas  was  introduced;  and 
when  it  was  extinguished,  that  part  of  the 
wire  of  platinum  which  had  been  hottest, 
remained  ignited,  and  continued  so  for 
many  minutes.  When  it  was  removed  into 
a  dark  room,  it  was  evident  that  there  was 
no  flame  in  the  cylinder. 

It  was  immediately  obvious  that  this  was 
the  result  which  he  had  hoped  to  attain  by 
other  methods,  and  the  oxygen  and  coal- 
gas  in  contact  with  the  hot  wire,  combin- 
ed without  flame,  and  yet  produced  heat 
enough  to  preserve  the  wire  ignited,  and 
keep  up  their  own  secret  combustion.  The 
truth  of  this  conclusion  was  proved  by  in- 
troducing a  heated  wire  of  platinum  into  a 
similar  mixture.  It  immediately  became 
ignited  nearly  to  whiteness,  as  if  it  had 
been  in  actual  combustion  itself,  and  con- 
tinued  glowing  for  a  long  while.  When  it 
•was  extinguished,  the  inflammability  of  the 
mixture  was  found  to  be  entirely  destroyed. 
A  temperature  much  below  ignition  only, 
was  necessary  for  producing  this  curious 
phenomenon,  and  the  wire  was  repeatedly 
taken  out  and  cooled  in  the  atmosphere 
till  it  ceased  to  be  visibly  red;  yet  when 
admitted  again,  it  instantly  became  red- 
hot. 

The  same  phenomena  were  produced 
with  mixtures  of  olefiant  gas  and  air,  car 
bonic  oxide,  prussic  gas,  and  hydrogen; 
and  in  this  last  case  with  a  rapid  produc- 
tion- of  water.  The  degree  of  heat  could 
be  regulated  by  the  thickness  of  the  wire. 
When  of  the  same  thickness,  the  wire  be- 
came more  ignited  in  hydrogen,  than  iu 
mixtures  of  olefiant  gas,  and  more  in  mix- 
tures of  olefiant  gas,  than  in  those  of  gase- 
ous oxide  of  carbon. 

When  the  wire  was  very  fine,  as  l-80th 
of  an  inch  in  diameter,  its  heat  increased 
in  very  combustible  mixtures,  so  as  to  ex- 
plode them.  The  same  wire  in  less  com- 
bustible mixtures,  continued  merely  bright 
red,  or  dull  red,  according  to  the  nature  of 
the  mixture.  In  mixtures  not  explosive  bv 
flame  within  certain  limits,  these  curious 
phenomena  took  place,  whether  the  air  or 
the  inflammable  gas  was  in  excess.  The 
same  circumstances  occurred  with  certain 
inflammable  vapours.  Those  of  ether,  al- 
cohol, oil  of  turpentine,  naphtha,  and  cam- 
phor, have  been  tried.  There  cannot  be  a 
better  mode  of  illustrating  the  fact,  than 
by  an  experiment  on  the  vapour  of  ether 
9T  of  alcohol,  which  any  person  may  make 


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in  a  minute.  Let  a  drop  of  ether  be  thrown 
into  a  cold  glass,  or  a  drop  of  alcohol  into 
a  warm  one;  let  a  few  coils  of  wire  of  pla- 
tinum, of  the  l-60ih  or  1.70th  of  an  inch, 
be  heated  at  a  hot  poker  or  a  candle,  and 
let  it  be  brought  into  the  glass:  In  some 
part  of  the  glass,  it  will  become  glowing, 
almost  white-hot,  and  will  continue  so,»as 
long  as  a  sufficient  quantity  of  vapour  and 
of  air,  remain  in  the  glass. 

When  the  experiment  on  the  slow  com- 
bustion of  ether  is  made  in  the  dark,  a  pale 
phosphorescent  light  is  perceived  above 
the  wire,  which  is  of  course  most  distinct 
when  the  wire  ceases  to  be  ignited.  This 
appearance  is  connected  with  the  forma- 
tion of  a  peculiar  acrid  volatile  substance, 
possessed  of  acid  properties.  See  ACID 
(LAMPIC).  The  above  experiment  has 
been  ingeniously  varied  by  sticking  loose- 
ly on  the  wick  of  a  spirit  lamp,  a  coil  of 
fine  platinum  wire,  about  j^-$  of  an  inch 
in  thickness.  There  should  be  about  16 
spiral  amis,  one-half  of  which  should  sur- 
Kound  the  wick,  and  the  other  rise  above 
it.  Having  lighted  the  lamp  for  an  instant, 
on  blowing  it  out,  the  wire  will  become 
brightly  ignited,  and  will  continue  to  glow 
as  long  as  any  alcohol  remains.  A  cylin- 
der of  camphor  may  be  substituted  for 
both  wick  and  spirit.  The  ignition  is  very 
bright,  and  exhales  an  odoriferous  vapour. 
With  oil  of  turpentine^  the  lamp  burns  in- 
visibly without  igniting  the  wire;  for  a 
dense  column  of  vapour  is  perceived  to  as- 
cend from  the  wire,  diffusing  a  smell  by 
many  thought  agreeable.  By  adding  essen- 
tial oils  in  small  quantities  to  the  alcohol, 
various  aromas  may  be  made  to  perfume 
the  air  of  an  apartment.  But  the  film  of 
charcoal  which  in  this  case  collects  on  the 
platina  coil,  must  be  removed  by  ignition 
over  another  spirit  flame,  otherwise  the  ef- 
fect ceases  after  a  certain  time. 

The  chemical  changes  in  general,  pro- 
iuced  by  slow  combustion,  appear  worthy 
«f  investigation.  A  wire  of  platinum  in- 
troduced under  the  usual  circumstances 
into  a  mixture  of  prussic  gas  (cyanogen), 
nnd  oxygen  in  excess,  became  ignited  to 
whiteness,  and  the  yellow  vapours  of  ni- 
irous  acid  were  observed  in  the  mixture. 
In  a  mixture  of  defiant  gas,  non-explosive 
from  the  excess  of  inflammable  gas,  much 
carbonic  oxide  was  formed.  Platinum  and 
palladium,  metals  of  low  conducting 
powers,  and  small  capacities  for  heat,  alone 
succeed  in  producing  the  above  phenome- 
na. A  film  of  carbon  or  sulphur  deprives 
£ven  these  metals  of  this  property.  Thin 
laminae  of  the  metals,  if  their  form  admits 
of  a  free  circulation  of  air,  answer  as  well 
as  fine  wires;  and  a  large  surface  of  plati- 
num may  be  made  red-hot  in  the  vapou"  of 
ether,  or  in  a  combustible  mixture  of  coal 
gas  and  air. 


Sir  H.  Davy  made  an  admirable  practical 
application  of  these  new  facts.  By  hang- 
ing some  coils  of  fine  platinum  wire,  or  a 
fine  sheet  of  platinum  or  palladium,  above 
the  wick  of  the  safe -lamp  in  the  wire-gauze 
cylinder,  he  has  supplied  the  coal-miner 
with  light  in  mixtures  of  fire-damp  no 
longer  explosive.  Should  the  flame  be  ex> 
tinguished  by  the  quantity  of  fire-damp, 
the  glow  of  the  platinum  will  continue  to 
guide  him;  and  by  placing  the  lamp  in  dif- 
ferent parts  of  the  gallery,  the  relative 
brightness  of  the  wire  will  show  the  state 
of  the  atmosphere  in  these  parts.  Nor  can 
there  be  any  danger  with  respect  to  respi- 
ration wherever  the  wire  continues  ignit- 
ed; for  even  this  phenomenon  ceases,  when 
the  foul  air  forms  about  f  of  the  volume  of 
the  atmosphere. 

Into  a  wire-gauze  safe -lamp,  a  small  cage 
made  of  fine  wire  of  platinum,  of  l-70th  of 
an  inch  in  thickness,  was  introduced,  and 
fixed  by  means  of  a  thick  wire  of  pla- 
tinum, about  2  inches  above  the  lighted 
wirk.  This  apparatus  was  placed  in  a 
large  receiver,  in  which,  by  means  of  a 
gas-holder,  the  air  could  be  contaminated. 
to  any  extent  with  coal-gas.  As  soon  as 
there  was  a  slight  admixture  of  coal-gas, 
the  platinum  became  ignited.  The  igni- 
tion continued  to  increase  till  the  flame  of 
the  wick  was  extinguished,  and  till  the 
whole  cylinder  became  filled  with  flame. 
It  then  diminished.  When  the  quantity  of 
coal-gas  was  increased  so  as  to  extinguish 
the  flame,  the  cage  of  platinum,  at  the  mo- 
ment of  the  extinction,  became  white  hot, 
presenting  a  most  brilliant  light.  By  in- 
creasing the  quantity  of  the  coal-gas  still 
fui'ther,  the  ignition  of  the  platinum  be- 
came less  vivid.  When  its  light  was  bare- 
ly sensible,  small  quantities  of  air  were  ad- 
mitted, and  it  speedily  increased.  By  re- 
gulating the  admission  of  coal-gas  and  air, 
it  again  became  white-hot,  and  soon  after 
lighted  the  flame  in  the  cylinder,  which  as 
usual,  by  the  addition  of  more  atmosphe 
ric  air,  rekindled  the  flame  of  the  wick. 

This  beautiful  experiment  has  been  very 
often  repeated,  and  always  with  the  same 
results.  When  the  wire  for  the  support  of 
the  cage,  whether  of  platinum,  silver,  or 
copper,  was  very  thick,  it  retained  suffi- 
cient heat,  to  enable  the  fine  platinum  wire 
to  rekindle  in  a  proper  mixture  half  a  mi- 
nute after  its  light  had  been  entirely  des- 
troyed, by  an  atmosphere  of  pure  coal-gag. 
The  phenomenon  of  the  ignition  of  the  pla- 
tinum, takes  place  feebly  in  a  mixture  con- 
sisting of  two  of  air  and  one  of  coal-gas; 
and  brilliantly  in  a  mixture  consisting  of 
three  of  air  and  one  of  coal-gas.  The 
greater  the  quantity  of  heat  produced,  the 
greater  may  be  the  quantity  of  the  coal- 
gas,  so  that  a  large  tissue  of  wire  made 
white-hot,  will  burn  in  a  more  inflammable. 


COM 


COM 


mixture  (that  is,  containing-  more  inflam- 
mable gas),  than  one  made  red-hot,  if  a 
mixture  of  three  parts  of  air  and  one  of 
fire-damp,  be  introduced  into  a  bottle,  and 
inflamed  at  its  point  of  contact  with  the 
atmosphere,  it  will  not  explode,  but  will 
burn  like  a  pure  inflammable  substance. 
If  a  fine  wire  of  platinum,  coiled  at  its  end, 
be  slowly  passed  through  the  flame,  it  will 
continue  ignited  in  the  body  of  the  mix- 
ture, and  the  same  gaseous  matter  will  be 
found  to  be  inflammable,  and  to  be  a  sup- 
porter of  combustion.  When  a  large  cage 
of  wire  of  platinum  is  introduced  into  a 
very  small  safe-lamp,  even  explosive  mix- 
tures of  fire-damp  are  burned  without 
flame;  and  bv  placing1  any  cage  of  platinum 
in  the  bottom  of  the  lamp  round  the  wick; 
the  wire  is  prevented  from  being  smoked. 
Care  should  be  taken  of  course,  that  no 
filament  of  the  platinum  protrude  through 
the  wire-gauze.  It  is  truly  wonderful,  that 
a  slender  tissue  of  platinum,  which  does 
not  cost  one  shilling,  and  which  is  imper- 
ishable, should  afford  in  the  dark  and  dan- 
gerous recesses  of  a  coal  mine,  a  most  bril- 
liant light,  perfectly  safe,  in  atmospheres 
in  which  the  flame  of  the  safety-lamp  is 
extinguished;  and  which  glows  in  every 
mixture  of  carburetted  hydrogen  gas  that 
is  respirable.  When  the  atmosphere  be- 
comes again  explosive,  the  flame  is  re- 
lighted. 

It  is  no  less  surprising,  that  thus  also 
we  can  burn  any  inflammable  vapour, 
either  with  or  without  flame,  at  pleasure, 
and  make  a  slender  wire  consume  it,  either 
with  a  white  or  red  heat. 

6.  We  shall  conclude  the  subject  of 
combustion  with  some  practical  inferences. 

The  facts  detailed  on  insensible  com- 
bustion, explain  why  so  much  more  heat  is 
obtained  from  fuel,  when  it  is  burned 
quickly  than  slowly;  and  they  show,  that  in 
all  cases  the  temperature  of  the  acting  bo- 
dies should  be  kept  as  high  as  possible, 
not  only  because  the  general  increment  of 
heat  is  greater,  but  likewise  because  those 
combinations  are  prevented,  which,  at 
lower  temperatures,  take  place  without 
any  considerable  production,  of  heat. 
Thus,  in  the  argand  lamp,  and  in  the  best 
fire-places,  the  increase  of  effect  does  not 
depend  merely  upon  the  rapid  current  of 
air,  but  likewise  upon  the  heat  preserved 
by  the  arrangement  of  the  materials  of 
the  chimney,  and  communicated  to  the 
matters  entering  into  inflammation. 

These  facts  likewise  explain,  the  source 
of  the  great  error,  into  which  Mr.  Dalton 
has  fallen  in  estimating  the  heat  given  out 
in  the  combustion  of  charcoal;  and  they  in- 
dicate methods  by  which  temperature  may 
be  increased,  and  the  limits  to  certain  me- 
thods. Currents  of  flame  can  never  raise 

VOL.  I. 


the  heat  of  bodies  exposed  to  them,  high- 
er than  a  certain  degree,  that  is,  their  own 
temperature.  But  by  compression,  there 
can  be  no  doubt,  that  the  heat  of  flameg 
from  pure  supporters  and  combustible 
matter  may  be  greatly  increased,  probably 
in  the  ratio  of  their  compression.  In  the 
blow -pipe  of  oxygen  and  hydrogen,  the 
maximum  of  temperature  is  close  to  the 
aperture  from  which  the  gases  are  disen- 
gaged, that  is,  where  their  density  is 
greatest.  Probably  a  degree  of  tempera- 
ture far  beyond  any  that  has  yet  been  at- 
tained, may  be  produced  by  throwing  the 
flame  from  compressed  oxygen  and  hydro- 
gen into  the  voltaic  arc,  and  thus  combin- 
ing the  two  most  powerful  agents  for  in- 
creasing temperature. 

The  nature  of  the  light,  and  form  of 
flames,  can  now  be  clearly  understood. 
When  in  flames  pure  gaseous  matter  is 
burnt,  the  light  is  extremely  feeble.  The 
density  of  a  common  flame,  is  proportional 
to  the  quantity  of  solid  charcoal,  the  first 
deposited  and  afterwards  burned.  The 
form  of  the  flame  is  conical,  because  the 
greatest  heat  is  in  the  centre  of  the  explo- 
sive mixture.  In  looking  stedfastly  at 
flame,  the  part  where  the  combustible  mat- 
ter is  volatilized  is  seen,  and  it  appears 
dark,  contrasted  with  the  part  in  which  it 
begins  to  burn;  that  is,  where  it  is  so 
mixed  with  air  as  to  become  explosive. 
The  heat  diminishes  towards  the  top  of 
the  flame,  because  in  this  part  the  quanti- 
ty of  oxygen  is  least.  When  the  wick  in- 
creases to  a  considerable  size,  from  col- 
lecting charcoal,  it  cools  the  flame  by  ra- 
diation, and  prevents  a  proper  quantity  of 
air  from  mixing  with  its  central  part;  in 
consequence,  the  charcoal  thrown  off  from 
the  top  of  the  flame  is  only  red-hot,  and 
the  greater  part  of  it  escapes  unconsumed. 

The  intensity  of  the  light  of  flames  in 
the  atmosphere  is  increased  by  condensa- 
tion and  diminished  by  rarefaction,  appa- 
rently in  a  higher  ratio  than  their  heat: 
More  particles  capable  of  emitting  light 
exist  in  the  denser  atmospheres,  and  yet 
most  of  these  particles  in  becoming  capa- 
ble of  emitting  light,  absorb  heat,  which 
could  not  be  the  case  in  the  condensation 
of  a  pure  supporting  medium. 

The  facts  on  rarefaction  of  inflammable 
gases  show,  that  the  luminous  appearances 
of  shooting  stars  and  meteors,  cannot  be 
owing  to  any  inflammation  of  elastic  fluids, 
but  must  depend  on  the  ignition  of  solid 
bodies.  Dr.  Halley  calculated  the  height 
of  a  meteor  at  ninety  miles,  and  the  great 
American  meteor  which  threw  down 
showers  of  stones,  was  estimated  at  seven- 
teen miles  high.  The  velocity  of  motion 
of  these  bodies  must  in  all  cases  be  im- 
mensely great,  and  the  heat  produced  by 
42 


cox 


cox 


the  compression  of  the  most  ratified  air, 
from  the  velocity  of  motion,  must  be  pro- 
bably sufficient  to  ignite  the  mass.  All  the 
phenomena  may  be  explained,  if  falling 
stars  be  supposed  to  be  small  solid  bodies 
moving  around  the  earth  in  very  eccentric 
orbits,  which  become  ignited  only  when 
they  pass  with  immense  velocity  through 
the  upper  regions  of  the  atmosphere;  and 
if  the  meteoric  bodies  which  throw  down 
stones  with  explosions,  be  supposed  to  be 
similar  bodies  which  contain  either  com- 
bustible or  elastic  matter. 

When  the  common  electrical  or  voltaic 
electrical  spark  is  taken  in  rare  air,  the 
light  is  considerably  diminished,  as  well 
as  the  heat.  Yet,  in  a  receiver  that  con- 
tained air  60  times  rarer  than  that  of  the 
atmosphere,  a  piece  of  wire  of  platinum, 
placed  by  Sir  H.  Davy  in  the  centre  of  the 
luminous  arc,  produced  by  the  great 
voltaic  apparatus  of  the  Royal  Institution, 
became  white-hot;  and  that  this  was  not 
owing  to  the  electrical  conducting  powers 
of  the  platinum,  was  proved  by  repeating 
the  experiment  with  a  filament  of  glass, 
which  instantly  fused  in  the  same  position. 
It  is  evident  from  this,  that  electrical  heat 
and  light  may  appear  in  atmospheres,  in 
which  the  flame  of  combustible  bodies 
could  not  exist;  and  the  fact  is  interesting 
from  its  possible  application  in  explaining 
the  phenomena  of  the  Aurora  Borealis  and 
•Mustralis. 

Finally,  -we  may  establish  it  as  an  axiom, 
that  combustion  is  not  the  great  phenomenon 
of  chemical  nature;  but  an  adventitious  ac- 
cidental accessory  to  chemical  combination,  or 
decomposition;  that  is,  to  the  internal  motions 
of  the  particles  of  bodies,  tending  to  arrange 
them  in  a  neiv  chemical  constitution. 

Several  cases  of  death,  from  spontaneous 
combustion  of  the  body,  are  on  record. 
The  appearances  resemble  those  which 
would  be  produced  by  phosphuretted  hy- 
drogen.* 

COMPTONITE.  A  new  mineral,  found 
in  drusy  cavities,  in  ejected  masses,  on 
Mount  Vesuvius.  It  occurs  crystallized, 
in  straight  four-sided  prisms,  which  are 
usually  truncated  on  their  lateral  edges, 
so  as  to  form  eight-sided  prisms,  termina- 
ted with  flat  summits.  Transparent,  or 
semi-transparent.  Gelatinizes  with  acids. 
It  is  sometimes  accompanied  with  acicular 
Arragonite.  It  was  first  brought  to  this 
country  by  Lord  Coinpton,  in  1818. 

*  CONCRETIONS  (MORBID).  Solid  de- 
posites,  formed  by  disease  in  the  soft 
parts,  or  in  the  cavities  of  animal  bodies. 
The  former  are  usually  called  ossifications, 
as  they  seem  to  consist  of  calcareous 
phosphate.  They  are  named,  according 
to  the  part  in  which  they  are  deposited, 
pineal,  salivary,  pulmonary,  pancreatic, 
hepatic,  prostatic,  gouty.  Deposites  in 


cavities  are  generally  styled  calculi,  from 
their  resemblance  to  pebbles.  These  are 
intestinal,  gall-stones  or  biliary,  renal,  and 
urinary.  See  the  respective  articles* 

*  CONGELATION.  In  addition  to  the 
methods  pointed  out  under  CALORIC,  for 
effecting  artificial  congelation,  we  shall 
here  describe  the  elegant  mode  by  the  air- 
pump,  recently  perfected  by  Professor 
Leslie. 

The  very  ingenious  Dr.  Cullen  seems  to 
have  been  the  first  who  applied  the  vacuum 
of  an  air-pump  to  quicken  the  evaporation 
of  liquids,  with  a  view  to  the  abstraction 
of  heat,  or  artificial  congelation.  In  the 
year  1755,  he  plunged  a  full  phial  of  ether 
into  a  tumbler  of  water,  and  on  placing  it 
under  the  receiver,  and  exhausting  the 
air,  the  ether  boiled,  and  the  surrounding 
water  froze. 

In  the  year  1777,  Mr.  Edward  Nairne,  a 
very  eminent  London  optician,  published 
in  the  Transactions  of  the  Royal  Society, 
"  an  account  of  some  experiments  made 
with  an  air-pump."  After  stating  that  at  a 
certain  point  of  rarefaction,  the  moisture 
about  the  pump  furnished  an  atmosphere 
of  vapour,  which  affected  his  comparative 
results  with  the  mercurial  gauge  and  pear 
guage,  he  says,  **  1  now  put  some  sulphu- 
ric acid  into  the  receiver,  as  a  means  of 
trying  to  make  the  remaining  contents  of 
the  receiver,  when  exhausted  as  much  as 
possible,  to  consist  of  permanent  air  only, 
unadulterated  -with  vapour."  He  was  thus 
enabled  by  this  artificial  dryness  to  exhibit 
certain  electrical  phenomena  to  great  ad- 
vantage. The  next  step  which  Mr.  Nairne 
took,  was  to  produce  artificial  cold  by  the 
air-pump.  "Having  lately  received  from 
my  friend  Dr.  Lind,"  he  says,  "  some  ether 
prepared  by  the  ingenious  Mr.  Woulfe,  I 
was  very  desirous  to  try  whether  1  could 
produce  any  considerable  degree  of  cold  by 
the  evaporation  of  ether  under  a  receiver 
whilst  exhausting."  Accordingly  he  suc- 
ceeded in  sinking  a  thermometer,  whose 
bulb  was  from  time  to  time  dipped  into 
the  ether  in  vacuo,  103°  below  56°,  the 
temperature  of  the  apartment.  Mr.  Nairne 
made  no  attempt  to  condense  the  vapour 
in  vacuo  by  chemical  means,  and  thus  to 
favour  its  renewed  formation  from  the  li- 
quid surface;  which  I  consider  to  be  the 
essence  of  Professor  Leslie's  capital  im- 
provement, on  Cullen's  plan  of  artificial  re- 
frigeration. After  Nairne's  removing  the 
vapour  of  water  by  sulphuric  acid  to  pro- 
duce artificial  dryness,  there  was  indeed 
but  a  slight  step  to  the  production  of  arti- 
ficial cold,  by  the  very  same  arrangement; 
but  still  this  step  does  not  appear  to  have 
been  attempted  by  any  person  from  the 
year  1777  till  1810,  when  Professor  Leslie 
was  naturally  led  to  make  it,  by  the  train 


CON 


CON 


of  his  researches  on  evaporation  and  hy- 
gTometry. 

The  extreme  rapidity  of  evaporation  in 
vacuo,  may  be  inferred  from  Dr.  Robison's 
position,  that  all  liquids  boil  in  it,  at  a 
temperature  120°  to  125°  lower  than  their 
usual  boiling-  point  in  the  atmosphere. 
Could  we  find  a  liquid  or  solid  substance 
which  would  rapidly  imbibe  alcohol,  ether 
or  sulphuret  of  carbon,  we  would  probably 
be  able  to  effect  reductions  of  temperature 
prodigiously  greater  than  any  hitherto 
reached.  Water,  however,  has  no  doubt 
one  advantage,  in  the  superior  latent  heat 
of  its  vapour,  which  must  compensate  in  a 
considerable  degree  for  its  inferior  ra- 
pidity of  vaporization. 

In  the  month  of  June  1810,  Professor 
Leslie  having  introduced  a  surface  of  sul- 
phuric acid  under  the  receiver  of  an  air- 
pump,  and  also  a  watch-glass  filled  with 
water,  he  found  that  after  a  few  strokes  of 
the  pump,  the  water  was  converted  into  a 
solid  cake  of  ice,  which  being  left  in  the 
rarefied  medium,  continued  to  evaporate, 
and  after  the  interval  of  about  an  hour,  to- 
tally disappeared.  When  the  air  has  been 
rarefied  250  times,  the  utmost  that  under 
such  circumstances  can  perhaps  be  effect- 
ed, the  surface  of  evaporation  is  cooled 
down  120°  Fahrenheit  in  winter,  and  would 
probably,  from  more  copious  evaporation 
and  condensation,  sink  near  200°  in  sum- 
mer. If  the  air  be  rarefied  only  50  times, 
a  depression  of  80°,  or  even  100°,  will  be 
produced. 

We  are  thus  enabled  by  this  elegantcom- 
bination,  to  freeze  a  mass  of  water  in  the 
hottest  weather,  and  to  keep  it  frozen,  till 
it  gradually  wastes  away,  by  a  continued 
but  invisible  process  of  evaporation.  The 
only  thing  required  is,  that  the  surface  of 
the  acid  should  approach  tolerably  near  to 
that  of  the  water,  and  should  have  a  great- 
er extent;  for  otherwise  the  moisture  would 
exhale  more  copiously  than  it  could  be 
transferred  and  absorbed,  and  consequent- 
ly the  dryness  of  the  rarefied  medium 
would  become  reduced,  and  its  evaporating 
energy  essentially  impaired.  The  acid 
should  be  poured  to  the  depth  of  perhaps 
half  an  inch,  in  a  broad  flat  dish,  which  is 
covered  by  a  receiver  of  a  form  nearly 
hemispherical;  the  water  exposed  to  con- 
gelation  may  be  contained  in  a  shallow  cup, 
about  half  the  width  of  the  dish,  and  hav- 
ing its  rim  suppoi'ted  by  a  narrow  porce- 
lain ring,  upheld  above  the  surface  of  the 
acid  by  three  slender  feet.  It  is  of  conse- 
quence that  the  water  should  be  insulated 
as  much  as  possible,  or  should  present  only 
a  humid  surface  to  the  contact  of  the  sur- 
rounding medium;  for  the  dry  sides  of  the 
cup  might  receive,  by  radiation  from  the 
external  air,  such  accessions  of  heat,  as 


greatly  to  diminish,  if  not  to  counteract 
the  refrigerating  effects  of  evaporation. 
This  inconvenience  is  in  a  great  measure 
obviated,  by  investing  the  cup  with  an 
outer  case,  at  the  interval  of  about  half  an 
inch.  If  both  the  cup  and  its  case  consist 
of  glass,  the  process  of  congelation  is  view- 
ed most  completely;  yet  when  they  are 
formed  of  a  bright  metal,  the  effect  ap- 
pears, on  the  whole,  mom  striking.  But 
the  preferable  mode,  and  that  which  pre- 
vents any  waste  of  the  powers  of  refrigera- 
tion, is  to  expose  the  water  in  a  saucer  of 
porous  earthen  ware.  At  the  instant  of 
congelation,  a  beautiful  network  of  icy  spi- 
culae  pervades  the  liquid  mass. 

The  disposition  of  the  water  to  fill  the 
receiver  with  vapour,  will  seldom  permit 
even  a  good  air-pump  to  produce  greater 
rarefaction  than  that  indicated  by  3-10ths 
of  an  inch  of  mercury,  beneath  the  baro- 
metrical height,  at  the  time.  But  every 
practical  object  may  be  obtained  by  more 
moderate  rarefactions,  and  a  considerable 
surface  of  acid.  The  process  goes  on  more 
slowly,  but  the  ice  is  very  solid,  especially 
if  the  water  have  been  previously  purged 
of  its  air  by  distillation,  or  boiling  for  a 
considerable  time.  If  we  use  a  receiver^ 
with  a  sliding  wire  passing  down  from  its 
top  through  a  collar  of  leathers,  and  attach 
to  it  a  disc  of  glass;  on  applying  this  to  the 
surface  of  the  water  cup,  we  may  instantly 
suspend  the  process  of  congelation;  and 
raising  the  disc  as  suddenly,  permit  the 
advancement  of  the  process. 

In  exhibiting  the  different  modifications 
of  this  system  of  congelation  to  my  pupils, 
I  have  been  accustomed  for  many  years  to 
recommend  the  employment  of  a  series  of 
cast-iron  plates,  attachable  by  screws  and 
stop-cocks  to  the  air-pump.  Each  iron  disc 
has  a  receiver  adapted  to  it.  Thus,  we 
may  with  one  air-pump,  successively  put 
any  number  of  freezing  processes  in  ac- 
tion. A  cast-iron  drum  of  considerable  di- 
mensions being  filled  with  steam,  by  heat- 
ing a  small  quantity  of  water  in  it,  will 
sufficiently  expel  the  air  for  producing  the 
requisite  vacuum.  When  it  is  cooled  by 
affusion  of  water,  one  of  the  above  trans- 
ferrer  plates  being  attached  to  the  stop- 
cock on  its  upper  surface,  would  easily 
enable  us,  without  any  air-pump,  to  effect 
congelation  by  means  of  sulphuric  acid,  in 
the  attenuated  atmosphere.  Suppose  the 
capacity  of  the  receiver,  to  be  l-60th  of  the 
iron  cylinder;  an  aeriform  rarefaction  to 
this  degree  would  be  effected  in  a  moment 
by  a  turn  of  the  stop-cock;  and  on  its  be- 
ing returned,  the  moisture  below  would 
be  cut  off,  and  the  acid  would  speedily 
condense  the  small  quantity  of  vapour 
which  had  ascended. 

This  cheap  and  powerful  plan  was  pub- 


CON 


COP 


licly  recommended  by  me  upwards  of  ten 
years  ago,  when  I  had  a  glass  model  of  it 
made  for  class  illustration. 

The  combined  powers  of  rarefaction,  va- 
porization, and  absorption,  are  capable  of 
effecting  the  congelation  of  quicksilver.  If 
this  metal,  contained  in  a  hollow  pear- 
shaped  piece  of  ice,  be  suspended  by  fffoss 
threads  near  a  broad  surface  of  sulphuric 
acid,  under  a  receiver,  on  urging  the  rare- 
faction, it  will  become  frozen,  and  may  be 
kept  in  the  solid  state  for  several  hours. 
Or  otherwise,  having  introduced  mercury 
into  the  large  bulb  of  a  thermometer,  and 
attached  the  stem  to  the  sliding  rod  of  the 
receiver,  place  this  over  the  sulphuric  acid, 
and  water  cup  on  the  air-pump  plate.  Af- 
ter the  air  has  been  rarefied  about  50  times, 
let  the  bulb  be  dipped  repeatedly  into  the 
very  cold  but  unfrozen  water,  and  again 
drawn  up  about  an  inch.  In  this  way  it 
will  become  incrusted  with  successive  coats 
of  ice,  to  the  twentieth  of  an  inch  thick. 
The  cup  of  water  being  now  withdrawn 
from  the  receiver,  the  pendent  icicle  cut 
away  from  the  bulb,  and  the  surface  of  the 
ice  smoothed  with  a  warm  finger,  the  re- 
ceiver is  again  to  be  replaced,  and  the  bulb 
being  let  down  within  half  an  inch  of  the 
acid,  the  exhaustion  must  be  pushed  to  the 
utmost.  When  the  syphon-gauge  arrives  at 
the  tenth  of  an  inch,  the  icy  crust  opens 
with  fissures,  and  the  mercury  having 
gradually  descended  in  the  tube,  till  it 
reach  its  point  of  congelation,  or  39°  be- 
low zero,  sinks  by  a  sudden  contraction 
almost  into  the  cavity  of  the  bulb.  The 
apparatus  being  now  removed,  and  the  ball 
speedily  broken,  the  metal  appears  a  solid 
shining  mass,  that  will  bear  the  stroke  of 
a  hammer.  A  still  greater  degree  of  cold 
may  be  produced,  by  applying  the  same 
process  to  cool  the  atmosphere,  which  sur- 
rounds the  receiver. 

When  the  acid  has  acquired  one-tenth  of 
water,  its  refrigerating  power  is  diminish- 
ed only  one-hundredth.  When  the  quan- 
tity of  moisture  is  equal  to  one-fourth  of 
the  concentrated  acid,  the  power  of  gene- 
rating cold  is  reduced  by  a  twentieth;  and 
when  the  dilution  is  one-half,  the  cooling 
powers  become  one-half  or  probably  less. 
Sulphuric  acid  is  hence  capable  of  effect- 
ing the  congelation  of  more  than  twenty 
times  its  weight  of  water,  before  it  has  im- 
bibed nearly  its  own  bulk  of  that  liquid, 
or  has  lost  about  one-eighth  of  its  refrige- 
rating power.  The  acid  should  then  be 
removed,  and  reconcentrated  by  heat. 

The  danger  of  using  a  corrosive  acid  in 
unskilful  hands,  may  be  obviated  by  using 
oatmeal,  desiccated  nearly  to  brownness  be- 
fore a  kitchen-fire,  and  allowed  to  cool  in 
close  vessels.  With  a  body  of  this,  a  foot 
in  diameter,  and  an  inch  deep,  Professor 
Leslie  froze  a  pound  and  a  quarter  of  wa- 


ter, contained  in  a  hemispherical  porous 
cup.  Muriate  of  lime  in  ignited  poi'ous 
pieces,  may  also  be  employed  as  an  ab- 
sorbent. Even  mouldering  trap  or  whin- 
stone,  has  been  used  for  experimental  il- 
lustration with  success. 

By  the  joint  operation  of  radiation  and 
evaporation  from  the  surface  of  water,  the 
natives  of  India  are  enabled  to  procure  a 
supply  of  ice,  when  the  temperature  of  the 
air  is  many  degrees  above  the  freezing 
point.  Not  far  from  Calcutta,  in  large  open 
plains,  three  or  four  excavations  are  made 
in  the  ground,  about  30  feet  square,  and 
2  feet  deep,  the  bottom  of  which  is  covered 
to  the  thickness  of  nearly  a  foot  with  su- 
gar canes,  or  dried  stalks  of  Indian  corn. 
On  this  bed  are  placed  rows  of  small  un- 
glazed  earthen  pans,  about  an  inch  and  a 
quarter  deep,  and  somewhat  porous.  In 
the  dusk  of  the  evening,  during  the  months 
of  December,  January,  and  February,  they 
arc  filled  with  soft  water,  previously  boiled 
and  suffered  to  cool.  When  the  weather 
is  very  fine  and  clear,  a  great  part  of  the 
water  becomes  frozen  during  the  night. 
The  pans  are  regularly  visited  at  sunrise, 
and  their  contents  emptied  into  baskets 
which  retain  the  ice.  These  are  now  car- 
ried to  a  conservatory  made  by  sinking  a 
pit  14  or  15  feet  deep,  lined  with  straw  un- 
der a  layer  of  coarse  blanketing.  The  small 
sheets  of  ice  are  thrown  down  into  the  ca- 
vity, and  rammed  into  a  solid  mass.  The 
mouth  of  the  pit  is  then  closed  up  with 
straw  and  blankets,  and  sheltered  by  a 
thatched  roof. 

For  some  additional  facts,  on  this  inte- 
resting subject,  see  the  sequel  of  the  arti- 
cle DEW.* 

*  CONITE.  An  ash  or  greenish -gray  co- 
loured mineral,  which  becomes  brown  on 
exposure  to  the  air.  It  is  massive  or  stalac- 
titic,  is  dull  internally,  and  has  a  small 
grained  uneven  fracture.  It  is  brittle;  sp. 
gr.  2.85.  It  dissolves  in  nitric  acid,  with 
slight  effervescence,  and  blackens  without 
fusing  before  the  blow-pipe.  Its  constitu- 
ents are  67.5  carbonate  of  magnesia,  28 
carbonate  of  lime,  3.5  oxide  of  iron,  and  1 
water.  It  is  found  in  the  Meissner  trap 
hill  in  Hessia,  in  Saxony,  and  Iceland.  Dr. 
Macculloch  has  given  the  name  Conite  to  a 
pulverulent  mineral,  as  fusible  as  glass, 
into  a  transparent  bead,  which  he  found  in 
Mull  and  Glenfarg,  in  the  trap  hills  of  Kil- 
patrick,  and  the  Isle  of  Sky." 

COPAL,  improperly  called  gum  copal,  is 
a  hard,  shining,  transparent,  citron -colour- 
ed, odoriferous,  concrete  juice  of  an  Ame- 
rican tree,  but  which  has  neither  the  solu- 
bility in  water  common  to  gums,  nor  the 
solubility  in  alcohol  common  to  resins,  at 
least  in  any  considerable  degree.  By  these 
properties  it  resembles  amber.  It  may  be 
dissolved  by  digestion  in  linseed  oil,  ren- 


COP 


COP 


dered  drying  by  quicklime,  with  a  heat 
very  little"  less  than  sufficient  to  boil  or  de- 
compose the  oil.  This  solution,  diluted 
with  oil  of  turpentine,  forms  a  beautiful 
transparent  varnish,  which,  when  properly 
applied,  and  slowly  dried,  is  very  hard,  and 
very  durable.  This  varnish  is  applied  to 
snuff-boxes,  tea-boards,  and  other  utensils. 
It  preserves  and  gives  lustre  to  paintings, 
and  greatly  restores  the  decayed  colours 
of  old  pictures,  by  filling  up  the  cracks, 
and  rendering  the  surfaces  capable  of  re- 
flecting light  more  uniformly. 

Mr.  Sheldrake  has  found,  that  camphor 
has  a  powerful  action  on  copal;  for  if  pow- 
dered copal  be  triturated  with  a  little  cam- 
phor, it  softens,  and  becomes  a  coherent 
mass;  and  camphor  added  either  to  alcohol 
or  oil  of  turpentine,  renders  it  a  solvent  of 
copal.  Half  an  ounce  of  camphor  is  suffi- 
cient for  a  quart  of  oil  of  turpentine,  which 
should  be  of  the  best  quality;  and  the  co- 
pal, about  the  quantity  of  a  large  walnut, 
should  be  broken  into  very  small  pieces, 
but  not  reduced  to  a  fine  powder.  The 
mixture  should  be  set  on  a  fire  so  brisk  as 
to  make  the  mixture  boil  almost  immedi- 
ately; and  the  vessel  Mr.  S.  recommends  to 
be  of  tin  or  other  metal,  strong,  shaped 
like  a  wine  bottle  with  a  long  neck,  and 
capable  of  holding  two  quarts.  The  mouth 
should  be  stopped  with  a  cork,  in  which  a 
notch  is  cut  to  prevent  the  vessel  from 
bursting.  It  is  probably  owing  to  the  quan- 
tity of  camphor  it  contains,  that  oil  of  la- 
vender is  a  solvent  of  copal.  Camphor  and 
alcohol  dissolve  copal  still  more  readily 
than  camphor  and  oil  of  turpentine. 

Lewis  had  observed,  that  solution  of  am- 
monia enabled  oil  of  turpentine  to  dissolve 
copal;  but  it  requires  such  nice  manage- 
ment of  the  fire  that  it  seldom  succeeds 
completely. 

*  In  the  51st  volume  of  Tilloch's  Maga- 
zine, Mr.  Cornelius  Varley  states,  that  a 
good  varnish  may  be  made  by  pouring  upon 
the  purest  lumps  of  copal,  reduced  to  a  fine 
mass,  in  a  mortar,  colourless  spirits  of  tur- 
pentine, to  about  one-third  higher  than  the 
copal,  and  triturating  the  mixture  occa- 
sionally in  the  course  of  the  d?.y.  Next 
morning  it  may  be  poured  off'  into  a  bottle 
for  use.  Successive  portions  of  oil  of  tur- 
pentine may  thus  be  worked  with  the  same 
copal  mass.  Camphorated  oil  of  turpen- 
tine, and  oil  of  spike-lavender,  are  also  re- 
commended as  separate  solvents  without 
trituration.  The  latter,  however,  though 
very  g'ood  for  drawings  or  prints,  will  not 
do  for  varnishing  pictures,  as  it  dissolves 
the  paint  underneath,  und  runs  down  while 
drying.* 

COPPER  is  a  metal  of  a  peculiar  reddish- 
brown  colour;  hard,  sonorous,  verv  mallea- 
ble and  ductile;  of  considerable  tenacity, 
and  of  a  specific  gravity  from  8.6  to  8.9, 


At  a  degree  of  heat  far  below  ignition,  the 
surface  of  a  piece  of  polished  copper  be- 
comes covered  with  various  ranges  of  pris- 
matic colours,  the  red  of  each  order  being 
nearest  the  end  which  has  been  most  heat- 
ed; an  effect  which  must  doubtless  be  at- 
tributed to  oxidation,  the  stratum  of  oxide 
being  thickest  where  the  heat  is  greatest, 
and  growing  gradually  thinner  and  thinner 
towards  the  colder  part.  A  greater  de- 
ree  of  heat  oxidizes  it  more  rapidly,  so 
that  it  contracts  thin  powdery  scales  on  its 
surface,  which  may  be  easily  rubbed  off; 
the  flame  of  the  fuel  becoming  at  the  same 
time  of  a  beautiful  bluish-green  colour.  In 
a  heat,  nearly  the  same  as  is  necessary  to 
melt  gold  or  silver,  it  melts  and  exhibits  a 
bluish-green  flame;  by  a  violent  heat  it 
boils,  and  is  volatilized  partly  in  the  me- 
tallic state. 

Copper  rusts  in  the  airj  but  the  corroded 
part  is  very  thin,  and  preserves  the  metal 
beneath  from  farther  corrosion. 

*  We  have  two  oxides  of  copper,  the 
black,  procurable  by  heat,  or  by  drying 
the  hydrated  oxide,  precipitated  by  potash 
from  the  nitrate.  It  consists  of  8  copper 
-j-  2  oxygen.  It  is  a  deutoxide.  The  pro- 
toxide is  obtained  by  digesting  a  solution 
of  muriate  of  copp'er  with  copper  turn- 
ings, in  a  close  phial.  The  colour  passes 
from  green  to  dark  brown,  and  gray  crys- 
talline grains  are  deposited.  The  solution 
of  these  yields,  by  potash,  a  precipitate  of 
an  orange  colour,  which  is  the  protoxide. 
It  consists  of  8  copper  -{-  1  oxygen.  Pro- 
toxide of  copper  has  been  lately  found  by 
Mr.  Mushet,  in  a  mass  of  copper,  which 
had  been  exposed  to  heat  for  a  considera- 
ble time,  in  one  of  the  melting  furnaces  of 
the  mint  under  his  superintendence. 

Copper,  in  filings,  or  thin  laminae,  intro- 
duced into  chlorine,  unites  with  flame  into 
the  chloride,  of  which  there  are  two  varie- 
ties; the  protochloride,  a  fixed  yellow  sub- 
stance, and  the  cleutochloride,  a  yellowish- 
brown  pulverulent  sublimate.  1.  The  crys- 
talline grains  deposited  from  the  above  mu- 
riatic solution,  are  protochloride.  The  pro- 
tochloride is  conveniently  made  by  heating 
together  two  parts  of  corrosive  sublimate, 
and  one  of  copper  filings.  An  amber- 
coloured  translucent  substance,  first  dis- 
covered by  Boyle,  who  called  it  resin  of 
copper,  is  obtained.  It  is  fusible  at  a  heat 
just  below  redness;  and  in  a  close  vessel, 
or  a  vessel  with  :*  narrow  orifice,  is  not  de- 
composed or  sublimed  by  a  strong  red  heat. 
Rut  if  air  be  admitted  it  is  dissipated  in 
dense  white  fumes.  It  is  insoluble  in  wa- 
ter. It  effervesces  in  nitric  acid.  It  dis- 
solves silently  in  muriatic  acid,  from  which 
it  may  be  precipitated  by  water.  By  slow 
cooling  of  the  fused  mass  Dr  John  Davy 
obtained  it  crystallized,  apparently  in  small 
plates,  semitransparent,  and  of  a  light  yel- 


COP 

low  colour.    It  consists,  by  the  same  inge- 
nious chemist,  of 

Chlorine,  36       or  1  prime  =  4.45       35.8 
Copper,    64       or  1  prime       8.00       64.2 


100 


12.45      100.0 


2.  Dentochloride  is  best  made  by  slowly 
evaporating  to  dryness,  at  a  temperature 
not  much  above  4-00°  Fahr.  the  deliques- 
cent muriate  of  copper.  It  is  a  yellow  pow- 
der. By  absorption  of  moisture  from  the 
air,  it  passes  from  yellow  to  white,  and 
then  green,  reproducing-  common  muriate. 
Heat  converts  it  into  protochloride,  with 
the  disengagement  of  chlorine.  Dr.  Davy 
ascertained  the  chemical  constitution  of 
both  these  compounds,  by  separating  the 
copper  with  iron,  and  the  chlorine  by  ni- 
trate of  silver.  The  deutochloride  consists 
of  Chlorine,  53  2  primes  8.9  52-7 
Copper,  47  1  do.  8.0  47-3 

100  16.9     1000 

The  iodide  of  copper  is  formed  by  drop- 
ping aqueous  hydriodate  of  potash  into  a 
solution  of  any  cupreous  salt  It  is  an  in- 
soluble dark  brown  powder. 

Phosphuret  of  copper  is  made  by  project- 
ing phosphorus  into  red-hot  copper.  It  is 
of  a  white  colour,  harder  than  iron,^pretty 
fusible,  but  not  ductile.  Its  sp.  gr.  is  7.12. 
It  crystallizes  in  tour-sided  prisms.  Proust, 
its  discoverer,  says  it  consists  of  20  phos- 
phorus -f-  80  copper.  1.5  or  3.0  phospho- 
rus -f-  8.0  copper,  form  the  equivalent  pro- 
portions by  theory.  Heat  burns  out  the 
phosphorus,  and  scorifies  the  copper. 

8-ulphuret  of  copper  is  formed  by  mixing 
together  eight  parts  of  copper  filings,  and 
two  of  sulphur,  and  exposing  the  mixture 
to  a  gentle  heat.  Whenever  the  sulphur  is 
raised  a  little  above  its  melting  tempera- 
ture, combustion  suddenly  pervades  the 
whole  mass  with  explosive  violence. 

Ignition,  with  reciprocal  saturation,  con- 
stitutes a  true  combustion,  of  which  every 
character  is  here.  And  since  the  experi- 
ment succeeds  perfectly  well  in  vacua,  or 
in  azote,  we  are  entitled  to  consider  sul- 
phur as  a  true  supporter  of  combustion,  if 
this  name  be  retained  in  chemistry;  a  name 
indicating,  what  no  person  can  prove,  that 
one  of  the  combining  bodies  is  a  mere  sup- 
porter, and  the  other  a  mere  combustible. 
Combustion  is,  on  the  contrary,  shown  by 
this  beautiful  experiment,  to  be  indepen- 
dent of  those  bodies  vulgarly  reckoned 
supporters.  Indeed,  sulphur  bears  to  cop- 
per the  same  electrical  relation,  that  oxy- 
gen and  chlorine  bear  to  this  metal.  Hence 
sulphur  is  at  once  a  supporter  and  com- 
bustible, in  the  fullest  sense;  a  fact  fatal  to 
this  technical  distinction,  since  one  body 
cannot  be  possessed  of  diametrically  op- 
posite qualities. 


COP 

When  a  disc  of  copper,  with  an  insulat- 
ed handle,  is  made  to  touch  a  disc  of  sul- 
phur, powerful  electrical  changes  ensue; 
and  at  a  higher  temperature  we  see,  that 
the  reciprocal  attractive  forces,  or  the  cor- 
puscular movements  which  accompany  en- 
ergetic affinity,  excite  the  phenomena  of 
combustion.  To  say  that  one  of  the  com- 
bining bodies  contains  a  latent  magazine 
of  heat  and  light,  to  feed  the  flame  of  the 
other  body,  is  an  hypothesis  altogether  des- 
titute of  proof,  which  should  therefore 
have  no  place  in  one  of  the  exact  sciences, 
far  less  be  made  the  groundwork  of  a  che- 
mical system. 

Sulphuret  of  copper  consists,  according 
to  Berzelius,  of  very  nearly  8  copper  -f-  2 
sulphur.  We  may  regard  it  as  containing 
a  prime  of  each  constituent.* 

The  sulphuric  acid,  when  concentrated 
and  boiling,  dissolves  copper.  If  water  be 
added  to  this,  it  forms  a  blue  solution  of 
copper,  which,  by  evaporation,  affords  blue 
crystals,  that  require  about  four  times 
their  weight  of  water  to  dissolve  them. 

The  solutions  of  copper  in  sulphuric 
acid  are  slightly  caustic.  Magnesia,  lime, 
and  the  fixed  alkalis,  precipitate  the  metal 
from  them  in  the  form  of  oxide.  Volatile 
alkali  precipitates  all  the  solution  of  cop- 
per, but  redissolves  the  oxide,  and  pro- 
duces a  deep  blue  colour.  There  are  cer- 
tain mineral  waters  in  Hungary,  Sweden, 
Ireland,  and  in  various  parts  of  England, 
which  contain  sulphate  of  copper,  and 
from  which  it  is  precipitated  by  the  addi- 
tion  of  pieces  of  old  iron. 

Nitric  acid  dissolves  copper  with  great 
rapidity,  and  disengages  a  large  quantity 
of  nitrous  gas.  Part  of  the  metal  falls 
down  in  the  form  of  an  oxide;  and  the  fil- 
trated or  decanted  solution,  which  is  of  a 
much  deeper  blue  colour  than  the  sulphu- 
ric solution,  affords  crystals  by  slow  eva- 
poration. This  salt  is  deliquescent,  very 
soluble  in  water,  but  most  plentifully  when 
the  fluid  is  heated.  Its  solution,  exposed 
to  the  air  in  shallow  vessels,  deposites  an 
oxide  of  a  green  colour.  Lime  precipi- 
tates the  metal  of  a  pale  blue,  fixed  alkalis 
of  a  bluish-white.  Volatile  alkali  throws 
down  bluish  flocks,  which  are  quickly  re- 
dissolved,  and  produce  a  lively  blue  colour 
in  the  fluid. 

*  The  saline  combinations  of  copper 
were  formerly  called  sales  veneris,  because 
Venus  was  the  mythological  name  of  cop- 
per. They  have  the  following  general  cha- 
racters: 1.  They  are  mostly  soluble  in 
water,  and  their  solutions  have  a  green  or 
blue  colour,  or  acquire  one  of  these  co- 
lours on  exposure  to  air.  2.  Ammonia 
added  to  the  solutions,  produces  a  deep 
blue  colour.  3.  Ferroprussiate  of  potash 
gives  a  reddish-brown  precipitate,  with  cu- 
preous salts.  4.  Gallic  acid  gives  a  brown 


COP 


COP 


preciqitate.  5.  Hydrosulphuret  of  potash 
gives  a  black  precipitate.  6.  A  plate  of 
iron  immersed  in  these  solutions  throws 
down  metallic  copper,  and  very  rapidly  if 
there  be  a  slight  excess  of  acid.  The  prot- 
oxide of  copper  can  be  combined  with  the 
acids  only  by  very  particular  management. 
All  the  ordinary  salts  of  copper  have  the 
peroxide  for  a  base. 

Acetate  of  copper.  The  joint  agency  of 
air  and  acetic  acid,  is  necessary  to  the  pro- 
duction of  the  cupreous  acetates.  By  ex- 
posing- copper  plates  to  the  vapours  of  vine- 
gar, the  bluish-green  verdigris  is  formed, 
which  by  solution  in  vinegar  constitutes 
acetate  of  copper.  This  salt  crystallizes  in 
four-sided  truncated  pyramids.  Its  colour 
is  a  fine  bluish-green.  Its  sp.  gr.  is  1.78. 
It  has  an  austere  metallic  taste;  and  swal- 
lowed, proves  a  violent  poison.  Boiling 
water  dissolves  one-fifth  of  the  salt,  of 
which  it  deposites  the  greater  part  on  cool- 
ing. It  is  soluble  also  in  alcohol.  It  ef- 
floresces by  exposure  to  air.  By  heat,  in  a 
retort,  it  yields  acetic  acid,  and  pyro-ace- 
tic  spirit.  Sulphuretted  hydrogen  throws 
down  the  copper  from  solutions  of  this 
salt,  in  the  state  of  sulphuret.  Dr.  Thom- 
son gives  the  following  account  of  its  com- 
position: "  According  to  Proust,  the  ace- 
tate of  copper  is  composed  of 

61  acid  and  water, 

39  oxide, 

100 

*'  If  we  suppose  it  a  compound  of  1  atom 
acid,  1  atom  oxide,  and  8  atoms  water,  its 
constituents  will  be 

Acetic  acid,  25.12 

Peroxide  of  copper,  39.41 
Water,  35.47 


100.00 

"I  consider  these  to  be  its  true  constitu- 
ents." Here  we  have  an  amusing  specimen 
of  atomical  reasoning;  beginning  the  syllo- 
gism with  a  supposition,  and  concluding  it 
with  a  certainty.  1  had  occasion  to  ana- 
lyze this  salt  with  some  care  about  two 
years  ago,  and  found  it  to  consist  by  expe- 
riment of 

Exper.  Theory. 

Acetic  acid,  52.0  2  atoms  13.26  51.98 
Perox.  of  cop.  39.6  1  do.  10.00  39.20 
Water,  8.4  1  do.  2.25  8.82 


consist  of  acid  and  water,  37 
Oxide,  63 

The  proportion  of  40  acid  -f-  60  oxide, 
is  that  of  1  atom  of  each,  to  use  the  hypo- 
pothetical  term.  Now  Proust's  experiments 
seem  to  leave  uncertainty  to  the  amount  of 
that  difference.  This  salt  should  be  called 
probably  the  acetate.  Proust's  insoluble 
part  of  verdigris  will  become  the  subace- 
tate. This  constitutes  44  per  cent,  and  the 
other  56.  But  the  proportions  will  fluctu- 
ate; and  an  intermixture  of  carbonate  may 
be  expected  occasionally. 

Jlrseniatc  of  copper  presents  us  with  many 
sub-species  which  are  found  native.  The 
arseniate  may  be  formed  artificially  by  di- 
gesting arsenic  acid  on  copper,  or  by  ad- 
ding arseniate  of  potash  to  a  cupreous  sa- 
line solution. 

1.  Obtuse  octahedral  araeniate,  consisting 
of  two  four-sided  pyramids,  applied  base 
to  base,  of  a  deep  sky-blue  or  grass-green 
colour.  Their  sp.  gr.  is  2.88.  They  con- 
sist, according  to  Chenevix,  of  14.3  acid 
-j-  50  brown  oxide  -f-  35.7  water.  2.  Hex- 
ahedral  arseniate  is  found  in  fine  six-sided 
laminae,  divisible  into  thin  scales.  Its  co- 
lour is  a  deep  emerald-green;  and  its  sp. 
gr.  2.548.  It  consists,  by  Vauquelin,  of  43 
acid  -f-  39  oxide  -f-  18  water.  When  arse- 
niate of  ammonia  is  poured  into  nitrate  of 
copper,  this  variety  precipitates  in  small  blue 
crystals.  3.  Acute  octahedral  arseniate,  com- 
posed of  two  four-sided  pyramids,  applied 
base  to  base,  and  sometimes  in  rhomboidal 
prisms,  with  dihedral  summits.  It  con- 
sists of  29  acid  -f-  50  oxide  -f-  21  water. 
The  last  ingredient  is  sometimes  wanting. 
4.  Trihedral  urseniate  occurs  also  in  other 
forms.  Colour  bluish-green.  It  consists, 
by  Chenevix,  of  30  acid  -f-  54  oxide,  -f-  16 
water.  5.  Superarseniate.  On  evaporating 
the  supernatant  solution  in  the  second  va- 
riety artificially  made,  and  adding  alcohol, 
M.  Chenevix  obtained  a  precipitate  in 
small  blue  rhomboidal  crystals.  They  were 
composed  of  40.1  acid  -}-  35.5  oxide  4- 
24.4  water.  The  following  is  a  general  ta- 
ble of  the  composition  of  these  arseniates:—  • 


100.0  25.51    100.00 

Instead  of  35^  per  cent  of  water,  which 
the  Doctor  pitches  on  at  random,  it  has  not 
9;  and  instead  of  only  25  of  acid,  it  really 
contains  more  than  double  that  quantity. 
The  crystallized  salt  is  a  binacetate  of  dip- 
per. 

The  subacetate  of  Proust,  obtained  by 
dissolving  verdigris  in  water,  is  said  to 


Add. 
1.00 
1.00 
1.00 
1.00 
1.00 


Oxide. 
3.70 
2.76 
1.72 
1.80 
0.88 


Water. 

250 

1.00 

0.70 

0.53 

0.60 


It  will  require  the  atomical  couch  of  Pro- 
crustes, to  accommodate  these  proportions 
to  the  number  14.5,  recently  pitched  upon 
for  arsenic  acid  by  Dr.  Thomson. 

Arsenite  of  copper,  called  Scheele's  green, 
is  prepared  by  the  old  prescription  of  mix- 
ing- a  solution  of  2  parts  of  sulphate  of 
copper  in  44  of  water,  with  a  solution  of 
2  parts  of  potash  of  commerce,  and  1  of 
pulverized  ai'senious  acid,  also  in  44  of 


COP 


COP 


water.  Both  solutions  being  warm,  the  first 
is  to  be  gradually  poured  into  the  second. 
The  grass-green  insoluble  precipitate  is  to 
be  well  washed  with  water. 

Carbonate  of  copper.  Of  this  compound 
there  are  three  native  varieties,  the  green, 
the  blue,  and  the  anhydrous,  According 
to  Mr.  R.  Phillips,  the  following  is  th*  or- 
der of  their  composition: — 

1st.  3d.  3J. 

Carbonic  acid,  2  "5         11  OJ         2.75 

Deutox.  copper,  10.00  30.00  10.00 
Water,  I. US  2.25  0.00 

Weights  of  primes,  13. 875      43.25       12.75 

The  artificial  carbonate,  obtained  by 
Proust,  on  adding  an  alkaline  carbonate  to 
a  solution  of  the  nitrate  of  copper,  is  the 
same  with  the  second  kind. 

Chlorate  of  copper  is  a  deflagrating  deli- 
quescent green  salt. 

Fluate  of  copper  is  in  small  blue-coloured 
crystals. 

Hydriodate  of  copper  is  a  grayish-white 
powder. 

Protomwiate  of  copper  has  already  been 
described  in  treating  of  the  chlorides. 

Deutomuriate  of  copper,  formed  by  dis- 
solving the  deutoxide  in  muriatic  acid,  or 
by  heating  muriatic  acid  on  copper  filings, 
yields  by  evapoi*ation  crystals  of  a  grass- 
green  colour,  in  the  form  of  rectangular  pa- 
rallelepipeds. Their  sp.  gr.  is  1.68.  They 
are  caustic,  very  deliquescent,  and  of 
course  very  soluble  in  water.  According 
to  Berzelius,  it  consists  of  acid,  40.2 
Deutoxide,  59.8 
lOOO 

The  ammonia-nitrate  evaporated,  yields  a 
fulminating  copper.  Crystals  of  nitrate, 
mixed  with  phosphorus,  and  struek  with  a 
hammer,  detonate.  When  pulverized,  then 
slightly  moistened,  and  suddenly  wrapt 
up  firm,  in  tin-foil,  the  nitrate  produces  an 
explosive  combustion.  The  nitrate  seems 
to  consist  of  a  prime  of  acid  -j-  a  prime  of 
deutoxide,  besides  water  of  crystallization. 

Subnitrate  of  copper  is  the  blue  precipi- 
tate, occasioned  by  adding  a  little  potash 
to  the  neutral  nitric  solution. 

Nitrite  of  copper  is  formed  by  mixing  ni- 
trite of  lead  with  sulphate  of  copper. 

The  sulphate  or  blue  vitriol  of  commerce 
is  a  bisulphate.  Its  sp.  gr.  is  2.2.  It  con- 
sists of 

Acid,  31.38     2  primes,     10.0         32.0 

Oxide,  32.32  1  do.  10.0  32.0 
Water,  36.30  10  do.  11.25  36.0 


10000  31.25     100.0 

A  mixed  solution  of  this  sulphate  and 
sal  ammoniac,  forms  an  ink,  whose  traces 
are  invisible  in  the  cold,  but  become  yellow 
when  heated;  and  vanish  again  as  the  paper 
cools. 


A  neutral  sulphate  of  copper  may  be 
formed  by  saturating  the  excess  of  acid 
with  oxide  of  copper.  It  crystallizes  in 
four-sided  pyramids,  separated  by  qua- 
drangular prisms. 

Mr.  Proust  formed  a  subsulphate  by  ad- 
ding a  little  pure  potash  to  a  solution  of 
the'last  salt.  A  green-coloured  precipitate 
falls. 

Protosulphite  of  copper  is  formed  by  pass- 
ing  a  current  of  sulphurous  acid  gas  through 
the  deutoxide  of  copper  diffused  in  water. 
It  is  deprived  of  a  part  of  its  oxygen,  and 
combines  with  the  acid.  The  sulphate,  si- 
multaneously produced,  dissolves  in  the 
water;  while  the  sulphite  forms  small  red 
crystals,  from  which  merely  long  ebulli- 
tion in  water  expels  the  acid. 

Sulphite  of  potash  and  copper  is  made  by 
adding  the  sulphite  of  potash  to  nitrate  of 
copper.  A  yellow  flocculent  precipitate, 
consisting  of  minute  crystals,  falls. 

Ammonia-sulphate  of  copper  is  the  salt 
formed  by  adding  water  of  ammonia  to 
solution  of  the  bisulphate.  It  consists,  ac- 
cording to  Berzelius,  of  1  prime  of  the 
cupreous,  and  1  of  the  ammoniacal  sul- 
phate, combined  together;  or  20.0  -f-  7.13 
-f-  14.625  of  water. 

Subsulphate  of  ammonia  and  copper  is 
formed  by  adding  alcohol  to  the  solution 
of  the  preceding  salt,  which  precipitates 
the  subsulphate.  It  is  the  cuprum  ammoni- 
acum  of  the  pharmacopoeia.  According  to 
Berzelius,  it  consists  of 

Acid,  32.25  or  nearly  2  primes, 

Deutox.  of  copper,  34.00  1     do. 

Ammonia,  26.40  4    do. 

Water,  7.35  2    do. 

100.00 

Sulphate  of  potash  and  copper  is  formed 
by  digesting  bisulphate  of  potash  on  the 
deutoxide  or  carbonate  of  copper.  Its 
crystals  are  greenish-coloured,  flat  paral- 
lelopipedons.  It  seems  to  consist  of  * 
primes  of  sulphate  of  potash  +  1  prime  of 
bisulphate  of  copper  +  12  of  water. 

The  following  acids,  antimonic,  anti- 
monious,  boracic,  chromic,  molybdic,  phos- 
phoric, tungstic,  form  insoluble  salts 
with  deutoxide  of  copper.  The  first  two 
are  green,  the  third  is  brown,  the  fourth 
and 'fifth  green,  and  the  sixth  white.  The 
benzoate  is  in  green  crystals,  sparingly  so- 
luble. The  oxalate  is  also  green.  The 
binoxalates  of  potash  and  soda,  with  ox- 
ide of  copper,  give  triple  salts,  in  green 
needle-form  crystals.  There  are  also  am- 
monia-oxalates  in  different  varieties.  Tar- 
trate  of  copper  forms  dark  bluish-green 
crystals.  Cream-tartrate  of  copper  is  a 
bluish-green  powder,  commonly  called 
Brunswick  Green. 

To  obtain  pure  copper  for  experiments, 


COP 


COP 


we  precipitate  it  in  the  metallic  state,  by 
immersing-  a  plate  of  iron  in  a  solution  of 
tlie  deutomuriate.  The  pulverulent  copper 
must  be  washed  with  dilute  muriatic  acid.* 

In  the  wet  way  Brunswick  or  Friezland 
green  is  prepared  by  pouring  a  saturated 
solution  of  muriate  of  ammonia  over  cop- 
per tilings  or  shreds  in  a  close  vessel,  keep- 
ing the  mixture  in  a  warm  place,  and  ad- 
ding more  of  the  solution  from  time  to 
time,  till  three  parts  of  muriate  and  two  of 
copper  have  been  used.  After  standing  a 
few  weeks,  the  pigment  is  to  be  separated 
from  the  unoxidized  copper,  by  washing 
through  a  sieve;  and  then  it  is  to  be  well 
Washed,  and  dried  slowly  in  the  shade. 
This  green  is  almost  always  adulterated 
wit!)  ceruse. 

This  metal  combines  very  readily  witli 
gold,  silver,  and  mercury.  It  unites  im- 
perfectly with  iron  in  the  way  of  fusion. 
Tin  combines  with  copper,  at  a  tempera- 
ture much  lower  than  is  necessary  to  fuse 
the  copper  alone.  On  this  is  grounded  the 
method  of  tinning  copper  vessels.  For  this 
purpose,  they  are  first  scraped  or  scoured; 
uf'ter  which  they  are  rubbed  with  sal  am- 
moniac. They  are  then  heated,  and  sprink- 
led with  powdered  resin,  which  defends 
the  clean  surface  of  the  copper  from  ac- 
quiring the  slight  film  of  oxide,  that  would 
prevent  the  adhesion  of  the  tin  to  its  sur- 
face. The  melted  tin  is  then  poured  in, 
and  spread  about.  An  extremely  small 
quantity  adheres  to  the  copper,  which  may 
perhaps  be  supposed  insufficient  to  prevent 
the  noxious  effects  of  the  copper,  as  per- 
fectly as  might  be  wished. 

"When  tin  is  melted  with  copper,  it  com- 
poses the  compound  called  bronze.  In  this 
metal  the  specific  gravity  is  always  greater 
than  would  be  deduced  by  computation 
from  the  quantities  and  specific  gravities 
of  its  component  parts.  The  uses  of  this 
hard,  sonorous,  and  durable  composition, 
in  the  fabrication  of  cannon,  bells,  statues, 
and  other  articles,  are  well  known.  Bronzes 
and  bell-metals  are  not  usually  made  of 
copper  and  tin  only,  but  have  other  admix- 
tures, consisting  of  lead,  zinc,  or  arsenic, 
according  to  the  motives  of  profit,  or  other 
inducements  of  the  artist.  But  the  atten- 
tion of  the  philosopher  is  more  particularly 
directed  to  the  mixture  of  copper  and  tin, 
on  account  of  its  being  the  substance  of 
which  the  speculums  of  reflecting  tele- 
scopes are  made.  See  SPECULUM.  The 
ancients  made  cutting  instruments  of  this 
alloy.  A  dagger  analyzed  by  Mr.  Hielm 
consisted  of  83-j  copper,  and  16£  tin. 

Copper  unites  with  bismuth,  and  forms  a 
reddish-white  alloy.  With  arsenic  it  forms 
a  white  brittle  compound,  called  tombac. 
"With  zinc  it  forms  the  compound  called 
brass,  and  distinguished  bv  various  other 
VOL.  I. 


names,  according  to  the  proportions  of  the 
two  ingredients.  It  is  not  easy  to  unite 
these  two  metals  in  considerable  propor- 
tions by  fusion,  because  the  zinc  is  burnt 
or  volatilized  at  a  heat  inferior  to  that 
which  is  required  to  melt  copper;  but  they 
unite  very  well  in  the  way  of  cementation. 
In  the  brass  works,  copper  is  granulated 
by  pouring  it  through  a  plate  of  iron,  per- 
forated with  small  holes  and  luted  with 
clay,  into  a  quantity  of  water  about  foul* 
feet  deep,  and  continually  renewed:  to  pre- 
vent the  dangerous  explosions  of  this  me- 
tal, it  is  necessary  to  pour  but  a  small  quan- 
tity at  a  time.  There  are  various  methods 
of  combining  this  granulated  copper,  or 
other  small  pieces  of  copper,  with  the  va- 
pour of  zinc.  Calamine,  which  is  an  ore 
of  zinc,  is  pounded,  calcined,  and  mixed 
with  the  divided  copper,  together  with  a 
portion  of  charcoal.  These  being  exposed 
to  the  heat  of  a  wind  furnace,  the  zinc  be- 
comes revived,  rises  in  vapour,  and  com- 
bines with  the  copper,  which  it  converts 
into  brass.  The  heat  must  be  continued 
for  a  greater  or  less  number  of  hours,  ac- 
cording to  the  thickness  of  the  pieces  of 
copper,  and  other  circumstances;  and  at 
the  end  of  the  process,  the  heat  being  sud- 
denly raised,  causes  the  brass  to  melt,  and 
occupy  the  lower  part  of  the  crucible.  The 
most  scientific  method  of  making  brass 
seems  to  be  that  mentioned  by  Cramer. 
The  powdered  calamine,  being  mixed  with 
an  equal  quantity  of  charcoal  and  a  portion, 
of  clay,  is  to  be  rammed  into  a  melting  ves- 
sel, and  a  quantity  of  copper,  amounting  to 
two-thirds  of  the  weight  of  calamine,  must 
be  placed  on  the  top,  and  covered  with  char- 
coal. By  this  management  the  volatile  zinc 
ascends,  and  converts  the  copper  into  brass, 
which  flows  into  the  rammed  clay;  conse- 
quently, if  the  calamine  contain  lead,  or  any 
other  metal,  it  will  not  enter  into  the  brass, 
the  zinc  alone  being  raised  by  the  heat. 

A  fine  kind  of  brass,  which  is  supposed 
to  be  made  by  cementation  of  copper  plates 
with  calamine,  is  hammered  out  into  leaves 
in  Germany;  and  is  sold  very  cheap  in  this 
country,  under  the  name  of  Dutch  gold,  or 
Dutch  metal.  It  is  about  five  times  as  thick 
as  gold  leaf;  that  is  to  say,  it  is  about  one 
sixty-thousandth  of  an  inch  thick. 

Copper  unites  readily  with  antimony,  and 
affords  a  compound  of  a  beautiful  violet 
colour.  It  does  not  readily  unite  with  man- 
ganese. "With  tungsten  it  forms  a  dark 
brown  spongy  alloy,  which  is  somewhat 
ductile.  Seen  ORES  or  COPPER. 

*  Verdigris,  and  other  preparations  of 
copper,  act  as  virulent  poisons,  when  intro- 
duced in  very  small  quantities  into  the  sto- 
machs of  animals.  A  few  grains  are  suf- 
ficient for  this  effect.  Death  is  commonly 
preceded  "by  very  decided  nervous  disgr- 
43 


COR 


ders,  such  as  convulsive  movements,  te- 
tanus, general  insensibility,  or  a  palsy  of 
the  lower  extremites.  This  event  happens 
frequently  so  soon,  that  it  could  not  be  oc- 
casioned by  inflammation  or  erosion  of  the 
primes  vice;  and  indeed,  where  these  parts 
are  apparently  sound.  It  is  probable  that 
the  poison  is  absorbed,  and  through  the 
circulation,  acts  on  the  brain  and  nerves. 
The  cupreous  preparations  are  no  doubt 
very  acrid,  and  if  death  do  not  follow  yieir 
immediate  impression  on  the  sentient  sys- 
tem, they  will  certainly  inflame  the  intes- 
tinal canal.  The  symptoms  produced  by 
a  dangerous  dose  of  copper  are  exactly 
similar  to  those  which  are  enumerated  un- 
der arsenic,  only  the  taste  of  copper  is 
strongly  felt.  The  only  chemical  antidote 
to  cupreous  solutions  whose  operation  is 
well  understood,  is  water  strongly  impreg- 
nated with  sulphuretted  hydrogen.  The 
alkaline  hydrosulphurets  are  acrid,  and 
ought  not  to  be  prescribed. 

But  we  possess  in  sugar,  an  antidote  to 
this  poison  of  undoubted  efficacy,  though 
its  mode  of  action  be  obscure.  M.  Duval 
introduced  into  the  stomach  of  a  dog,  by 
means  of  a  caoutchouc  tube,  a  solution  in 
acetic  acid,  of  four  French  drachms  of  ox- 
ide of  copper.  Some  minutes  afterwards 
he  injected  into  it  four  ounces  of  strong 
sirup.  He  repeated  this  injection  every 
half-hour,  and  employed  altogether  12 
ounces  of  sirup.  The  animal  experien- 
ced some  tremblings  and  convulsive  move- 
ments. But  the  last  injection  was  follow- 
ed by  a  perfect  calm.  The  animal  fell 
asleep,  and  awakened  free  from  any  ail- 
ment. 

Orfila  relates  several  cases  of  individuals 
who  had  by  accident  or  intention  swallow- 
ed poisonous  doses  of  acetate  of  copper, 
and  who  recovered  by  getting  large  doses 
of  sugar.  He  uniformly  found,  that  a  dose 
of  verdigris  which  would  kill  a  dog  in  the 
course  of  an  hour  or  two,  might  be  swal- 
lowed with  impunity,  provided  it  was  mix- 
ed with  a  considerable  quantity  of  sugar. 

As  alcohol  has  the  power  of  completely 
neutralizing,  in  the  ethers,  the  strongest 
muriatic  and  hydriodic  acids,  so  it  would 
appear,  that  sugar  can  neutralize  the  ox- 
ides of  copper  and  lead.  The  neutral  sac- 
charate  of  lead,  indeed,  was  employed  by 
Berzelius  in  his  experiments,  to  determine 
the  prime  equivalent  of  sugar.  If  we  boil 
for  half  an  hour,  in  a  flask,  an  ounce  of 
white  sugar,  an  ounce  of  water,  and  10 
grains  of  verdigris,  we  obtain  a  green  li- 
quid, which  is  not  affected  by  the  nicest 
tests  of  copper,  such  as  ferroprussiate  of 
potash,  ammonia,  and  the  hydrosulphurets. 
An  insoluble  green  carbonate  of  copper  re- 
mains at  the  bottom  of  the  flask.* 

COPPERAS.     Sulphate  of  iron. 

*  CORALS  seem  to  consist  of  carbonate 


of  lime  and  animal  matter,  in  equal  pro- 
portions.* 

CORK  is  the  bark  of  a  tree  of  the  oak 
kind,  very  common  in  Spain  and  the  other 
southern  parts  of  Europe. 

By  the  action  of  the  nitric  acid  it  was 
found  to  be  acidified.  See  ACID  (SUBE- 
RIC). 

*  Cork  has  been  recently  analyzed  by 
Chevreul  by  digestion,  first  in  water  and 
then  in  alcohol.  By  distillation  there  came 
over  an  aromatic  principle,  and  a  little  ace- 
tic acid.     The  watery  extract  contained  a 
yellow  and  a  red  colouring  matter,  an  un- 
determined acid,  gallic  acid,  an  astringent 
substance,  a  substance  containing  azote,  a 
substance  soluble  in  water  and  insoluble 
in  alcohol,  gallate  of  iron,  lime,  and  traces 
of  magnesia.     20  parts  of  cork  treated  in 
this  way,  left  17.15  of  insoluble  matter. 
The  undissolved  residue  being  treated  a 
sufficient  number  of  times  with  alcohol, 
yielded  a  variety  of  bodies,  but  which  seem 
reducible  to  three;  namely,  cerin,  resin,  and 
an  oil.     The  ligneous  portion  of  the  cork 
still    weighed    14  parts,  which  is    called 
suber.* 

CORK  (Fossil,).     See  ASBESTOS. 
CORROSIVE  SUBLIMATE.    See  MERCU- 
RY. 

*  CORUNDUM.     According  to  Professor 
Jameson,  this  mineral  genus  contains  3  spe- 
cies, viz.  octahedral  corundum,  rhomboidal 
corundum,  and  prismatic  corundum. 

1.  Octahedral,  is  subdivided  into  3  sub- 
species, viz.  automalite,  ceylanite,  and  spi- 
nel. 

2.  Rhomboidal  corundum,  contains  4  sub- 
species, viz.  salamstone,  sapphire,  emery, 
and  corundum,  or  adamantine  spar. 

3.  Prismatic,  or  chrysoberyl.     See  the 
several  sub-species,  under  their  titles  in 
the  Dictionary.* 

*  COTTON.  This  vegetable  fibre  is  solu- 
ble in  strong  alkaline  leys.  It  has  a  strong 
affinity  for  some  earths,  particularly  alu- 
mina, several  metallic  oxides,  and  tannin. 
Nitric  acid,  aided  by  heat,  converts  cotton 
into  oxalic  acid.* 

*  COUCH.     The  heap  of  moist  barley 
about  16  inches  deep  on  the  malt-floor.* 

*  CREAM.   The  oily  part  of  milk,  which 
rises  to  the  surface  of  that  liquid,  mixed 
with  a  little  curd  and  serum.  When  churn- 
ed, butter  is  obtained.    Heat  separates  the 
oily  part,  but  injures  its  flavour.* 

CREAM  OF  TARTAR.  See  ACID  (TAR- 
TARIC). 

*  CRICHTONITE.     A  mineral  so  called 
in  honour  of  Dr.  Crichton,  physician  to  the 
Emperor  of  Russia,  an  eminent  mineralo- 
gist. It  has  a  velvet-black  colour,  and  crys- 
tallizes  in  very  acute    small   rhomboids. 
Lustre    splendent,   inclining   to    metallic; 
fracture    conchoidal;     opaque;     scratches 
fluor  spar,  but  not  glass.    Infusible  before 


CRU 


CRY 


the  blow-pipe.  It  occurs  in  primitive  rocks 
along-  with  octahedrite.  Professor  Jame- 
son thinks  it  may  probably  be  a  new  spe- 
cies of  titanium-ore.* 

CROCUS.  The  yellow  or  saffron-colour- 
ed oxides  or  iron  and  copper  were  former- 
ly called  crocus  martis  and  crocus  veneris. 
That  of  iron  is  still  called  crocus  simply, 
by  the  workers  in  metal  who  use  it. 

*  CROSS-STONE.  Harmotome,  or  pyra- 
midal zeolite.  Its  colour  is  grayish-white, 
passing  into  smoke-gray,  sometimes  mas- 
sive, but  usually  crystallized.  Primitive 
form,  a  double  four-sided  pyramid,  of  121° 
58'  and  86°  36'.  Its  principal  secondary 
forms  are,  a  broad  rectangular  four-sided 
prism,  rather  acutely  acuminated  on  the 
extremities  with  4  planes,  which  are  set 
on  the  lateral  edges;  the  preceding  figure, 
in  which  the  edges  formed  by  the  meeting 
of  the  acuminating  planes,  that  rest  on  the 
broader  lateral  planes,  are  truncated;  twin 
crystals  of  the  first  form,  intersecting  each 
other,  in  such  a  manner  that  a  common  axis 
and  acumi nation  are  formed,  and  the  broad- 
er lateral  planes  make  four  re-entering  an- 
gles. The  crystals  are  not  large.  The 
surface  of  the  smaller  lateral  planes  is 
double-plumosely  streaked.  Lustre  glis- 
tening, between  vitreous  and  pearly.  Of 
the  cleavage,  2  folia  are  oblique,  and  1  pa- 
rallel to  the  axis.  Fracture  perfect  con- 
choidal.  Translucent  and  semi-transparent. 
Harder  than  fluor  spar,  but  not  so  hard  as 
apatite.  Easily  frangible.  Sp.  gr.  2.35.  It. 
fuses  with  intumescence  and  phosphores- 
cence, into  a  colourless  glass.  Its  consti- 
tuents are  49  silica,  16  alumina,  18  bary- 
tes,  and  15  water,  by  Klaproth.  It  has 
hitherto  been  found  only  in  mineral  veins 
and  agate-balls.  It  occurs  at  Andreasberg 
in  the  Hartz,  at  Kongsberg  in  Norway,  at 
Oberstein,  Strontian  in  Argyllshire,  and 
also  near  Old  Kilpatrick  in  Scotland. 
Jameson* 

*  CROTON  ELEUTHERIA.      Cascarilla 
bark.  The  following  is  Trommsdorf's  ana- 
lysis of  this  substance,  characterized  by 
its  emitting  the  smell  of  musk  when  burn- 
ed.     Mucilage  and  bitter  principle    864 
parts,  resin  688,  volatile  matter  72,  water 
48,  woody  fibres  3024;  in  4696  parts.* 

*  CRUSTS,  the  bony  coverings  of  crabs, 
lobsters,  &c.     Mr.  Hatchett  found  them  to 
be  composed  of  a  cartilaginous  substance, 
like  coagulated  albumen,  carbonate  of  lime, 
and  phosphate  of  lime.     The  great  excess 
of  the  second,  above  the  third  ingredient, 
distinguishes  them  from  bones;  while  the 
quantity  of  the  third,  distinguishes  them 
from  shells.     Egg-shells    and   snail-shells 
belong  to  crusts  in  composition;  but  the 
animal  matter  is  in  smaller  quantity.     By 
Merat-Guillot,  100  parts  of  lobster  crust, 
consist  of  60  carbonate  of  lime,  14  phos- 
phate of  lime,  and  26  cartilaginous  matter. 


100  of  hen's  egg-shells,  consist  of  89.6  car- 
bonate of  lime,  5.7  phosphate  of  lime,  4.7 
animal  matter.* 

*  CRYOLITE.  A  mineral  which  occurs 
massive,  disseminated,  and  in  thick  lamel- 
lar concretions.  Its  colours  are  white  and 
yellowish-brown.  Lustre  vitreous,  inclin- 
ing to  pearly.  Cleavage  fourfold,  in  which 
the  folia  are  parallel  with  an  equiangular 
four-sided  pyramid.  Fracture  uneven. 
Translucent.  Harder  than  gypsum.  Easily 
frangible.  Sp.  gr.  2.95.  It  becomes  more 
translucent  in  water.  It  melts  in  the  heat 
of  a  candle.  Before  the  blow -pipe,  it  be- 
comes first  very  liquid,  and  then  assumes 
a  slaggy  appearance.  It  consists,  by  Klap- 
roth, of  24  alumina,  36  soda,  and  40  fluoric 
acid  and  water.  It  is  therefore  a  soda- 
fluate  of  alumina.  If  we  regard  it  as  com- 
posed of  definite  proportions,  we  may 
have 

1  prime  alumina,  3.2  26.33 

1  do.       soda,         3.95  32.51 

2  do.       acid,         2.75  22.6 
2  do.       water,      2.25  18.5 

12.15  100.00 

Vauquelin's  analysis  of  the  same  miner- 
al gives  47  acid  and  water,  32  soda,  and  21 
alumina.  This  curious  and  rare  mineral  has 
hitherto  been  found  only  in  West  Green- 
land, at  the  arm  of  the  sea  named  Arksut, 
30  leagues  from  the  colony  of  Juliana  Hope. 
It  occurs  in  gneiss.  Mr.  Allan  of  Edin- 
burgh had  the  merit  of  recognizing  a  large 
quantity  of  this  mineral,  in  a  neglected 
heap  brought  into  Leith,  from  a  captured 
Danish  vessel.  It  had  been  collected  in 
Greenland  by  that  indefatigable  mineralo- 
gist M.  Gieseke.* 

*  CRYOPHORUS.  The  frost-bearer  or 
carrier  of  cold,  an  elegant  instrument  in- 
vented by  Dr.  Wollaston,  to  demonstrate 
the  relation  between  evaporation  at  low 
temperatures,  and  the  production  of  cold. 
If  32  grains  of  water,  says  this  profound 
philosopher,  were  taken  at  the  tempera- 
ture of  62°,  and  if  one  grain  of  this  were 
converted  into  vapour  by  absorbing  960°, 

960° 

then  the  whole  quantity  would  lose 

32 

=  30°,  and  thus  be  reduced  to  the  tem- 
perature of  32°.  If  from  the  31  grains 
which  still  remain  in  the  state  of  water, 
four  grains  more  were  converted  into  va- 
pour by  absorbing  960°,  then  the  remain, 
ing  27  grains  must  have  lost  ^y  of  960* 
=  142°,  which  is  rather  more  than  suffi- 
cient to  convert  the  whole  into  ice.  In  an 
experiment  conducted  upon  a  small  scale, 
the  proportional  quantity  evaporated  did 
not  differ  much  from  this  estimate. 

If  it  be  also  true  that  water,  in  assuming" 
the  gaseous  state,  even  at  a  low  tempera 
ture,  expands  to  1800  times  its  former  bulk* 


CRY 


CRY 


then  in  attempting  to  freeze  the  small 
quantity  of  water  above  mentioned,  it 
would  be  requisite  to  have  a  dry  vacuum 
with  the  capacity  of  5X1800=9000  grains 
of  water.  But  let  a  glass  tube  be  taken, 
having  its  internal  diameter  about  one- 
eighth  of  an  inch,  with  a  ball  at  each  ex- 
tremity of  about  one  inch  diameter,  and 
let  the  tube  be  bent  to  a  right  angle  at  the 
distance  of  half  an  inch  from  each  ball. 
One  of  these  balls  should  be  somewhat  less 
than  half  full  of  water,  and  the  remaining 
cavity  should  be  as  perfect  a  vacuum  as 
can  readily  be  obtained;  which  is  effected 
by  making  the  water  boil  briskly  in  the 
one  ball,  before  sealing  up  the  capillary 
opening  left  in  the  other.  If  the  empty 
ball  be  immersed  in  a  freezing  mixture  of 
snow  and  salt,  the  water  in  the  other  ball, 
though  at  the  distance  of  two  or  three  feet, 
will  be  frozen  solid  in  the  course  of  a  very 
few  minutes.  The  vapour  contained  in  the 
empty  ball  is  condensed  by  the  common 
operation  of  cold,  and  the  vacuum  produ- 
ced by  this  condensation  gives  opportunity 
for  a  fresh  quantity  to  arise  from  the  oppo- 
site ball,  with  proportional  reduction  of  its 
temperature.* 

*  CRYSTAL.  When  fluid  substances  are 
suffered  to  pass  with  adequate  slowness  to 
the  solid  state,  the  attractive  forces  fre- 
quently arrange  their  ultimate  particles,  so 
as  to  form  regular  polyhedral  figures,  or 
geometrical  solids,  to  which  the  name  of 
crystals  has  been  given.  Most  of  the  so- 
lids which  compose  the  mineral  crust  of 
the  earth,  are  found  in  the  crystallized 
state.  Thus  granite  consists  of  crystals  of 
quartz,  feldspar,  and  mica.  Even  moun- 
tain masses  like  clay-slate,  have  a  regular 
tabulated  form.  Perfect  mobility  among 
the  corpuscles  is  essential  to  crystalliza- 
tion. The  chemist  produces  it  either  by 
igneous  fusion,  or  by  solution  in  a  liquid. 
When  the  temperature  is  slowly  lowered 
in  the  former  case,  or  the  liquid  slowly  ab- 
stracted by  evaporation  in  the  latter,  the 
attractive  forces  resume  the  ascendancy, 
and  arrange  the  particles  in  symmetrical 
forms.  Mere  approximation  of  the  parti- 
cles, however,  is  not  alone  sufficient  for 
crystallization.  A  hot  saturated  saline  so- 
lution, when  screened,  from  all  agitation, 
will  contract  by  cooling  into  a  volume 
much  smaller,  tliMi  what  it  occupies  in  the 
solid  state,  without  crystallizing.  Hence 
the  molecules  must  not  only  be  brought 
within  a  certain  limit  of  each  other,  for 
their  concreting  into  crystals;  but  they 
must  also  change  the  direction  of  their 
poles,  from  the  fluid  collocation,  to  their 
position  in  the  solid  state. 

This  re\ersion  of  the  poles  may  be  ef- 
fected, 1st,  By  contact  of  any  part  of  the 
fluid,  with  a  point  of  a  solid,  of  similar 
composition  previously  formed.  2il,  Vi- 


bratory motions,  communicated  either  from 
the  atmosphere,  or  any  other  moving  body, 
by  deranging,  however  slightly,  the  fluid 
polar  direction,  will  instantly  determine 
the  solid  polar  arrangement,  when  the  bal- 
ance had  been  rendered  nearly  even,  by 
previous  removal  of  the  interstitial  fluid. 
On  this  principle  we  explain  the  regular 
figures  which  particles  of  dust  or  iron  as- 
sume, when  they  are  placed  on  a  vibrating 
plane,  in  the  neighbourhood  of  electrized 
or  magnetized  bodies.  3d,  Negative  or 
resinous  voltaic  electricity  instantly  deter- 
mines the  crystalline  arrangement,  while 
positive  voltaic  electricity  counteracts  it. 
On  this  subject,  I  beg  to  refer  the  reader 
to  an  experimental  paper,  which  I  publish- 
ed in  the  fourth  volume  of  the  Journal  of 
Science,  p.  106.  Light  also  favours  crys- 
tallization, as  is  exemplified  with  camphor 
dissolved  in  spirits,  which  crystallizes  in 
bright,  and  re -dissolves  in  gloomy  weather. 

It  might  be  imagined,  that  the  same  bo- 
dy would  always  concrete  in  the  same,  or 
at  least  in  a  similar  crystalline  form.  This 
position  is  true,  in  general,  for  the  salts 
crystallized  in  the  laboratory;  and  on  this 
uniformity  of  figure,  one  of  the  principal 
criteria  between  different  salts  depends. 
But  even  these  forms  are  liable  to  many 
modifications,  from  causes  apparently 
slight;  and  in  nature,  we  find  frequently 
the  same  chemical  substance,  crystallized 
in  forms  apparently  very  dissimilar.  Thus, 
•carbonate  of  lime  assumes  the  form  of  a 
rhomboid,  of  a  regular  hexahedral  prism, 
of  a  solid  terminated  by  12  scalene  trian- 
gles, or  of  a  dodecahedron  with  pentago- 
nal faces,  &c.  Bisulphuret  of  iron  or  mar- 
tial pyrites  produces  sometimes  cubes  and 
sometimes  regular  octohedrons,  at  one 
time  dodecahedrons  with  pentagonal  faces, 
at  another  icosahedrons  with  triangular 
faces,  &c. 

While  one  and  the  same  substance  lends 
itself  to  so  many  transformations,  we  meet 
with  very  different  substances,  which  pre- 
sent absolutely  the  same  form.  Thus 
fluate  of  lime,  muriate  of  soda,  sulphurer. 
of  iron,  sulphuret  of  lead,  &c.  crystallize 
in  cubes,  under  certain  circumstances;  and 
in  other  cases,  the  same  minerals,  as  well 
as  sulphate  of  alumina  and  the  diamond, 
assume  the  form  of  a  regular  octohedron. 

Rome  de  1'Isle  first  referred  the  study 
of  crystallization,  to  principles  conforma- 
ble to  observation.  He  arranged  together, 
as  far  as  possible,  crystals  of  the  same  na- 
ture. Among  the  different  forms  relative 
to  each  species,  he  chose  one  as  the  most 
proper,  from  its  simplicity,  to  be  regarded 
as  the  primitive  form;  and  by  supposing  it 
truncated  in  different  ways,  he  deduced 
the  other  forms  from  it,  and  determined  a 
gradation,  a  series  of  transitions  between 
this  same  form,  and  that  of  polyhedrons, 


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CRY 


which  seemed  to  be  still  further  removed 
from  it.  To  the  descriptions  and  figures 
which  he  gave  of  the  crystalline  forms,  he 
added  the  results  of  the  mechanical  mea- 
surement of  their  principal  angles,  and 
showed  that  these  angles  were  constant  in 
each  variety. 

The  illustrious  Bergmann,  by  endeavour- 
ing to  penetrate  to  the  mechanism  of  the 
structure  of  crystals,  considered  the  differ- 
ent forms  relative  to  one  and  the  same  sub- 
stance, as  produced  by  a  superposition  of 
planes,  sometimes  constant  and  sometimes 
variable,  and  decreasing  around  one  and 
the  same  primitive  form.  He  applied  this 
primary  idea  to  a  small  number  of  crystal- 
line forms,  and  verified  it  with  respect  to 
a  variety  of  calcareous  spar$  by  fractures, 
which  enabled  him  to  ascertain  the  posi- 
tion of  the  nucleus,  or  of  the  primitive 
form,  and  the  successive  order  of  the  la- 
minze  covering  this  nucleus.  Bergmann, 
however,  stopped  here,  and  did  not  trou- 
ble himself  either  with  determining  the 
laws  of  structure,  or  applying  calculation 
to  it.  It  was  a  simple  sketch,  of  the  most 
prominent  point  of  view  in  mineralogy,  but 
in  which  we  see  the  hand  of  the  same  mas- 
ter who  so  successfully  filled  up  the  out- 
lines of  chemistry. 

In  the  researches  which  M.  Haiiy  under- 
took, about  the  same  period,  on  the  struc- 
ture of  crystals,  he  proposed  combining 
the  form  and  dimensions  of  integrant  mo- 
lecules with  simple  and  regular  laws  of  ar- 
rangement, and  submitting  these  laws  to 
calculation.  This  work  produced  a  ma- 
thematical theory,  which  he  reduced  to 
analytical  formulae,  representing  every  pos- 
sible case,  and  the  application  of  which  to 
known  forms  leads  to  valuations  of  angles, 
constantly  agreeing  with  observation. 

Theory  of  the  structure  of  Crystals. 

Primitive  forms. — The  idea  of  referring 
to  one  of  the  same  primitive  forms,  all  the 
forms  which  may  be  assumed  by  a  mineral 
substance,  of  which  the  rest  may  be  re- 
garded as  being  modifications  only,  has 
frequently  suggested  itself  to  various  phi- 
losophers, who  have  made  crystallography 
their  study* 

The  mechanical  division  of  minerals, 
which  is  the  only  method  of  ascertaining 
their  true  primitive  form,  proves  that  this 
form  is  invariable  while  we  operate  upon  the 
same  substance,  however  diversified  or  dis- 
similar the  forms  of  the  crystals  belonging 
to  this  substance  may  be.  Two  or  three 
examples  will  serve  to  place  this  truth  in 
its  proper  light. 

Take  a  regular  hexahedral  prism  of  car- 
bonate of  lime  (PI.  XIII.  figs  1  and  2). 

§  This  is  what  has  been  called  dent  de 
tochon,  but  which  M.  Haiiy  calls  metastatic. 


If  we  try  to  divide  it  parallel  to  the  edges, 
from  the  contours  of  the  bases,  we  shall 
find,  that  three  of  these  edges  taken  alter- 
nately in  the  upper  part,  for  instance,  the 
edges  If,  c  d,  b  m,  may  be  referred  to  this 
division:  and  in  order  to  succeed  in  the 
same  way  with  respect  to  the  inferior  base, 
we  must  chuse.not  the  edges  l'j', c'  d' b'  mt 
which  correspond  with  the  preceding-,  but 
the  intermediate  edges  <?  f,  b'  c',  /  m'. 

The  six  sections  will  uncover  an  equal 
number  of  trapeziums.  Three  of  the  lat- 
ter are  represented  upon  fig.  2.  viz.  the 
two  which  intercept  the  edges  //,  c  d,  and 
are  designated  by  p  p  o  o,  a  a  k  k,  and  that 
which  intercepts  the  lower  edge  d'  /',  and 
which  is  marked  by  the  letters  n  n  i  i, 

Each  of  these  trapeziums  will  have  a 
lustre  and  polish,  from  which  we  may 
easily  ascertain,  that  it  coincides  with  one 
of  the  natural  joints  of  which  the  prism  is 
the  assemblage.  We  shall  attempt  in  vain 
to  divide  the  prism  in  any  other  direction. 
But  if  we  continue  the  division  parallel  to 
the  first  sections,  it  will  happen  that  on  one 
hand  the  surfaces  of  the  bases  will  always 
become  narrower,  while  on  the  other  hand, 
the  altitudes  of  the  lateral  planes  will  de- 
crease; and  at  the  term  at  which  the  bases 
have  disappeared,  the  prism  will  be  chang- 
ed into  a  dodecahedron  (fig.  3.),  with  pen- 
tagonal faces,  six  of  which,  such  as  o  o  i  O 
e,  o  I  k  i  it  &c.  will  be  the  residues  of  the 
planes  of  the  prism;  and  the  six  others 
E  A  I  o  o,  O  A/  K  2  z,  &c.  will  be  the  imme- 
diate result  of  the  mechanical  division. 

Beyond  this  same  term, the  extreme  faces 
will  preserve  their  figure  and  dimensions, 
while  the  lateral  faces  will  incessantly  di- 
minish in  height,  until  the  points  o,  k,  of 
the  pentagon  o  1  k  i  i,  coming  to  be  con- 
founded with  the  points  z,  i,  and  so  on  with 
the  other  points  similarly  situated,  each 
pentagon  will  be  reduced  to  a  simple  tri- 
angle, as  we  see  in  fig.  4.§ 

Lastly,  when  new  sections  have  oblitera- 
ted these  triangles,  so  that  no  vestige  of 
the  surface  of  the  prism  remains  (fig.  1.), 
we  shall  have  the  nucleus  or  the  primitive 
form,  which  will  be  an  obtuse  rhomboid 
(fig.  5.),  the  grand  angle  of  which  E  A  I  or 
E  O  I,  is  10i°  32'  lo"  * 

§  The  points  which  are  confounded,  two 
and  two,  upon  this  figure,  are  each  marked 
with  the  two  letters  which  served  to  desig- 
nate them  when  they  were  separated,  as  in 
fig.  3. 

$  It  is  observed,  that  each  trapezium, 
such  as  p  f>  o  o  (fig.  2.)  uncovered  by  the 
first  sections,  is  very  sensibly  inclined  from 
the  same  quantity,  as  well  upon  the  resi- 
due p  p  d  e  b  m  of  the  base,  as  upon  the 
residue  o  o  Jr  lr  of  the  adjacent  plane.  Set- 
ting out  from  this  equality  of  inclinations, 
we  deduce  from  it,  by  calculation,  the  va- 


CRY 


CRY 


If  we  try  to  divide  a  crystal  of  another 
species,  we  shall  have  a  different  nucleus. 
For  instance,  a  cube  of  fluate  of  lime  will 
give  a  regular  octohedron,  which  we  suc- 
ceed in  extracting-  by  dividing'  the  cube 
upon  its  eight  solid  angles,  which  will  in 
the  first  place  discover  eight  equilateral 
triangles,  and  we  may  pursue  the  division, 
always  parallel  to  the  first  sections,  until 
nothing  more  remains  of  the  faces  of  the 
cube.  The  nucleus  of  the  crystals  of'0 sul- 
phate of  barytes  will  be  a  straight  prism 
with  rhombous  bases;  that  of  the  crystals 
of  phosphate  of  lime,  a  regular  hexahedral 
prism?  that  of  sulphuretted  lead,  a  cube, 
&c.;  and  each  of  these  forms  will  be  con- 
stant relative  to  the  entire  species,  in  such 
a  manner,  that  its  angles  will  not  undergo 
any  appreciable  variation. 

Having  adopted  the  word  primitive  form 
in  order  to  designate  the  nucleus  of  crys- 
tals, M.  Haiiy  calls  secondary  forms,  such 
varieties  as  differ  from  the  primitive  form. 
In  certain  species,  crystallization  also 
produces  this  last  form  immediately. 

We  may  define  the  primitive  form,  a  so- 
lid of  a  constant  form,  engaged  symmetri- 
cally in  all  the  crystals  of  one  and  the  same 
species,  and  the  faces  of  which  follow  the 
directions  of  the  laminae  which  form  these 
crystals. 

The  primitive  forms  hitherto  observed, 
are  reduced  to  six,  viz.  the  parallelopipe- 
don,  the  octohedron,  the  tetrahedron,  the 
regular  hexahedral  prism,  the  dodecahe- 
dron with  rhombous  planes,  all  equal  and 
similar,  and  the  dodecahedron  with  trian- 
gular planes,  composed  of  two  straight  py- 
ramids joined  base  to  base. 

Forms  of  integrant  Molecules. — The  nu- 
cleus of  a  crystal  is  not  the  last  term  of 
of  its  mechanical  division.  It  may  always 
be  subdivided  parallel  to  its  different  faces, 
and  sometimes  in  other  directions  also. 
The  whole  of  the  surrounding  substance 
is  capable  of  being  divided  by  strokes  pa- 
rallel to  those  which  take  place  with  re- 
spect to  the  primitive  form. 

If  the  nucleus  be  a  parallelopipedon, 
which  cannot  be  subdivided  except  by 
blows  parallel  to  its  faces,  like  that  which 
takes  place  with  respect  to  carbonated 
lime,  it  is  evident  that  the  integrant  mole- 
cule will  be  similar  to  this  nucleus  itself. 

But  it  may  happen  that  the  parallelopipe- 
don admits  of  further  sections  in  other  di- 
rections than  the  former. 

We  may  reduce  the  forms  of  the  inte- 
grant molecules  of  all  crystals  to  three, 
which  are,  the  tetrahedron,  or  the  simplest 
of  the  pyramids;  the  triangular  prism,  or 
the  simplest  of  all  the  prisms;  and  the  pa- 

lue  of  the  angles  with  the  precision  of  mi- 
nutes and  seconds,  which  mechanical  mea- 
surements are  not  capable  of  attaining. 


rallelopipedon,  or  the  simplest  among  the 
solids,  which  have  their  faces  parallel  two 
and  two.  And  since  four  planes  at  least 
are  necessary  for  circumscribing  a  space, 
it  is  evident  that  the  three  forms  in  ques- 
tion, in  which  the  number  of  faces  is  suc- 
cessively four, five,  and  six, have  still,  in  this 
respect,  the  greatest  possible  simplicity. 

Laws  to  -which  the  Structure  is  subjected. 
— After  having  determined  the  primitive 
forms,  and  those  of  the  integrant  molecules, 
it  remains  to  inquire  into  the  laws  pursued 
by  these  molecules  in  their  arrangement,  in 
order  to  produce  these  regular  kinds  of 
envelopes,  which  disguise  one  and  the  same 
primitive  form  in  so  many  different  ways. 

Now,  observation  shows,  that  this  sur- 
rounding matter  is  an  assemblage  of  lami- 
nae, which,  setting  out  from  the  primitive 
form,  decrease  in  extent,  both  on  all  sides 
at  once,  and  sometimes  in  certain  particu- 
lar parts  only.  This  decrement  i  effected 
by  regular  subtractions  of  one  jr  more 
rows  of  integrant  molecules;  and  the  the- 
ory, in  determining  the  number  of  these 
rows  by  means  of  calculation,  succeeds  in 
representing  all  the  known  results  of  crys- 
tallization, and  even  anticipates  future  dis- 
coveries, indicating  forms  which,  being  still 
hypothetical  only,  may  one  day  be  present- 
ed to  the  inquiries  of  the  philosopher. 

Decrements  on  the  Edges. — Let  s  sf  (fig. 
6.  PI.  XIII.)  be  a  dodecahedron  with  rhom- 
bic planes.  This  solid,  which  is  one  of  the 
six  primitive  forms  of  crystals,  also  pre- 
sents itself  occasionally  as  a  secondary 
form,  and  in  this  case  it  has  as  a  nucleus, 
sometimes  a  cube,  and  sometimes  an  octo- 
hedron. Supposing  the  nucleus  to  be  a 
cube: — 

In  order  to  extract  this  nucleus,  it  is 
sufficient  successively  to  remove  the  six 
solid  angles  composed  of  four  planes,  such 
as  «,  r,  t,  &c.  by  sections  adapted  to  the 
direction  of  the  small  diagonals.  These 
sections  will  display  as  many  squares  A  E 
O  I,  E  O  O'  E', 1  O  O'  i'  (fig.  7.),  &c.  which 
will  be  the  faces  of  the  cube. 

Let  us  conceive  that  each  of  these  faces 
is  subjected  to  a  series  of  decreasing  la- 
minae solely  composed  of  cubic  molecules, 
and  that  every  one  of  these  laminae  exceeds 
the  succeeding  one,  towards  its  four  edges, 
by  a  quantity  equal  to  one  course  of  these 
same  molecules.  Afterwards  we  shall  de- 
signate the  decreasing  laminae  which  enve- 
lope the  mucleus,  by  the  name  of  lamina 
of  superposition.  Now,  it  is  easy  to  con- 
ceive that  the  different  series  will  produce 
six  quadrangular  pyramids,  similar  in  some 
respects  to  the  quadrangular  steps  of  a  co- 
lumn, which  will  rest  on  the  faces  of  the 
cube.  Three  of  these  pyramids  are  repre- 
sented in  fig.  8.  and  have  their  summits  in 
s,  tt  r'. 
Now,  as  there  are  six  quadrangular  py- 


CRY 


CRY 


ramids,  we  shall  therefore  have  twenty -four 
triangles;  such  as  O  «  I,  O  *  I,  &c.  But 
because  the  decrement  is  uniform  from  s 
to  ty  and  so  on  with  the  rest;  the  triangles 
taken  two  and  two  are  on  a  level,  and  form 
a  rhomb  s  O  1 1.  The  surface  of  the  solid 
will  therefore  be  composed  of  twelve  equal 
and  similar  rhombs;  i.  e.  this  solid  will 
have  the  same  form  with  that  which  is  the 
subject  of  the  problem.  This  structure 
takes  place,  although  imperfectly,  with  re- 
spect to  the  crystals  called  boracic  spars. 

The  dodecahedron  now  under  conside- 
ration, is  represented  by  fig.  8.  in  such  a 
way  that  the  progress  of  the  decrement 
may  be  perceived  by  the  eye.  On  examin- 
ing the  figure  attentively,  we  shall  find 
that  it  has  been  traced  on  the  supposition, 
that  the  cubic  nucleus  has  on  each  of  its 
edges  17  ridges  of  molecules;  whence  it 
follows,  that  each  of  its  faces  is  composed 
of  289  facets  of  molecules,  and  that  the 
whole  solid  is  equal  to  4913  molecules.  On 
this  hypothesis,  there  are  eight  laminae  of 
superposition,  the  last  of  which  is  reduced 
to  a  simple  cube,  whose  edges  determine 
the  numbers  of  molecules  which  form  the 
series  15, 13,  11,  9,  7,  5,  3,  1,  the  differ- 
ence being  2,  because  there  is  one  course 
subtracted  from  each  extremity. 

Now,  if  instead  of  this  coarse  kind  of 
masonry,  which  lias  the  advantage  of  speak- 
ing to  the  eye,  we  substitute  in  our  ima- 
gination the  infinitely  delicate  architecture 
of  nature,  we  must  conceive  the  nucleus 
as  being  composed  of  an  incomparably 
greater  number  of  imperceptible  cubes. 
In  this  case,  the  number  of  laminae  of  su- 
perposition will  also  be  beyond  comparison 
greater  than  on  the  preceding  hypothesis. 
By  a  necessary  consequence,  the  furrows 
which  form  these  laminae  by  the  alternate 
projecting  and  re-entering  of  their  edges, 
will  not  be  cognizable  by  our  senses;  and 
this  is  what  takes  place  in  the  polyhedra 
which  crystallization  has  produced  at  lei- 
sure, without  being  disturbed  in  its  pro- 
gress. 

M.  Huiiy  calls  decrements  in  breadth,  those 
in  which  each  lamina  has  only  the  height 
of  a  molecule,  so  that  their  whole  effect, 
by  one,  two,  three,  Sec.  courses,  is  in  the 
way  of  breadth.  Decrements  in  height  are 
those  in  which  each  lamina,  exceeding 
only  the  following  one  by  a  single  course 
in  the  direction  of  the  breadth,  may  have 
a  height  double,  triple,  quadruple,  Stc.  to 
that  of  a  molecule:  this  is  expressed  by 
saying  that  the  decrement  takes  place  by 
two  courses,  three  courses,  &c.  in  height. 

We  are  indebted  to  Dr.  Wollaston  for 
ideas  on  the  ultimate  cause  of  crystalline 
forms,  equally  ingenious  and  profound. 
They  were  communicated  to  the  Royal  So- 
ciety, and  published  in  their  transactions 
for  the  year  1813, 


Among  the  known  forms  of  crystallized 
bodies,  there  is  no  one  common  to  a  greater 
number  of  substances  than  the  regular  oc- 
tohedron,  and  no  one  in  which  a  corres- 
ponding difficulty  has  occurred  wi  h  re- 
gard to  determining  which  modification  of 
its  form  is  to  be  considered  as  primitive; 
since  in  all  these  substances  the  tetrahe- 
dron appears  to  have  equal  claim  to  be  re- 
ceived as  the  original  from  which  all  their 
other  modifications  are  to  be  derived. 

The  relation  of  these  solids  to  each  other 
is  most  distinctly  exhibited  to  those  who 
are  not  much  conversant  with  crystallo- 
graphy, by  assuming  the  tetrahedron  as 
primitive,  for  this  may  immediately  be 
converted  into  an  octohedron  by  the  re- 
moval of  four  smaller  tetrahedrons  from 
its  solid  angles.  (Plate  XIV.  fig.  1.) 

The  substance  which  most  readily  admits 
of  division  by  fracture  into  these  forms,  is 
fluor  spar;  and  there  is  no  difficulty  in  ob- 
taining a  sufficient  quantity  for  such  expe- 
riments. But  it  is  not,  in  fact,  either  the 
tetrahedron  or  the  octohedron,  which  first 
presents  itself  as  the  apparent  primitive 
form  obtained  by  fracture. 

If  we  form  a  plate  of  uniform  thickness 
by  two  successive  divisions  of  the  spar,  pa- 
rallel to  each  other,  we  shall  find  the  plate 
divisible  into  prismatic  rods,  the  section  of 
which  is  a  rhomb  of  70°  32'  and  109°  28' 
nearly;  and  if  we  again  split  these  rods 
transversely,  we  shall  obtain  a  number  of 
regular  acute  rhomboids,  all  similar  to 
each  other,  having  their  superficial  angles 
60°  and  120°  and  presenting  an  appearance 
of  primitive  molecule,  from  which  all  the 
other  modifications  of  such  crystals  might 
very  simply  be  derived.  And  we  find, 
moreover,  that  the  whole  mass  of  fiuor 
might  be  divided  into,  and  conceived  to 
consist  of,  these  acute  rhomboids  alone, 
which  may  be  put  together  so  as  to  fit  each 
other  without  any  intervening  vacuity. 

But,  since  the  solid  thus  obtained  (as  re- 
presented fig.  2.)  may  be  again  split  by  na- 
tural fractures  at  right  angles  to  its  axis 
(fig.  3.),  so  that  a  regular  tetrahedron  may 
be  detached  from  each  extremity,  while  the 
remaining  portion  assumes  the  form  of  a 
regular  octohedron;  and  since  every  rhom- 
boid that  can  be  obtained,  must  admit  of 
the  same  division  into  one  octohedron  and 
two* tetrahedrons,  the  rhomboid  can  no 
longer  be  regarded  as  the  primitive  form; 
and  since  the  parts  into  which  it  is  divi- 
sible are  dissimilar,  we  are  left  in  doubt 
which  of  them  is  to  have  precedence  as 
primitive. 

In  the  examination  of  this  question, 
whether  we  adopt  the  octohedron  or  the 
tetrahedron  as  the  primitive  form,  since 
neither  of  them  can  fill  space  without  leav- 
ing vacuities,  there  is  a  difficulty  in  con- 
ceiving any  arrangement  in  which  the  par- 


CRY 

tides  will  remain  at  rest:  for,  whether  we 
suppose,  with  the  Abbe  Haliy,  that  the  par- 
ticles are  tetrahedral  with  octohedral  cavi- 
ties, or,  on  the  contrary,  octohedral  parti- 
cles regularly  arranged  with  tetrahedral 
cavities,  in  each  case  the  mutual  contact 
of  adjacent  particles  is  only  at  their  edges; 
and,  although  in  such  an  arrangement  it 
must  be  admitted  that  there  may  be  an 
equilibrium,  it  is  evidently  unstable,  and 
ill  adapted  to  form  the  basis  of  any  per- 
manent crystal.  • 

With  respect  to  fluor  spar  and  such  other 
substances  as  assume  the  octohedral  and 
tetrahedral  forms,  all  difficulty  is  removed, 
says  Dr.  Wollaston,  by  supposing  the  ele- 
mentary particles  to  be  perfect  spheres, 
which,  by  mutual  attraction,  have  assum- 
ed that  arrangement  which  brings  them 
as  near  to  each  other  as  possible. 

The  relative  position  of  any  number  of 
equal  balls  in  the  same  plane,  when  gently 
pressed  together,  forming  equilateral  tri- 
angles with  each  other  (as  represented 
perspectively  in  fig.  4.),  is  familiar  to  every 
one;  and  it  is  evident  that,  if  balls  so  plac- 
ed were  cemented  together,  and  the  stra- 
tum thus  formed  were  afterwards  broken, 
the  straight  lines  in  which  they  would  be 
disposed  to  separate  would  form  angles  of 
60°  with  each  other. 

If  a  single  ball  were  placed  any  where  at 
rest  upon  the  preceding  stratum,  it  is  evi- 
dent that  it  would  be  in  contact  with  three 
of  the  lower  balls  (as  in  fig.  5.),  and  that 
the  lines  joining  the  centres  of  four  balls 
so  in  contact,  or  the  planes  touching  their 
surfaces,  would  include  a  regular  tetrahe- 
dron, having  all  its  equilateral  triangles. 

The  construction  of  an  octahedron,  by 
means  of  spheres  alone,  is  as  simple  as  that 
of  the  tetrahedron.  For,  if  four  balls  be 
placed  in  contact  on  the  same  plane,  in  form 
of  a  square,  then  a  single  ball  resting  upon 
them  in  the  centre,  being  in  contact  with 
each  pair  of  balls,  will  present  a  triangular 
face  rising  from  each  side  of  the  square, 
iind  the  whole  together  will  represent  the 
superior  apex  of  an  octohedron;  so  that  a 
sixth  ball  similarly  placed  underneath  the 
square  will  complete  the  octohedral  group, 
fig.  6. 

There  is  one  observation  with  regard  to 
these  forms  that  will  appear  paradoxical, 
namely  that  a  structure,  which,  in  this  case, 
was  begun  upon  a  square  foundation,  is 
really  intrinsically  the  same  as  that  which 
is  begun  upon  the  triangular  basis.  But  if 
we  lay  the  octohedral  group,  which  con- 
sists of  six  balls,  on  one  of  its  triangular 
sides,  and,  consequently,  with  an  opposite 
triangular  face  uppermost,  the  two  groups, 
consisting  of  three  balls  each,  are  then  si- 
tuated precisely  as  they  would  be  found  in 
two  adjacent  strata  of  the  triangular  ar- 
rangement. Hence,  in  this  position,  we 


CRY 

may  readily  convert  the  octohedron  into  a 
regular  tetrahedron,  by  addition  of  four 
more  balls  (fig.  ?.).  One  placed  on  the  top 
of  the  three  that  are  uppermost  forms  the 
apex;  and  if  the  triangular  base,  on  which 
it  rests,  be  enlarged  by  addition  of  three 
more  balls,  regularly  disposed  around  it, 
the  entire  group  of  ten  balls  will  then  be 
found  to  represent  a  regular  tetrahedron. 

For  the  purpose  of  representing  the 
acute  rhomboid,  two  balls  must  be  appli- 
ed at  opposite  sides  of  the  smallest  octo- 
hedral group,  as  in  fig.  9.  And  if  a  greater 
number  of  balls  be  placed  together,  fig. 
10.  and  11.  in  the  same  form,  then  a  com- 
plete tetrahedral  group  may  be  removed 
from  each  extremity,  leaving  a  central  oc- 
tohedron, as  may  be  seen  in  fig.  11.  which 
corresponds  to  fig.  3. 

We  have  seen,  that  by  due  application 
of  spheres  to  each  other,  all  the  most  sim- 
ple forms  of  one  species  of  crystal  will  be 
produced,  and  it  is  needless  to  pursue  any 
other  modifications  of  the  same  form, 
which  must  result  from  a  series  of  decre- 
ments produced  according  to  known  laws. 

Since  then  the  simplest  arrangement  of 
the  most  simple  solid  that  can  be  imagined, 
affords  so  complete  a  solution  of  one  of  the 
most  difficult  questions  in  crystallography, 
we  are  naturally  led  to  inquire  what  forms 
would  probably  occur  from  the  union  of 
othersolids  most  nearly  allied  to  the  sphere. 
And  it  will  appear  that  by  the  supposition 
of  elementary  particles  that  are  spheroidi- 
cal, we  may  frame  conjectures  as  to  the 
origin  of  other  angular  solids  well  known. 
to  crystallographers. 

The  obtuse  Rhomboid. 

If  we  suppose  the  axis  of  our  elementary 
speroid  to  be  its  shortest  dimension,  a 
class  of  solids  will  be  formed  which  are  nu- 
merous in  crystallography.  Jt  has  been  re- 
marked above,  that  by  the  natural  group- 
ing of  spherical  particles,  fig.  10.  one  re- 
suiting  solid  is  an  acute  rhomboid,  similar 
to  that  of  fig.  2.  having  certain  determin- 
ate angles,  and  its  greatest  dimension  in 
the  direction  of  its  axis.  Now,  if  other 
particles  having  the  same  relative  arrange- 
ment be  supposed  to  have  the  form  of  ob- 
late spheroids,  the  resulting  solid,  fig.  12. 
will  still  be  a  regular  rhomboid;  but  the 
measures  of  its  angles  will  be  different 
from  those  of  the  former,  and  will  be  more 
or  less  obtuse  according  to  the  degree  of 
oblateness  of  the  primitive  spheroid. 

It  is  at  least  possible  that  carbonate  of 
lime  and  other  substances,  of  which  the 
forms  are  derived  from  regular  rhomboids 
as  their  primitive  form,  may,  in  fact,  con- 
sist of  oblate  spheroids  as  elementary  par- 
ticles. 

Hexagonal  Prisms. 

If  our  elementary  spheroid  be  on  the 


CRY 


CRY 


contrary  oblong,  instead  of  oblate,  It  is 
evident  that,  by  mutual  attraction,  their 
centres  will  approach  nearest  to  each  other 
when  their  axes  are  parallel,  and  their 
shortest  diameters  in  the  same  plane  (fig1. 
13.).  The  manifest  consequence  of  this 
structure  would  be,  that  a  solid  so  formed 
would  be  liable  to  split  into  plates  at  rig-lit 
ang-les  to  the  axes,  and  the  plutes  would 
divide  into  prisms  of  three  or  six  sides 
with  all  their  angles  equal,  as  occurs  in 
phosphate  of  lime,  beryl,  &c. 

It  may  farther  be  observed,  that  the 
proportion  of  the  height  to  the  base  of 
such  a  prism,  must  depend  on  the  ratio 
between  the  axes  of  the  elementary  sphe- 
roid. 

The  Cube. 

Let  a  mass  of  matter  be  supposed  to 
consist  of  spherical  particles  all  of  the 
same  size,  but  of  two  different  kinds  in 
equal  numbers,  represented  by  black  and 
white  balls;  and  let  it  be  required  that,  in 
their  perfect  intermixture,  every  black  ball 
shall  be  equally  distant  from  all  surround- 
ing white  balls,  and  that  all  adjacent  balls 
of  the  same  denomination  shall  also  be 
equidistant  from  each  other.  The  Doctor 
shows,  that  these  conditions  will  be  fulfil- 
led, if  the  arrangement  be  cubical,  and 
that  the  particles  will  be  in  equilibria.  Fig. 
14.  represents  a  cube  so  constituted  of 
balls,  alternately  black  and  white  through- 
out. The  four  black  balls  are  in  view. 
The  distances  of  their  centres  being  every 
way  a  superficial  diagonal  of  the  cube, 
they  are  equidistant,  and  their  configura- 
tion represents  a  regular  tetrahedron;  and 
the  same  is  the  relative  situation  of  the 
four  white  balls.  The  distances  of  dissi- 
milar adjacent  balls  are  likewise  evidently 
equal;  so  that  the  conditions  of  their  union 
are  complete,  as  far  as  appears  in  the  small 
group:  and  this  is  a  correct  representative 
of  the  entire  mass,  that  would  be  compo- 
sed of  equal  and  similar  cubes. 

There  remains  one  observation  with  re- 
gard to  the  spherical  form  of  elementary 
particles,  whether  actual  or  virtual,  that 
must  be  regarded  as  favourable  to  the  fore- 
going hypothesis,  namely,  that  many  of 
those  substances,  which  we  have  most  rea- 
son to  think  simple  bodies,  as  among  the 
class  of  metals,  exhibit  this  further  evi- 
dence of  their  simple  nature,  that  they 
crystallize  in  the  octohedral  form,  as  they 
would  do  if  their  particles  were  spherical. 
I  But  it  must,  on  the  contrary,  be  acknow- 
ledged, that  we  can  at  present  assign  no 
reason  why  the  same  appearance  of  simpli- 
city should  take  place  in  fluor  spar,  which 
is  presumed  to  contain  at  least  two  ele- 
ments; and  it  is  evident  that  any  attempts 
to  trace  a  general  correspondence  between 

VOL.  I. 


the  crystallographical  and  supposed  die. 
mical  elements  of  bodies,  must  in  the 
present  state  of  these  sciences,  be  prema- 
ture. 

Any  sphere  when  not  compressed  will 
be  surrounded  by  twelve  others,  and,  con- 
sequently, by  a  slight  degree  of  compres- 
sion, will  be  converted  into  a  dodecahe- 
dron, according  to  the  most  probable  hy- 
pothesis of  simple  compression. 

The  instrument  for  measuring  the  angles 
of  crystals  is  called  a  goniometer,  of  which, 
there  are  two  kinds.  1.  The  goniometer 
of  M.  Carangeau,  used  by  M.  Haiiy,  con- 
sists of  two  parallel  blades,  jointed  like 
those  of  scissars,  and  capable  of  being  ap- 
plied to  a  graduated  semicircular  sector, 
which  gives  the  angle  to  which  the  joint 
is  opened,  in  consequence  of  the  previous 
apposition  of  the  two  blades  to  the  angle 
of  the  crystal.  2.  The  reflective  goniome- 
ter of  Dr.  Wollaston,  an  admirable  inven- 
tion, which  measures  the  angles  of  the 
minutest  possible  crystals  with  the  utmost 
precision.  An  account  of  this  beautiful  in- 
strument may  be  found  in  the  Phil.  Trans, 
for  1809,  and  in  Tilloch's  Magazine  for 
February  1810,  vol.  35.  Mr.  William  Phil- 
lips published,  in  the  2d  volume  of  the 
Geological  Transactions,  an  elaborate  se- 
ries of  measurements  with  this  goniometer. 
A  striking-  example  of  the  power  of  this 
instrument  in  detecting  the  minutest  forms 
with  precision  was  afforded,  by  its  appli- 
cation to  a  crystalline  jet-black  sand,  which 
Dr.  Clarke  got  from  the  island  Jean  Mayen, 
in  the  Greenland  seas.  "  Having  there- 
fore," says  Dr.  Clarke,  "selected  a  crystal 
of  this  form,  but  so  exceedingly  minute  as 
scarcely  to  be  discernible  to  the  naked  eye, 
I  fixed  it  upon  the  moveable  plane  of  Dr. 
Wollaston's  reflecting-  goniometer.  A  dou- 
ble image  was  reflected  by  one  of  the 
planes  of  the  crystal,  but  the  image  re- 
flected by  the  contiguous  plane  was  clear 
and  perfectlv  perceptible,  by  which  I  was 
enabled  to  measure  the  angle  of  inclina- 
tion; and  after  repeating  the  observation 
several  times,  I  found  it  equal  to  92°  or 
92|°.  Hence  it  is  evident  that  these  crys- 
tals are  not  zircons,  although  they  possess 
a  degree  of  lustre  quite  equal  to  that  of 
zircon.  In  this  uncertainty,  1  sent  a  small 
portion  of  the  sand  to  Dr.  Wollaston,  and 
requested  that  he  would  himself  measure 
tbeonffeof  the  particles  exhibiting  splen- 
dant  surfaces.  Dr.  Wollaston  pronounced 
the  substance  to  be  pyroxene;  having  an 
angle,  according  to  his  observation,  of  92^°. 
He  also  informed  me  that  the  sand  was 
similar  to  that  of  Bolsenna  in  Italy."  Such 
a  ready  means  of  minute  research  forms  a 
delightful  aid  to  the  chemical  philosopher, 
as  well  as  the  mineralogist.  M.  Haiiy,  by 
a  too  rij^id  adherence  to  the  principle  of 
44 


CRY 


CRY 


geometrical  simplicity,  obtained  an  erro-  carbonates  of  lime  the  same  angle  as  to 
neous  determination  of  the  angles  in  the  the    simple  carbonate,  the  error  became 
primary  form  of  carbonate  of  lime,  amount-  still  greater,  as  will  appear  from  the  follow- 
ing to  36  minutes  of  a  degree.   And  by  as-  ing  comparative  measurements, 
signing  to  the  magnesian  and  ferriferous 


Observed  angle  by 
Dr.  Wollaston's 
goniometer. 

Carbonate  of  lime,  105°     5' 

Magnesian  carbonate,       106°  15' 
Ferriferous  carbonate,      10?°   •(/ 


M .  Haiiy  will  no  doubt  accommodate  his 
results  to  these  indications  of  Dr.  Wollas- 
ton's  goniometer,  and  give  his  theory  all 
the  perfection  which  its  scientific  value 
and  elegance  deserve. 

M.  Beudant  has  lately  made  many  ex- 
periments to  discover,  why  a  saline  prin- 
ciple of  a  certain  kind  sometimes  im- 
presses its  crystalline  form  upon  a  mixture, 
in  which  it  does  not,  by  any  means,  form 
the  greatest  part;  and  also  with  the  view 
of  determining,  why  one  saline  substance 
may  have  such  an  astonishing  number  of 
secondary  forms,  as  we  sometimes  meet 
with. 

The  presence  of  urea  makes  common 
salt  take  an  octohedral  form  although  in 
pure  water  it  crystallizes  in  cubes,  similar 
to  its  primitive  molecules.  Sal  ammo- 
niac, which  crystallizes  in  pure  water  in 
octohedrons,  by  means  of  urea  crystallizes 
in  cubes.  A  very  slight  excess  or  defi- 
ciency of  base  in  alum,  causes  it  to  assume 
either  cubical  or  octohedral  secondary 
forms;  and  these  forms  are  so  truly  se- 
condary, that  an  octohedral  crystal  of 
alum,  immerged  in  a  solution  which  is 
richer  in  respect  to  its  basis,  becomes  en- 
veloped with  crystalline  layers,  which 
give  it  at  length  the  form  of  a  cube. 

The  crystalline  form  in  muddy  solutions 
acquires  greater  simplicity,  losing  all  those 
additional  facets  which  would  otherwise 
modify  their  predominant  form. 

In  a  gelatinous  deposite,  crystals  are 
rarely  found  in  groups,  but  almost  always 
single,  and  of  a  remarkable  sharpness  and 
regularity  of  form,  and  they  do  not  under- 
go any  variations,  but  those  which  may  re- 
sult from  the  chemical  action  of  the  sub- 
stance forming  the  deposite.  Common 
salt  crystallized  in  a  solution  of  borax,  ac- 
quires truncations  at  the  solid  angles  of  its 
cubes;  and  alum  crystallized  in  muriatic 
acid,  takes  a  form  which  M.  Beudant  has 
never  been  able  to  obtain  in  any  other 
manner. 

30  or  40  per  cent  of  sulphate  of  copper 
may  be  united  to  the  rhomboidal  crystal- 
lization of  sulphate  of  iron,  but  it  reduces 
this  sulphate  to  a  pure  rhomboid,  without 
any  truncation  either  of  the  angles  or  the 
edges.  A  small  portion  of  acetate  of  cop- 


Theoretic  angle. 

104°  28'  40" 
104°  28'  40" 
104°  28'  40" 


Error. 

0°  36'  20" 
1°  46'  20" 
2°  31'  20" 


per  reduces  sulphate  of  iron  to  the  same 
simple  rhomboidal  form,  notwithstanding 
that  this  form  is  disposed  to  become  com- 
plicated with  additional  surfaces.  Sulphate 
of  alumina  brings  sulphate  of  iron  to  a 
rhomboid,  with  the  lateral  angles  only 
truncated,  or  what  M.  Haiiy  calls  his  va- 
riett  unitaire;  and  whenever  this  variety 
of  green  vitriol  is  found  in  the  market, 
where  it  is  very  common,  we  may  be  sure, 
according  to  M.  Beudant,  that  it  contains 
alumina. 

Natural  crystals  mixed  with  foreign 
substances,  are  in  general  more  simple 
than  others,  as  is  shown  in  a  specimen  of 
axinite  or  violet  schorl  of  Dauphine,  one 
extremity  of  which  being  mixed  with  chlo- 
rite, is  reduced  to  its  primitive  form; 
while  the  other  end,  which  is  pure,  is  va- 
ried by  many  facets  produced  by  different 
decrements. 

In  a  mingled  solution  of  two  or  more 
salts,  of  nearly  equal  solubility,  the  crys- 
tallization of  one  of  them  may  be  some- 
times determined,  by  laying  or  suspending 
in  the  liquid,  a  crystal  of  that  particular 
salt. 

M.  Le  Blanc  states,  that  on  putting  in- 
to a  tall  and  narrow  cylinder,  crystals  at 
different  heights,  in  the  midst  of  their  sa- 
turated saline  solution,  the  crystals  at  the 
bottom  increase  faster  than  those  at  the 
surface,  and  that  there  arrives  a  period 
when  those  at  the  bottom  continue  to  en- 
large, while  those  at  the  surface  diminish 
and  dissolve. 

Those  salts  which  are  apt  to  give  up 
their  water  of  crystallization  to  the  atmos- 
phere, and  of  course  become  efflorescent, 
may  be  preserved  by  immersion  in  oil,  and 
subsequent  wiping  of  their  surface. 

In  the  Wernerian  language  of  crystalli- 
zation, the  following  terms  are  employed: 
When  a  secondary  form  differs  from  the 
cube,  the  octohedron,  &c.  only  in  having 
several  of  its  angles  or  edges  replaced  by 
a  face,  this  change  of  the  geometrical  form 
is  called  a  truncation.  The  alteration  in 
the  principal  form  produced  by  two  new 
faces  inclined  to  one  another,  and  which  re- 
place by  a  kind  of  bevel,  an  angle,  or  an 
edge,  is  called  a  beveltnent.  When  these 
new  faces  are  to  the  number  of  three  or 


CRY 


CUR 


more,  they  produce  what  Werner  termed 
a  pointing,  or  acumination.  When  two  faces 
unite  by  an  edge  in  the  manner  of  a  roof, 
they  have  been  called  culmination.  Keplacc- 
ment  is  occasionally  used  for  bevelment. 

The  reader  will  find  some  curious  ob- 
servations on  crystallization,  by  Mr.  J.  F. 
Daniell,  in  the  1st  volume  of  the  Journal  of 
Science. 

Professor  Mohs,  successor  to  Werner  in 
Freyberg,  Dr.  Weiss,  professor  of  miner- 
alogy, in  Berlin,  and  M.  Brochant,  profes- 
sor of  mineralogy  in  Paris,  have  each  re- 
cently published  systems  of  mineralogy. 
Pretty  copious  details,  relative  to  the  first, 
are  given  in  the  3d  volume  of  the  Edin- 
burgh Philosophical  Journal.* 

In  a  paper  in  the  Journal  de  Physique, 
M.  Le  Blanc  gives  instructions  for  obtain- 
ing crystals  of  large  size.  His  method  is 
to  employ  flat  glass  or  china  vessels:  to 
pour  into  these  the  solutions  boiled  down 
to  the  point  of  crystallization:  to  select  the 
neatest  of  the  small  crystals  formed,  and 
put  them  into  vessels  with  more  of  the  mo- 
ther-water of  a  solution  that  has  been 
brought  to  crystallize  confusedly:  to  turn 
the  crystals  at  least  once  a  day;  and  to 
supply  them  from  time  to  time  with  fresh 
mother-water.  If  the  crystals  be  laid  on 
their  sides  they  will  increase  most  in 
length;  if  on  their  ends,  most  in  breadth. 
When  they  have  ceased  to  grow  larger, 
they  must  be  taken  out  of  the  liquor,  or 
they  will  soon  begin  to  diminish.  It  may 
be  observed  in  general,  that  very  large 
crystals  are  less  transparent  than  those 
that  are  small. 

The  crystals  of  metals  may  be  obtained 
by  fusing  them  in  a  crucible  with  a  hole 
in  its  bottom,  closed  by  a  stopper,  which 
is  to  be  drawn  out  after  the  vessel  has 
been  removed  from  the  fire,  and  the  sur- 
face of  the  metal  has  begun  to  congeal. 
The  same  effect  may  be  observed  if  the 
metal  be  poured  into  a  plate  or  dish,  a  lit- 
tle inclined,  which  is  to  be  suddenly  inclin- 
ed in  the  opposite  direction,  as  soon  as  the 
metal  begins  to  congeal  round  its  edges. 
In  the  first  method,  the  fluid  part  of  the 
metal  runs  out  of  the  hole,  leaving  a  kind 
of  cup  lined  with  crystals:  in  the  latter 
way,  the  superior  part,  which  is  fluid,  runs 
off',  and  leaves  a  plate  of  metal  studded 
over  with  crystals. 

The  operation  of  crystallizing,  or  crys- 
tallization, is  of  great  utility  in  the  purify- 
ing of  various  saline  substances.  Most 
salts  are  suspended  in  water  in  greater 
quantities  at  more  elevated  temperatures, 
and  separate  more  or  less  by  cooling.  In 
this  property,  and  likewise  in  the  quantity 
of  salt  capable  of  being  suspended  in  a 
given  quantity  of  water,  they  differ  greatly 
from  each  other.  It  is  therefore  practica- 
ble in  general  to  separate  salts  by  due  man- 


agement of  the  temperature  and  evapora- 
tion. For  example,  if  a  solution  of  nitre 
and  common  salt  be  evaporated  over  the 
fire,  and  a  small  quantity  be  now  and 
then  taken  out  for  trial,  it  will  be  found, 
at  a  certain  period  of  the  concentration, 
that  a  considerable  portion  of  salt  will 
separate  by  cooling,  and  that  this  salt 
is  for  the  most  part  pure  nitre.  When  this 
is  seen,  the  whole  fluid  may  be  cooled  to 
separate  part  of  the  nitre,  after  which,  eva- 
poration may  be  proceeded  upon  as  before. 
This  manipulation  depends  upon  the  diffe- 
rent properties  of  the  two  salts  with  regard 
to  their  solubility  and  crystallization  in  like 
circumstances.  For  nitre  is  considerably 
more  soluble  in  hot  than  in  cold  water, 
while  common  salt  is  scarcely  more  soluble 
in  the  one  case  than  in  the  other.  The  com- 
mon salt  consequently  separates  in  crystals 
as  the  evaporation  of  the  heated  fluid  goes 
on,  and  is  taken  out  with  a  ladle  from  time 
to  time,  whereas  the  nitre  is  separated  by 
successive  coolings  at  proper  periods. 

*CITBE  ORE.  Hexahedral  Olivenite.  Wur- 
felerz.  Wern.  This  mineral  has  a  pistacio- 
green  colour,  of  various  shades.  It  occurs 
massive,  and  crystallized  in  the  perfect 
cube;  in  a  cube  with  four  diagonally  op- 
posite angles  truncated;  or  in  one  trun- 
cated on  all  its  angles;  or  finally,  both  on 
its  edges  and  angles. 

The  crystals  are  small,  with  planes 
smooth  and  splendent.  Lustre  glistening. 
Cleavage  parallel  with  the  truncations  of 
the  angles.  Translucent.  Streak  straw-yel- 
low. Harder  than  gypsum.  Easily  fran- 
gible. Sp.  gr.  3.0.  Fuses  with  disengage- 
ment of  arsenical  vapours.  Its  constitu- 
ents are,  31  arsenic  acid,  45.5  oxide  of  iron, 
9  oxide  of  copper,  4  silica,  and  10.5  water, 
by  Chenevix.  Vauquelin's  analysis  gives  no 
copper  nor  silica,  but  48  iron,  18  arsenic 
acid,  2  to  3  carbonate  of  lime,  and  32  wa- 
ter. It  is  found  in  veins,  accompanied 
with  iron-shot  quartz,  in  Tincroft  and  va- 
rious other  mines  of  Cornwall,  and  at  St. 
Leonard  in  the  Haut-Vienne  in  France.  As 
an  arseniate  of  iron,  it  might  be  ranked 
among  the  ores  of  either  this  metal  or  ar- 
senic.— Jameson* 

CUPEL.  A  shallow  earthen  vessel,  some- 
what resembling  a  cup,  from  which  it  de- 
rives its  name.  It  is  made  of  phosphate  of 
lime,  or  the  residue  of  burned  bones  ram- 
med into  a  mould,  which  gives  it  its  figure. 
This  vessel  is  used  in  assays  wherein  the 
precious  metals  are  fused  with  lead,  which 
becomes  converted  into  glass,  and  carries 
the  impure  alloy  with  it.  See  ASSAY. 

CUPEL  LATION.  The  refining  of  gold  by 
scorification  with  lead  upon  the  cupel,  is 
called  cupellation.  See  ASSAY. 

CURD.  The  coagulum  which  separates 
from  milk  upon  the  addition  of  acid,  oi* 
other  substances.  See  MILK. 


DAT 


DEC 


•CYANITE,  or  KYANITE.  Disthene  of 
Haiiy.  Its  principal  colour  is  Berlin-blue, 
which  passes  into  gray  and  green.  It  oc- 
curs massive  and  disseminated,  also  in  dis- 
tinct concretions.  The  primitive  form  of  its 
crystals  is  an  oblique  four-sided  prism;  and 
the  secondary  forms  are,  an  oblique  four- 
sided  prism,  truncated  on  the  lateral  edges, 
and  a  twin  crystal.  The  planes  are  streak- 
ed, splendent,  and  pearly.  Cleavage  three- 
fold. Translucent  or  transparent.  Surface 
of  the  broader  lateral  planes  as  harik  as 
apatite;  that  of  the  angles,  as  quartz.  Ea- 
sily frangible.  Sp.  gr.  3.5.  When  pure  it  is 
idio-electric.  Some  crystals  by  friction  ac- 
quire negative,  others  positive  electricity; 


hence  Haiiy's  name.  It  is  infusible  before 
the  blow-pipe.  It  consists,  by  Klaproth,  of 
43  silica,  55.5  alumina,  0.50  iron,  and  a 
trace  of  potash.  It  occurs  in  the  granite 
and  mica  slate  of  primitive  mountains.  It 
is  found  near  Banchory  in  Aberdeenshire, 
and  Bocharm  in  Banftshire;  at  Airolo  on 
St.  Gothard,  and  in  various  countries  of 
Europe,  as  well  as  in  Asia  and  America. 
It  is  cut  and  polished  in  India  as  an  infe- 
rior sort  of  sapphire. — Jameson.* 

*  CYANOGEN.     The  compound  base  of 
prussic  acid.     See  PRUSSINE.* 

*  CYMOPHANE  of  Haiiy.    The  CHRYSO- 
BERYJL..* 


D 


nAMPS.  The  permanently  elastic  fluids 
which  are  extricated  in  mines,  and 
re  destructive  to  animal  life,  are  called 
damps  by  the  miners.  The  chief  distinc- 
tions made  by  the  miners,  are  choak-damp, 
•which  extinguishes  their  candles,  hovers 
about  the  bottom  of  the  mine,  and  consists 
for  the  most  part  of  carbonic  acid  gas;  and 
fire-damp,  or  hydrogen  gas,  which  occupies 
the  superior  spaces,  and  does  great  mis- 
chief by  exploding  whenever  it  comes  in 
contact  with  their  lights.  See  GAS,  COM- 
BUSTION, &  LAMP. 

*  DAOURITE.     A  variety  of  red  schorl 
from  Siberia.* 

*  DAPHNIN.      The    bitter  principle  of 
Daphne  stlpina,  discovered  by  M.  Vauque- 
lin.     From  the  alcoholic   infusion   of  this 
bark,  the  resin  was  separated  by  its  con- 
centration.   On  diluting  the  tincture  with 
water,  filtering,  and  adding  acetate  of  lead, 
a  yellow  dap/mate  of  lead  fell,  from  which 
sulphuretted  hydrogen  separated  the  lead, 
and  left  the  daphnin  in  small  transparent 
crystals.     They  are  hard,  of  a  grayish  co- 
lour, a  bitter  taste  when  heated,  evaporate 
in  acrid  acid  vapours,  sparingly  soluble  in 
cold,  but  moderately  in  boiling  water.     It 
is  stated,  that  its  solution  is  not  precipita- 
ted by  acetate  of  lead;  yet  acetate  of  lead 
is  employed  in  the  first  process  to  throw7  it 
down.* 

*  DATOLITE.  Datholit  of  Werner.  This 
species  is  divided  into  two  sub-species,  viz. 
Common  Datolite,  and  Botrioidal  Datolite. 

1.  Common  Datolite.  Colour  white  of 
various  shades,  and  greenish -gray,  inclin- 
ing to  celadine-grecn.  It  occurs  in  large 
coarse,  and  small  granular  distinct  concre- 
tions, and  crystallized.  Primitive  form,  an 
oblique  four-sided  prism  of  109°  28'  and 
70°  3£'.  The  principal  secondary  forms, 
are  the  low  oblique  four-sided  prism,  and 
the  rectangular  four-sided  prism,  flatly 
acuminated  on  the  extremities,  with  four 


planes  which  are  set  on  the  lateral  planes. 
The  crystals  are  small  and  in  druses.  Lus- 
tre shining  and  resinous.  Cleavage  imper- 
fect, parallel  with  the  lateral  planes  of  the 
prism.  Fracture  fine  grained,  uneven,  or 
imperfect  conchoidal.  Translucent  or 
transparent.  Fully  as  hard  as  apatite.  Very 
brittle,  and  difficultly  frangible.  Sp.  gr.  2.9. 
When  exposed  to  the  flame  of  a  candle  it 
becomes  opaque,  and  may  then  be  rubbed 
down  between  the  fingers.  Before  the  blow- 
pipe it  intumesces  into  a  milk-white  co- 
loured mass,  and  then  melts  into  a  globule 
of  a  pale  rose  colour.  Its  constituents  are, 
by  Klaproth,  silica  36.5,  lime  35.5,  boracic 
acid  24.0,  water  4,  trace  of  iron  and  man- 
ganese. It  is  associated  with  large  folia- 
ted granular  calcareous  spar,  at  the  mine  of 
Nodebroe,  near  Arcndal  in  Norway.  It  re- 
sembles prehnite,  but  is  distinguished  by 
its  resinous  lustre,  compact  fracture,  infe- 
rior hardness,  and  not  becoming  electric 
by  heating. — Jameso?).* 

*  2.  BOTRIOIDAL  DATOLITE.  SceBoT- 

RYOLITE.* 

*  DATURA.     A    vegeto-alkali  obtained 
from  DATURA  STRAMONIUM.* 

*  DEAD-SEA  WATER.     Sec  WATER.* 
DECANTATION.    The  action  of  pouring* 

oft' the  clearer  part  of  a  fluid  by  gently  in- 
clining the  vessel  after  the  grosser  parts 
have  been  suffered  to  subside. 

DECOCTION.  The  operation  of  boiling. 
This  term  is  likewise  used  to  denote  the 
fluid  itself  which  has  been  made  to  take  up 
certain  soluble  principles  by  boiling'.  Thus 
we  say  a  decoction  of  the  bark,  or  other 
parts  of  vegetables,  of  flesh,  &c. 

DECOMPOSITION  is  now  understood  to 
imply  the  separation  of  the  component 
parts  or  principles  of  bodies  from  each 
other. 

The  decomposition  of  bodies  forms  a 
very  large  part  of  chemical  science.  It 
seems  probable  frtim  the  operations  we  arfe 


BEL 


DEL 


acquainted  with,  that  it  seldom  takes  place 
but  in  consequence  of  some  combination 
or  composition  having  been  effected.  Tt 
would  be  difficult  to  point  out  an  instance 
of  the  separation  of  any  of  the  principles 
of  bodies  which  has  been  effected,  unless 
in  consequence  of  some  new  combination. 
The  only  exceptions  seem  to  consist  in 
those  separations  which  are  made  by  heat, 
and  voltaic  electricity.  See  ANALYSIS, 
GAS,  METALS,  ORES,  SALTS,  MINERAL 
WATERS. 

*  DECREPITATION.  The  crackling- 
noise  which  several  salts  make  when  sud- 
denly heated,  accompanied  by  a  violent  ex- 
foliation of  their  particles.  This  pheno- 
menon has  been  ascribed  by  Dr.  Thomson, 
and  other  chemical  compilers,  to  the  "  sud- 
den conversion  of  the  water  which  they 
contain  into  steam."  But  the  very  example, 
sulphate  of  barytes,  to  which  these  words 
are  applied,  is  the  strongest  evidence  of 
the  falseness  of  the  explanation;  for  abso- 
lutely dry  sulphate  of  barytes  decrepitates 
furiously,  without  any  possible  formation 
of  steam,  or  any  loss  of  weight.  The  same 
thing1  holds  with  regard  to  common  salt, 
calcareous  spars,  and  sulphate  of  potash, 
which  contain  no  water.  In  fact,  it  is  the 
salts  which  are  anhydrous,  or  destitute  of 
water,  which  decrepitate  most  powerfully; 
those  that  contain  water,  generally  enter 
into  tranquil  liquefaction  on  being  heated. 
Salts  decrepitate,  for  the  same  reason  that 
glass,  quartz,  and  cast-iron  crack,  with  an 
explosive  force,  when  very  suddenly  heat- 
ed; namely,  from  the  unequal  expansion  of 
the  laminae  which  compose  them,  in  conse- 
quence of  their  being  imperfect  conduc- 
tors of  heat.  The  true  cleavage  of  mine- 
rals may  often  be  detected  in  this  way,  for 
they  fly  asunder  at  their  natural  fissures.* 

•j-  DEFLAGRATION.  This  word  is  used 
by  electricians  and  chemists,  to  denote 
that  kind  of  combustion,  which  takes  place 
in  metallic  wires,  or  leaves,  when  subject- 
ed to  galvanic  or  electric  discharges.  See 
GALVANIC  DEFLAGRATCR^ 

*  DELPHINITE.     See  PISTACITE.* 

*  DELPHINIA.    A  new  vegetable  alkali, 
recently  discovered  by  MM.  Lasseigne  and 
Feneulle,  in  the   Delphinium  staphysagria, 
or  Stavesacre.     It  is  thus  obtained: 

The  seeds,  deprived  of  their  husks,  and 
ground,  are  to  be  boiled  in  a  small  quanti- 
ty of  distilled  water,  and  then  pressed  in  a 
cloth.  The  decoction  is  to  be  filtered,  and 
boiled  for  a  few  minutes  with  pure  mag- 
nesia. It  must  then  be  re-filtered,  and  the 
residuum  left  on  the  filter  is  to  be  well 
washed,  and  then  boiled  with  highly  recti- 
fied alcohol,  which  dissolves  out  the  alkali. 
By  evaporation,  a  whiu  pulverulent  sub- 
stance, presenting  a  few  crystalline  points, 
is  obtained. 


It  may  also  be  procured  by  the  action  of 
dilute  sulphuric  acid,  on  the  bruised  but 
unshelled  seeds.  The  solution  of  sulphate 
thus  formed,  is  precipitated  by  subcarbo- 
nate  of  potash.  Alcohol  separates  from 
this  precipitate  the  vegetable  alkali  in  an 
impure  state 

Pure  delphinia  obtained  by  the  first  pro- 
cess, is  crystalline  while  wet,  but  becomes 
opaque  on  exposure  to  air.  Its  taste  is  bit- 
ter and  acrid.  When  heated  it  melts;  and 
on  cooling  becomes  hard  and  brittle  like 
resin.  If  more  highly  heated,  it  blackens 
and  is  decomposed.  Water  dissolves  a 
very  small  portion  of  it.  Alcohol  and 
ether  dissolve  it  very  readily.  The  alco- 
holic solution  renders  sirup  of  violets 
green,  and  restores  the  blue  tint  of  litmus 
reddened  by  an  acid.  It  forms  soluble 
neutral  salts  with  acids.  Alkalis  precipi- 
tate the  delphinia  in  a  white  gelatinous 
state,  like  alumina. 

Sulphate  of  delphinia  evaporates  in  the 
air,  does  not  crystallize,  but  becomes  a 
transparent  mass  like  gum.  It  dissolves 
in  alcohol  and  water,  and  its  solution  has 
a  bitter  acrid  taste.  In  the  voltaic  circuit 
it  is  decomposed,  giving  up  its  alkali  at 
the  negative  pole- 

Nitrate  of  delphinia,  when  evaporated 
to  dryness,  is  a  yellow  crystalline  mass.  If 
treated  with  excess  of  nitric  acid,  -it  be- 
comes converted  into  a  yellow  matter,  little 
soluble  in  water,  but  soluble  in  boiling  al- 
cohol. This  solution  is  bitter,  is  not  pre- 
cipitated by  potash,  ammonia,  or  lime-wa- 
ter, and  appears  to  contain  no  nitric  acid, 
though  itself  is  not  alkaline.  It  is  not  de- 
stroyed by  further  quantities  of  acid,  nor 
does  it  form  oxalic  acid  Strychnia  and 
morphia  take  a  red  colour  from  nitric  acid, 
but  delphinia  never  does.  The  muriate  is 
very  soluble  in  water. 

The  acetate  of  delphinia  does  not  crys- 
tallize, but  forms  a  hard  transparent  mass, 
bitter  and  acrid,  and  readily  decomposed 
by  cold  sulphuric  acid.  The  oxalate  forms 
small  white  plates,  resembling  in  taste  the 
preceding  salts. 

Delphinia,  calcined  with  oxide  of  copper, 
gave  no  other  gas  than  carbonic  acid.  It 
exists  in  the  seeds  of  the  stavesacre,  in  com- 
bination with  malic  acid,  and  associated 
with  the  following  principles:  1.  A  brown 
bitter  principle,  precipitable  by  acetate  of 
lead.  2.  Volatile  oil.  3.  Fixed  oil.  4.  Albu- 
men. 5.  Animalized  matter.  6.  Mucus.  7. 
Saccharine  murus.  8.  Yellow  bitter  princi- 
ple, not  precipivabie  by  acetate  of  lead.  9. 
Mineral  salts. — Jlnnales  de  Chimie  et  Phg- 
sique,  vol.  xii.  p.  f,58  * 

DELIQUESCENCE.  The  spontaneous  as- 
sumption of  the  fluid  state  by  certain  sa- 
line substances,  when  left  exposed  to  the 
air,  in  consequence  of  the  water  they  attract 
from  it. 


DEW 


DEW 


DEPHLEGMATION.  Any  method  by 
Which  bodies  are  deprived  of  water. 

DEPHLOGISTICATED.  A  term  of  theold 
chemistry,  implying  deprived  ofphlogiston, 
or  the  inflammable  principle,  and  nearly 
synonymous  with  what  is  now  expressed  by 
oxygenated,  or  oxidized. 

DEPHLOGISTICATED  AIR.  The  same 
with  oxygen  gas. 

DERBYSHIRE  SPAR.  A  combination  of 
calcareous  earth  with  a  peculiar  acid  called 
the  FLUORIC,  which  see. 


Wells  shows  that  very  little  is  ever  depo- 
sited in  opposite  circumstances;  and  that 
little  only  when  the  clouds  are  very  high. 
It  is  never  seen  on  nights  both  cloudy  and 
windy;  and  if  in  the  course  of  the  night  the 
weather,  from  being  serene,  should  become 
dark  and  stormy,  dew  which  had  been  de- 
posited will  disappear.  In  calm  weather,  if 
the  sky  be  partially  covered  with  clouds, 
more  dew  will  appear  than  if  it  were  en- 
tirely uncovered. 

Dew  probably  begins  in  the  country  to 


*  DESICCATION  is  most  elegantly accom-  appear  upon  grass,  in  places  shaded  from 
plished,  by  means  of  the  air-pump  and  sul-  the  sun,  during  clear  and  calm  weather, 
phuric  acid,  as  is  explained  under  CONGE-  soon  after  the  heat  of  the  atmosphere  has 
LATION  *  declined,  and  continues  to  be  deposited 

DESTRUCTIVE  DISTILLATION.  When  through  the  whole  night,  and  for  a  little 
organized  substances,  or  their  products,  after  sunrise.  Its  quantity  will  depend  in, 
are  exposed  to  distillation,  until  the  whole  some  measure  on  the  proportion  of  mois- 
has  suffered  all  that  the  furnace  can  effect,  ture  in  the  atmosphere,  and  is  consequently 

greater  after  rain  than  after  a  long-  tract  of 
dry  weather;  and  in  Europe,  with  southerly 
and  westerly  winds,  than  with  those  which 
blow  from  the  north  and  the  east.  The  di- 
rection of  the  sea  determines  this  relation, 
of  the  winds  to  dew.  For  in  Egypt,  dew  is 
scarcely  ever  observed  except  while  the 
northerly  or  Etesian  winds  prevail.  Hence 
also,  dew  is  generally  more  abundant  in 
spring  and  autumn,  than  in  summer.  And 
it  is  always  very  copious  on  those  clear 
nights  which  are  followed  by  misty  morn- 
ings, which  show  the  air  to  be  loaded  with 

son.  The  first  stated,  in  the  Phil.  Trans,  for  moisture.  Arid  a  clear  morning,  following  a 
1771,  that  on  a  winter  night,  during  which  cloudy  night,  determines  a  plentiful  depo- 
the  atmosphere  was  several  times  misty  and  sition  of  the  retained  vapour.  When  warmth 
clear  alternately,  he  observed  a  thermome-  of  atmosphere  is  compatible  with  clearness, 
ter,  suspended  in  the  air, always  to  rise  from  as  is  the  case  in  southern  latitudes,  though 
a  half  to  a  whole  degree,  whenever  the  for- 
mer state  began,  and  to  fall  as  much  as 
soon  as  the  weather  became  serene. 


the  process  is  called  destructive  distilla- 
tion. 

DETONATION.  A  sudden  combustion 
and  explosion.  See  COMBUSTION,  FULMI- 
NATING i'o \VDEHS,  and  GUNPOWDER. 

*  DEW.  The  moisture  insensibly  depo- 
sited from  the  atmosphere  on  the  surface 
of  the  earth. 

The  first  facts  which  could  lead  to  the 
just  explanation  of  this  interesting,  and,  till 
very  lately,  inexplicable  natural  phenome- 
non, are  due  to  the  late  Mr.  A.  Wilson, 
professor  of  astronomy  in  Glasgow,  and  his 


Dr. 

Patrick  Wilson  communicated,  in  1786,  to 
the  Royal  Society  of  Edinburgh,  a  valuable 
paper  on  hoar-frost,  which  was  published 
in  the  first  volume  of  their  Transactions. 
It  is  replete  with  new  and  valuable  obser- 
vations, whose  minute  accuracy  subsequent 
experience  has  confirmed.  Dr.  Wilson  had 
previously,  in  1781,  described  the  surface 
of  snow,  during  a  clear  and  calm  night,  to 
be  16°  colder  than  air  2  feet  above  it;  and 
in  the  above  paper  he  shows,  that  the  depo- 
sition of  dew  and  hoar-frost  is  uniformly 
accompanied  with  the  production  of  cold- 
He  was  the  first  among  philosophical  ob- 
servers who  noticed  this  conjunction.  But 
the  different  force  with  which  different  sur- 
faces project  or  radiate  heat  being  then  un- 
known, Dr.  Wilson  could  not  trace  the  phe- 
nomena of  dew  up  to  their  ultimate  source. 
This  important  contribution  to  science  has 
been  lately  made  by  Dr.  Wells,  in  his  very 
ingenious  and  masterly  essay  on  dew. 

1.  Phenomena  of  De-w. 

Aristotle  justly  remarked,  that  dew  ap- 
pears only  on  calm  and  clear  nights.  Dr. 


seldom  in  our  country,  the  dew  becomes 
much  more  copious,  because  the  air  then 
contains  more  moisture.  Dew  continues  to 
form  with  increased  copiousness  as  the 
night  advances,  from  the  increased  refri- 
geration of  the  ground. 

2.  On  the  cause  of  dew. 

Dew,  according  to  Aristotle,  is  a  species 
of  rain,  formed  in  the  lower  atmosphere,  in 
consequence  of  its  moisture  being  con- 
densed by  the  cold  of  the  night  into  minute 
drops.  Opinions  of  this  kind,  says  Dr. 
Wells,  are  still  entertained  by  many  per- 
sons, among  whom  is  the  very  ingenious 
Professor  Leslie.  (Relat.  of  Heat  and  Mois- 
ture, p.  37.  and  132.)  A  fact,  however,  first 
taken  notice  of  by  Gerstin,  who  published 
his  treatise  on  dew  in  1773,  proves  them  to 
be  erroneous;  for  he  found  that  bodies  a 
little  elevated  in  the  air,  often  become 
moist  with  dew,  while  similar  bodies,  lying 
on  the  ground,  remain  dry,  though  neces- 
sarily, from  their  position,  as  liable  to  be 
wetted,  by  whatever  falls  from  the  heavens, 
as  the  former.  The  above  notion  is  perfect- 
ly refuted,  by  what  will  presently  appear 
relative  to  metallic  surfaces  exposed  to  the 
air  in  a  horizontal  position,  which  remain 


DEW 


DEW 


dry,  while  every  thing  around  them  is  co- 
vered with  dew. 

After  a  long  period  of  drought,  when  the 
air  was  very  still  and  the  sky  serene,  Dr. 
Wells  exposed  to  the  sky,  28  minutes  be- 
fore sunset,  previously  weighed  parcels  of 
wool  and  swandown,  upon  a  smooth,  un- 
painted,  and  perfectly  dry  fir  table,  5  feet 
long,  3  broad,  and  nearly  3  in  height,  which 
had  been  placed  an  hour  before,  in  the  sun- 
shine, in  a  large  level  grass  field.  The  wool, 
12  minutes  after  sunset,  was  found  to  be 
14°  colder  than  the  air,  and  to  have  ac- 
quired no  weight.  The  swandown,  the 
quantity  of  which  was  much  greater  than 
that  of  the  wool,  was  at  the  same  time  13° 
colder  than  the  air,  and  was  also  without 
any  additional  weight.  In  20  minutes  more, 
the  swandown  was  14£  colder  than  the 
neighbouring  air,  and  was  still  without  any 
increase  of  its  weight.  At  the  same  time 
the  grass  was  15°  colder  than  the  air  four 
feet  above  the  ground. 

Dr.  Wells,  by  a  copious  induction  of  facts 
derived  from  observation  and  experiment, 
establishes  the  proposition,  that  bodies  be- 
come colder  than  the  neighbouring  air  BE- 
FORE they  are  dewed.  The  cold  therefore 
which  Dr.  Wilson  and  Mr.  Six  conjectured 
to  be  the  effect  of  dew,  now  appears  to  be 
its  cause.  But  what  makes  the  terrestrial 
surface  colder  than  the  atmosphere?  The 
radiation  or  projection  of  heat  into  free 
space.  Now  the  researches  of  Professor 
Leslie  and  Count  llumford  have  demonstra- 
ted, that  different  bodies  project  heat  with 
very  different  degrees  of  force. 

In  the  operation  of  this  principle,  there- 
fore, conjoined  with  the  power  of  a  concave 
mirror  of  cloud  or  any  other  awning,  to  re- 
flect or  throw  down  again  those  calorific 
emanations  which  would  be  dissipated  in  a 
clear  sky,  we  shall  find  a  solution  of  the 
most  mysterious  phenomena  of  dew.  Two 
circumstances  must  here  be  considered: — 

1.  The  exposure  of  the  particular  surface 
to  be  dewed,  to  the  free  aspect  of  the  sky. 

2.  The  peculiar  radiating  power  of  the 
surface.     1.  Whatever  diminishes  the  view 
of  the  sky,  as  seen  from  the  exposed  body, 
obstructs  the  depression  of  its  tempera- 
ture,  and   occasions   the  quantity  of  dew 
formed  upon  it,  to  be  less  than  would  have 
occurred,  if  the  exposure  to  the  sky  had 
been  complete. 

Dr.  Wells  bent  a  sheet  of  pasteboard  into 
the  shape  of  a  penthouse,  making  the  angle 
of  flexure  90  degrees,  and  leaving  both  ends 
open.  This  was  placed  one  evening  with 
its  ridge  uppermost,  upon  a  grass-plat  in 
the  direction  of  the  wind,  as  well  as  this 
could  be  ascertained.  He  then  laid  10 
grains  of  white,  and  moderately  fine  wool, 
not  artificially  dried,  on  the  middle  part  of 
that  spot  of  the  grass  which  was  sheltered 
by  the  roof,  and  the  same  quantity  on  ano- 


ther part  of  the  grass-plat,  fully  exposed  to 
the  sky.  In  the  morning  the  sheltered  wool 
was  found  to  have  Jtereased  in  weight  only 
2  grains,  but  that  wiich  had  been  exposed 
to  the  sky  16  grains.  He  varied  the  expe- 
riment on  the  same  night,  by  placing  up- 
right on  the  grass-plat  a  hollow  cylinder  of 
baked  clay,  1  foot  diameter,  and  2£  feet 
high.  On  the  grass  round  the  outer  edge 
of  the  cylinder,  were  laid  10  grains  of  wool, 
which  in  this  situation,  as  there  was  not 
the  least  wind,  would  have  received  as 
much  rain,  as  a  like  quantity  of  wool,  fully 
exposed  to  the  sky.  But  the  quantity  of 
moisture  acquired  by  the  wool,  partially 
screened  by  the  cylinder  from  the  aspect 
of  the  sky  was  only  about  2  grains,  while 
that  acquired  by  the  same  quantity  fully 
exposed,  was  16  grains.  Repose  of  a  body 
seems  necessary  to  its  acquiring  its  utmost 
coolness,  and  a  full  deposite  of  dew.  Gravel 
walks  and  pavements  project  heat,  and  ac- 
quire dew,  less  readily  than  a  grassy  sur- 
face. Hence  wool  placed  on  the  former  has 
its  temperature  less  depressed  than  on  the 
latter,  and  therefore  is  less  bedewed.  Nor 
does  the  wool  here  attract  moisture  by  ca- 
pillary action  on  the  grass,  for  the  same  ef- 
fect happens  if  it  be  placed  in  a  saucer. 
Nor  is  it  by  hygrometric  attraction,  for  in 
a  cloudy  night,  wool  placed  on  an  elevated 
board  acquired  scarcely  any  increase  of 
weight. 

If  wool  be  insulated  a  few  feet  from  the 
ground  on  a  bad  conductor  of  heat,  as  a 
board,  it  will  become  still  colder  than  when 
in  contact  with  the  earth,  and  acquire  fully 
more  dew,  than  on  the  grass.  At  the  wind- 
ward end  of  the  board,  it  is  less  bedewed 
than  at  the  sheltered  end,  because  in  the 
former  case,  its  temperature  is  nearer  to 
that  of  the  atmosphere.  Hough  and  porous 
surfaces,  as  shavings  of  wood,  take  more 
dew  than  smooth  and  solid  wood;  and  raw 
silk  and  fine  cotton  are  more  powerful  in  this 
respect  than  even  wool.  Glass  projects  heat 
rapidly,  and  is  as  rapidly  coated  with  dew. 
But  bright  metals  attract  dew  much  less 
powerfully  than  other  bodies.  If  we  coat  a 
piece  of  glass,  partially,  with  bright  tin-foil, 
or  silver  leaf,  the  uncovered  portion  of  the 
glass  quickly  becomes  cold  by  radiation,  on 
exposure  to  a  clear  nocturnal  sky,  and  ac- 
quires moisture;  which  beginning  on  those 
parts  most  remote  from  the  metal,  gradu- 
ally approaches  it.  Thus  also,  if  we  coat 
outwardly  a  portion  of  a  window  pane  with 
tin-foil,  in  a  clear  night,  then  moisture  will 
be  deposited  inside,  on  every  part  except 
opposite  to  the  metal.  But  if  the  metal  be 
inside,  then  the  glass  under  and  beyond  it 
will  be  sooner,  or  most  copiously  bedewed. 
In  the  first  case,  the  tin-foil  prevents  the 
glass  under  it  from  dissipating  its  heat, 
and  therefore  it  can  receive  no  dew;  in  the 
second  case,  the  tin-foil  prevents  the  glass 


DEW 


DEW 


which  it  coats,  from  receiving  the  calorific 
influence  of  the  apartment,  and  hence  it  is 
sooner  refrigerated  by.|external  radiation, 
than  the  rest  of  the  pane.  Gold,  silver, 
copper,  and  tin,  bad  radiators  of  heat,  and 
excellent  conductors,  acquire  dew  with 
greater  difficulty  than  platina,  which  is  a 
niore  imperfect  conductor;  or  than  lead, 
zinc,  and  steel,  which  are  better  radiators. 

Hence  dew  which  has  formed  upon  a 
metal  will  often  disappear,  while  other 
substances  in  the  neighbourhood  retrain 
wet;  and  a  metal  purposely  moistened,  will 
become  dry,  while  neighbouring  bodies  are 
acquiring  moisture.  This  repulsion  of  dew 
is  communicated  by  metals  to  bodies  in 
contact  with.,  or  near  them.  Wool  laid  on 
metal  acquires  less  dew,  than  wool  laid  on 
the  contiguous  grass. 

If  the  night  becomes  cloudy,  after  having 
been  very  clear,  thoug-h  there  be  no  change 
with  respect  to  calmness,  a  considerable 
alteration  in  the  temperature  of  the  grass 
always  ensues.  Upon  one  such  night,  the 
grass,  after  having  been  12°  colder  than 
the  air,  became  only  2°  colder;  the  atmos- 
pheric temperature  being  the  same  at  both 
observations.  On  a  second  night,  grass  be- 
came 9°  warmer  in  the  space  of  an  hour 
and  a  half;  on  a  third  night,  in  less  than  45 
minutes,  the  temperature  of  the  grass  rose 
15°,  while  that  of  the  neighbouring  air  in- 
creased only  3^°.  During  a  fourth  night, 
the  temperature  of  the  grass  at  half  past 
9  o'clock  was  32°.  In  20  minutes  after- 
wards, it  was  found  to  be  39°,  the  sky  in 
the  mean  time  having  become  cloudy.  At 


the  end  of  20  minutes  more,  the  sky 
clear,  the  temperature  of  the  grass  was 
again  32°.  A  thermometer  lying  on  a  grass- 
plat,  will  sometimes  rise  several  degrees, 
when  a  cloud  comes  to  occupy  the  zenith 
of  a  clear  sky. 

Wher,  during  a  clear  and  still  night, 
different  thermometers,  placed  in  different 
situations,  were  examined,  at  the  same 
time,  those  which  were  situated  where 
most  dew  was  formed,  were  always  found 
to  be  the  lowest.  On  dewy  nights  the  tem- 
perature of  the  earth,  half  an  inch^or  an 
inch  beneath  the  surface,  is  always  found 
much  warmer  than  the  grass  upon  it,  or 
the  air  above  it.  The  differences  on  five' 
such  nights,  were  from  12  to  16  degrees. 

In  making  experiments  with  thermome- 
ters it  is  necessary  to  coat  their  bulbs  with 
silver  or  gold  leaf,  otherwise  their  glassy 
surface  indicates  a  lower  temperature  than 
that  of  the  air,  or  the  metallic  plate  it 
touches.  Swandown  seems  to  exhibit  great- 
er cold,  on  exposure  to  the  aspect  of  a 
clear  sky,  than  any  thing  else.  When  grass 
is  14°  below  the  atmospheric  temperature, 
swanclown  is  commonly  15°.  Fresh  un- 
broken straw  and  shreds  of  paper,  rank  in 
this  respect  with  swandovvn.  Charcoal, 
lampblack,  and  rust  of  iron,  are  also  very 
productive  of  cold.  Snow  stands  4°  or  5° 
higher  than  swanclown  laid  upon  it  in  a  clt- ar 
night. 

The  following  tabular  view  of  observa- 
tions by  Dr.  Wells,  is  peculiarly  instruc- 
tive:— 


6h.  45' 

7k. 

7h.  20' 

7h.  40' 

8A.  45' 

Heat  of  the  air  4  feet  above  the  grass, 

603° 

60|Q 

59« 

53" 

54° 

wool  on  a  raised  board,      -     - 

53  i 

54£ 

51$ 

48£ 

444 

swandown  on  the  same,     -     - 

54£ 

53 

51 

47^ 

42:1 

surface  of  the  raised  board,  - 

58 

57 

55i 

— 

—  —  —  —    grass-plat,  

53 

51 

49£ 

49 

42 

The  temperature  always  falls  in  clear 
nights,  but  the  deposition  of  dew,  depend- 
ing on  the  moisture  of  the  air,  may  occur 
or  not.  Now,  if  cold  were  the  effect  of 
dew,  the  cold  connected  with  dew  ought 
to  be  always  proportional  to  the  quantity 
of  that  fluid;  but  this  is  contradicted  by 
experience.  On  the  other  hand,  if  it  be 
granted  that  dew  is  water  precipitated 
from  the  atmosphere,  by  the  cold  of  the 
body  on  which  it  appears,  the  same  degree 
of  cold  in  the  precipitating  body  may  be 
attended  with  much,  with  little,  or  with 
no  dew,  according  to  the  existing  state  of 
the  air  in  regard  to  moisture,  all  of  which 
circumstances  are  found  really  to  take 
place.  The  actual  precipitation  of  dew, 
indeed,  ought  to  evolve  heat. 

A  very  few  degrees  of  difference  of  t.crrr- 


perature  between  the  grass  and  the  atmos- 
phere  is  sufficient  to  determine  the  forma- 
tion of  dew,  when  the  air  is  in  a  proper 
state.  But  a  difference  of  even  30°,  or 
more,  sometimes  exists,  by  the  radiation 
of  heat  from  the  earth  to  the  heavens.  And 
hence,  the  air  near  the  refrigerated  sur- 
face must  be  colder  than  that  somewhat 
elevated.  Agreeably  to  Mr.  Six's  observa- 
tions, the  atmosphere,  at  the  height  of  220 
feet,  is  often,  upon  such  nights,  10°  warmer 
than  what  it  is  seven  feet  above  the  ground. 
And  had  not  the  lower  air  thus  imparted 
some  of  its  heat  to  the  surface,  the  latter 
would  have  been  probably  40°  under  the 
temperature  of  the  air. 

Insulated  bodies,   or  prominent  points, 
are  sooner  covered  with  hoar-frost  and  dew 
others?  teaiise  tire  equilibrium  of 


DEW 


DEW 


tfceir  temperature  is  more  difficult  to  be 
restored.  As  ae'.-ial  stillness  is  necessary 
to  the  cooling*  effect  of  radiation,  we  can 
understand  why  the  hurtful  effects  of  cold, 
heavy  fog's,  and  dews,  occur  chiefly  in  hol- 
low and  cnniiiien  places,  and  less  frequently 
on  hills  In  like  manner,  the  leaves  of 
trees  often  remain  dry  throughout  the 
the  night,  while  the  blades  of  grass  are 
covered  with  dew. 

No  direct  experiments  can  be  made  to 
ascertain  the  manner  in  which  clouds  pre- 
vent 6r  lessen  the  appearance  of  a  cold  at 
night,  upon  the  surface  of  the  earth,  greater 
than  that  of  the  atmosphere.  But  it  may 
be  concluded  from  the  preceding  observa- 
tions, that  they  produce  this  effect  almost 
entirely  by  radiating-  heat  to  the  earth,  in 
return  for  that  which  they  intercept  in  its 
progress  from  the  earth  towards  the  hea- 
vens. The  heat  extricated  by  the  conden- 
sation of  transparent  vapour  into  cloud 
must  soon  be  dissipated;  whereas,  the  ef- 
fect of  greatly  lessening-  or  preventing-  al- 
together the  appearance  of  a  greater  cold 
on  the  earth  than  that  of  the  air,  will  be 
produced  by  a  cloudy  sky  during-  the  whole 
of  a  long-  night. 

We  can  thus  explain,  in  a  more  satisfac- 
tory manner  than  has  usually  been  done, 
the  sudden  warmth  that  is  felt  in  winter, 
when  a  fleece  of  clouds  supervenes  in  clear 
frosty  weather.  Chemists  ascribed  this  sud- 
den and  powerful  change  to  the  disengage- 
ment of  the  latent  heat  of  the  condensed 
vapours;  but  Dr.  Wells's  thermometric  ob-- 
servalions  on  the  sudden  alternations  of 
temperature  by  cloud  and  clearness,  ren- 
der that  opinion  untenable.  We  find  the 
atmosphere  itself,  indeed,  at  moderate  ele- 
vations, of  pretty  uniform  temperature, 
while  bodies  at  the  surface  of  the  ground 
suffer  great  variations  in  their  temperature. 
This  single  fact  is  fatal  to  the  hypothesis 
derived  from  the  doctrines  of  latent  heat. 

"  I  had  often,"  says  Dr.  Wells,  "  smiled, 
in  the  pride  of  half  knowledge,  at  the 
means  frequently  employed  by  gardeners, 
to  protect  tender  plants  from  cold,  as  it 
appeared  to  me  impossible  that  a  thin  mat, 
or  any  such  flimsv  substance,  could  prevent 
them  from  attaining  the  temperature  of  the 
atmosphere,  by  which  alone  I  thought  them 
liable  to  be  injured.  But  when  1  had  learn- 
ed, that  bodies  on  the  surface  of  the  earth 
become,  during-  a  still  and  serene  night, 
colder  than  the  atmosphere,  by  radiating 
their  heat  to  the  heavens,  1  perceived  im- 
mediately a  just  reason  ibr  the  practice, 
which  I  had  before  deemed  useless,  lie- 
ing  desirous,  however,  of  acquiring-  some 
precise  information  on  this  subject,  1  iixtd 
perpendicularlv,  in  the  earth  of  a  grass- 
pi  it,  four  small  sticks,  and  over  their  up- 
f,-i  extrc'iuitics,  which  were  t»ix  inches 
VfK..  i. 


above  the  grass,  and  formed  the  corners 
of  a  square  whose  sides  were  two  feet 
long,  I  drew  tightly  a  very  thin  cambric 
handkerchief.  In  this  disposition  of  things, 
therefore,  nothing  existed  to  prevent  the 
free  passage  of  air  from  the  exposed  grass 
to  that  which  was  sheltered,  except  the 
four  small  sticks,  and  there  was  no  sub- 
stance to  radiate  downwards  to  the  latter 
grass,  except  the  cambric  handkerchief.'* 

The  sheltered  grass,  however,  was  found 
nearly  of  the  same  temperature  as  the  air, 
while  the  unsheltered  was  5°  or  more  cold- 
er. One  night  the  fully  exposed  grass  was 
11°  colder  than  the  air;  but  the  sheltered 
grass  was  only  3®  colder.  Hence  we  se* 
the  power  of  a  very  slight  awning,  to  avert 
or  lessen  the  injurious  coldness  of  the 
ground.  To  have  the  full  advantage  of 
such  protection  from  the  chill  aspect  of 
the  sky,  the  covering  should  not  touch  the 
subjacent  bodies.  Garden  walls  act  partly 
on  the  same  principle.  Snow  screens  plants 
from  this  chilling  radiation.  In  warm  cli- 
mates, the  deposition  of  dewy  moisture  on. 
animal  substances  hastens  their  putrefac- 
tion. As  this  is  apt  to  happen  only  in  clear 
nights,  it  was  anciently  supposed  that  bright 
moonshine  favoured  animal  corruption. 

From  this  rapid  emission  of  heat  from, 
the  surface  of  the  ground,  we  can  now  ex- 
plain the  formation  of  ice  during  the  night 
in  Bengal,  while  the  temperature  of  the  air 
is  above  32°.  The  nights  most  favourably 
for  this  effect,  are  those  which  are  the 
calmest  and  most  serene,  and  on  which  the 
air  is  so  dry  as  to  deposite  little  dew  after 
midnight.  Clouds  and  frequent  changes 
of  wind  are  certain  preventives  of  conge- 
lation. 300  persons  are  employed  in  this 
operation  at  one  place.  The  enclosures 
formed  on  the  ground  are  four  or  five  feet 
wide,  and  have  walls  only  four  inches  high. 
In  these  enclosures,  previously  bedded  with 
dry  straw,  broad,  shallow,  unglazed  earthen 
pans  are  set,  containing  unboiled  pump-wa- 
ter. Wind,  which  so  greatly  promotes  eva- 
poration, prevents  the  freezing  altogether, 
and  dew  forms  in  a  greater  or  less  degree 
during  the  whole  of  the  nights  most  pro- 
ductive of  ice.  If  evaporation  were  con- 
cerned in  the  congelation,  wetting  the  straw 
would  promote  it.  But  Mr.  Williams,  in 
the  8.3d  vol.  of  the  Phil.  Trans,  says,  that 
itb  necasaury  to  the  success  of  the  process 
that  the  straw  be  drii.  In  proof  of  this  lie 
mentions,  that  when  the  straw  becomes  wet 
by  accident  it  is  renewed;  and  that  when 
he  purposely  wetted  it  in  some  of  the  in- 
closures,  the  formation  of  ice  there  was  al- 
ways prevented.  Moist  straw  both  conducts 
heat  and*  raises  vapour  from  the  ground,  so 
as  to  obstruct  the  congelation.  According 
to  Mi-.  Leslie,  water  stands  at  the  head  of 
radiating  substances,  bee  CA-u.ou.tv,.* 


DIA 


DIA 


*  DIALLASS.    A  species  of  the  genus  Schil- 
ler spar,    Diallage  has  a  grass-green  colour. 
It  occurs  massuve  or  disseminated.     Lustre 
glistening  and  pearly.     Cleavage  imperfect 
double.     Translucent.     Harder   than   fluor 
spar.     Brittle.     Sp.gr.  31.    It  melts  before 
the  blow-pipe  into  a  gray  or  greenish  ena- 
mel.    Its  constituents  are  50  silica,  11   alu- 
mina, 6  magnesia,  13  lime,  5.3  oxide  of  iron, 
1.5  oxide  of  copper,  7'5  oxide  of  chrome. — 
Vauquelin      It  occurs  in  the  island  of  Corsi- 
ca, and  in  Mont  Rosa  in  Switzerland,  hl«ng 
with    saussurite.     It  is  the  verde  di  Corsica 
duro  of  artists,  by  whom  it  is  fashioned  into 
ring-stones  and  snuff-boxes.     It  is  the  sma- 
ragdite  of  Saussure. 

The  diallage  in  the  rock  is  called  gabbro.* 

*  D'A.voxu.     Colours  white  and  gray,  also 
red,  brown,  yellow,  green,  blue,  and  black. 
The  two  last  are  rare.     When  cut  it  exhi- 
bits a  beautiful  play  of  colours  in  the  sunbeam. 
It  occurs  in  rolled  pieces,  and  also  crystal- 
lized :  1st,  In  the  octohedron,  in  which  each 
pl-me  is  inclined  to  the  i  djacent,  at  an  angle 
of  1U9C  28'  16".     The-  faces  are  usually  cur- 
v.lm.-ar.     This  is  the  fundamental  figure. — 
2d,  A  simple  three-sided  pyramid,  truncated 
on  ail  the  angles.     3d,  A  segment,  of  the  oc- 
tohedron.    4th,  Twin  Crystal    5th,  Octohe- 
dron,   with  all  the  edges  truncated.     6th, 
Octohedron,  flatly  bevelled  on  all  the  edges. 
7th,  Khornboidal  dodecahedron.     8th,  Octo- 
hedron with  convex  faces,  in  which  each  is 
divided  into  three  triangular  ones,  forming 
altogether  24  faces.      9th,    Octohedron,  in 
which  each  convex  face  is  divided  into  six 
planes,  forming  48  in  all.     10th,  Rhomboi- 
dal  dodecahedron,  with   diagonally  broken 
planes,     llth,  A  flat  double  three-sided  py- 
ramid.    I2rh,  Very  flat  double  three-sided 
pyramid,  with  cylindrical  convex  faces.  13th, 
Very   flat  double  six-sided  pyramid.     14th, 
Cube  truncated  on  the  edges.  Crystal  small. 
Surface  rough,  uneven,  or  streaked.  Lustre 
splendent,  and  internally  perfect  adamantine. 
Cleavage  octohedral,  or  parallel  to  the  sides 
oi  an  octohedron.  Foliated  structure.  Frag- 
ments octohedral  or  tetrahedral.  Semi  trans- 
pftrent.    Refracts  single.  Scratches  all  known 
minerals.     Rather  easily  frangible.     Streak 
gray.  Sp.  gr.  3.4  to  3-6l   It  consists  of  pure 
carbon,   as  we  shall  presently  demonstrate. 
When  rubbed,  whether  in  the  rough  or  po- 
lished  state,    it    shows  positive   electricity; 
whereas  rough  quartz  affords  negative.    It 
becomes  phosphorescent  on  exposure  to  the 
sun,  or  the  electric  spark,  and  shines  with  a 
fiery  light.     In  its  power  of  refracting  light 
it  is  exceeded  only  by  red  lead-ore,  and  or- 
pimeut.     It  reflects  all  the  light  falling  on 
its  posterior  surface  at  an  angle  of  incidence 
greater  than  24°  13',  whence  its  great  lustre 
is  urriv.-d.     Artificial  gerns  reflect  the  half 
of  this  light.     It  occurs  in  imbedded  grains 
and  crystals  in  a  sandstone  in  Brazil,  which 


rests  on  chlorite  and  clay-slate.  In  India 
the  diamond  bed  of  clay  is  underneath  beds 
of  red  or  bluish -black  clay;  and  also  in  allu- 
vial tracts  both  in  India  and  Brazil.  For  the 
mode  of  working  diamond  mines,  and  cutting 
and  polishing  diamonds,  consult  Jameson's 
Mineralogy,  vol.  i.  p.  11. 

The  diamond  is  the  most  valued  of  all  mi- 
nerals. Dr.  Wollaston  has  explained  the 
cutting  principle  of  glaziers'  diamonds,  with 
his  accustomed  sagacity,  in  the  Phil.  Trans, 
for  1816. 

The  weight,  and  consequently  the  value 
of  diamonds,  is  estimated  in  carats,  one  of 
which  is  equal  to  four  grains,  and  the  price 
of  one  diamond,  compared  to  that  of  another 
of  equal  colour,  transparency,  purity,  form, 
&c.  is  as  the  squares  of  the  respective  weights. 
The  average  price  of  rough  diamonds  that 
are  worth  working,  is  about  L.  2  for  the  first 
carat.  The  value  of  a  cut  diamond  being 
equal  to  that  of  a  rough  diamond  of  double 
weight,  exclusive  of  the  price  of  workman- 
ship, the  cost  of  a  wrought  diamond  of 


1  carat  is 

2  do.   is  23 

3  do.   is  32 

4  do    is  42 


L.8 

X  L.8,  =  32 
X  L.8,  =  72 
X  L.8,  =  128 


100   do.   is  1002   x  L.8,  =  80000. 

This  rule,  however,  is  not  extended  t« 
diamonds  of  more  than  20  carats.  The  lar- 
ger ones  are  disposed  of  at  prices  inferior  to 
their  value  by  that  computation.  The  snow- 
white  diamond  is  most  highly  prized  by  the 
jeweller.  If  transparent  and  pure,  it  is  said 
to  be  of  the  first  water. 

The  carat  grain  is  different  from  the  Troy 
grain.  156  carats  make  up  the  weight  of 
one  oz.  troy;  or  6 12  diamond  grains  are  con- 
tained in  the  Troy  ounce. 

From  the  high  refractive  power  of  the 
diamond,  MM.  Biot  and  Arago  supposed 
that  it  might  contain  hydrogen.  Sir  H.  Da- 
vy, from  the  action  of  potassium  on  it,  and 
its  non-conduction  of  electricity,  suggested 
in  his  third  Bakerian  lecture  that  a  minute 
portion  of  oxygen  might  exist  in  it;  and  in 
his  new  experiments  on  the  fluoric  com- 
pounds, he  threw  out  the  idea,  that  it  might 
be  the  carbonaceous  principle,  combined 
with  some  new,  light,  and  subtle  element,  of 
the  oxygenous  and  chlorine  class. 

This  unrivalled  chemist,  during  his  resi- 
dence at  Florence  in  March  1814,  made 
several  experiments  on  the  combustion  of 
the  diamond  and  of  plumbago  by  means  of 
the  great  lens  in  the  cabinet  of  natural  his- 
tory, the  same  instrument  as  that  employed 
in  the  first  trials  on  the  action  of  the  solar 
heat  on  'he  diamond,  instituted  in  1694  by 
Cosmo  III.  Grand  Duke  of  Tuscany.  He 
subsequently  made  a  series  of  researches  on 


DIA 


DIG 


the  combustion  of  different  kinds  of  char. 
coal  at  Rome.  His  mode  of  investigation 
was  peculiarly  elegant,  and  led  to  the  most 
decisive  results. 

He  found  that  diamond,  when  strongly 
ignited  by  the  lens,  in  a  thin  capsule  of  pla- 
tinum, perforated  with  many  orifices,  so  as  to 
admit  a  free  circulation  of  air,  continued  to 
burn  with  a  steady  brilliant  red  light,  visible 
in  the  brightest  sunshine,  after  it  was  with- 
drawn from  the  focus.  Some  time  after  the 
diamonds  were  removed  out  of  the  focus, 
indeed,  a  wire  of  platina  that  attached  them 
to  the  tray  was  fused,  though  their  weight 
was  only  1.84  grains.  His  apparatus  con- 
sisted of  clear  glass  globes  of  the  capacity  of 
from  14  to  40  cubic  inches,  having  single  a- 
pertures  to  which  stop-cocks  were  attached 
A  small  hollow  cylinder  of  platinum  was  at- 
tached to  one  end  of  the  stop-cock,  and  was 
mounted  with  the  Iktle  perforated  capsule 
for  containing  the  diamond.  When  the  ex- 
periment was  to  be  made,  the  globe  con- 
taining the  capsule  and  the  substance  to  be 
burned  was  exhausted  by  an  excellent  air 
pump,  and  pure  oxygen,  from  chlorate  of 
potash,  was  then  introduced.  The  change 
of  volume  in  the  gas  after  combustion  was 
estimated  by  means  of  a  fine  tube  connected 
with  a  stop-cock,  adapted  by  a  proper  screw 
to  the  stop-cock  of  the  globe,  and  the  ab- 
sorption was  judged  of  by  the  quantity  of 
mercury  that  entered  the  tube,  which  af- 
forded a  measure  so  exact,  that  no  altera- 
tion however  minute  could  be  overlooked. 
He  had  previously  satisfied  himself  that  a 
quantity  of  moisture,  less  than  l-100th  of  a 
grain,  is  rendered  evident  by  deposition  on 
a  polished  surface  of  glass ;  for  a  piece  of 
paper  weighing  one  grain  was  introduced 
into  a  tube  of  about  four  cubic  inches  capa- 
city, whose  exterior  was  slightly  heated  by 
a  candle.  A  dew  was  immediately  percep- 
tible on  the  inside  of  the  glass,  though  the 
paper,  when  weighed  in  a  balance  turning 
with  1  100th  of  a  grain,  indicated  no  appre- 
ciable diminution. 

The  diamonds  were  always  heated  to  red- 
ness before  they  were  introduced  into  the 
capsule.  During  their  combustion,  the  glass 
globe  was  kept  cool  by  the  application  of 
water  to  that  part  of  it  immediately  above 
the  capsule,  and  where  the  heat  was  great- 
est. 

From  the  results  of  his  different  experi- 
ments, conducted  with  the  most  unexcep- 
tionable precision,  it  is  demonstrated,  that 
diamond  affords  no  other  substance  by  its 
combustion  than  pure  carbonic  acid  gas ; 
and  that  the  process  is  merely  a  solution  of 
diamond  in  oxygen,  without  any  change  in 
the  volume  of  the  gas.  It  likewise  appears, 
that  in  the  combustion  of  the  different  kinds 
of  charcoal,  water  is  produced ;  and  that 
from  the  diminution  of  the  volume  of  the 
oxygen,  there  is  every  reason  to  bejievethat 


the  water  is  formed  by  the  combustion  of 
hydrogen  existing  in  strongly  ignited  char- 
coal. As  the  charcoal  from  oil  of  turpen- 
tine left  no  residuum,  no  other  cause  but  the 
presence  of  hydrogen  can  be  assigned  for 
the  diminution  occasioned  in  the  volume  of 
the  gas  during  its  combustion. 

The  only  chemical  difference  perceptible 
between  diamond  and  the  purest  charcoal  is, 
that  the  last  contains  a  minute  portion  of 
hydrogen  ;  but  can  a  quantity  of  an  element, 
less  in  some  cases  than  1 -50,000th  part  of 
the  weight  of  the  substance,  occasion  so 
great  a  difference  in  physical  and  chemical 
characters?  The  opinion  of  Mr.  Tennant, 
that  the  difference  depends  on  crystalliza- 
tion, seems  to  be  correct.  Transparent  so- 
lid bodies  are  in  general  non-conductors  of 
electricity  ;  and  it  is  probable  that  the  same 
corpuscular  arrangements  which  give  to  mat- 
ter the  power  of  transmitting  and  polarizing 
light,  are  likewise  connected  with  its  rela- 
tions to  electricity.  Thus  water,  the  hy- 
drates of  the  alkalis,  and  a  number  of  other 
bodies  which  are  conductors  of  electricity 
when  fluid,  become  non-conductors  in  their 
crystallized  form. 

That  charcoal  is  more  inflammable  than 
the  diamond,  may  be  explained  from  the 
looseness  of  its  texture,  and  from  the  hydro- 
gen it  contains.  But  the  diamond  appears 
to  burn  in  oxygen  with  as  much  facility  as 
plumbago,  so  that  at  least  one  distinction 
supposed  to  exist  between  the  diamond  and 
common  carbonaceous  substances  is  done 
away  by  these  researches.  The  power  pos- 
sessed by  certain  carbonaceous  substances  of 
absorbing  gases,  and  separating  colouring 
matters  from  fluids,  is  probably  mechanical, 
and  dependent  on  their  porous  organic 
structure  ;  for  it  belongs  in  the  highest  de- 
gree to  vegetable  and  animal  charcoal,  and 
it  does  not  exist  in  plumbago,  coak,  or  an- 
thracite. 

The  nature  of  the  chemical  difference  be- 
tween the  diamond  and  other  carbonaceous 
substances,  may  be  demonstrated  by  ignit.ng 
them  in  chlorine,  when  muriatic  acid  is  pro- 
duced from  the  latter,  but  not  the  former. — 
The  visible  acid  vapour  is  owing  to  the  mois- 
ture present  in  the  chlorine  uniting  to  the 
dry  muriatic  gas  But  charcoal,  after  be- 
ing intensely  ignited  in  chlorine,  is  not  al- 
tered in  its  conducting  power  or  colour  — 
This  circumstance  is  in  favour  of  the  opi- 
nion, that  the  minute  quantity  of  hydrogen 
is  not  the  cause  of  the  great  difference  be- 
tween the  physical  properties  of  the  diamond 
and  charcoal.* 

It  does  not  appear  that  any  sum  exceed- 
ing one  hundred  and  fifty  thousand  pounds 
has  been  given  for  a  diamond. 

*DICHROITE.   See  IOHTE.* 

DIGESTION.  The  slow  action  of  a  splvent 
upon  any  substance. 


DIG 


DIG 


*  DTGHSTTO-V.  The  conversion  of  food  into 
thyme  in  the  stomach  of  animals  by  the 
solvent  power  of  the  gastric  juice.  Some 
interesting  researches  have  been  lately  made 
on  this  subject  by  Dr.  Wilson  Philip  and  Dr. 
Front. 

JPltenomenrt)  &?<!.  of  digestion  in  a  rabbit. — 
A  rabbit  which  had  been  kept  without  food 
for  twelve  hours,  was  fed  upon  a  mixture  of 
bran  and  oats.  About  two  hours  afterwards 
\t  was  killed,  and  examined  immediately 
while  still  warm,  \vhen  the  following  cir- 
cumstances were  noticed:  The  stomach  Tvas 
rnoderately  distended,  with  a  pulpy  mass, 
which  consisted  of  the  food  in  a  minute  state 
of  division,  and  so  intimately  mixed,  that  the 
different  articles  of  which  it  was  composed 
could  be  barely  recognized.  The  digestive 
process,  however,  did  not  appear  to  have 
taken  place  equally  thrnughouUhe  mass,  but 
seemed  to  be  confined  principally  to  the 
superficies,  or  where  it  was  in  contact  with  tiie 
stomach.  The  smell  of  this  muss  was  pecu- 
liar, and  difficult  to  be  described.  It  might 
be  denominated  fatuous  and  disagreeable. 
On  being  wrapped  up  in  a  piece  of  linen, 
and  subjected  to  moderate  pressure,  it  yield- 
ed upwards  of  half  a  fluid  ounce  of  an  opaque 
reddish-brown  fluid,  which  instantly  red- 
dened litmus  paper  very  strongly.  It  in- 
stantly coagulated  milk,  and,  moreover, 
seemed  to  possess  the  property  of  reclis- 
solving  the  curd  and  converting  it  into  a  fluid, 
Very  similar  to  itself  in  appearance.  It  was 
not  coagulated  by  heat  or  acids;  and,  m 
short,  did  not  exnibit  any  evidence  <>f  nit,  a!- 
tmminous  principle.  On  being  evaporate  u  to 
dryness,  and  burned,  it  yielded  very  copious 
traces  of  an  alkaline  muriate,  with  slight 
traces  of  an  alkaline  phosphate  and  sulphate; 
also  of  various  earthy  salts,  as  the  sulpha  te 
phesphate,  and  carbonate  of  lime. 

"The  fi ret  thing,"  says  Dr.  P.  "which 
strikes  the  eye  on  inspecting  the  stomachs 
of  rabbits  which  have  lately  eaten,  is,  that 
the  new  is  never  mixed  with  the  old  food. 
The  former  is  always  found  in  the  centre  sur- 
rounded on  all  sides  by  ihe  old  food,  except 
that  on  the  upper  part  between  the  new 
food  and  the  smaller  curvature  of  the  stom- 
ach, there  is  sometimes  little  or  no  old  food. 
If  the  old  and  the  new  food  are  of  different 
kinds,  and  the  animal  be  killed  after  taking 
the  latter,  unless  a  great  length  of  time  has 
elapsed  after  taking  it,  the  line  of  separation 
is  perfectly  evident,  so  that  the  old  may  be 
removed  without  disturbing  the  new  food. 

"  it  appears  that  in  proportion  as  the  food 
is  digested,  it  is  moved  along  the  great  cur- 
vature, when  the  change  in  it  is  rendered 
Biore  perfect,  to  the  pvloric  portion.  The 
layer  of  food  lying  next  the  surface  of  the 
Stomach,  is  first  digested.  In  proportion  as 
this  undergoes  the  proper  change,  it  is  moved 
on  by  tiie  niiiscuLr  action  of  the  stomach, 


and  that  next  in  turn  succeeds  to  undergo 
the  same  change.  Thus  a  continual  motion 
is  going  on;  that  part  of  the  food  which  lies 
next  the  surface  of  the  stomach  passing  to- 
wards the  pylorus,  and  the  more  central 
parts  approaching  the  surface." 

Dr.  Philip  has  remarked,  that  the  great 
end  of  the  stomach  is  the  part  most  usually 
found  acted  upon  by  the  digestive  fluids 
after  death. 

The  following  phenomena  were  observed 
by  Dr.  Prout:  — 

Comparative  examination  of  the  contents  of 
the  duodena  of  t?vo  dogs,  one  of  -which  had 
been  fed  on  vegetable  food,  the  other  on  animal 
food  rmhj.  The  chymous  mass  from  vegeta- 
ble food  (principally  bread)  was  composed 
of  a  semi-fluid,  opaque,  yellowish-white  part, 
containing  another  portion  of  a  similar  co- 
lour, but  firmer  consistence,  mixed  with  it. 
Its  specific  gravity  was  1.056.  It  showed 
no  traces  of  a  free  acid,  or  alkali;  but  coagu- 
lated milk  completely,  when  assisted  by  a 
gentle  heat. 

That  from  animal  food  was  more  thick 
and  viscid  than  that  from  vegetable  food, 
and  its  colour  was  more  inclined  to  red.  Its 
sp.  gr.  was  1.022.  It  showed  no  truces  of 
a  free  acid  or  alkali;  nor  did  it  coagulate 
milk  even  when  assisted  by  the  most  favour- 
able circumstances. 

On  being  subjected  to  analysis,  these  two 
specimens  were  found  to  consist  of 

Chyme  from     Chyme  from 
vegetable  food,   ammul  lood. 

Water,  bb.6  bO.O 

Gastric  principle,  united 

with    the    alimentary 

matters,  and  apparent- 

ly    constituting     the 

chyme,    mixed     with 

excrementitious    mat- 

ter, ...  6.0  15.8 

Albuminous  matter,  part- 

ly consisting  of  fibrin, 

derived  from  the  flesh 

on  which  the  animal 

had  been  fed, 


Biliary  principle,       -  1.6 

Vegetable  gluten?     -  5.0 


Saline  matters, 
Insoluble  residuum, 


0.7 

0.2 

100.0 


1.3 

1.7 

0.7 
0.5 

100.0 


Very  similar  phenomena  were  observed  in 
other  instances.  But  when  the  animal  was 
opened  at  a  longer  period  after  feeding,  Dr. 
Prout  generally  found  much  stronger  evi- 
dences of  albuminous  matter,  not  only  in 
the  duodenum,  but  nearly  throughout  th§ 
whole  of  the  small  intestines.  The  quantity, 
hov.'i  ver,  was  generally  very  minute  in  the 
iieuin;  and  where  it  enters  "the  coecum,  no 


DIS 


DIS 


traces  of  this  principle  could  be  perceived 
See  SANGUIFICATION.* 

DIGESTIVE  SALT.     Muriate  of  potash. 

DIGESTER.  The  digester  is  an  instrument 
invented  by  Mr.  Papin  about  the  beginning 
of  the  last  century.  It  is  a  strong  vessel  of 
copper  or  iron,  with  a  cover  adapted  to 
screw  on  with  pieces  of  felt  or  paper  inter- 
posed. A  valve  with  a  small  aperture  is 
made  in  the  cover,  the  stopper  of  which 
valve  may  be  more  or  less  loaded  either  by 
actual  weights,  or  by  pressure  from  an  ap- 
paratus on  the  principle  of  the  steelyard. 

The  purpose  of  this  vessel  is  to  prevent 
the  loss  of  heat  by  evaporation.  The  solvent 
power  of  water  when  heated  in  this  vessel 
is  greatly  increased. 

*  DIOPSIDE.     A  sub-species  of  oblique  edg- 
ed augite.     Its  colour  is  greenish-white.    It 
occurs  massive,  disseminated,  and  crystalliz- 
ed:   1.  In  low  oblique  four-sided  prisms.    2. 
The  same,   truncated   on  the  acute  lateral 
edges,  bevelled  on  the  obtuse   edges,  and 
the  edge  of  the   bevelment  truncated.    3. 
Eight-sided   prisms.     The    broader   lateral 
planes  are    deeply    longitudinally  streaked, 
the  others  are  smooth.     Lustre  shining  and 
pearly.     Fracture   uneven.     Translucent. — 
As  hard  as  augite.     Sp.  gr.  3.  3      It  melts 
with    difficulty    before    the    blow-pipe.       It 
consists  of  57.5.  silica,  18.25  magnesia   16.5 
lime,  6  iron  and  manganese. — Lmtgier.     It 
is  found  in  the  hill  Ciarmetta  in  Piedmont; 
also  in  the  black   rock   at  Mussa,    near  the 
town  of  Ala,  in  veins  along  with  epidote    or 
pistacite,  and  hyacinth -red  garnets.     It  is  the 
Alalite  and  Mussite  of  Bonvoisin.* 

*  DIOPTASK.    Emerald  copper-ore.* 

*  DIPPEL'S  animal  oil,  an  oily  matter  ob- 
tained in  the  igneous  decomposition  of  horns 
in  a  retort.     Rectified,  it  becomes  colourless, 
aromatic,  and  as  light  and  volatile  as  ether. 
It  changes  sirup  of  violets  to  a  green  from 
its  holding  a  little  ammonia  in  solution.* 

*  DIPYHE.     Schmelszstein. 

This  mineral  is  distinguished  by  two  char- 
acters; it  is  fusible  with  intumescence  by 
the  blow-pipe,  and  it  e mits  on  coals  a  taint 
phosphorescence.  It  is  found  in  small  prisms 
united  in  bundles,  of  a  grayish  or  reddish- 
white.  These  crystals  are  splendent,  hard 
enough  to  scratch  glass;  their  longitudinal 
fracture  is  lamellar,  and  their  cross  fracture 
conchoidal.  Its  sp.  gr.  is  2.63.  The  primi- 
tive form  appears  to  be  the  regular  six-sided 
prism.  It  consists  of  60  silica,  24  alumina, 
10  lime,  2  water,  and  4  loss. —  Vmtquelin.  It 
occurs  in  a  white  or  reddish  steatite,  mingled 
with  sulphuret  of  iron,  on  the  right  bank  of 
the  torrent  of  Mauleon  in  the  western  Py- 
renees.* 

*  DISTILLATION.      The   yaporization   and 
subsequent   condensation   of   a   liquid,    by 
means  of  an  alembic,  or  still  and  refrigera- 
tory, or  of  a  retort  and  a  receiver.    The  old 


distinctions  of  distiUatio  per  latiis,  per  asctn- 
sum,  and  f>er  decenaiim,  are  now  discarded. 

Under  LABORATOH?,  a  drawing  and  de- 
scription of  a  large  still  of  an  ingenious  con- 
struction is  given.  The  late  celebrated  Mr. 
Watt  having  ascertained,  that  liquids  boiled 
in  vaciio  at  much  lower  temperatures  than 
under  the  pressure  of  the  atmosphere,  appli- 
ed this  fuct  to  distillation;  but  he  seems,  ac- 
cording to  Dr.  Black's  report  of  the  experi- 
ment, to  have  found  no  economy  of  fuel  in 
this  elegant  process ;  for  the  latent  heat  of 
the  vapour  raised  in  vacito,  appeared  to  be 
considerably  greater  than  that  raised  in  or- 
dinary circumstances.  Mr.  Henry  Tritton 
has  lately  contrived  a  very  simple  apparatus 
for  performing  this  operation  in  raciio  ;  and 
though  no  saving  of  fuel  should  be  made,  yet 
superior  flavour  may  be  secured  to  the  dis- 
tilled spirits  and  essential  oils,  in  conse- 
quence of  the  moderation  of  the  heat.  The 
still  is  of  the  common  form;  but  instead  of 
being  placed  immediately  over  a  fire,  it  is 
immersed  in  a  vessel  containing  hot  water. 
The  pipe  from  the  capital  bends  down  and 
terminates  in  a  cylinder  or  barrel  of  metal 
plunged  in  a  cistern  of  cold  liquid.  From 
the  bottom  of  this  barrel,  a  pipe  proceeds 
to  another  of  somewhat  larger  dimensions, 
which  is  surrounded  with  cold  water,  and 
furnished  at  its  top  with  an  exhausting 
syringe. 

The  pipe  from  the  bottom  of  the  still,  for 
emptying  it,  and  that  from  the  bottom  of 
each  barrel,  are  provided  with  stop-cocks. 
Hence,  on  exhausting  the  air,  the  liquid  will 
distil  rapidly,  when  the  body  of  the  alembic 
is  surrounded  with  boiling  water.  When  it 
is  wished  to  withdraw  a  portion  of  the  dis- 
tilled liquor,  the  stop-cock  at  the  bottom  of 
the  first  receiver  is  shut,  so  that  on  opening 
that  at  the  sec  >nd,  in  order  to  empty  it,  the 
vacuum  is  maintained  in  the  still.  It  is  evi- 
dent that  the  first  receiver  may  be  surround- 
ed with  a  portion  of  the  liquid  to  be  distil- 
led, as  I  have  already  explained  in  treating 
of  alcohol.  By  this  means  the  utmost  econ- 
omy of  fuel  may  be  observed.  . 

The  term  distillation,  is  often  applied  in 
this  countr),  to  the  whole  process  of  con- 
verting malt  or  other  saccharine  matter,  into 
spirits  or  alcohol. 

In  making  malt  whiskey,  one  part  of  bruis- 
ed malt,  with  from  four  to  nine  parts  of  bar- 
ley meal,  and  a  proportion  of  seeds  of  oats, 
corresponding  to  that  of  the  raw  grain,  is  in- 
fused in  a  mash-tun  of  cast  iron,  with  from 
12  to  13  wine  gallons  of  water,  at  150* 
Fahr.  for  every  bushel  of  the  mixed  farina- 
ceous matter.  The  agitation  then  given  by 
manual  labour  or  machinery  to  break  down 
and  equally  diffuse  the  lumps  of  meal,  con- 
stitutes the  process  of  mashing.  This  opera- 
tion continues  two  hours  or  upwards,  accord- 
ing to  the  proportion  of  tmmalte«i  barley;. 


DIS 


DIS 


during  which  the  temperature  is  kept  up,  by 
the  effusion  of  seven  or  eight  additional  gal- 
lons of  water,  a  few  degrees  under  the  boil- 
ing temperature.  The  infusion  termed  -wort 
having  become  progressively  sweeter,  is  al- 
lowed to  settle  for  two  hours,  and  is  run  off 
from  the  top,  to  the  amount  of  about  one- 
third  the  bulk  of  water  employed.  About 
eight  gallons  more  of  water,  a  little  under 
200°  F.  are  now  admitted  to  the  residuum, 
infused  £»r  nearly  half  an  hour  with  agita- 
tion, and  then  left  to  subside  for  an  fcour 
and  a  half,  when  it  is  drawn  off.  Some- 
times a  third  affusion  of  boiling  water,  equal 
to  the  first  quantity,  is  made,  and  this  infu- 
sion is  generally  reserved  to  be  poured  on 
new  farina;  or  it  is  concentrated  by  boiling 
and  added  10  the  former  liquors.  In  Scot- 
land, the  distiller  is  stipposed  by  law,  to  ex- 
tract per  cent  14  gallons  of  spirits,  sp.  gr. 
0.91917,  or  1  to  10  over  proof;  and  must  pay 
duty  accordingly.  Hence,  his  wort  must 
have  at  least  the  strength  of  55£  pounds  of 
saccharine  matter,  per  barrel,  previous  to 
letting  it  down  into  the  fermenting  tun;  and 
the  law  does  not  permit  it  to  be  stronger 
than  75  pounds.  Every  gallon  of  the  above 
spirits  contains  4.6  pounds  of  alcohol,  sp.gr. 
0.825,  and  requires  for  its  production  the 
complete  decomposition  of  twice  4.6  pounds 
of  sugar  =  9.2  pounds.  But  since  we  can 
never  count  on  decomposing  above  four- 
fifihs  of  the  saccharine  matter  of  wort,  we 
must  add  one-fifth  to  9.2  pounds,  when  we 
shall  have  11^  pounds  for  the  weight  of 
saccharine  matter,  equivalent  in  practice  to 
one  gallon  of  the  legal  spirits.  Hence,  the 
distiller  is  compelled  to  raise  the  strength  of 
lies  wort  up  to  nearly  70  pounds  per  barrel 
as  indicated  by  his  saccharometer.  This 
concentration  is  to  be  regretted,  as  it  mate- 
rially injures  the  flavour  of  the  spirit.  The 
thinner  worts  of  the  Dutch,  give  a  decided 
superiority  to  their  alcohols.  At  62  pounds 
per  barrel,  we  should  have  about  12  per 
cent  of  spirits  of  the  legal  standard. 

To  prevent  acetification,  it  is  necessary 
to  cool  the  worts  down  to  the  proper  fer- 
menting temperature  of  70°,  or  65°,  as  ra- 
pidly as  possible.  Hence,  they  are  pumped 
immediately  from  the  mash-tun  into  exten- 
sive wooden  troughs,  two  or  three  inches 
deep,  exposed  in  open  sheds  to  the  cool  air; 
or  they  are  made  to  traverse  the  convolu- 
tions of  a  pipe,  immersed  in  cold  water. — 
The  wort  being  now  run  into  the  ferment- 
ing1 tun,  yeast  is  introduced  and  added  in 
nearly  equal  successive  portions,  during  three 
days;  amounting  in  all  to  about  one  gallon,  for 
every  two  bushels  of  farinaceous  matter.  The 
temperature  rises  in  three  or  four  days,  to  its 
maximum  of  80°;  and  at  the  end  of  10  or  12 
days  the  fermentation  is  completed;  the  tuns 
being  closed  up  during  the  last  half  of  the 
period.  The  distillers  do  not  collect  th« 


yeast  from  their  fermenting  tuns,  but  allow 
it  to  fall  down,  on  the  supposition  that  it  en- 
hances  the  quantity  of  alcohol. 

The  specific  gravity  of  the  liquid  has  now 
probably  sunk  from  1.060,  that  of  wort 
equivalent  to  about  56  pounds  per  barrel,  to 
1.005,  or  1.000;  and  consists  of  alcohol  mix- 
ed with  undecomposed  saccharine  and  fari- 
naceous matter.  The  larger  the  proportion 
of  alcohol,  the  more  sugar  will  be  preserved 
unchanged;  and  hence  the  impolicy  of  the 
present  laws  on  distillation. 

Some  years  ago,  when  the  manufacturer 
paid  a  duty  for  the  season,  merely  according 
to  the  measurement  of  his  still,  it  was  his  in- 
terest to  work  it  off  with  the  utmost  possible 
speed.  Hence  the  form  of  still  and  furnace 
described  under  LABOUATOKY,  was  contrived 
by  some  ingenious  Scotch  distillers,  by  which 
means  they  could  work  off  in  less  than  four 
minutes,  and  recharge,  an  80  gallon  still;  an 
operation  which  had  a  few  years  before  last- 
ed several  days,  and  which  the  vigilant  fra- 
mers  of  the  law,  after  recent  investigation, 
deemed  possible  only  in  eight  minutes.  The 
waste  of  fuel  was  however  great.  The  du- 
ties being  now  levied  on  the  product  of  spi- 
rit, the  above  contest  against  time  no  longer 
exists.  It  has  been  supposed,  but  J  think 
on  insufficient  grounds,  that  quick  distilla- 
tion injures  the  flavour  of  spirits.  This  I 
believe  to  depend,  almost  entirely,  on  the 
mode  of  conducting  the  previous  fermenta- 
tion. 

In  distilling  off  the  spirit  from  the  ferment- 
ed wort  or  wash,  a  hydrometer  is  used  to  as- 
certain its  progressive  diminution  of  strength, 
and  when  it  acquires  a  certain  weakness, 
the  process  is  stopped  by  opening  the  stop- 
cock of  the  pipe,  which  issues  from  the  bot- 
tom of  the  still,  and  the  spent  wash  is  re- 
moved. There  is  generally  introduced  into 
the  still,  a  bit  of  soap,  whose  oily  principle 
spreading  on  the  surface  of  the  boiling  li- 
quor, breaks  the  large  bubbles,  and  of  course 
checks  the  tendency  to  froth  up.  The  spirits 
of  the  first  distillation,  called  in  Scotland 
low  wines,  are  about  0.975  sp.  gravity,  and 
contain  nearly  20  percent  of  alcohol  of  0.825. 
Redistillation  of  the  low  wines,  or  doubling, 
gives  at  first  the  fiery  spirit  called  first -shot, 
milky  and  crude,  from  the  presence  of  a  lit- 
tle oil.  This  portion  is  returned  into  the  low 
wines,  "What  flows  next  is  clear  spirit,  and 
is  received  in  one  vessel,  till  its  density  di- 
minish to  a  certain  degree.  The  remain- 
ing spirituous  liquor,  culled  faints,  is  mixed 
with  low  wines,  and  subjected  to  another  dis- 
tillation. 

The  manufacturer  is  hindered  by  law 
from  sending  out  of  his  distillery,  stronger 
spirits  than  1  to  10  over  hydrometer  proof, 
equivalent  to  sp.  gr.  0.90917;  or  weaker  spi- 
rits than  1  in  6  under  proof,  whose  sp.  gr. 
isfl.9385. 


DIS 


DOL 


The  following  is  said  to  be  the  Dutch 
mode  of  making  Geneva: — 

One  cwt.  of  barley  malt  and  two  cwts.  of 
rye  meal  are  mashed  with  460  gallons  of 
water,  heated  to  162°F.  After  the/orin^ 
have  been  infused  for  a  sufficient  time,  cold 
water  is  added,  till  the  wort  becomes  equiva- 
lent to  45  pounds  of  saccharine  matter  per 
barrel.  Into  a  vessel  of  500  gallons  capa- 
city, the  wort  is  now  put  at  the  temperature 
of  80°,  with  half  a  gallon  of  yeast.  The 
fermentation  instantly  begins,  and  is  finished 
in  48  hours,  during  which  the  heat  rises  to 
90°.  The  wash,  not  reduced  lower  than 
12  or  15  pounds  per  barrel,  is  put  into  the 
still  along  with  the  grains.  Three  distilla- 
tions are  required;  and  at  the  last,  a  few 
juniper  berries  and  hops  are  introduced  to 
communicate  flavour.  The  attenuation  of 
45  pounds  in  the  wort,  to  only  15  in  the 
wash  shows  that  the  fermentation  is  here 
very  imperfect  and  uneconomical;  as  indeed 
we  might  infer  from  the  small  proportion  of 
yeast,  and  the  precipitancy  of  the  process  of 
fermentation.  On  the  other  hand,  the  very 
large  proportion  of  porter  yeast  in  a  cor- 
rupting state,  used  by  the  Scotch  distillers, 
cannot  fail  to  injure  the  flavour  of  their 
spirits. 

Rum  is  obtained  from  the  fermentation  of 
the  coarsest  sugar  and  molasses  in  the  West 
Indies,  dissolved  in  water  in  the  proportion 
of  .nearly  a  pound  to  the  gallon.  The  yeast 
is  procured  chiefly  from  the  rum  tvort.  The 
preceding  details  give  sufficient  instruction 
for  the  conduct  of  this  modification  of  the 
process. 

Sykes*  hydrometer  is  now  universally 
used  in  the^collection  of  the  spirit  revenue 
in  Great  Britain.  It  consists,  first  of  a  flat 
stem,  3.4  inches  long,  which  is  divided  on 
both  sides  into  11  equal  pails,  each  of  which 
is  subdivided  into  two,  the  scale  being  num- 
bered from  0  to  11.  This  stem  is  soldered 
into  a  brass  ball  1.6  inch  in  diameter,  into 
the  under  part  of  which  is  fixed  a  small  co- 
nical stem  1.13  inch  long,  at  whose  end  is 
a  pear-shaped  loaded  bulb,  half  an  inch  in 
diameter.  The  whole  instrument,  which  is 
made  of  brass,  is  6.7  inches  long.  The  in- 
strument is  accompanied  with  8  circular 
weights,  numbered  10,  20,  30,40, 50, 60,70, 
80,  and  another  weight  of  the  form  of  a  paral- 
lelopiped.  Each  of  the  circular  weights  is  cut 
into  its  centre,  so  that  it  can  be  placed  on  the 
inferior  conical  stem,  and  slid  down  to  the 
bulb;  but  in  consequence  of  the  enlargement 
of  the  cone,  they  cannot  slip  off  at  the  bottom, 
but  must  be  drawn  up  to  the  thin  part  for  this 
purpose.  The  square  weight  of  the  form  of  a 
parallelepiped,  has  a  square  notch  in  one  of 
its  sides,  by  which  it  can  be  placed  on  the 
summit  of  the  stem.  In  using  this  instru- 
ment, it  is  immersed  in  the  spirit,  and  press- 
ed down  by  tire  hand  to  O,  till  the  whole  di- 


vided part  of  the  stem  be  wet.  The  force  of 
the  hand  required  to  sink  it,  will  be  a  guide 
in  selecting  the  proper  weight.  Having 
taken  one  of  the  circular  weights,  which  is- 
necessary  for  this  purpose,  it  is  slipped  on 
the  conical  stem.  The  instrument  is  again 
immersed  and  pressed  down  as  before  to  O, 
and  is  then  allowed  to  rise  and  settle,  at  any 
point  of  the  scale.  The  eye  is  then  brought 
to  the  level  of  the  surface  of  the  spirit,  and 
the  part  of  the  stem  cut  by  the  surface,  as 
seenfrom  below,  is  marked.  The  number 
thus  indicated  by  the  stem  is  added  to  the 
number  of  the  weight  employed,  and  with 
this  sum  at  the  side,  and  the  temperature  of 
the  spirits  at  the  top,  the  strength  per  cent  is 
found  in  a  table  of  6  quarto  pages.  «  The 
strength  is  expressed  in  numbers  denoting 
the  excess  or  deficiency  per  cent  of  proof- 
spirit  in  any  sample,  and  the  number  itself 
(having  its  decimal  point  removed  two  places 
to  the  left)  becomes  a  factor,  whereby  the 
gauged  content  of  a  cask  or  vessel  of  such, 
spirit  being-  multiplied,  and  the  product  be- 
ing added  to  the  gauged  content,  if  over 
proof,  or  deducted  from  it  if  under  proof, 
the  result  will  be  the  actual  quantity  of 
proof  spirit  contained  in  such  cask  or  ves- 
sel."* 

*DISTHENE.     See  CTASTITE.* 

*  DISTINCT    CONCHETJOXS.      A  term    in 

MlXERALOGY.* 

DOCIMASTIC  ART.  This  name  is  given  to 
the  art  of  assaying.  See  ASSAY,  BLOW- 
PIPE, ANALYSIS,  and  the  several  metals. 

*DOLOMITE.  Of  this  calcareo-magneaan 
carbonate,  we  have  three  sub-species 

1.  Dolomite,  of  which  there  are  two  kinds. 

§  1st.  Granular  Dolomite. 

White  granular.  It  occurs  massive,  and 
in  fine  granular  distinct  concretions,  loosely 
aggregated.  Lustre  glimmering  and  pearly. 
Fracture  in  the  large,  imperfect  slaty.  Faint- 
ly translucent.  As  hard  as  fluor.  Brittle 
Sp.  gr.  2.83.  It  effervesces  feebly  with 
acids.  Phosphorescent  on  heated  iron,  or 
by  friction.  Its  constituents  are  46.5  car- 
bonate of  magnesia,  52.08  carbonate  of  lime, 
0.25  oxide  of  manganese,  and  0.5  oxide  of 
iron.  Klaproth.  Beds  of  dolomite,  con- 
taining tremolite,  occur  in  the  island  of  lona, 
in  the  mountain  group  of  St.  Gothard,  in  the 
Appenines,  and  in  Carinthia.  A  beautiful 
white  variety  used  by  ancient  sculptors,  is 
found  in  the  Isle  of  Tenedos.  Jameson. 

The  flexible  variety  was  first  noticed  in 
the  Bprghese  palace  at  Rome;  but  the  other 
varieties  of  dolomite,  and  also  common  gra- 
nular limestone,  may  be  rendered  flexible, 
by  exposing  them  in  thin  and  long  slabs  to 
a  heat  of  480°  Fahr.  for  6  hours. 

§  2d,  Brown  Doloinite,  or  magnesian  lime- 
stone of  Tennant. 

Colour,  yellowish-gray  and  yellowish- 
brown.  Massive,  and  in  minute  granulai' 


DRA 


DYE 


concretions.  Lustre  internally  glistening. 
Fracture  splintery.  Translucent  on  the 
edges.  Harder  than  calcareous  spar.  Brittle. 
Sp.  gr.  of  crystals,  2.8.  It  dissolves  slowly, 
and  with  feeble  effervescence;  and  when 
calcined,  it  is  long  in  re-absorbing  carbonic 
acid  from  the  air.  Its  constituents  are, 
lime  29.5,  magnesia  20.3,  carbonic  acid 
47.2.  Alumina  and  iron  0.8.  Tennant.  In 
the  north  of  England  it  occurs  in  beds  of 
considerable  thickness,  and  great  extent, 
resting  on  the  Newcastle  coal  formatbn. 
In  the  Isle  of  Man,  it  occurs  in  a  limestone 
which  rests  on  gray-wacke.  It  occurs  in 
trap-rocks  in  Fifeshire.  When  laid  on  land 
after  being  calcined,  it  prevents  vegetation, 
unless  the  quantity  be  smalll. 

To  the  proceeding  variety  we  must  refer 
zjleocible  dolomite  found  near  Tinmouth  Cas- 
tle. It  is  >ello  wish -gray,  passing  into  cream- 
yellow.  Massive.  Dull.  Fraciure  earthy. 
Opaque.  Yields  readily  to  the  knife,  in 
thin  plates,  very  flexible.  Sp.  gr.  2.54;  but 
the  stone  is  porous.  It  dissolves  in  acids  as 
readily  as  common  carbonate  of  lirne.  Its 
constituents  are  said  to  be  62  carbona-.e  of 
lirne,  and  06  carbonate  of  magnesia.  When 
made  moderately  dry,  it  loses  its  flexibility; 
but  when  either  very  moist  or  very  dry,  it 
is  very  flexible. 

2d.  Columnar  Do'omite.  Colour  pale  gray- 
ish-white. Massive,  and  in  thin  prismatic 
concretions.  Cleavage  imperfect.  Fracture 
uneven.  Lustre  vitreous,  inclining  to  pearly. 
Breaks  into  acicular  fragments.  Feebly 
translucent.  Brittle.  Sp.  gr.  2.76.  Its  con- 
stituents are  51  carbonate  of  lime,  47  car- 
bonate of  magnesia,  1  carbonated  hydrate  of 
iron.  It  occurs  in  serpentine  in  Kussia. 

3d,  Compact  Dolomite,  or  Gurhoflte.  Co- 
lour snow-white.  Massive.  Dull.  Fracture 
rlat  conchoidal.  Slightly  translucent  on  the 
edges.  Semi-hard.  Difficultly  irangible.  Sp. 
g-r  2.76.  When  pulverized,  it  dissolves 
•with  effervescence  in  hot  nitric  acid.  It 
consists  of  70.5  carbonate  of  lime,  and  29.5 
carbonate  of  magnesia.  It  occurs  in  veins 
in  serpentine  rocks,  near  GurhofT,  in  Lower 
Austria.* 

DHACO-MITIGATUS.  Calomel.  See  MER- 
etjiir.* 

*  DRAGON'S  BLOOD.  A  brittle  dark  red 
coloured  resin,  imported  from  the  East  In- 
dies, the  product  afpterocarput  draco,  anddra- 
Gisna  draco.  It  is  insoluble  in  water,  but 
soluble  in  a  great  measure  in  alcohol.  The 
solution  imparts  a  beautiful  red  stain  to  hot 
marble.  It  dissolves  in  oils.  It  contains  a 
little  benzoic  acid.* 

*DaAwiNe  SLATE.  Black  chalk.  Co- 
lour grayish  black.  Massive.  Lustre  of 
the  principal  fracture,  glimmering;  of  the 
cross  fracture,  dull.  Fracture  of  the  former 
slaty,  of  the  latter,  tine  earthy.  Opaque. 
it  writes.  Streak  same  colour,  and  glis- 


tening. Very  soft.  Sectile.  Easily  fran- 
gible. It  adheres  slightly  to  the  tongue, — 
Feels  fine,  but  meagre.  Sp.  gr.  2.11.  It 
is  infusible.  Its  constituents  are,  silica  64.06, 
alumina  11,  carbon  11,  water  7.2,  iron  2.75 
It  occurs  in  beds  in  primitive  and  transition 
clay-slate,  also  in  secondary  formations.  It 
is  found  in  the  coal  formation  of  Scotland, 
and  in  most  countries.  It  is  used  in  crayon- 
painting.  The  trace  of  bituminous  shale 
is  brownish  and  irregular;  that  of  black 
chalk  is  regular  and  black.  The  best  kind 
is  found  in  Spain,  Italy,  and  France.* 

DUCTILITY.  That  property  or  texture  of 
bodies,  which  renders  it  practicable  to  draw 
them  out  in  length,  while  their  thickness  is 
diminished  without  any  actual  fracture  of 
their  parts.  This  term  is  almost  exclusively 
applied  to  metals. 

Most  authors  confound  the  words  malle- 
ability, laminability,  and  ductility  together, 
and  use  them  in  a" loose  indiscriminate  way; 
but  they  are  very  different.  Malleability  i* 
the  property  of  a  body  which  enlarges  one 
or  two  of  its  three  dimensions,  by  a  blow  or 
pressure  very  suddenly  applied.  Lamina- 
bility belongs  to  bodies  extensible  in  dimen- 
sion by  a  gradually  applied  pressure.  And 
ductility  is  properly  to  be  attributed  to  such 
bodies  as  can  be  rendered  longer  and  thin- 
ner by  drawing  them  through  a  hole  of  less 
area  than  the  transverse  section  of  the  body 
so  drawn. 

DTEIXO.  The  art  of  dyeing  consists  in 
fixing  upon  cloths  of  various  kinds  any  co- 
lour which  may  be  required,  in  such  a  man- 
ner as  that  they  shall  not  be  easily  altered 
by  those  agents,  to  which  the  cloth  will 
most  probably  be  exposed. 

As  there  can  be  no  cause  by  which  any 
colouring  matter  can  adhere  to  any  cloth, 
except  an  attraction  subsisting  between  the 
two  substances,  it  must  follow,  that  there 
will  be  few  tinging  matters  capable  of  in- 
delibly or  strongly  attaching  themselves  by 
simple  application. 

Dyeing  is  therefore  a  chemical  art. 

The  most  remarkable  general  fact  in  the 
art  of  Dyeing,  consists  in  the  different  de- 
grees of  facility,  with  which  animal  and 
vegetable  substances  attract  and  retain  co- 
louring matter,  or  rather  the  degree  of  faci- 
lity with  which  the  dyer  finds  he  can  tinge 
them  with  any  intended  colour.  The  chief 
materials  of  stuff  to  be  dyed  are  wool,  silk, 
cotton,  and  linen,  of  which  the  former  two 
are  more  easily  dyed  than  the  latter.  This 
has  been  usually  attributed  to  their  greater 
attraction  to  the  tinging  matter. 

Wool  is  naturally  so  much  disposed  to 
combine  with  colouring  matter,  that  it  re- 
quires but  little  preparation  for  the  imme- 
diate process  of  dyeing;  nothing  more 
being  required  than  to  cleanse  it,  by  scour- 
iujf,  from  a  fatty  substance,  called  the 


DYE 


DYE 


which  is  contained  in  the  fleece.  For  this 
purpose  an  alkaline  liquor  is  necessary;  but 
as  alkalis  injure  the  texture  of  the  wool,  a 
very  weak  solution  may  be  used.  For  if 
more  alkali  were  present  than  is  sufficient 
to  convert  the  yolk  into  soap,  it  would  at- 
tack the  wool  itself.  Putrid  urine  is  there- 
fore generally  used,  as  being-  cheap,  and 
containing1  a  volatile  alkali,  which,  uniting 
with  the  grease,  renders  it  soluble  in  water. 

Silk,  when  taken  from  the  cocoon,  is  co- 
vered with  a  kind  of  varnish,  which,  be- 
cause it  does  not  easily  yield  either  to  wa- 
ter or  alcohol,  is  usually  said  to  be  soluble 
in  neither.  It  is  therefore  usual  to  boil  the 
silk  with  an  alkali,  to  disengage  this  mat- 
ter. Much  care  is  necessary  in  this  opera- 
tion, because  the  silk  itself  is  easily  cor- 
roded or  discoloured.  Fine  soap  is  com- 
monly used,  but  even  this  is  said  to  be  de- 
trimental; and  the  white  China  silk,  which 
is  supposed  to  be  prepared  without  soap, 
has  a  lustre  superior  to  that  of  Europe.  Silk 
loses  about  one-fourth  of  its  weight  by  be- 
ing1 deprived  of  its  varnish.  See  BLEACH- 
ING. 

The  intention  of  the  previous  prepara- 
tions seems  to  be  of  two  kinds.  The  first 
to  render  the  stuff  or  material  to  be  dyed 
as  clear  as  possible,  in  order  that  the  aque- 
ous fluid  to  be  afterward  applied,  may  be 
imbibed,  and  its  contents  adhere  to  the  mi- 
nute internal  surfaces.  The  second  is,  that 
the  stuff  may  be  rendered  whiter  and  more 
capable  of  reflecting  the  light,  and  conse- 
quently enabling  the  colouring  matter  to 
exhibit  more  brilliant  tints. 

Some  of  the  preparations,  however,  though 
considered  merely  as  preparative,  do  real- 
ly constitute  part  of  the  dyeing  processes 
themselves.  In  many  instances  a  material 
is  applied  to  the  stuff,  to  which  it  adheres; 
and  when  another  suitable  material  is  ap- 
plied, the  result  is  some  colour  desired. 
Thus  we  might  dye  a  piece  of  cotton  black, 
by  immersing  it  in  ink;  but  the  colour  would 
be  neither  good  nor  durable,  because  the 
particles  of  precipitated  matter,  formed  of 
the  oxide  of  iron  and  acid  of  galls,  are  al- 
ready concreted  in  masses  too  gross  either 
to  enter  the  cotton,  or  to  adhere  to  it  with 
any  considerable  degree  of  strength.  But 
if  the  cotton  be  soaked  in  an  infusion  of 
galls,  then  dried,  and  afterward  immersed 
in  a  solution  of  sulphate  of  iron  (or  other 
ferruginous  salt),  the  acid  of  galls  being 
every  where  diffused  through  the  body  of 
the  cotton,  will  receive  the  particles  of  ox- 
ide of  iron,  at  the  very  instant  of  their 
transmission  from  the  fluid,  or  dissolved 
to  the  precipitated  or  solid  state,  by  which 
means  a  perfect  covering  of  the  black  inky 
matter  will  be  applied  in  close  contact  with 
the  surface  of  the  most  minute  fibres  of 
the  cotton.  This  dve  will  therefore  not 
Vol.  T. 


only  be  more  intense,  but  likewise  more 
adherent,  and  durable. 

The  French  dyers,  and  after  them  the 
English,  have  given  the  name  of  mordant 
to  those  substances  which  are  previously 
applied  to  piece  goods,  in  order  that  they 
may  afterward  take  a  required  tinge  or 
dye. 

It  is  evident,  that  if  the  mordant  be  uni- 
versally applied  over  the  whole  of  a  piece 
of  goods,  and  this  be  afterward  immersed 
in  the  dye,  it  will  receive  a  tinge  over  all 
its  surface;  but  if  it  be  applied  only  in 
parts,  the  dye  will  strike  in  those  parts 
only.  The  former  process  constitutes  the 
art  of  dyeing,  properly  so  called;  and  the 
latter,  the  art  of  printing  woollens,  cot- 
tons, or  linens,  called  calico-printing. 

In  the  art  of  printing  piece  goods,  the 
mordant  is  usually  mixed  with  gum  or 
starch,  and  applied  by  means  of  blocks  or 
wooden  engravings  in  relief,  or  from  cop- 
perplates, and  the  colours  are  brought  out 
by  immersion  in  vessels  filled  with  suitable 
compositions.  Dyers  call  the  latter  fluid 
the  bath  The  art  of  printing  affords  many 
processes,  in  which  the  effect  of  mordants, 
both  simple  and  compound,  is  exhibited. 
The  following  is  taken  from  Berthollet. 

The  mordant  employed  for  linens,  in- 
tended to  receive  different  shades  of  red, 
is  prepared  by  dissolving  in  eig'ht  pounds 
of  hot  water,  three  pounds  of  alum,  and 
one  pound  of  acetate  of  lead,  to  which 
two  ounces  of  potash,  and  afterward  two 
ounces  of  powdered  chalk,  are  added. 

In  this  mixture  the  sulphuric  acid  com- 
bines with  the  lead  of  the  acetate  and  falls 
down,  because  insoluble,  while  the  argilla- 
ceous earth  of  the  alum  unites  with  the 
acetic  acid  disengaged  from  the  acetate  of 
lead.  The  mordant  therefore  consists  of 
of  an  argillaceous  acetic  salt,  and  the  small 
quantities  of  alkali  and  chalk  serve  to  neu- 
tralize any  disengaged  acid,  which  might 
be  contained  in  the  liquid. 

Several  advantages  are  obtained  by  thus 
changing-  the  acid  of  the  alum.  First,  the 
argillaceous  earth  is  more  easily  disen- 
gaged from  the  acetic  acid,  in  the  subse- 
quent processes,  than  it  would  have  been 
from  the  sulphuric.  Secondly,  this  weak 
acid  does  less  harm  when  it  comes  to  be 
disengaged  by  depriving  it  of  its  earth. 
And  thirdly,  the  acetate  of  alumina  not 
being-  crystullizable  like  the  sulphate,  does 
not  separate  or  curdle  by  drying1  on  the 
face  of  the  blocks  for  printing,  when  it  is 
mixed  with  gum  or  starch. 

When  the  design  has  been  impressed  by 
transferring  the  mordant  from  the  face  of 
the  wooden  blocks  to  the  cloth,  it  is  then 
put  into  a  bath  of  madder,  with  proper 
attention,  that  the  whole  shall  be  equally 
exposed  to  this  fluid.  Here  the  piece  be- 
46 


DYE 


comes  of  a  red  colour,  but  deeper  in  those 
places  where  <he  mordant  was  applied. 
-•For  some  of  the  argillaceous  earth  had  be- 
fore quitted  the  acetic  acid,  to  combine 
with  the  cloth;  and  this  serves  as  an  inter- 
medium to  fix  the  colouring  matter  of  the 
madder,  in  the  same  manner  as  the  acid  of 
galls,  in  the  former  instance,  fixed  the  par- 
ticles of  oxide  of  iron.  With  the  piece  in 
this  state,  the  calico-printer  has  only  there- 
fore to  avail  himself  of  the  difference  be- 
tween a  fixed  and  ,a  fugitive  colour,  ife 
therefore  boils  the  piece  with  bran,  and 
spreads  it  on  the  grass.  The  fecula  of  the 
bran  takes  up  part  of  the  colour,  and  the 
action  of  the  sun  and  air  renders  more  of 
it  combinable  with  the  same  substance. 

In  other  cases,  the  elective  attraction  of 
the  stuff  to  be  dyed  has  a  more  marked 
agency.  A  very  common  mordant  for 
woollens  is  made  by  dissolving  alum  and 
tartar  together;  neither  of  which  is  decom- 
posed, but  may  be  recovered  by  crystalli- 
zation upon  evaporating  the  liquor.  Wool 
is  found  to  be  capable  of  decomposing  a 
solution  of  alum,  and  combining  with  its 
earth;  but  it  seems  as  if  the  presence  of 
disengaged  sulphuric  acid  served  to  injure 
the  wool,  which  is  rendered  harsh  by  this 
method  of  treatment,  though  cottons  and 
linens  are  not,  which  have  less  attraction 
for  the  earth.  Wool  also  decomposes  the 
alum,  in  a  mixture  of  alum  and  tartar;  b.ut 
in  this  case  there  can  be  no  disengagement 
of  sulphuric  acid,  as  it  is  immediately  neu- 
tralized by  the  alkali  of  the  tartar. 

Metallic  oxides  have  so  great  an  attrac- 
tion for  many  colouring  substances,  that 
they  quit  the  acids  in  which  they  were  dis- 
solved, and  are  precipitated  in  combination 
•with  them.  These  oxides  are  also  found 
by  experiment  to  be  strongly  disposed  to 
combine  with  animal  substances;  whence 
in  many  instances  they  serve  as  mordants, 
or  the  medium  of  union  between  the  co- 
louring particles  and  animal  bodies. 

The  colours  which  the  compounds  of 
metallic  oxides  and  colouring  particles  as- 
sume,  then,  are  the  product,  of  the  colour 
peculiar  to  the  colouring  particles,  and  of 
that  peculiar  to  the  metallic  oxide. 

*  The  following  are  the  dye-stuffs  used 
by  the  calico-printers  for  producing  fast 
colours.  The  mordants  are  thickened 
with  gum,  or  calcined  starch,  and  applied 
with  the  block,  roller,  plates,  or  pencil. 

1 .  Black.     The  cloth  is  impregnated  with 
acetate  of  iron  (iron  liquor),  and  dyed  in 
a  bath  of  madder  and  logwood. 

2.  Purple.    The  preceding  mordant  of 
iron,  diluted;  with  the  same  dyeing  bath, 

3  Crimson.  The  mordant  for  purple, 
united  with  a  portion  of  acetate  of  alumi- 
na, or  red  mordant,  and  the  above  bath. 

4.  Red.    Acetate  of  alumina  is  the  mor- 


dant, (see  ALUMINA),  and  madder  is  the 
dye-stuff. 

5.  Pale  red  of  different   shades.     The 
preceding  mordant  diluted  with  water,  and 
a  weak  madder  bath. 

6.  Brown  or  Pompadour.     A  mixed  mor- 
dant, containing  a  somewhat  larger  pro- 
portion of  the  red  than  of  the  black;  and 
the  dye  of  madder. 

7.  Orange.     The  red  mordant;  and  a  bath 
first  of  madder,  and  then  of  quercitron. 

8.  Yelloiv.     A  strong  red  mordant;  and 
the  quercitron    bath,    whose   temperature 
should  be  considerably  under  the  boiling 
point  of  water. 

9.  Blue.     Indigo,  rendered  soluble  and 
greenish-yellow  coloured,   by  potash   and 
orpiment.     It  recovers  its  blue  colour,  by 
exposure  to  air,  and  thereby  also  fixes  firm- 
ly on  the  cloth.     An  indigo  vat  is  also  made, 
with  that  blue  substance,  diffused  in  water 
with  quicklime  and  copperas.     These  sub- 
stances are  sapposed  to  deoxidize  indigo, 
and  at  the  same  time  to  render  it  soluble. 

Golden-dye.  The  cloth  is  immersed  al- 
ternately in  a  solution  of  copperas  and  lime- 
water.  The  protoxide  of  iron  precipitated 
on  the  fibre,  soon  passes  by  absorption  of 
atmospherical  oxygen,  into  the  golden-co- 
loured deutoxide. 

Buff.  The  preceding  substances,  in  a 
more  dilute  state. 

Blue  vat,  in  which  white  spots  are  left 
on  a  blue  ground  of  cloth,  is  made,  by  ap- 
plying to  these  points  a  paste  composed  of 
a  solution  of  sulphate  of  copper  and  pipe- 
clay; and  after  they  are  dried,  immersing  it 
stretched  on  frames  for  a  definite  number 
of  minutes,  in  the  yellowish-green  vat,  of  1 
part  of  indigo,  2  of  copperas,  and  2  of  lime, 
with  water. 

Green.  Cloth  dyed  blue,  and  well  wash- 
ed, is  imbued  with  the  aluminous  acetate, 
dried,  and  subjected  to  the  quercitron  bath. 

In  the  above  cases,  the  cloth,  after  re- 
ceiving the  mordant  paste,  is  dried,  and 
put  through  a  mixture  of  cow  dung  and 
warm  water.  It  is  then  put  into  the  dye- 
ing vat  or  copper. 

Fugitive  Colours. 

All  the  above  colours  are  given,  by  ma- 
king decoctions  of  the  different  colouring 
woods;  and  receive  the  slight  degree  of 
fixity  they  possess,  as  well  as  great  brillian- 
cy, in  consequence  of  their  combination  or 
admixture  with  the  nitro-muriate  of  tin. 

1.  Red  is  frequently  made  from  Brazil 
and  Peachwood. 

2.  Black.     A  strong  extract  of  galls,  and 
deuto-nitrate  of  iron. 

3.  Purple.    Extract  of  logwood  and  the 
deuto-nitrate. 

4.  Yelloiv.     Extract  of  quercitron  bark, 
or  French  berriesj  and  the  tin  solution. 

5.  Blue.    Prussian  blue  and  solution  of 
tin. 


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